diff --git a/src/Makefile b/src/Makefile
index 84fcd73d..d1f8c940 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -810,7 +810,7 @@ OBJS = main.o init.o graph.o $(APIOBJ) misc.o special.o \
        transform.o pversion.o factory.o $(PLATFORMOBJ) \
        loadsave.o loadsavefuncs.o \
        pngformat.o motoformats.o stformats.o c64formats.o cpcformats.o \
-       ifformat.o msxformats.o packbits.o \
+       ifformat.o msxformats.o packbits.o giformat.o \
        fileformats.o miscfileformats.o libraw2crtc.o \
        brush_ops.o buttons_effects.o layers.o \
        oldies.o tiles.o colorred.o unicode.o gfx2surface.o \
@@ -823,7 +823,7 @@ TESTSOBJS = $(patsubst %.c,%.o,$(wildcard tests/*.c)) \
             miscfileformats.o fileformats.o oldies.o libraw2crtc.o \
             loadsavefuncs.o packbits.o tifformat.o c64load.o 6502.o \
             pngformat.o motoformats.o stformats.o c64formats.o cpcformats.o \
-            ifformat.o msxformats.o \
+            ifformat.o msxformats.o giformat.o \
             op_c.o colorred.o \
             unicode.o \
             io.o realpath.o version.o pversion.o \
diff --git a/src/fileformats.c b/src/fileformats.c
index cfd1807e..3051bad5 100644
--- a/src/fileformats.c
+++ b/src/fileformats.c
@@ -56,7 +56,6 @@
 #include "global.h"
 #include "loadsave.h"
 #include "loadsavefuncs.h"
-#include "misc.h"
 #include "struct.h"
 #include "io.h"
 #include "pages.h"
@@ -1806,1347 +1805,6 @@ void Save_ICO(T_IO_Context * context)
 /** @} */
 
 
-//////////////////////////////////// GIF ////////////////////////////////////
-/**
- * @defgroup GIF GIF format
- * @ingroup loadsaveformats
- * Graphics Interchange Format
- *
- * The GIF format uses LZW compression and stores indexed color pictures
- * up to 256 colors. It has the ability to store several pictures in the same
- * file : GrafX2 takes advantage of this feature for storing layered images
- * and animations.
- *
- * GrafX2 implements GIF89a :
- * https://www.w3.org/Graphics/GIF/spec-gif89a.txt
- *
- * @{
- */
-
-/// Logical Screen Descriptor Block
-typedef struct
-{
-  word Width;   ///< Width of the complete image area
-  word Height;  ///< Height of the complete image area
-  byte Resol;   ///< Informations about the resolution (and other)
-  byte Backcol; ///< Proposed background color
-  byte Aspect;  ///< Informations about aspect ratio. Ratio = (Aspect + 15) / 64
-} T_GIF_LSDB;
-
-/// Image Descriptor Block
-typedef struct
-{
-  word Pos_X;         ///< X offset where the image should be pasted
-  word Pos_Y;         ///< Y offset where the image should be pasted
-  word Image_width;   ///< Width of image
-  word Image_height;  ///< Height of image
-  byte Indicator;     ///< Misc image information
-  byte Nb_bits_pixel; ///< Nb de bits par pixel
-} T_GIF_IDB;
-
-/// Graphic Control Extension
-typedef struct
-{
-  byte Block_identifier;  ///< 0x21
-  byte Function;          ///< 0xF9
-  byte Block_size;        ///< 4
-  byte Packed_fields;     ///< 11100000 : Reserved
-                          ///< 00011100 : Disposal method
-                          ///< 00000010 : User input flag
-                          ///< 00000001 : Transparent flag
-  word Delay_time;        ///< Time for this frame to stay displayed
-  byte Transparent_color; ///< Which color index acts as transparent
-  word Block_terminator;  ///< 0x00
-} T_GIF_GCE;
-
-enum DISPOSAL_METHOD
-{
-  DISPOSAL_METHOD_UNDEFINED = 0,
-  DISPOSAL_METHOD_DO_NOT_DISPOSE = 1,
-  DISPOSAL_METHOD_RESTORE_BGCOLOR = 2,
-  DISPOSAL_METHOD_RESTORE_PREVIOUS = 3,
-};
-
-
-/// Test if a file is GIF format
-void Test_GIF(T_IO_Context * context, FILE * file)
-{
-  char signature[6];
-
-  (void)context;
-  File_error=1;
-
-  if (Read_bytes(file,signature,6))
-  {
-    /// checks if the signature (6 first bytes) is either GIF87a or GIF89a
-    if ((!memcmp(signature,"GIF87a",6))||(!memcmp(signature,"GIF89a",6)))
-      File_error=0;
-  }
-}
-
-
-// -- Lire un fichier au format GIF -----------------------------------------
-
-typedef struct {
-  word nb_bits;        ///< bits for a code
-  word remainder_bits; ///< available bits in @ref last_byte field
-  byte remainder_byte; ///< Remaining bytes in current block
-  word current_code;   ///< current code (generally the one just read)
-  byte last_byte;      ///< buffer byte for reading bits for codes
-  word pos_X;          ///< Current coordinates
-  word pos_Y;
-  word interlaced;     ///< interlaced flag
-  word pass;           ///< current pass in interlaced decoding
-  word stop;           ///< Stop flag (end of picture)
-} T_GIF_context;
-
-
-/// Reads the next code (GIF.nb_bits bits)
-static word GIF_get_next_code(FILE * GIF_file, T_GIF_context * gif)
-{
-  word nb_bits_to_process = gif->nb_bits;
-  word nb_bits_processed = 0;
-  word current_nb_bits;
-
-  gif->current_code = 0;
-
-  while (nb_bits_to_process)
-  {
-    if (gif->remainder_bits == 0) // Il ne reste plus de bits...
-    {
-      // Lire l'octet suivant:
-
-      // Si on a atteint la fin du bloc de Raster Data
-      if (gif->remainder_byte == 0)
-      {
-        // Lire l'octet nous donnant la taille du bloc de Raster Data suivant
-        if(Read_byte(GIF_file, &gif->remainder_byte)!=1)
-        {
-          File_error=2;
-          return 0;
-        }
-        if (gif->remainder_byte == 0) // still nothing ? That is the end data block
-        {
-          File_error = 2;
-          GFX2_Log(GFX2_WARNING, "GIF 0 sized data block\n");
-          return gif->current_code;
-        }
-      }
-      if(Read_byte(GIF_file,&gif->last_byte)!=1)
-      {
-        File_error = 2;
-        GFX2_Log(GFX2_ERROR, "GIF failed to load data byte\n");
-        return 0;
-      }
-      gif->remainder_byte--;
-      gif->remainder_bits=8;
-    }
-
-    current_nb_bits=(nb_bits_to_process<=gif->remainder_bits)?nb_bits_to_process:gif->remainder_bits;
-
-    gif->current_code |= (gif->last_byte & ((1<<current_nb_bits)-1))<<nb_bits_processed;
-    gif->last_byte >>= current_nb_bits;
-    nb_bits_processed += current_nb_bits;
-    nb_bits_to_process -= current_nb_bits;
-    gif->remainder_bits -= current_nb_bits;
-  }
-
-  return gif->current_code;
-}
-
-/// Put a new pixel
-static void GIF_new_pixel(T_IO_Context * context, T_GIF_context * gif, T_GIF_IDB *idb, int is_transparent, byte color)
-{
-  if (!is_transparent || color!=context->Transparent_color)
-    Set_pixel(context, idb->Pos_X+gif->pos_X, idb->Pos_Y+gif->pos_Y,color);
-
-  gif->pos_X++;
-
-  if (gif->pos_X >= idb->Image_width)
-  {
-    gif->pos_X=0;
-
-    if (!gif->interlaced)
-    {
-      gif->pos_Y++;
-      if (gif->pos_Y >= idb->Image_height)
-        gif->stop = 1;
-    }
-    else
-    {
-      switch (gif->pass)
-      {
-        case 0 :
-        case 1 : gif->pos_Y+=8;
-                 break;
-        case 2 : gif->pos_Y+=4;
-                 break;
-        default: gif->pos_Y+=2;
-      }
-
-      if (gif->pos_Y >= idb->Image_height)
-      {
-        switch(++(gif->pass))
-        {
-        case 1 : gif->pos_Y=4;
-                 break;
-        case 2 : gif->pos_Y=2;
-                 break;
-        case 3 : gif->pos_Y=1;
-                 break;
-        case 4 : gif->stop = 1;
-        }
-      }
-    }
-  }
-}
-
-
-/// Load GIF file
-void Load_GIF(T_IO_Context * context)
-{
-  FILE *GIF_file;
-  int image_mode = -1;
-  char signature[6];
-
-  word * alphabet_stack;     // Pile de décodage d'une chaîne
-  word * alphabet_prefix;  // Table des préfixes des codes
-  word * alphabet_suffix;  // Table des suffixes des codes
-  word   alphabet_free;     // Position libre dans l'alphabet
-  word   alphabet_max;      // Nombre d'entrées possibles dans l'alphabet
-  word   alphabet_stack_pos; // Position dans la pile de décodage d'un chaîne
-
-  T_GIF_context GIF;
-  T_GIF_LSDB LSDB;
-  T_GIF_IDB IDB;
-  T_GIF_GCE GCE;
-
-  word nb_colors;       // Nombre de couleurs dans l'image
-  word color_index; // index de traitement d'une couleur
-  byte size_to_read; // Nombre de données à lire      (divers)
-  byte block_identifier;  // Code indicateur du type de bloc en cours
-  byte initial_nb_bits;   // Nb de bits au début du traitement LZW
-  word special_case=0;       // Mémoire pour le cas spécial
-  word old_code=0;       // Code précédent
-  word byte_read;         // Sauvegarde du code en cours de lecture
-  word value_clr;        // Valeur <=> Clear tables
-  word value_eof;        // Valeur <=> End d'image
-  long file_size;
-  int number_LID; // Nombre d'images trouvées dans le fichier
-  int current_layer = 0;
-  int last_delay = 0;
-  byte is_transparent = 0;
-  byte is_looping=0;
-  enum PIXEL_RATIO ratio;
-  byte disposal_method = DISPOSAL_METHOD_RESTORE_BGCOLOR;
-
-  byte previous_disposal_method = DISPOSAL_METHOD_RESTORE_BGCOLOR;
-  word previous_width=0;
-  word previous_height=0;
-  word previous_pos_x=0;
-  word previous_pos_y=0;
-
-  /////////////////////////////////////////////////// FIN DES DECLARATIONS //
-
-
-  number_LID=0;
-  
-  if ((GIF_file=Open_file_read(context)))
-  {
-    file_size=File_length_file(GIF_file);
-    if ( (Read_bytes(GIF_file,signature,6)) &&
-         ( (memcmp(signature,"GIF87a",6)==0) ||
-           (memcmp(signature,"GIF89a",6)==0) ) )
-    {
-
-      // Allocation de mémoire pour les tables & piles de traitement:
-      alphabet_stack   =(word *)malloc(4096*sizeof(word));
-      alphabet_prefix=(word *)malloc(4096*sizeof(word));
-      alphabet_suffix=(word *)malloc(4096*sizeof(word));
-
-      if (Read_word_le(GIF_file,&(LSDB.Width))
-      && Read_word_le(GIF_file,&(LSDB.Height))
-      && Read_byte(GIF_file,&(LSDB.Resol))
-      && Read_byte(GIF_file,&(LSDB.Backcol))
-      && Read_byte(GIF_file,&(LSDB.Aspect))
-        )
-      {
-        // Lecture du Logical Screen Descriptor Block réussie:
-
-        Original_screen_X=LSDB.Width;
-        Original_screen_Y=LSDB.Height;
-
-        ratio=PIXEL_SIMPLE;          //  (49 + 15) / 64 = 1:1
-        if (LSDB.Aspect != 0) {
-          if (LSDB.Aspect < 25)      //  (17 + 15) / 64 = 1:2
-            ratio=PIXEL_TALL;
-          else if (LSDB.Aspect < 41) //  (33 + 15) / 64 = 3:4
-            ratio=PIXEL_TALL3;
-          else if (LSDB.Aspect > 82) // (113 + 15) / 64 = 2:1
-            ratio=PIXEL_WIDE;
-        }
-
-        Pre_load(context, LSDB.Width,LSDB.Height,file_size,FORMAT_GIF,ratio,(LSDB.Resol&7)+1);
-
-        // Palette globale dispo = (LSDB.Resol  and $80)
-        // Profondeur de couleur =((LSDB.Resol  and $70) shr 4)+1
-        // Nombre de bits/pixel  = (LSDB.Resol  and $07)+1
-        // Ordre de Classement   = (LSDB.Aspect and $80)
-
-        nb_colors=(1 << ((LSDB.Resol & 0x07)+1));
-        if (LSDB.Resol & 0x80)
-        {
-          // Palette globale dispo:
-
-          if (Config.Clear_palette)
-            memset(context->Palette,0,sizeof(T_Palette));
-
-          // Load the palette
-          for(color_index=0;color_index<nb_colors;color_index++)
-          {
-            Read_byte(GIF_file,&(context->Palette[color_index].R));
-            Read_byte(GIF_file,&(context->Palette[color_index].G));
-            Read_byte(GIF_file,&(context->Palette[color_index].B));
-          }
-        }
-
-        // On lit un indicateur de block
-        Read_byte(GIF_file,&block_identifier);
-        while (block_identifier!=0x3B && !File_error)
-        {
-          switch (block_identifier)
-          {
-            case 0x21: // Bloc d'extension
-            {
-              byte function_code;
-              // Lecture du code de fonction:
-              Read_byte(GIF_file,&function_code);   
-              // Lecture de la taille du bloc:
-              Read_byte(GIF_file,&size_to_read);
-              while (size_to_read!=0 && !File_error)
-              {
-                switch(function_code)
-                {
-                  case 0xFE: // Comment Block Extension
-                    // On récupère le premier commentaire non-vide, 
-                    // on jette les autres.
-                    if (context->Comment[0]=='\0')
-                    {
-                      int nb_char_to_keep = MIN(size_to_read, COMMENT_SIZE);
-                      
-                      Read_bytes(GIF_file,context->Comment,nb_char_to_keep);
-                      context->Comment[nb_char_to_keep+1]='\0';
-                      // Si le commentaire etait trop long, on fait avance-rapide
-                      // sur la suite.
-                      if (size_to_read>nb_char_to_keep)
-                        fseek(GIF_file,size_to_read-nb_char_to_keep,SEEK_CUR);
-                    }
-                    // Lecture de la taille du bloc suivant:
-                    Read_byte(GIF_file,&size_to_read);
-                    break;
-                  case 0xF9: // Graphics Control Extension
-                    // Prévu pour la transparence
-                    if ( Read_byte(GIF_file,&(GCE.Packed_fields))
-                      && Read_word_le(GIF_file,&(GCE.Delay_time))
-                      && Read_byte(GIF_file,&(GCE.Transparent_color)))
-                    {
-                      previous_disposal_method = disposal_method;
-                      disposal_method = (GCE.Packed_fields >> 2) & 7;
-                      last_delay = GCE.Delay_time;
-                      context->Transparent_color= GCE.Transparent_color;
-                      is_transparent = GCE.Packed_fields & 1;
-                      GFX2_Log(GFX2_DEBUG, "GIF Graphics Control Extension : transp=%d (color #%u) delay=%ums disposal_method=%d\n", is_transparent, GCE.Transparent_color, 10*GCE.Delay_time, disposal_method);
-                      if (number_LID == 0)
-                        context->Background_transparent = is_transparent;
-                      is_transparent &= is_looping;
-                    }
-                    else
-                      File_error=2;
-                    // Lecture de la taille du bloc suivant:
-                    Read_byte(GIF_file,&size_to_read);
-                    break;
-
-                  case 0xFF: // Application Extension
-                    // Normally, always a 11-byte block
-                    if (size_to_read == 0x0B)
-                    {
-                      char aeb[0x0B];
-                      Read_bytes(GIF_file,aeb, 0x0B);
-                      GFX2_Log(GFX2_DEBUG, "GIF extension \"%.11s\"\n", aeb);
-                      if (File_error)
-                        ;
-                      else if (!memcmp(aeb,"NETSCAPE2.0",0x0B))
-                      {
-                        is_looping=1;
-                        // The well-known Netscape extension.
-                        // Load as an animation
-                        Set_image_mode(context, IMAGE_MODE_ANIMATION);
-                        // Skip sub-block
-                        do
-                        {
-                          if (! Read_byte(GIF_file,&size_to_read))
-                            File_error=1;
-                          fseek(GIF_file,size_to_read,SEEK_CUR);
-                        } while (!File_error && size_to_read!=0);
-                      }
-                      else if (!memcmp(aeb,"GFX2PATH\x00\x00\x00",0x0B))
-                      {
-                        // Original file path
-                        Read_byte(GIF_file,&size_to_read);
-                        if (!File_error && size_to_read > 0)
-                        {
-                          free(context->Original_file_directory);
-                          context->Original_file_directory = malloc(size_to_read);
-                          Read_bytes(GIF_file, context->Original_file_directory, size_to_read);
-                          Read_byte(GIF_file, &size_to_read);
-                          if (!File_error && size_to_read > 0)
-                          {
-                            free(context->Original_file_name);
-                            context->Original_file_name = malloc(size_to_read);
-                            Read_bytes(GIF_file, context->Original_file_name, size_to_read);
-                            Read_byte(GIF_file, &size_to_read); // Normally 0
-                          }
-                        }
-                      }
-                      else if (!memcmp(aeb,"CRNG\0\0\0\0" "1.0",0x0B))
-                      {            
-                        // Color animation. Similar to a CRNG chunk in IFF file format.
-                        word rate;
-                        word flags;
-                        byte min_col;
-                        byte max_col;
-                        //
-                        Read_byte(GIF_file,&size_to_read);
-                        for(;size_to_read>0 && !File_error;size_to_read-=6)
-                        {
-                          if ( (Read_word_be(GIF_file,&rate))
-                            && (Read_word_be(GIF_file,&flags))
-                            && (Read_byte(GIF_file,&min_col))
-                            && (Read_byte(GIF_file,&max_col)))
-                          {
-                            if (min_col != max_col)
-                            {
-                              // Valid cycling range
-                              if (max_col<min_col)
-                              SWAP_BYTES(min_col,max_col)
-                              
-                              context->Cycle_range[context->Color_cycles].Start=min_col;
-                              context->Cycle_range[context->Color_cycles].End=max_col;
-                              context->Cycle_range[context->Color_cycles].Inverse=(flags&2)?1:0;
-                              context->Cycle_range[context->Color_cycles].Speed=(flags&1)?rate/78:0;
-                                                  
-                              context->Color_cycles++;
-                            }
-                          }
-                          else
-                          {
-                            File_error=1;
-                          }
-                        }
-                        // Read end-of-block delimiter
-                        if (!File_error)
-                          Read_byte(GIF_file,&size_to_read);
-                        if (size_to_read!=0)
-                          File_error=1;
-                      }
-                      else if (0 == memcmp(aeb, "GFX2MODE", 8))
-                      {
-                        Read_byte(GIF_file,&size_to_read);
-                        if (size_to_read > 0)
-                        { // read the image mode. We'll set it after having loaded all layers.
-                          char * label = malloc((size_t)size_to_read + 1);
-                          Read_bytes(GIF_file, label, size_to_read);
-                          label[size_to_read] = '\0';
-                          image_mode = Constraint_mode_from_label(label);
-                          GFX2_Log(GFX2_DEBUG, "    mode = %s (%d)\n", label, image_mode);
-                          free(label);
-                          Read_byte(GIF_file,&size_to_read);
-                          // be future proof, skip following sub-blocks :
-                          while (size_to_read!=0 && !File_error)
-                          {
-                            if (fseek(GIF_file,size_to_read,SEEK_CUR) < 0)
-                              File_error = 1;
-                            if (!Read_byte(GIF_file,&size_to_read))
-                              File_error = 1;
-                          }
-                        }
-                      }
-                      else
-                      {
-                        // Unknown extension, skip.
-                        Read_byte(GIF_file,&size_to_read);
-                        while (size_to_read!=0 && !File_error)
-                        {
-                          if (fseek(GIF_file,size_to_read,SEEK_CUR) < 0)
-                            File_error = 1;
-                          if (!Read_byte(GIF_file,&size_to_read))
-                            File_error = 1;
-                        }
-                      }
-                    }
-                    else
-                    {
-                      fseek(GIF_file,size_to_read,SEEK_CUR);
-                      // Lecture de la taille du bloc suivant:
-                      Read_byte(GIF_file,&size_to_read);
-                    }
-                    break;
-                    
-                  default:
-                    // On saute le bloc:
-                    fseek(GIF_file,size_to_read,SEEK_CUR);
-                    // Lecture de la taille du bloc suivant:
-                    Read_byte(GIF_file,&size_to_read);
-                    break;
-                }
-              }
-            }
-            break;
-            case 0x2C: // Local Image Descriptor
-            {
-              if (number_LID!=0)
-              {
-                // This a second layer/frame, or more.
-                // Attempt to add a layer to current image
-                current_layer++;
-                Set_loading_layer(context, current_layer);
-                if (context->Type == CONTEXT_MAIN_IMAGE && Main.backups->Pages->Image_mode == IMAGE_MODE_ANIMATION)
-                {
-                  // Copy the content of previous layer.
-                  memcpy(
-                    Main.backups->Pages->Image[Main.current_layer].Pixels,
-                    Main.backups->Pages->Image[Main.current_layer-1].Pixels,
-                    Main.backups->Pages->Width*Main.backups->Pages->Height);
-                }
-                else
-                {
-                  Fill_canvas(context, is_transparent ? context->Transparent_color : LSDB.Backcol);
-                }
-              }
-              else
-              {
-                // First frame/layer, fill canvas with backcolor
-                Fill_canvas(context, is_transparent ? context->Transparent_color : LSDB.Backcol);
-              }
-              // Duration was set in the previously loaded GCE
-              Set_frame_duration(context, last_delay*10);
-              number_LID++;
-              
-              // lecture de 10 derniers octets
-              if ( Read_word_le(GIF_file,&(IDB.Pos_X))
-                && Read_word_le(GIF_file,&(IDB.Pos_Y))
-                && Read_word_le(GIF_file,&(IDB.Image_width))
-                && Read_word_le(GIF_file,&(IDB.Image_height))
-                && Read_byte(GIF_file,&(IDB.Indicator))
-                && IDB.Image_width && IDB.Image_height)
-              {
-                GFX2_Log(GFX2_DEBUG, "GIF Image descriptor %u Pos (%u,%u) %ux%u %s%slocal palette(%ubpp)\n",
-                         number_LID, IDB.Pos_X, IDB.Pos_Y, IDB.Image_width, IDB.Image_height,
-                         (IDB.Indicator & 0x40) ? "interlaced " : "", (IDB.Indicator & 0x80) ? "" : "no ",
-                         (IDB.Indicator & 7) + 1);
-                // Palette locale dispo = (IDB.Indicator and $80)
-                // Image entrelacée     = (IDB.Indicator and $40)
-                // Ordre de classement  = (IDB.Indicator and $20)
-                // Nombre de bits/pixel = (IDB.Indicator and $07)+1 (si palette locale dispo)
-    
-                if (IDB.Indicator & 0x80)
-                {
-                  // Palette locale dispo
-    
-                  if (Config.Clear_palette)
-                    memset(context->Palette,0,sizeof(T_Palette));
-
-                  nb_colors=(1 << ((IDB.Indicator & 0x07)+1));
-                  // Load the palette
-                  for(color_index=0;color_index<nb_colors;color_index++)
-                  {   
-                    Read_byte(GIF_file,&(context->Palette[color_index].R));
-                    Read_byte(GIF_file,&(context->Palette[color_index].G));
-                    Read_byte(GIF_file,&(context->Palette[color_index].B));
-                  }
-                  
-                }
-                if (number_LID!=1)
-                {
-                  // This a second layer/frame, or more.
-                  if (context->Type == CONTEXT_MAIN_IMAGE && Main.backups->Pages->Image_mode == IMAGE_MODE_ANIMATION)
-                  {
-                    // Need to clear previous image to back-color.
-                    if (previous_disposal_method==DISPOSAL_METHOD_RESTORE_BGCOLOR)
-                    {
-                      int y;
-                      for (y=0; y<previous_height; y++)
-                        memset(
-                          Main.backups->Pages->Image[Main.current_layer].Pixels
-                           + (previous_pos_y+y)* Main.backups->Pages->Width+previous_pos_x,
-                          is_transparent ? context->Transparent_color : LSDB.Backcol,
-                          previous_width);
-                    }
-                  }
-                }
-                previous_height=IDB.Image_height;
-                previous_width=IDB.Image_width;
-                previous_pos_x=IDB.Pos_X;
-                previous_pos_y=IDB.Pos_Y;
-                
-                File_error=0;
-                if (!Read_byte(GIF_file,&(initial_nb_bits)))
-                  File_error=1;
-    
-                value_clr    =(1<<initial_nb_bits)+0;
-                value_eof    =(1<<initial_nb_bits)+1;
-                alphabet_free=(1<<initial_nb_bits)+2;
-
-                GIF.nb_bits  =initial_nb_bits + 1;
-                alphabet_max      =((1 <<  GIF.nb_bits)-1);
-                GIF.interlaced    =(IDB.Indicator & 0x40);
-                GIF.pass         =0;
-    
-                /*Init_lecture();*/
-    
-
-                GIF.stop = 0;
-    
-                //////////////////////////////////////////// DECOMPRESSION LZW //
-    
-                GIF.pos_X=0;
-                GIF.pos_Y=0;
-                alphabet_stack_pos=0;
-                GIF.last_byte    =0;
-                GIF.remainder_bits    =0;
-                GIF.remainder_byte    =0;
-
-                while ( (GIF_get_next_code(GIF_file, &GIF)!=value_eof) && (!File_error) )
-                {
-                  if (GIF.current_code > alphabet_free)
-                  {
-                    GFX2_Log(GFX2_INFO, "Load_GIF() Invalid code %u (should be <=%u)\n", GIF.current_code, alphabet_free);
-                    File_error=2;
-                    break;
-                  }
-                  else if (GIF.current_code != value_clr)
-                  {
-                    byte_read = GIF.current_code;
-                    if (alphabet_free == GIF.current_code)
-                    {
-                      GIF.current_code=old_code;
-                      alphabet_stack[alphabet_stack_pos++]=special_case;
-                    }
-
-                    while (GIF.current_code > value_clr)
-                    {
-                      if (GIF.current_code >= 4096)
-                      {
-                        GFX2_Log(GFX2_ERROR, "Load_GIF() GIF.current_code = %u >= 4096\n", GIF.current_code);
-                        File_error = 2;
-                        break;
-                      }
-                      alphabet_stack[alphabet_stack_pos++] = alphabet_suffix[GIF.current_code];
-                      GIF.current_code = alphabet_prefix[GIF.current_code];
-                    }
-
-                    special_case = alphabet_stack[alphabet_stack_pos++] = GIF.current_code;
-
-                    do
-                      GIF_new_pixel(context, &GIF, &IDB, is_transparent, alphabet_stack[--alphabet_stack_pos]);
-                    while (alphabet_stack_pos!=0);
-
-                    alphabet_prefix[alphabet_free  ]=old_code;
-                    alphabet_suffix[alphabet_free++]=GIF.current_code;
-                    old_code=byte_read;
-
-                    if (alphabet_free>alphabet_max)
-                    {
-                      if (GIF.nb_bits<12)
-                        alphabet_max      =((1 << (++GIF.nb_bits))-1);
-                    }
-                  }
-                  else // Clear code
-                  {
-                    GIF.nb_bits   = initial_nb_bits + 1;
-                    alphabet_max  = ((1 <<  GIF.nb_bits)-1);
-                    alphabet_free = (1<<initial_nb_bits)+2;
-                    special_case  = GIF_get_next_code(GIF_file, &GIF);
-                    if (GIF.current_code >= value_clr)
-                    {
-                      GFX2_Log(GFX2_INFO, "Load_GIF() Invalid code %u just after clear (=%u)!\n",
-                               GIF.current_code, value_clr);
-                      File_error = 2;
-                      break;
-                    }
-                    old_code      = GIF.current_code;
-                    GIF_new_pixel(context, &GIF, &IDB, is_transparent, GIF.current_code);
-                  }
-                }
-
-                if (File_error == 2 && GIF.pos_X == 0 && GIF.pos_Y == IDB.Image_height)
-                  File_error=0;
-    
-                if (File_error >= 0 && !GIF.stop)
-                  File_error=2;
-                
-                // No need to read more than one frame in animation preview mode
-                if (context->Type == CONTEXT_PREVIEW && is_looping)
-                {
-                  goto early_exit;
-                }
-                // Same with brush
-                if (context->Type == CONTEXT_BRUSH && is_looping)
-                {
-                  goto early_exit;
-                }
-                
-              } // Le fichier contenait un IDB
-              else
-                File_error=2;
-            }
-            default:
-            break;
-          }
-          // Lecture du code de fonction suivant:
-          if (!Read_byte(GIF_file,&block_identifier))
-            File_error=2;
-        }
-
-        // set the mode that have been read previously.
-        if (image_mode > 0)
-          Set_image_mode(context, image_mode);
-      } // Le fichier contenait un LSDB
-      else
-        File_error=1;
-
-      early_exit:
-      
-      // Libération de la mémoire utilisée par les tables & piles de traitement:
-      free(alphabet_suffix);
-      free(alphabet_prefix);
-      free(alphabet_stack);
-      alphabet_suffix = alphabet_prefix = alphabet_stack = NULL;
-    } // Le fichier contenait au moins la signature GIF87a ou GIF89a
-    else
-      File_error=1;
-
-    fclose(GIF_file);
-
-  } // Le fichier était ouvrable
-  else
-    File_error=1;
-}
-
-
-// -- Sauver un fichier au format GIF ---------------------------------------
-
-/// Flush the buffer
-static void GIF_empty_buffer(FILE * file, T_GIF_context *gif, byte * GIF_buffer)
-{
-  word index;
-
-  if (gif->remainder_byte)
-  {
-    GIF_buffer[0] = gif->remainder_byte;
-
-    for (index = 0; index <= gif->remainder_byte; index++)
-      Write_one_byte(file, GIF_buffer[index]);
-
-    gif->remainder_byte=0;
-  }
-}
-
-/// Write a code (GIF_nb_bits bits)
-static void GIF_set_code(FILE * GIF_file, T_GIF_context * gif, byte * GIF_buffer, word Code)
-{
-  word nb_bits_to_process = gif->nb_bits;
-  word nb_bits_processed  =0;
-  word current_nb_bits;
-
-  while (nb_bits_to_process)
-  {
-    current_nb_bits = (nb_bits_to_process <= (8-gif->remainder_bits)) ?
-                          nb_bits_to_process: (8-gif->remainder_bits);
-
-    gif->last_byte |= (Code & ((1<<current_nb_bits)-1))<<gif->remainder_bits;
-    Code>>=current_nb_bits;
-    gif->remainder_bits    +=current_nb_bits;
-    nb_bits_processed  +=current_nb_bits;
-    nb_bits_to_process-=current_nb_bits;
-
-    if (gif->remainder_bits==8) // Il ne reste plus de bits à coder sur l'octet courant
-    {
-      // Ecrire l'octet à balancer:
-      GIF_buffer[++(gif->remainder_byte)] = gif->last_byte;
-
-      // Si on a atteint la fin du bloc de Raster Data
-      if (gif->remainder_byte==255)
-        // On doit vider le buffer qui est maintenant plein
-        GIF_empty_buffer(GIF_file, gif, GIF_buffer);
-
-      gif->last_byte=0;
-      gif->remainder_bits=0;
-    }
-  }
-}
-
-
-/// Read the next pixel
-static byte GIF_next_pixel(T_IO_Context *context, T_GIF_context *gif, T_GIF_IDB *idb)
-{
-  byte temp;
-
-  temp = Get_pixel(context, gif->pos_X, gif->pos_Y);
-
-  if (++gif->pos_X >= (idb->Image_width + idb->Pos_X))
-  {
-    gif->pos_X = idb->Pos_X;
-    if (++gif->pos_Y >= (idb->Image_height + idb->Pos_Y))
-      gif->stop = 1;
-  }
-
-  return temp;
-}
-
-
-/// Save a GIF file
-void Save_GIF(T_IO_Context * context)
-{
-  FILE * GIF_file;
-  byte GIF_buffer[256];   // buffer d'écriture de bloc de données compilées
-
-  word * alphabet_prefix;  // Table des préfixes des codes
-  word * alphabet_suffix;  // Table des suffixes des codes
-  word * alphabet_daughter;    // Table des chaînes filles (plus longues)
-  word * alphabet_sister;    // Table des chaînes soeurs (même longueur)
-  word   alphabet_free;     // Position libre dans l'alphabet
-  word   alphabet_max;      // Nombre d'entrées possibles dans l'alphabet
-  word   start;            // Code précédent (sert au linkage des chaînes)
-  int    descend;          // Booléen "On vient de descendre"
-
-  T_GIF_context GIF;
-  T_GIF_LSDB LSDB;
-  T_GIF_IDB IDB;
-
-
-  byte block_identifier;  // Code indicateur du type de bloc en cours
-  word current_string;   // Code de la chaîne en cours de traitement
-  byte current_char;         // Caractère à coder
-  word index;            // index de recherche de chaîne
-  int current_layer;
-
-  word clear;   // LZW clear code
-  word eof;     // End of image code
-
-  /////////////////////////////////////////////////// FIN DES DECLARATIONS //
-  
-  File_error=0;
-  
-  if ((GIF_file=Open_file_write(context)))
-  {
-    setvbuf(GIF_file, NULL, _IOFBF, 64*1024);
-    
-    // On écrit la signature du fichier
-    if (Write_bytes(GIF_file,"GIF89a",6))
-    {
-      // La signature du fichier a été correctement écrite.
-
-      // Allocation de mémoire pour les tables
-      alphabet_prefix=(word *)malloc(4096*sizeof(word));
-      alphabet_suffix=(word *)malloc(4096*sizeof(word));
-      alphabet_daughter  =(word *)malloc(4096*sizeof(word));
-      alphabet_sister  =(word *)malloc(4096*sizeof(word));
-
-      // On initialise le LSDB du fichier
-      if (Config.Screen_size_in_GIF)
-      {
-        LSDB.Width=Screen_width;
-        LSDB.Height=Screen_height;
-      }
-      else
-      {
-        LSDB.Width=context->Width;
-        LSDB.Height=context->Height;
-      }
-      LSDB.Resol  = 0xF7;  // Global palette of 256 entries, 256 color image
-      // 0xF7 = 1111 0111
-      // <Packed Fields>  =      Global Color Table Flag       1 Bit
-      //                         Color Resolution              3 Bits
-      //                         Sort Flag                     1 Bit
-      //                         Size of Global Color Table    3 Bits
-      LSDB.Backcol=context->Transparent_color;
-      switch(context->Ratio)
-      {
-        case PIXEL_TALL:
-        case PIXEL_TALL2:
-          LSDB.Aspect = 17; // 1:2 = 2:4
-          break;
-        case PIXEL_TALL3:
-          LSDB.Aspect = 33; // 3:4
-          break;
-        case PIXEL_WIDE:
-        case PIXEL_WIDE2:
-          LSDB.Aspect = 113; // 2:1 = 4:2
-          break;
-        default:
-          LSDB.Aspect = 0; // undefined, which is most frequent.
-          // 49 would be 1:1 ratio
-      }
-
-      // On sauve le LSDB dans le fichier
-
-      if (Write_word_le(GIF_file,LSDB.Width) &&
-          Write_word_le(GIF_file,LSDB.Height) &&
-          Write_byte(GIF_file,LSDB.Resol) &&
-          Write_byte(GIF_file,LSDB.Backcol) &&
-          Write_byte(GIF_file,LSDB.Aspect) )
-      {
-        // Le LSDB a été correctement écrit.
-        int i;
-        // On sauve la palette
-        for(i=0;i<256 && !File_error;i++)
-        {
-          if (!Write_byte(GIF_file,context->Palette[i].R)
-            ||!Write_byte(GIF_file,context->Palette[i].G)
-            ||!Write_byte(GIF_file,context->Palette[i].B))
-            File_error=1;
-        }
-        if (!File_error)
-        {
-          // La palette a été correctement écrite.
-
-          /// - "Netscape" animation extension :
-          /// <pre>
-          ///   0x21       Extension Label
-          ///   0xFF       Application Extension Label
-          ///   0x0B       Block Size
-          ///   "NETSCAPE" Application Identifier (8 bytes)
-          ///   "2.0"      Application Authentication Code (3 bytes)
-          ///   0x03       Sub-block Data Size
-          ///   0xLL       01 to loop
-          ///   0xSSSS     (little endian) number of loops, 0 means infinite loop
-          ///   0x00 Block terminator </pre>
-          /// see http://www.vurdalakov.net/misc/gif/netscape-looping-application-extension
-          if (context->Type == CONTEXT_MAIN_IMAGE && Main.backups->Pages->Image_mode == IMAGE_MODE_ANIMATION)
-          {
-            if (context->Nb_layers>1)
-              Write_bytes(GIF_file,"\x21\xFF\x0BNETSCAPE2.0\x03\x01\x00\x00\x00",19);
-          }
-          else if (context->Type == CONTEXT_MAIN_IMAGE && Main.backups->Pages->Image_mode > IMAGE_MODE_ANIMATION)
-          {
-            /// - GrafX2 extension to store ::IMAGE_MODES :
-            /// <pre>
-            ///   0x21       Extension Label
-            ///   0xFF       Application Extension Label
-            ///   0x0B       Block Size
-            ///   "GFX2MODE" Application Identifier (8 bytes)
-            ///   "2.6"      Application Authentication Code (3 bytes)
-            ///   0xll       Sub-block Data Size
-            ///   string     label
-            ///   0x00 Block terminator </pre>
-            /// @see Constraint_mode_label()
-            const char * label = Constraint_mode_label(Main.backups->Pages->Image_mode);
-            if (label != NULL)
-            {
-              size_t len = strlen(label);
-              // Write extension for storing IMAGE_MODE
-              Write_byte(GIF_file,0x21);  // Extension Introducer
-              Write_byte(GIF_file,0xff);  // Extension Label
-              Write_byte(GIF_file,  11);  // Block size
-              Write_bytes(GIF_file, "GFX2MODE2.6", 11); // Application Identifier + Appl. Authentication Code
-              Write_byte(GIF_file, (byte)len);    // Block size
-              Write_bytes(GIF_file, label, len);  // Data
-              Write_byte(GIF_file, 0);    // Block terminator
-            }
-          }
-
-          // Ecriture du commentaire
-          if (context->Comment[0])
-          {
-            Write_bytes(GIF_file,"\x21\xFE",2);
-            Write_byte(GIF_file, (byte)strlen(context->Comment));
-            Write_bytes(GIF_file,context->Comment,strlen(context->Comment)+1);
-          }
-          /// - "CRNG" Color cycing extension :
-          /// <pre>
-          ///   0x21       Extension Label
-          ///   0xFF       Application Extension Label
-          ///   0x0B       Block Size
-          ///   "CRNG\0\0\0\0" "CRNG" Application Identifier (8 bytes)
-          ///   "1.0"      Application Authentication Code (3 bytes)
-          ///   0xll       Sub-block Data Size (6 bytes per color cycle)
-          ///   For each color cycle :
-          ///     0xRRRR   (big endian) Rate
-          ///     0xFFFF   (big endian) Flags
-          ///     0xSS     start (lower color index)
-          ///     0xEE     end (higher color index)
-          ///   0x00       Block terminator </pre>
-          if (context->Color_cycles)
-          {
-            int i;
-            
-            Write_bytes(GIF_file,"\x21\xff\x0B" "CRNG\0\0\0\0" "1.0",14);
-            Write_byte(GIF_file,context->Color_cycles*6);
-            for (i=0; i<context->Color_cycles; i++)
-            {
-              word flags=0;
-              flags|= context->Cycle_range[i].Speed?1:0; // Cycling or not
-              flags|= context->Cycle_range[i].Inverse?2:0; // Inverted
-              
-              Write_word_be(GIF_file,context->Cycle_range[i].Speed*78); // Rate
-              Write_word_be(GIF_file,flags); // Flags
-              Write_byte(GIF_file,context->Cycle_range[i].Start); // Min color
-              Write_byte(GIF_file,context->Cycle_range[i].End); // Max color
-            }
-            Write_byte(GIF_file,0);
-          }
-          
-          // Loop on all layers
-          for (current_layer=0; 
-            current_layer < context->Nb_layers && !File_error;
-            current_layer++)
-          {
-            // Write a Graphic Control Extension
-            T_GIF_GCE GCE;
-            byte disposal_method;
-            
-            Set_saving_layer(context, current_layer);
-            
-            GCE.Block_identifier = 0x21;
-            GCE.Function = 0xF9;
-            GCE.Block_size=4;
-            
-            if (context->Type == CONTEXT_MAIN_IMAGE && Main.backups->Pages->Image_mode == IMAGE_MODE_ANIMATION)
-            {
-              // Animation frame
-              int duration;
-              if(context->Background_transparent)
-                disposal_method = DISPOSAL_METHOD_RESTORE_BGCOLOR;
-              else
-                disposal_method = DISPOSAL_METHOD_DO_NOT_DISPOSE;
-              GCE.Packed_fields=(disposal_method<<2)|(context->Background_transparent);
-              duration=Get_frame_duration(context)/10;
-              GCE.Delay_time=duration<0xFFFF?duration:0xFFFF;
-            }
-            else
-            {
-              // Layered image or brush
-              disposal_method = DISPOSAL_METHOD_DO_NOT_DISPOSE;
-              if (current_layer==0)
-                GCE.Packed_fields=(disposal_method<<2)|(context->Background_transparent);
-              else
-                GCE.Packed_fields=(disposal_method<<2)|(1);
-              GCE.Delay_time=5; // Duration 5/100s (minimum viable value for current web browsers)
-              if (current_layer == context->Nb_layers -1)
-                GCE.Delay_time=0xFFFF; // Infinity (10 minutes)
-            }
-            GCE.Transparent_color=context->Transparent_color;
-            GCE.Block_terminator=0x00;
-            
-            if (Write_byte(GIF_file,GCE.Block_identifier)
-             && Write_byte(GIF_file,GCE.Function)
-             && Write_byte(GIF_file,GCE.Block_size)
-             && Write_byte(GIF_file,GCE.Packed_fields)
-             && Write_word_le(GIF_file,GCE.Delay_time)
-             && Write_byte(GIF_file,GCE.Transparent_color)
-             && Write_byte(GIF_file,GCE.Block_terminator)
-             )
-            {
-              byte temp, max = 0;
-
-              IDB.Pos_X=0;
-              IDB.Pos_Y=0;
-              IDB.Image_width=context->Width;
-              IDB.Image_height=context->Height;
-              if(current_layer > 0)
-              {
-                word min_X, max_X, min_Y, max_Y;
-                // find bounding box of changes for Animated GIFs
-                min_X = min_Y = 0xffff;
-                max_X = max_Y = 0;
-                for(GIF.pos_Y = 0; GIF.pos_Y < context->Height; GIF.pos_Y++) {
-                  for(GIF.pos_X = 0; GIF.pos_X < context->Width; GIF.pos_X++) {
-                    if (GIF.pos_X >= min_X && GIF.pos_X <= max_X && GIF.pos_Y >= min_Y && GIF.pos_Y <= max_Y)
-                      continue; // already in the box
-                    if(disposal_method == DISPOSAL_METHOD_DO_NOT_DISPOSE)
-                    {
-                      // if that pixel has same value in previous layer, no need to save it
-                      Set_saving_layer(context, current_layer - 1);
-                      temp = Get_pixel(context, GIF.pos_X, GIF.pos_Y);
-                      Set_saving_layer(context, current_layer);
-                      if(temp == Get_pixel(context, GIF.pos_X, GIF.pos_Y))
-                        continue;
-                    }
-                    if (disposal_method == DISPOSAL_METHOD_RESTORE_BGCOLOR
-                      || context->Background_transparent
-                      || Main.backups->Pages->Image_mode != IMAGE_MODE_ANIMATION)
-                    {
-                      // if that pixel is Backcol, no need to save it
-                      if (LSDB.Backcol == Get_pixel(context, GIF.pos_X, GIF.pos_Y))
-                        continue;
-                    }
-                    if(GIF.pos_X < min_X) min_X = GIF.pos_X;
-                    if(GIF.pos_X > max_X) max_X = GIF.pos_X;
-                    if(GIF.pos_Y < min_Y) min_Y = GIF.pos_Y;
-                    if(GIF.pos_Y > max_Y) max_Y = GIF.pos_Y;
-                  }
-                }
-                if((min_X <= max_X) && (min_Y <= max_Y))
-                {
-                  IDB.Pos_X = min_X;
-                  IDB.Pos_Y = min_Y;
-                  IDB.Image_width = max_X + 1 - min_X;
-                  IDB.Image_height = max_Y + 1 - min_Y;
-                }
-                else
-                {
-                  // if no pixel changes, store a 1 pixel image
-                  IDB.Image_width = 1;
-                  IDB.Image_height = 1;
-                }
-              }
-
-              // look for the maximum pixel value
-              // to decide how many bit per pixel are needed.
-              for(GIF.pos_Y = IDB.Pos_Y; GIF.pos_Y < IDB.Image_height + IDB.Pos_Y; GIF.pos_Y++) {
-                for(GIF.pos_X = IDB.Pos_X; GIF.pos_X < IDB.Image_width + IDB.Pos_X; GIF.pos_X++) {
-                  temp=Get_pixel(context, GIF.pos_X, GIF.pos_Y);
-                  if(temp > max) max = temp;
-                }
-              }
-              IDB.Nb_bits_pixel=2;  // Find the minimum bpp value to fit all pixels
-              while((int)max >= (1 << IDB.Nb_bits_pixel)) {
-                IDB.Nb_bits_pixel++;
-              }
-              GFX2_Log(GFX2_DEBUG, "GIF image #%d %ubits (%u,%u) %ux%u\n",
-                       current_layer, IDB.Nb_bits_pixel, IDB.Pos_X, IDB.Pos_Y,
-                       IDB.Image_width, IDB.Image_height);
-            
-              // On va écrire un block indicateur d'IDB et l'IDB du fichier
-              block_identifier=0x2C;
-              IDB.Indicator=0x07;    // Image non entrelacée, pas de palette locale.
-              clear = 1 << IDB.Nb_bits_pixel; // Clear Code
-              eof = clear + 1;                // End of Picture Code
-    
-              if ( Write_byte(GIF_file,block_identifier) &&
-                   Write_word_le(GIF_file,IDB.Pos_X) &&
-                   Write_word_le(GIF_file,IDB.Pos_Y) &&
-                   Write_word_le(GIF_file,IDB.Image_width) &&
-                   Write_word_le(GIF_file,IDB.Image_height) &&
-                   Write_byte(GIF_file,IDB.Indicator) &&
-                   Write_byte(GIF_file,IDB.Nb_bits_pixel))
-              {
-                //   Le block indicateur d'IDB et l'IDB ont étés correctements
-                // écrits.
-    
-                GIF.pos_X=IDB.Pos_X;
-                GIF.pos_Y=IDB.Pos_Y;
-                GIF.last_byte=0;
-                GIF.remainder_bits=0;
-                GIF.remainder_byte=0;
-    
-#define GIF_INVALID_CODE (65535)
-                index=GIF_INVALID_CODE;
-                File_error=0;
-                GIF.stop=0;
-    
-                // Réintialisation de la table:
-                alphabet_free=clear + 2;  // 258 for 8bpp
-                GIF.nb_bits  =IDB.Nb_bits_pixel + 1; // 9 for 8 bpp
-                alphabet_max =clear+clear-1;  // 511 for 8bpp
-                GIF_set_code(GIF_file, &GIF, GIF_buffer, clear);  //256 for 8bpp
-                for (start=0;start<4096;start++)
-                {
-                  alphabet_daughter[start] = GIF_INVALID_CODE;
-                  alphabet_sister[start] = GIF_INVALID_CODE;
-                }
-    
-                ////////////////////////////////////////////// COMPRESSION LZW //
-    
-                start=current_string=GIF_next_pixel(context, &GIF, &IDB);
-                descend=1;
-    
-                while ((!GIF.stop) && (!File_error))
-                {
-                  current_char=GIF_next_pixel(context, &GIF, &IDB);
-    
-                  // look for (current_string,current_char) in the alphabet
-                  while ( (index != GIF_INVALID_CODE) &&
-                          ( (current_string!=alphabet_prefix[index]) ||
-                            (current_char      !=alphabet_suffix[index]) ) )
-                  {
-                    descend=0;
-                    start=index;
-                    index=alphabet_sister[index];
-                  }
-    
-                  if (index != GIF_INVALID_CODE)
-                  {
-                    // (current_string,current_char) == (alphabet_prefix,alphabet_suffix)[index]
-                    // We have found (current_string,current_char) in the alphabet
-                    // at the index position. So go on and prepare for then next character
-    
-                    descend=1;
-                    start=current_string=index;
-                    index=alphabet_daughter[index];
-                  }
-                  else
-                  {
-                    // (current_string,current_char) was not found in the alphabet
-                    // so write current_string to the Gif stream
-                    GIF_set_code(GIF_file, &GIF, GIF_buffer, current_string);
-
-                    if(alphabet_free < 4096) {
-                      // link current_string and the new one
-                      if (descend)
-                        alphabet_daughter[start]=alphabet_free;
-                      else
-                        alphabet_sister[start]=alphabet_free;
-
-                      // add (current_string,current_char) to the alphabet
-                      alphabet_prefix[alphabet_free]=current_string;
-                      alphabet_suffix[alphabet_free]=current_char;
-                      alphabet_free++;
-                    }
-    
-                    if (alphabet_free >= 4096)
-                    {
-                      // clear alphabet
-                      GIF_set_code(GIF_file, &GIF, GIF_buffer, clear);    // 256 for 8bpp
-                      alphabet_free=clear+2;  // 258 for 8bpp
-                      GIF.nb_bits  =IDB.Nb_bits_pixel + 1;  // 9 for 8bpp
-                      alphabet_max =clear+clear-1;    // 511 for 8bpp
-                      for (start=0;start<4096;start++)
-                      {
-                        alphabet_daughter[start] = GIF_INVALID_CODE;
-                        alphabet_sister[start] = GIF_INVALID_CODE;
-                      }
-                    }
-                    else if (alphabet_free>alphabet_max+1)
-                    {
-                      // On augmente le nb de bits
-    
-                      GIF.nb_bits++;
-                      alphabet_max = (1<<GIF.nb_bits)-1;
-                    }
-    
-                    // initialize current_string as the string "current_char"
-                    index=alphabet_daughter[current_char];
-                    start=current_string=current_char;
-                    descend=1;
-                  }
-                }
-    
-                if (!File_error)
-                {
-                  // Write the last code (before EOF)
-                  GIF_set_code(GIF_file, &GIF, GIF_buffer, current_string);
-    
-                  // we need to update alphabet_free / GIF.nb_bits here because
-                  // the decoder will update them after each code,
-                  // so in very rare cases there might be a problem if we
-                  // don't do it.
-                  // see http://pulkomandy.tk/projects/GrafX2/ticket/125
-                  if(alphabet_free < 4096)
-                  {
-                    alphabet_free++;
-                    if ((alphabet_free > alphabet_max+1) && (GIF.nb_bits < 12))
-                    {
-                      GIF.nb_bits++;
-                      alphabet_max = (1 << GIF.nb_bits) - 1;
-                    }
-                  }
-
-                  GIF_set_code(GIF_file, &GIF, GIF_buffer, eof);  // 257 for 8bpp    // Code de End d'image
-                  if (GIF.remainder_bits!=0)
-                  {
-                    // Write last byte (this is an incomplete byte)
-                    GIF_buffer[++GIF.remainder_byte]=GIF.last_byte;
-                    GIF.last_byte=0;
-                    GIF.remainder_bits=0;
-                  }
-                  GIF_empty_buffer(GIF_file, &GIF, GIF_buffer); // On envoie les dernières données du buffer GIF dans le buffer KM
-    
-                  // On écrit un \0
-                  if (! Write_byte(GIF_file,'\x00'))
-                    File_error=1;
-                }
-      
-              } // On a pu écrire l'IDB
-              else
-                File_error=1;
-            }
-            else
-              File_error=1;
-          }
-          
-          // After writing all layers
-          if (!File_error)
-          {
-            /// - If requested, write a specific extension for storing
-            /// original file path.
-            /// This is used by the backup system.
-            /// The format is :
-            /// <pre>
-            ///   0x21       Extension Label
-            ///   0xFF       Application Extension Label
-            ///   0x0B       Block Size
-            ///   "GFX2PATH" "GFX2PATH" Application Identifier (8 bytes)
-            ///   "\0\0\0"   Application Authentication Code (3 bytes)
-            ///   0xll       Sub-block Data Size : path size (including null)
-            ///   "..path.." path (null-terminated)
-            ///   0xll       Sub-block Data Size : filename size (including null)
-            ///   "..file.." file name (null-terminated)
-            ///   0x00       Block terminator </pre>
-            if (context->Original_file_name != NULL
-             && context->Original_file_directory != NULL)
-            {
-              long name_size = 1+strlen(context->Original_file_name);
-              long dir_size = 1+strlen(context->Original_file_directory);
-              if (name_size<256 && dir_size<256)
-              {
-                if (! Write_bytes(GIF_file,"\x21\xFF\x0BGFX2PATH\x00\x00\x00", 14)
-                || ! Write_byte(GIF_file,dir_size)
-                || ! Write_bytes(GIF_file, context->Original_file_directory, dir_size)
-                || ! Write_byte(GIF_file,name_size)
-                || ! Write_bytes(GIF_file, context->Original_file_name, name_size)
-                || ! Write_byte(GIF_file,0))
-                  File_error=1;
-              }
-            }
-          
-            // On écrit un GIF TERMINATOR, exigé par SVGA et SEA.
-            if (! Write_byte(GIF_file,'\x3B'))
-              File_error=1;
-          }
-
-        } // On a pu écrire la palette
-        else
-          File_error=1;
-
-      } // On a pu écrire le LSDB
-      else
-        File_error=1;
-
-      // Libération de la mémoire utilisée par les tables
-      free(alphabet_sister);
-      free(alphabet_daughter);
-      free(alphabet_suffix);
-      free(alphabet_prefix);
-
-    } // On a pu écrire la signature du fichier
-    else
-      File_error=1;
-
-    fclose(GIF_file);
-    if (File_error)
-      Remove_file(context);
-
-  } // On a pu ouvrir le fichier en écriture
-  else
-    File_error=1;
-
-}
-
-/* @} */
-
-
 //////////////////////////////////// PCX ////////////////////////////////////
 typedef struct
   {
diff --git a/src/giformat.c b/src/giformat.c
new file mode 100644
index 00000000..92bbacd1
--- /dev/null
+++ b/src/giformat.c
@@ -0,0 +1,1382 @@
+/* vim:expandtab:ts=2 sw=2:
+*/
+/*  Grafx2 - The Ultimate 256-color bitmap paint program
+
+    Copyright 2018 Thomas Bernard
+    Copyright 2011 Pawel Góralski
+    Copyright 2009 Petter Lindquist
+    Copyright 2008 Yves Rizoud
+    Copyright 2008 Franck Charlet
+    Copyright 2007 Adrien Destugues
+    Copyright 1996-2001 Sunset Design (Guillaume Dorme & Karl Maritaud)
+
+    Grafx2 is free software; you can redistribute it and/or
+    modify it under the terms of the GNU General Public License
+    as published by the Free Software Foundation; version 2
+    of the License.
+
+    Grafx2 is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with Grafx2; if not, see <http://www.gnu.org/licenses/>
+*/
+
+///@file giformats.c
+/// Saving and loading GIF
+
+#include <stdlib.h>
+#include <string.h>
+#include "struct.h"
+#include "global.h"
+#include "oldies.h"
+#include "io.h"
+#include "loadsave.h"
+#include "loadsavefuncs.h"
+#include "gfx2mem.h"
+#include "gfx2log.h"
+
+#ifndef MIN
+#define MIN(a,b) ((a)<(b)?(a):(b))
+#endif
+#ifndef MAX
+#define MAX(a,b) ((a)>(b)?(a):(b))
+#endif
+
+/**
+ * @defgroup GIF GIF format
+ * @ingroup loadsaveformats
+ * Graphics Interchange Format
+ *
+ * The GIF format uses LZW compression and stores indexed color pictures
+ * up to 256 colors. It has the ability to store several pictures in the same
+ * file : GrafX2 takes advantage of this feature for storing layered images
+ * and animations.
+ *
+ * GrafX2 implements GIF89a :
+ * https://www.w3.org/Graphics/GIF/spec-gif89a.txt
+ *
+ * @{
+ */
+
+/// Logical Screen Descriptor Block
+typedef struct
+{
+  word Width;   ///< Width of the complete image area
+  word Height;  ///< Height of the complete image area
+  byte Resol;   ///< Informations about the resolution (and other)
+  byte Backcol; ///< Proposed background color
+  byte Aspect;  ///< Informations about aspect ratio. Ratio = (Aspect + 15) / 64
+} T_GIF_LSDB;
+
+/// Image Descriptor Block
+typedef struct
+{
+  word Pos_X;         ///< X offset where the image should be pasted
+  word Pos_Y;         ///< Y offset where the image should be pasted
+  word Image_width;   ///< Width of image
+  word Image_height;  ///< Height of image
+  byte Indicator;     ///< Misc image information
+  byte Nb_bits_pixel; ///< Nb de bits par pixel
+} T_GIF_IDB;
+
+/// Graphic Control Extension
+typedef struct
+{
+  byte Block_identifier;  ///< 0x21
+  byte Function;          ///< 0xF9
+  byte Block_size;        ///< 4
+  byte Packed_fields;     ///< 11100000 : Reserved
+                          ///< 00011100 : Disposal method
+                          ///< 00000010 : User input flag
+                          ///< 00000001 : Transparent flag
+  word Delay_time;        ///< Time for this frame to stay displayed
+  byte Transparent_color; ///< Which color index acts as transparent
+  word Block_terminator;  ///< 0x00
+} T_GIF_GCE;
+
+enum DISPOSAL_METHOD
+{
+  DISPOSAL_METHOD_UNDEFINED = 0,
+  DISPOSAL_METHOD_DO_NOT_DISPOSE = 1,
+  DISPOSAL_METHOD_RESTORE_BGCOLOR = 2,
+  DISPOSAL_METHOD_RESTORE_PREVIOUS = 3,
+};
+
+
+/// Test if a file is GIF format
+void Test_GIF(T_IO_Context * context, FILE * file)
+{
+  char signature[6];
+
+  (void)context;
+  File_error=1;
+
+  if (Read_bytes(file,signature,6))
+  {
+    /// checks if the signature (6 first bytes) is either GIF87a or GIF89a
+    if ((!memcmp(signature,"GIF87a",6))||(!memcmp(signature,"GIF89a",6)))
+      File_error=0;
+  }
+}
+
+
+// -- Lire un fichier au format GIF -----------------------------------------
+
+typedef struct {
+  word nb_bits;        ///< bits for a code
+  word remainder_bits; ///< available bits in @ref last_byte field
+  byte remainder_byte; ///< Remaining bytes in current block
+  word current_code;   ///< current code (generally the one just read)
+  byte last_byte;      ///< buffer byte for reading bits for codes
+  word pos_X;          ///< Current coordinates
+  word pos_Y;
+  word interlaced;     ///< interlaced flag
+  word pass;           ///< current pass in interlaced decoding
+  word stop;           ///< Stop flag (end of picture)
+} T_GIF_context;
+
+
+/// Reads the next code (GIF.nb_bits bits)
+static word GIF_get_next_code(FILE * GIF_file, T_GIF_context * gif)
+{
+  word nb_bits_to_process = gif->nb_bits;
+  word nb_bits_processed = 0;
+  word current_nb_bits;
+
+  gif->current_code = 0;
+
+  while (nb_bits_to_process)
+  {
+    if (gif->remainder_bits == 0) // Il ne reste plus de bits...
+    {
+      // Lire l'octet suivant:
+
+      // Si on a atteint la fin du bloc de Raster Data
+      if (gif->remainder_byte == 0)
+      {
+        // Lire l'octet nous donnant la taille du bloc de Raster Data suivant
+        if(Read_byte(GIF_file, &gif->remainder_byte)!=1)
+        {
+          File_error=2;
+          return 0;
+        }
+        if (gif->remainder_byte == 0) // still nothing ? That is the end data block
+        {
+          File_error = 2;
+          GFX2_Log(GFX2_WARNING, "GIF 0 sized data block\n");
+          return gif->current_code;
+        }
+      }
+      if(Read_byte(GIF_file,&gif->last_byte)!=1)
+      {
+        File_error = 2;
+        GFX2_Log(GFX2_ERROR, "GIF failed to load data byte\n");
+        return 0;
+      }
+      gif->remainder_byte--;
+      gif->remainder_bits=8;
+    }
+
+    current_nb_bits=(nb_bits_to_process<=gif->remainder_bits)?nb_bits_to_process:gif->remainder_bits;
+
+    gif->current_code |= (gif->last_byte & ((1<<current_nb_bits)-1))<<nb_bits_processed;
+    gif->last_byte >>= current_nb_bits;
+    nb_bits_processed += current_nb_bits;
+    nb_bits_to_process -= current_nb_bits;
+    gif->remainder_bits -= current_nb_bits;
+  }
+
+  return gif->current_code;
+}
+
+/// Put a new pixel
+static void GIF_new_pixel(T_IO_Context * context, T_GIF_context * gif, T_GIF_IDB *idb, int is_transparent, byte color)
+{
+  if (!is_transparent || color!=context->Transparent_color)
+    Set_pixel(context, idb->Pos_X+gif->pos_X, idb->Pos_Y+gif->pos_Y,color);
+
+  gif->pos_X++;
+
+  if (gif->pos_X >= idb->Image_width)
+  {
+    gif->pos_X=0;
+
+    if (!gif->interlaced)
+    {
+      gif->pos_Y++;
+      if (gif->pos_Y >= idb->Image_height)
+        gif->stop = 1;
+    }
+    else
+    {
+      switch (gif->pass)
+      {
+        case 0 :
+        case 1 : gif->pos_Y+=8;
+                 break;
+        case 2 : gif->pos_Y+=4;
+                 break;
+        default: gif->pos_Y+=2;
+      }
+
+      if (gif->pos_Y >= idb->Image_height)
+      {
+        switch(++(gif->pass))
+        {
+        case 1 : gif->pos_Y=4;
+                 break;
+        case 2 : gif->pos_Y=2;
+                 break;
+        case 3 : gif->pos_Y=1;
+                 break;
+        case 4 : gif->stop = 1;
+        }
+      }
+    }
+  }
+}
+
+
+/// Load GIF file
+void Load_GIF(T_IO_Context * context)
+{
+  FILE *GIF_file;
+  int image_mode = -1;
+  char signature[6];
+
+  word * alphabet_stack;     // Pile de décodage d'une chaîne
+  word * alphabet_prefix;  // Table des préfixes des codes
+  word * alphabet_suffix;  // Table des suffixes des codes
+  word   alphabet_free;     // Position libre dans l'alphabet
+  word   alphabet_max;      // Nombre d'entrées possibles dans l'alphabet
+  word   alphabet_stack_pos; // Position dans la pile de décodage d'un chaîne
+
+  T_GIF_context GIF;
+  T_GIF_LSDB LSDB;
+  T_GIF_IDB IDB;
+  T_GIF_GCE GCE;
+
+  word nb_colors;       // Nombre de couleurs dans l'image
+  word color_index; // index de traitement d'une couleur
+  byte size_to_read; // Nombre de données à lire      (divers)
+  byte block_identifier;  // Code indicateur du type de bloc en cours
+  byte initial_nb_bits;   // Nb de bits au début du traitement LZW
+  word special_case=0;       // Mémoire pour le cas spécial
+  word old_code=0;       // Code précédent
+  word byte_read;         // Sauvegarde du code en cours de lecture
+  word value_clr;        // Valeur <=> Clear tables
+  word value_eof;        // Valeur <=> End d'image
+  long file_size;
+  int number_LID; // Nombre d'images trouvées dans le fichier
+  int current_layer = 0;
+  int last_delay = 0;
+  byte is_transparent = 0;
+  byte is_looping=0;
+  enum PIXEL_RATIO ratio;
+  byte disposal_method = DISPOSAL_METHOD_RESTORE_BGCOLOR;
+
+  byte previous_disposal_method = DISPOSAL_METHOD_RESTORE_BGCOLOR;
+  word previous_width=0;
+  word previous_height=0;
+  word previous_pos_x=0;
+  word previous_pos_y=0;
+
+  /////////////////////////////////////////////////// FIN DES DECLARATIONS //
+
+
+  number_LID=0;
+
+  if ((GIF_file=Open_file_read(context)))
+  {
+    file_size=File_length_file(GIF_file);
+    if ( (Read_bytes(GIF_file,signature,6)) &&
+         ( (memcmp(signature,"GIF87a",6)==0) ||
+           (memcmp(signature,"GIF89a",6)==0) ) )
+    {
+
+      // Allocation de mémoire pour les tables & piles de traitement:
+      alphabet_stack  = (word *)GFX2_malloc(4096*sizeof(word));
+      alphabet_prefix = (word *)GFX2_malloc(4096*sizeof(word));
+      alphabet_suffix = (word *)GFX2_malloc(4096*sizeof(word));
+
+      if (Read_word_le(GIF_file,&(LSDB.Width))
+      && Read_word_le(GIF_file,&(LSDB.Height))
+      && Read_byte(GIF_file,&(LSDB.Resol))
+      && Read_byte(GIF_file,&(LSDB.Backcol))
+      && Read_byte(GIF_file,&(LSDB.Aspect))
+        )
+      {
+        // Lecture du Logical Screen Descriptor Block réussie:
+
+        Original_screen_X=LSDB.Width;
+        Original_screen_Y=LSDB.Height;
+
+        ratio=PIXEL_SIMPLE;          //  (49 + 15) / 64 = 1:1
+        if (LSDB.Aspect != 0) {
+          if (LSDB.Aspect < 25)      //  (17 + 15) / 64 = 1:2
+            ratio=PIXEL_TALL;
+          else if (LSDB.Aspect < 41) //  (33 + 15) / 64 = 3:4
+            ratio=PIXEL_TALL3;
+          else if (LSDB.Aspect > 82) // (113 + 15) / 64 = 2:1
+            ratio=PIXEL_WIDE;
+        }
+
+        Pre_load(context, LSDB.Width,LSDB.Height,file_size,FORMAT_GIF,ratio,(LSDB.Resol&7)+1);
+
+        // Palette globale dispo = (LSDB.Resol  and $80)
+        // Profondeur de couleur =((LSDB.Resol  and $70) shr 4)+1
+        // Nombre de bits/pixel  = (LSDB.Resol  and $07)+1
+        // Ordre de Classement   = (LSDB.Aspect and $80)
+
+        nb_colors=(1 << ((LSDB.Resol & 0x07)+1));
+        if (LSDB.Resol & 0x80)
+        {
+          // Palette globale dispo:
+
+          if (Config.Clear_palette)
+            memset(context->Palette,0,sizeof(T_Palette));
+
+          // Load the palette
+          for(color_index=0;color_index<nb_colors;color_index++)
+          {
+            Read_byte(GIF_file,&(context->Palette[color_index].R));
+            Read_byte(GIF_file,&(context->Palette[color_index].G));
+            Read_byte(GIF_file,&(context->Palette[color_index].B));
+          }
+        }
+
+        // On lit un indicateur de block
+        Read_byte(GIF_file,&block_identifier);
+        while (block_identifier!=0x3B && !File_error)
+        {
+          switch (block_identifier)
+          {
+            case 0x21: // Bloc d'extension
+            {
+              byte function_code;
+              // Lecture du code de fonction:
+              Read_byte(GIF_file,&function_code);
+              // Lecture de la taille du bloc:
+              Read_byte(GIF_file,&size_to_read);
+              while (size_to_read!=0 && !File_error)
+              {
+                switch(function_code)
+                {
+                  case 0xFE: // Comment Block Extension
+                    // On récupère le premier commentaire non-vide,
+                    // on jette les autres.
+                    if (context->Comment[0]=='\0')
+                    {
+                      int nb_char_to_keep = MIN(size_to_read, COMMENT_SIZE);
+
+                      Read_bytes(GIF_file,context->Comment,nb_char_to_keep);
+                      context->Comment[nb_char_to_keep+1]='\0';
+                      // Si le commentaire etait trop long, on fait avance-rapide
+                      // sur la suite.
+                      if (size_to_read>nb_char_to_keep)
+                        fseek(GIF_file,size_to_read-nb_char_to_keep,SEEK_CUR);
+                    }
+                    // Lecture de la taille du bloc suivant:
+                    Read_byte(GIF_file,&size_to_read);
+                    break;
+                  case 0xF9: // Graphics Control Extension
+                    // Prévu pour la transparence
+                    if ( Read_byte(GIF_file,&(GCE.Packed_fields))
+                      && Read_word_le(GIF_file,&(GCE.Delay_time))
+                      && Read_byte(GIF_file,&(GCE.Transparent_color)))
+                    {
+                      previous_disposal_method = disposal_method;
+                      disposal_method = (GCE.Packed_fields >> 2) & 7;
+                      last_delay = GCE.Delay_time;
+                      context->Transparent_color= GCE.Transparent_color;
+                      is_transparent = GCE.Packed_fields & 1;
+                      GFX2_Log(GFX2_DEBUG, "GIF Graphics Control Extension : transp=%d (color #%u) delay=%ums disposal_method=%d\n", is_transparent, GCE.Transparent_color, 10*GCE.Delay_time, disposal_method);
+                      if (number_LID == 0)
+                        context->Background_transparent = is_transparent;
+                      is_transparent &= is_looping;
+                    }
+                    else
+                      File_error=2;
+                    // Lecture de la taille du bloc suivant:
+                    Read_byte(GIF_file,&size_to_read);
+                    break;
+
+                  case 0xFF: // Application Extension
+                    // Normally, always a 11-byte block
+                    if (size_to_read == 0x0B)
+                    {
+                      char aeb[0x0B];
+                      Read_bytes(GIF_file,aeb, 0x0B);
+                      GFX2_Log(GFX2_DEBUG, "GIF extension \"%.11s\"\n", aeb);
+                      if (File_error)
+                        ;
+                      else if (!memcmp(aeb,"NETSCAPE2.0",0x0B))
+                      {
+                        is_looping=1;
+                        // The well-known Netscape extension.
+                        // Load as an animation
+                        Set_image_mode(context, IMAGE_MODE_ANIMATION);
+                        // Skip sub-block
+                        do
+                        {
+                          if (! Read_byte(GIF_file,&size_to_read))
+                            File_error=1;
+                          fseek(GIF_file,size_to_read,SEEK_CUR);
+                        } while (!File_error && size_to_read!=0);
+                      }
+                      else if (!memcmp(aeb,"GFX2PATH\x00\x00\x00",0x0B))
+                      {
+                        // Original file path
+                        Read_byte(GIF_file,&size_to_read);
+                        if (!File_error && size_to_read > 0)
+                        {
+                          free(context->Original_file_directory);
+                          context->Original_file_directory = GFX2_malloc(size_to_read);
+                          Read_bytes(GIF_file, context->Original_file_directory, size_to_read);
+                          Read_byte(GIF_file, &size_to_read);
+                          if (!File_error && size_to_read > 0)
+                          {
+                            free(context->Original_file_name);
+                            context->Original_file_name = GFX2_malloc(size_to_read);
+                            Read_bytes(GIF_file, context->Original_file_name, size_to_read);
+                            Read_byte(GIF_file, &size_to_read); // Normally 0
+                          }
+                        }
+                      }
+                      else if (!memcmp(aeb,"CRNG\0\0\0\0" "1.0",0x0B))
+                      {
+                        // Color animation. Similar to a CRNG chunk in IFF file format.
+                        word rate;
+                        word flags;
+                        byte col1;
+                        byte col2;
+                        //
+                        Read_byte(GIF_file,&size_to_read);
+                        for(;size_to_read>0 && !File_error;size_to_read-=6)
+                        {
+                          if ( (Read_word_be(GIF_file, &rate))
+                            && (Read_word_be(GIF_file, &flags))
+                            && (Read_byte(GIF_file, &col1))
+                            && (Read_byte(GIF_file, &col2)))
+                          {
+                            if (col1 != col2)
+                            {
+                              // Valid cycling range
+                              context->Cycle_range[context->Color_cycles].Start = MIN(col1, col2);
+                              context->Cycle_range[context->Color_cycles].End = MAX(col1, col2);
+                              context->Cycle_range[context->Color_cycles].Inverse = (flags&2)?1:0;
+                              context->Cycle_range[context->Color_cycles].Speed = (flags&1)?rate/78:0;
+
+                              context->Color_cycles++;
+                            }
+                          }
+                          else
+                          {
+                            File_error=1;
+                          }
+                        }
+                        // Read end-of-block delimiter
+                        if (!File_error)
+                          Read_byte(GIF_file,&size_to_read);
+                        if (size_to_read!=0)
+                          File_error=1;
+                      }
+                      else if (0 == memcmp(aeb, "GFX2MODE", 8))
+                      {
+                        Read_byte(GIF_file,&size_to_read);
+                        if (size_to_read > 0)
+                        { // read the image mode. We'll set it after having loaded all layers.
+                          char * label = GFX2_malloc((size_t)size_to_read + 1);
+                          Read_bytes(GIF_file, label, size_to_read);
+                          label[size_to_read] = '\0';
+                          image_mode = Constraint_mode_from_label(label);
+                          GFX2_Log(GFX2_DEBUG, "    mode = %s (%d)\n", label, image_mode);
+                          free(label);
+                          Read_byte(GIF_file,&size_to_read);
+                          // be future proof, skip following sub-blocks :
+                          while (size_to_read!=0 && !File_error)
+                          {
+                            if (fseek(GIF_file,size_to_read,SEEK_CUR) < 0)
+                              File_error = 1;
+                            if (!Read_byte(GIF_file,&size_to_read))
+                              File_error = 1;
+                          }
+                        }
+                      }
+                      else
+                      {
+                        // Unknown extension, skip.
+                        Read_byte(GIF_file,&size_to_read);
+                        while (size_to_read!=0 && !File_error)
+                        {
+                          if (fseek(GIF_file,size_to_read,SEEK_CUR) < 0)
+                            File_error = 1;
+                          if (!Read_byte(GIF_file,&size_to_read))
+                            File_error = 1;
+                        }
+                      }
+                    }
+                    else
+                    {
+                      fseek(GIF_file,size_to_read,SEEK_CUR);
+                      // Lecture de la taille du bloc suivant:
+                      Read_byte(GIF_file,&size_to_read);
+                    }
+                    break;
+
+                  default:
+                    // On saute le bloc:
+                    fseek(GIF_file,size_to_read,SEEK_CUR);
+                    // Lecture de la taille du bloc suivant:
+                    Read_byte(GIF_file,&size_to_read);
+                    break;
+                }
+              }
+            }
+            break;
+            case 0x2C: // Local Image Descriptor
+            {
+              if (number_LID!=0)
+              {
+                // This a second layer/frame, or more.
+                // Attempt to add a layer to current image
+                current_layer++;
+                Set_loading_layer(context, current_layer);
+                if (context->Type == CONTEXT_MAIN_IMAGE && Main.backups->Pages->Image_mode == IMAGE_MODE_ANIMATION)
+                {
+                  // Copy the content of previous layer.
+                  memcpy(
+                    Main.backups->Pages->Image[Main.current_layer].Pixels,
+                    Main.backups->Pages->Image[Main.current_layer-1].Pixels,
+                    Main.backups->Pages->Width*Main.backups->Pages->Height);
+                }
+                else
+                {
+                  Fill_canvas(context, is_transparent ? context->Transparent_color : LSDB.Backcol);
+                }
+              }
+              else
+              {
+                // First frame/layer, fill canvas with backcolor
+                Fill_canvas(context, is_transparent ? context->Transparent_color : LSDB.Backcol);
+              }
+              // Duration was set in the previously loaded GCE
+              Set_frame_duration(context, last_delay*10);
+              number_LID++;
+
+              // lecture de 10 derniers octets
+              if ( Read_word_le(GIF_file,&(IDB.Pos_X))
+                && Read_word_le(GIF_file,&(IDB.Pos_Y))
+                && Read_word_le(GIF_file,&(IDB.Image_width))
+                && Read_word_le(GIF_file,&(IDB.Image_height))
+                && Read_byte(GIF_file,&(IDB.Indicator))
+                && IDB.Image_width && IDB.Image_height)
+              {
+                GFX2_Log(GFX2_DEBUG, "GIF Image descriptor %u Pos (%u,%u) %ux%u %s%slocal palette(%ubpp)\n",
+                         number_LID, IDB.Pos_X, IDB.Pos_Y, IDB.Image_width, IDB.Image_height,
+                         (IDB.Indicator & 0x40) ? "interlaced " : "", (IDB.Indicator & 0x80) ? "" : "no ",
+                         (IDB.Indicator & 7) + 1);
+                // Palette locale dispo = (IDB.Indicator and $80)
+                // Image entrelacée     = (IDB.Indicator and $40)
+                // Ordre de classement  = (IDB.Indicator and $20)
+                // Nombre de bits/pixel = (IDB.Indicator and $07)+1 (si palette locale dispo)
+
+                if (IDB.Indicator & 0x80)
+                {
+                  // Palette locale dispo
+
+                  if (Config.Clear_palette)
+                    memset(context->Palette,0,sizeof(T_Palette));
+
+                  nb_colors=(1 << ((IDB.Indicator & 0x07)+1));
+                  // Load the palette
+                  for(color_index=0;color_index<nb_colors;color_index++)
+                  {
+                    Read_byte(GIF_file,&(context->Palette[color_index].R));
+                    Read_byte(GIF_file,&(context->Palette[color_index].G));
+                    Read_byte(GIF_file,&(context->Palette[color_index].B));
+                  }
+
+                }
+                if (number_LID!=1)
+                {
+                  // This a second layer/frame, or more.
+                  if (context->Type == CONTEXT_MAIN_IMAGE && Main.backups->Pages->Image_mode == IMAGE_MODE_ANIMATION)
+                  {
+                    // Need to clear previous image to back-color.
+                    if (previous_disposal_method==DISPOSAL_METHOD_RESTORE_BGCOLOR)
+                    {
+                      int y;
+                      for (y=0; y<previous_height; y++)
+                        memset(
+                          Main.backups->Pages->Image[Main.current_layer].Pixels
+                           + (previous_pos_y+y)* Main.backups->Pages->Width+previous_pos_x,
+                          is_transparent ? context->Transparent_color : LSDB.Backcol,
+                          previous_width);
+                    }
+                  }
+                }
+                previous_height=IDB.Image_height;
+                previous_width=IDB.Image_width;
+                previous_pos_x=IDB.Pos_X;
+                previous_pos_y=IDB.Pos_Y;
+
+                File_error=0;
+                if (!Read_byte(GIF_file,&(initial_nb_bits)))
+                  File_error=1;
+
+                value_clr    =(1<<initial_nb_bits)+0;
+                value_eof    =(1<<initial_nb_bits)+1;
+                alphabet_free=(1<<initial_nb_bits)+2;
+
+                GIF.nb_bits  =initial_nb_bits + 1;
+                alphabet_max      =((1 <<  GIF.nb_bits)-1);
+                GIF.interlaced    =(IDB.Indicator & 0x40);
+                GIF.pass         =0;
+
+                /*Init_lecture();*/
+
+
+                GIF.stop = 0;
+
+                //////////////////////////////////////////// DECOMPRESSION LZW //
+
+                GIF.pos_X=0;
+                GIF.pos_Y=0;
+                alphabet_stack_pos=0;
+                GIF.last_byte    =0;
+                GIF.remainder_bits    =0;
+                GIF.remainder_byte    =0;
+
+                while ( (GIF_get_next_code(GIF_file, &GIF)!=value_eof) && (!File_error) )
+                {
+                  if (GIF.current_code > alphabet_free)
+                  {
+                    GFX2_Log(GFX2_INFO, "Load_GIF() Invalid code %u (should be <=%u)\n", GIF.current_code, alphabet_free);
+                    File_error=2;
+                    break;
+                  }
+                  else if (GIF.current_code != value_clr)
+                  {
+                    byte_read = GIF.current_code;
+                    if (alphabet_free == GIF.current_code)
+                    {
+                      GIF.current_code=old_code;
+                      alphabet_stack[alphabet_stack_pos++]=special_case;
+                    }
+
+                    while (GIF.current_code > value_clr)
+                    {
+                      if (GIF.current_code >= 4096)
+                      {
+                        GFX2_Log(GFX2_ERROR, "Load_GIF() GIF.current_code = %u >= 4096\n", GIF.current_code);
+                        File_error = 2;
+                        break;
+                      }
+                      alphabet_stack[alphabet_stack_pos++] = alphabet_suffix[GIF.current_code];
+                      GIF.current_code = alphabet_prefix[GIF.current_code];
+                    }
+
+                    special_case = alphabet_stack[alphabet_stack_pos++] = GIF.current_code;
+
+                    do
+                      GIF_new_pixel(context, &GIF, &IDB, is_transparent, alphabet_stack[--alphabet_stack_pos]);
+                    while (alphabet_stack_pos!=0);
+
+                    alphabet_prefix[alphabet_free  ]=old_code;
+                    alphabet_suffix[alphabet_free++]=GIF.current_code;
+                    old_code=byte_read;
+
+                    if (alphabet_free>alphabet_max)
+                    {
+                      if (GIF.nb_bits<12)
+                        alphabet_max      =((1 << (++GIF.nb_bits))-1);
+                    }
+                  }
+                  else // Clear code
+                  {
+                    GIF.nb_bits   = initial_nb_bits + 1;
+                    alphabet_max  = ((1 <<  GIF.nb_bits)-1);
+                    alphabet_free = (1<<initial_nb_bits)+2;
+                    special_case  = GIF_get_next_code(GIF_file, &GIF);
+                    if (GIF.current_code >= value_clr)
+                    {
+                      GFX2_Log(GFX2_INFO, "Load_GIF() Invalid code %u just after clear (=%u)!\n",
+                               GIF.current_code, value_clr);
+                      File_error = 2;
+                      break;
+                    }
+                    old_code      = GIF.current_code;
+                    GIF_new_pixel(context, &GIF, &IDB, is_transparent, GIF.current_code);
+                  }
+                }
+
+                if (File_error == 2 && GIF.pos_X == 0 && GIF.pos_Y == IDB.Image_height)
+                  File_error=0;
+
+                if (File_error >= 0 && !GIF.stop)
+                  File_error=2;
+
+                // No need to read more than one frame in animation preview mode
+                if (context->Type == CONTEXT_PREVIEW && is_looping)
+                {
+                  goto early_exit;
+                }
+                // Same with brush
+                if (context->Type == CONTEXT_BRUSH && is_looping)
+                {
+                  goto early_exit;
+                }
+
+              } // Le fichier contenait un IDB
+              else
+                File_error=2;
+            }
+            default:
+            break;
+          }
+          // Lecture du code de fonction suivant:
+          if (!Read_byte(GIF_file,&block_identifier))
+            File_error=2;
+        }
+
+        // set the mode that have been read previously.
+        if (image_mode > 0)
+          Set_image_mode(context, image_mode);
+      } // Le fichier contenait un LSDB
+      else
+        File_error=1;
+
+      early_exit:
+
+      // Libération de la mémoire utilisée par les tables & piles de traitement:
+      free(alphabet_suffix);
+      free(alphabet_prefix);
+      free(alphabet_stack);
+      alphabet_suffix = alphabet_prefix = alphabet_stack = NULL;
+    } // Le fichier contenait au moins la signature GIF87a ou GIF89a
+    else
+      File_error=1;
+
+    fclose(GIF_file);
+
+  } // Le fichier était ouvrable
+  else
+    File_error=1;
+}
+
+
+// -- Sauver un fichier au format GIF ---------------------------------------
+
+/// Flush the buffer
+static void GIF_empty_buffer(FILE * file, T_GIF_context *gif, byte * GIF_buffer)
+{
+  word index;
+
+  if (gif->remainder_byte)
+  {
+    GIF_buffer[0] = gif->remainder_byte;
+
+    for (index = 0; index <= gif->remainder_byte; index++)
+      Write_one_byte(file, GIF_buffer[index]);
+
+    gif->remainder_byte=0;
+  }
+}
+
+/// Write a code (GIF_nb_bits bits)
+static void GIF_set_code(FILE * GIF_file, T_GIF_context * gif, byte * GIF_buffer, word Code)
+{
+  word nb_bits_to_process = gif->nb_bits;
+  word nb_bits_processed  =0;
+  word current_nb_bits;
+
+  while (nb_bits_to_process)
+  {
+    current_nb_bits = (nb_bits_to_process <= (8-gif->remainder_bits)) ?
+                          nb_bits_to_process: (8-gif->remainder_bits);
+
+    gif->last_byte |= (Code & ((1<<current_nb_bits)-1))<<gif->remainder_bits;
+    Code>>=current_nb_bits;
+    gif->remainder_bits    +=current_nb_bits;
+    nb_bits_processed  +=current_nb_bits;
+    nb_bits_to_process-=current_nb_bits;
+
+    if (gif->remainder_bits==8) // Il ne reste plus de bits à coder sur l'octet courant
+    {
+      // Ecrire l'octet à balancer:
+      GIF_buffer[++(gif->remainder_byte)] = gif->last_byte;
+
+      // Si on a atteint la fin du bloc de Raster Data
+      if (gif->remainder_byte==255)
+        // On doit vider le buffer qui est maintenant plein
+        GIF_empty_buffer(GIF_file, gif, GIF_buffer);
+
+      gif->last_byte=0;
+      gif->remainder_bits=0;
+    }
+  }
+}
+
+
+/// Read the next pixel
+static byte GIF_next_pixel(T_IO_Context *context, T_GIF_context *gif, T_GIF_IDB *idb)
+{
+  byte temp;
+
+  temp = Get_pixel(context, gif->pos_X, gif->pos_Y);
+
+  if (++gif->pos_X >= (idb->Image_width + idb->Pos_X))
+  {
+    gif->pos_X = idb->Pos_X;
+    if (++gif->pos_Y >= (idb->Image_height + idb->Pos_Y))
+      gif->stop = 1;
+  }
+
+  return temp;
+}
+
+
+/// Save a GIF file
+void Save_GIF(T_IO_Context * context)
+{
+  FILE * GIF_file;
+  byte GIF_buffer[256];   // buffer d'écriture de bloc de données compilées
+
+  word * alphabet_prefix;  // Table des préfixes des codes
+  word * alphabet_suffix;  // Table des suffixes des codes
+  word * alphabet_daughter;    // Table des chaînes filles (plus longues)
+  word * alphabet_sister;    // Table des chaînes soeurs (même longueur)
+  word   alphabet_free;     // Position libre dans l'alphabet
+  word   alphabet_max;      // Nombre d'entrées possibles dans l'alphabet
+  word   start;            // Code précédent (sert au linkage des chaînes)
+  int    descend;          // Booléen "On vient de descendre"
+
+  T_GIF_context GIF;
+  T_GIF_LSDB LSDB;
+  T_GIF_IDB IDB;
+
+
+  byte block_identifier;  // Code indicateur du type de bloc en cours
+  word current_string;   // Code de la chaîne en cours de traitement
+  byte current_char;         // Caractère à coder
+  word index;            // index de recherche de chaîne
+  int current_layer;
+
+  word clear;   // LZW clear code
+  word eof;     // End of image code
+
+  /////////////////////////////////////////////////// FIN DES DECLARATIONS //
+
+  File_error=0;
+
+  if ((GIF_file=Open_file_write(context)))
+  {
+    setvbuf(GIF_file, NULL, _IOFBF, 64*1024);
+
+    // On écrit la signature du fichier
+    if (Write_bytes(GIF_file,"GIF89a",6))
+    {
+      // La signature du fichier a été correctement écrite.
+
+      // Allocation de mémoire pour les tables
+      alphabet_prefix = (word *)GFX2_malloc(4096*sizeof(word));
+      alphabet_suffix = (word *)GFX2_malloc(4096*sizeof(word));
+      alphabet_daughter = (word *)GFX2_malloc(4096*sizeof(word));
+      alphabet_sister = (word *)GFX2_malloc(4096*sizeof(word));
+
+      // On initialise le LSDB du fichier
+      if (Config.Screen_size_in_GIF)
+      {
+        LSDB.Width=Screen_width;
+        LSDB.Height=Screen_height;
+      }
+      else
+      {
+        LSDB.Width=context->Width;
+        LSDB.Height=context->Height;
+      }
+      LSDB.Resol  = 0xF7;  // Global palette of 256 entries, 256 color image
+      // 0xF7 = 1111 0111
+      // <Packed Fields>  =      Global Color Table Flag       1 Bit
+      //                         Color Resolution              3 Bits
+      //                         Sort Flag                     1 Bit
+      //                         Size of Global Color Table    3 Bits
+      LSDB.Backcol=context->Transparent_color;
+      switch(context->Ratio)
+      {
+        case PIXEL_TALL:
+        case PIXEL_TALL2:
+          LSDB.Aspect = 17; // 1:2 = 2:4
+          break;
+        case PIXEL_TALL3:
+          LSDB.Aspect = 33; // 3:4
+          break;
+        case PIXEL_WIDE:
+        case PIXEL_WIDE2:
+          LSDB.Aspect = 113; // 2:1 = 4:2
+          break;
+        default:
+          LSDB.Aspect = 0; // undefined, which is most frequent.
+          // 49 would be 1:1 ratio
+      }
+
+      // On sauve le LSDB dans le fichier
+
+      if (Write_word_le(GIF_file,LSDB.Width) &&
+          Write_word_le(GIF_file,LSDB.Height) &&
+          Write_byte(GIF_file,LSDB.Resol) &&
+          Write_byte(GIF_file,LSDB.Backcol) &&
+          Write_byte(GIF_file,LSDB.Aspect) )
+      {
+        // Le LSDB a été correctement écrit.
+        int i;
+        // On sauve la palette
+        for(i=0;i<256 && !File_error;i++)
+        {
+          if (!Write_byte(GIF_file,context->Palette[i].R)
+            ||!Write_byte(GIF_file,context->Palette[i].G)
+            ||!Write_byte(GIF_file,context->Palette[i].B))
+            File_error=1;
+        }
+        if (!File_error)
+        {
+          // La palette a été correctement écrite.
+
+          /// - "Netscape" animation extension :
+          /// <pre>
+          ///   0x21       Extension Label
+          ///   0xFF       Application Extension Label
+          ///   0x0B       Block Size
+          ///   "NETSCAPE" Application Identifier (8 bytes)
+          ///   "2.0"      Application Authentication Code (3 bytes)
+          ///   0x03       Sub-block Data Size
+          ///   0xLL       01 to loop
+          ///   0xSSSS     (little endian) number of loops, 0 means infinite loop
+          ///   0x00 Block terminator </pre>
+          /// see http://www.vurdalakov.net/misc/gif/netscape-looping-application-extension
+          if (context->Type == CONTEXT_MAIN_IMAGE && Main.backups->Pages->Image_mode == IMAGE_MODE_ANIMATION)
+          {
+            if (context->Nb_layers>1)
+              Write_bytes(GIF_file,"\x21\xFF\x0BNETSCAPE2.0\x03\x01\x00\x00\x00",19);
+          }
+          else if (context->Type == CONTEXT_MAIN_IMAGE && Main.backups->Pages->Image_mode > IMAGE_MODE_ANIMATION)
+          {
+            /// - GrafX2 extension to store ::IMAGE_MODES :
+            /// <pre>
+            ///   0x21       Extension Label
+            ///   0xFF       Application Extension Label
+            ///   0x0B       Block Size
+            ///   "GFX2MODE" Application Identifier (8 bytes)
+            ///   "2.6"      Application Authentication Code (3 bytes)
+            ///   0xll       Sub-block Data Size
+            ///   string     label
+            ///   0x00 Block terminator </pre>
+            /// @see Constraint_mode_label()
+            const char * label = Constraint_mode_label(Main.backups->Pages->Image_mode);
+            if (label != NULL)
+            {
+              size_t len = strlen(label);
+              // Write extension for storing IMAGE_MODE
+              Write_byte(GIF_file,0x21);  // Extension Introducer
+              Write_byte(GIF_file,0xff);  // Extension Label
+              Write_byte(GIF_file,  11);  // Block size
+              Write_bytes(GIF_file, "GFX2MODE2.6", 11); // Application Identifier + Appl. Authentication Code
+              Write_byte(GIF_file, (byte)len);    // Block size
+              Write_bytes(GIF_file, label, len);  // Data
+              Write_byte(GIF_file, 0);    // Block terminator
+            }
+          }
+
+          // Ecriture du commentaire
+          if (context->Comment[0])
+          {
+            Write_bytes(GIF_file,"\x21\xFE",2);
+            Write_byte(GIF_file, (byte)strlen(context->Comment));
+            Write_bytes(GIF_file,context->Comment,strlen(context->Comment)+1);
+          }
+          /// - "CRNG" Color cycing extension :
+          /// <pre>
+          ///   0x21       Extension Label
+          ///   0xFF       Application Extension Label
+          ///   0x0B       Block Size
+          ///   "CRNG\0\0\0\0" "CRNG" Application Identifier (8 bytes)
+          ///   "1.0"      Application Authentication Code (3 bytes)
+          ///   0xll       Sub-block Data Size (6 bytes per color cycle)
+          ///   For each color cycle :
+          ///     0xRRRR   (big endian) Rate
+          ///     0xFFFF   (big endian) Flags
+          ///     0xSS     start (lower color index)
+          ///     0xEE     end (higher color index)
+          ///   0x00       Block terminator </pre>
+          if (context->Color_cycles)
+          {
+            int i;
+
+            Write_bytes(GIF_file,"\x21\xff\x0B" "CRNG\0\0\0\0" "1.0",14);
+            Write_byte(GIF_file,context->Color_cycles*6);
+            for (i=0; i<context->Color_cycles; i++)
+            {
+              word flags=0;
+              flags|= context->Cycle_range[i].Speed?1:0; // Cycling or not
+              flags|= context->Cycle_range[i].Inverse?2:0; // Inverted
+
+              Write_word_be(GIF_file,context->Cycle_range[i].Speed*78); // Rate
+              Write_word_be(GIF_file,flags); // Flags
+              Write_byte(GIF_file,context->Cycle_range[i].Start); // Min color
+              Write_byte(GIF_file,context->Cycle_range[i].End); // Max color
+            }
+            Write_byte(GIF_file,0);
+          }
+
+          // Loop on all layers
+          for (current_layer=0;
+            current_layer < context->Nb_layers && !File_error;
+            current_layer++)
+          {
+            // Write a Graphic Control Extension
+            T_GIF_GCE GCE;
+            byte disposal_method;
+
+            Set_saving_layer(context, current_layer);
+
+            GCE.Block_identifier = 0x21;
+            GCE.Function = 0xF9;
+            GCE.Block_size=4;
+
+            if (context->Type == CONTEXT_MAIN_IMAGE && Main.backups->Pages->Image_mode == IMAGE_MODE_ANIMATION)
+            {
+              // Animation frame
+              int duration;
+              if(context->Background_transparent)
+                disposal_method = DISPOSAL_METHOD_RESTORE_BGCOLOR;
+              else
+                disposal_method = DISPOSAL_METHOD_DO_NOT_DISPOSE;
+              GCE.Packed_fields=(disposal_method<<2)|(context->Background_transparent);
+              duration=Get_frame_duration(context)/10;
+              GCE.Delay_time=duration<0xFFFF?duration:0xFFFF;
+            }
+            else
+            {
+              // Layered image or brush
+              disposal_method = DISPOSAL_METHOD_DO_NOT_DISPOSE;
+              if (current_layer==0)
+                GCE.Packed_fields=(disposal_method<<2)|(context->Background_transparent);
+              else
+                GCE.Packed_fields=(disposal_method<<2)|(1);
+              GCE.Delay_time=5; // Duration 5/100s (minimum viable value for current web browsers)
+              if (current_layer == context->Nb_layers -1)
+                GCE.Delay_time=0xFFFF; // Infinity (10 minutes)
+            }
+            GCE.Transparent_color=context->Transparent_color;
+            GCE.Block_terminator=0x00;
+
+            if (Write_byte(GIF_file,GCE.Block_identifier)
+             && Write_byte(GIF_file,GCE.Function)
+             && Write_byte(GIF_file,GCE.Block_size)
+             && Write_byte(GIF_file,GCE.Packed_fields)
+             && Write_word_le(GIF_file,GCE.Delay_time)
+             && Write_byte(GIF_file,GCE.Transparent_color)
+             && Write_byte(GIF_file,GCE.Block_terminator)
+             )
+            {
+              byte temp, max = 0;
+
+              IDB.Pos_X=0;
+              IDB.Pos_Y=0;
+              IDB.Image_width=context->Width;
+              IDB.Image_height=context->Height;
+              if(current_layer > 0)
+              {
+                word min_X, max_X, min_Y, max_Y;
+                // find bounding box of changes for Animated GIFs
+                min_X = min_Y = 0xffff;
+                max_X = max_Y = 0;
+                for(GIF.pos_Y = 0; GIF.pos_Y < context->Height; GIF.pos_Y++) {
+                  for(GIF.pos_X = 0; GIF.pos_X < context->Width; GIF.pos_X++) {
+                    if (GIF.pos_X >= min_X && GIF.pos_X <= max_X && GIF.pos_Y >= min_Y && GIF.pos_Y <= max_Y)
+                      continue; // already in the box
+                    if(disposal_method == DISPOSAL_METHOD_DO_NOT_DISPOSE)
+                    {
+                      // if that pixel has same value in previous layer, no need to save it
+                      Set_saving_layer(context, current_layer - 1);
+                      temp = Get_pixel(context, GIF.pos_X, GIF.pos_Y);
+                      Set_saving_layer(context, current_layer);
+                      if(temp == Get_pixel(context, GIF.pos_X, GIF.pos_Y))
+                        continue;
+                    }
+                    if (disposal_method == DISPOSAL_METHOD_RESTORE_BGCOLOR
+                      || context->Background_transparent
+                      || Main.backups->Pages->Image_mode != IMAGE_MODE_ANIMATION)
+                    {
+                      // if that pixel is Backcol, no need to save it
+                      if (LSDB.Backcol == Get_pixel(context, GIF.pos_X, GIF.pos_Y))
+                        continue;
+                    }
+                    if(GIF.pos_X < min_X) min_X = GIF.pos_X;
+                    if(GIF.pos_X > max_X) max_X = GIF.pos_X;
+                    if(GIF.pos_Y < min_Y) min_Y = GIF.pos_Y;
+                    if(GIF.pos_Y > max_Y) max_Y = GIF.pos_Y;
+                  }
+                }
+                if((min_X <= max_X) && (min_Y <= max_Y))
+                {
+                  IDB.Pos_X = min_X;
+                  IDB.Pos_Y = min_Y;
+                  IDB.Image_width = max_X + 1 - min_X;
+                  IDB.Image_height = max_Y + 1 - min_Y;
+                }
+                else
+                {
+                  // if no pixel changes, store a 1 pixel image
+                  IDB.Image_width = 1;
+                  IDB.Image_height = 1;
+                }
+              }
+
+              // look for the maximum pixel value
+              // to decide how many bit per pixel are needed.
+              for(GIF.pos_Y = IDB.Pos_Y; GIF.pos_Y < IDB.Image_height + IDB.Pos_Y; GIF.pos_Y++) {
+                for(GIF.pos_X = IDB.Pos_X; GIF.pos_X < IDB.Image_width + IDB.Pos_X; GIF.pos_X++) {
+                  temp=Get_pixel(context, GIF.pos_X, GIF.pos_Y);
+                  if(temp > max) max = temp;
+                }
+              }
+              IDB.Nb_bits_pixel=2;  // Find the minimum bpp value to fit all pixels
+              while((int)max >= (1 << IDB.Nb_bits_pixel)) {
+                IDB.Nb_bits_pixel++;
+              }
+              GFX2_Log(GFX2_DEBUG, "GIF image #%d %ubits (%u,%u) %ux%u\n",
+                       current_layer, IDB.Nb_bits_pixel, IDB.Pos_X, IDB.Pos_Y,
+                       IDB.Image_width, IDB.Image_height);
+
+              // On va écrire un block indicateur d'IDB et l'IDB du fichier
+              block_identifier=0x2C;
+              IDB.Indicator=0x07;    // Image non entrelacée, pas de palette locale.
+              clear = 1 << IDB.Nb_bits_pixel; // Clear Code
+              eof = clear + 1;                // End of Picture Code
+
+              if ( Write_byte(GIF_file,block_identifier) &&
+                   Write_word_le(GIF_file,IDB.Pos_X) &&
+                   Write_word_le(GIF_file,IDB.Pos_Y) &&
+                   Write_word_le(GIF_file,IDB.Image_width) &&
+                   Write_word_le(GIF_file,IDB.Image_height) &&
+                   Write_byte(GIF_file,IDB.Indicator) &&
+                   Write_byte(GIF_file,IDB.Nb_bits_pixel))
+              {
+                //   Le block indicateur d'IDB et l'IDB ont étés correctements
+                // écrits.
+
+                GIF.pos_X=IDB.Pos_X;
+                GIF.pos_Y=IDB.Pos_Y;
+                GIF.last_byte=0;
+                GIF.remainder_bits=0;
+                GIF.remainder_byte=0;
+
+#define GIF_INVALID_CODE (65535)
+                index=GIF_INVALID_CODE;
+                File_error=0;
+                GIF.stop=0;
+
+                // Réintialisation de la table:
+                alphabet_free=clear + 2;  // 258 for 8bpp
+                GIF.nb_bits  =IDB.Nb_bits_pixel + 1; // 9 for 8 bpp
+                alphabet_max =clear+clear-1;  // 511 for 8bpp
+                GIF_set_code(GIF_file, &GIF, GIF_buffer, clear);  //256 for 8bpp
+                for (start=0;start<4096;start++)
+                {
+                  alphabet_daughter[start] = GIF_INVALID_CODE;
+                  alphabet_sister[start] = GIF_INVALID_CODE;
+                }
+
+                ////////////////////////////////////////////// COMPRESSION LZW //
+
+                start=current_string=GIF_next_pixel(context, &GIF, &IDB);
+                descend=1;
+
+                while ((!GIF.stop) && (!File_error))
+                {
+                  current_char=GIF_next_pixel(context, &GIF, &IDB);
+
+                  // look for (current_string,current_char) in the alphabet
+                  while ( (index != GIF_INVALID_CODE) &&
+                          ( (current_string!=alphabet_prefix[index]) ||
+                            (current_char      !=alphabet_suffix[index]) ) )
+                  {
+                    descend=0;
+                    start=index;
+                    index=alphabet_sister[index];
+                  }
+
+                  if (index != GIF_INVALID_CODE)
+                  {
+                    // (current_string,current_char) == (alphabet_prefix,alphabet_suffix)[index]
+                    // We have found (current_string,current_char) in the alphabet
+                    // at the index position. So go on and prepare for then next character
+
+                    descend=1;
+                    start=current_string=index;
+                    index=alphabet_daughter[index];
+                  }
+                  else
+                  {
+                    // (current_string,current_char) was not found in the alphabet
+                    // so write current_string to the Gif stream
+                    GIF_set_code(GIF_file, &GIF, GIF_buffer, current_string);
+
+                    if(alphabet_free < 4096) {
+                      // link current_string and the new one
+                      if (descend)
+                        alphabet_daughter[start]=alphabet_free;
+                      else
+                        alphabet_sister[start]=alphabet_free;
+
+                      // add (current_string,current_char) to the alphabet
+                      alphabet_prefix[alphabet_free]=current_string;
+                      alphabet_suffix[alphabet_free]=current_char;
+                      alphabet_free++;
+                    }
+
+                    if (alphabet_free >= 4096)
+                    {
+                      // clear alphabet
+                      GIF_set_code(GIF_file, &GIF, GIF_buffer, clear);    // 256 for 8bpp
+                      alphabet_free=clear+2;  // 258 for 8bpp
+                      GIF.nb_bits  =IDB.Nb_bits_pixel + 1;  // 9 for 8bpp
+                      alphabet_max =clear+clear-1;    // 511 for 8bpp
+                      for (start=0;start<4096;start++)
+                      {
+                        alphabet_daughter[start] = GIF_INVALID_CODE;
+                        alphabet_sister[start] = GIF_INVALID_CODE;
+                      }
+                    }
+                    else if (alphabet_free>alphabet_max+1)
+                    {
+                      // On augmente le nb de bits
+
+                      GIF.nb_bits++;
+                      alphabet_max = (1<<GIF.nb_bits)-1;
+                    }
+
+                    // initialize current_string as the string "current_char"
+                    index=alphabet_daughter[current_char];
+                    start=current_string=current_char;
+                    descend=1;
+                  }
+                }
+
+                if (!File_error)
+                {
+                  // Write the last code (before EOF)
+                  GIF_set_code(GIF_file, &GIF, GIF_buffer, current_string);
+
+                  // we need to update alphabet_free / GIF.nb_bits here because
+                  // the decoder will update them after each code,
+                  // so in very rare cases there might be a problem if we
+                  // don't do it.
+                  // see http://pulkomandy.tk/projects/GrafX2/ticket/125
+                  if(alphabet_free < 4096)
+                  {
+                    alphabet_free++;
+                    if ((alphabet_free > alphabet_max+1) && (GIF.nb_bits < 12))
+                    {
+                      GIF.nb_bits++;
+                      alphabet_max = (1 << GIF.nb_bits) - 1;
+                    }
+                  }
+
+                  GIF_set_code(GIF_file, &GIF, GIF_buffer, eof);  // 257 for 8bpp    // Code de End d'image
+                  if (GIF.remainder_bits!=0)
+                  {
+                    // Write last byte (this is an incomplete byte)
+                    GIF_buffer[++GIF.remainder_byte]=GIF.last_byte;
+                    GIF.last_byte=0;
+                    GIF.remainder_bits=0;
+                  }
+                  GIF_empty_buffer(GIF_file, &GIF, GIF_buffer); // On envoie les dernières données du buffer GIF dans le buffer KM
+
+                  // On écrit un \0
+                  if (! Write_byte(GIF_file,'\x00'))
+                    File_error=1;
+                }
+
+              } // On a pu écrire l'IDB
+              else
+                File_error=1;
+            }
+            else
+              File_error=1;
+          }
+
+          // After writing all layers
+          if (!File_error)
+          {
+            /// - If requested, write a specific extension for storing
+            /// original file path.
+            /// This is used by the backup system.
+            /// The format is :
+            /// <pre>
+            ///   0x21       Extension Label
+            ///   0xFF       Application Extension Label
+            ///   0x0B       Block Size
+            ///   "GFX2PATH" "GFX2PATH" Application Identifier (8 bytes)
+            ///   "\0\0\0"   Application Authentication Code (3 bytes)
+            ///   0xll       Sub-block Data Size : path size (including null)
+            ///   "..path.." path (null-terminated)
+            ///   0xll       Sub-block Data Size : filename size (including null)
+            ///   "..file.." file name (null-terminated)
+            ///   0x00       Block terminator </pre>
+            if (context->Original_file_name != NULL
+             && context->Original_file_directory != NULL)
+            {
+              long name_size = 1+strlen(context->Original_file_name);
+              long dir_size = 1+strlen(context->Original_file_directory);
+              if (name_size<256 && dir_size<256)
+              {
+                if (! Write_bytes(GIF_file,"\x21\xFF\x0BGFX2PATH\x00\x00\x00", 14)
+                || ! Write_byte(GIF_file,dir_size)
+                || ! Write_bytes(GIF_file, context->Original_file_directory, dir_size)
+                || ! Write_byte(GIF_file,name_size)
+                || ! Write_bytes(GIF_file, context->Original_file_name, name_size)
+                || ! Write_byte(GIF_file,0))
+                  File_error=1;
+              }
+            }
+
+            // On écrit un GIF TERMINATOR, exigé par SVGA et SEA.
+            if (! Write_byte(GIF_file,'\x3B'))
+              File_error=1;
+          }
+
+        } // On a pu écrire la palette
+        else
+          File_error=1;
+
+      } // On a pu écrire le LSDB
+      else
+        File_error=1;
+
+      // Libération de la mémoire utilisée par les tables
+      free(alphabet_sister);
+      free(alphabet_daughter);
+      free(alphabet_suffix);
+      free(alphabet_prefix);
+
+    } // On a pu écrire la signature du fichier
+    else
+      File_error=1;
+
+    fclose(GIF_file);
+    if (File_error)
+      Remove_file(context);
+
+  } // On a pu ouvrir le fichier en écriture
+  else
+    File_error=1;
+
+}
+
+/* @} */