Lua: matchcolor2() now takes an optional argument that is the weight of lightness in color proximity algorithm (instead of the 0.25 default).

git-svn-id: svn://pulkomandy.tk/GrafX2/trunk@1821 416bcca6-2ee7-4201-b75f-2eb2f807beb1

src/factory.c

@@ -711,12 +711,23 @@ int L_MatchColor2(lua_State* L)
   int c;
   int nb_args=lua_gettop(L);
 
-  LUA_ARG_LIMIT (3, "matchcolor2");
+  if (nb_args < 3 || nb_args > 4)
+  {
+    return luaL_error(L, "matchcolor2: Expected 3 or 4 arguments, but found %d.", nb_args);
+  }
   LUA_ARG_NUMBER(1, "matchcolor2", r, -DBL_MAX, DBL_MAX);
   LUA_ARG_NUMBER(2, "matchcolor2", g, -DBL_MAX, DBL_MAX);
   LUA_ARG_NUMBER(3, "matchcolor2", b, -DBL_MAX, DBL_MAX);
-  
+  if (nb_args == 3)
+  {
     c = Best_color_perceptual(clamp_byte(r),clamp_byte(g),clamp_byte(b));
+  }
+  else // nb_args == 4
+  {
+    float weight;
+    LUA_ARG_NUMBER(4, "matchcolor2", weight, -DBL_MAX, DBL_MAX);
+    c = Best_color_perceptual_weighted(clamp_byte(r),clamp_byte(g),clamp_byte(b),weight);
+  }   
   lua_pushinteger(L, c);
   return 1;
 }

src/windows.c

@@ -2720,6 +2720,49 @@ byte Best_color_perceptual(byte r,byte g,byte b)
   return best_color;
 }
 
+byte Best_color_perceptual_weighted(byte r,byte g,byte b,float l_weight)
+{
+  
+  int col;  
+  float best_diff=255.0*1.56905;
+  byte  best_color=0;
+  float target_bri;
+  float bri;
+  float diff_b, diff_c, diff;
+
+  // Similar to Perceptual_lightness();
+  target_bri = sqrt(0.26*r*0.26*r + 0.55*g*0.55*g + 0.19*b*0.19*b);
+  
+  for (col=0; col<256; col++)
+  {
+    if (Exclude_color[col])
+      continue;
+
+    diff_c = sqrt(
+      (0.26*(Main_palette[col].R-r))*
+      (0.26*(Main_palette[col].R-r))+
+      (0.55*(Main_palette[col].G-g))*
+      (0.55*(Main_palette[col].G-g))+
+      (0.19*(Main_palette[col].B-b))*
+      (0.19*(Main_palette[col].B-b)));
+    // Exact match
+    if (diff_c==0)
+      return col;
+
+    bri = sqrt(0.26*Main_palette[col].R*0.26*Main_palette[col].R + 0.55*Main_palette[col].G*0.55*Main_palette[col].G + 0.19*Main_palette[col].B*0.19*Main_palette[col].B);
+    diff_b = abs(target_bri-bri);
+
+    diff=l_weight*(diff_b-diff_c)+diff_c;
+    if (diff<best_diff)
+    {
+      best_diff=diff;
+      best_color=col;
+    } 
+  }
+
+  return best_color;
+}
+
 byte Best_color_perceptual_except(byte r,byte g,byte b, byte except)
 {
   

src/windows.h

@@ -101,6 +101,7 @@ byte Best_color(byte red,byte green,byte blue);
 byte Best_color_nonexcluded(byte red,byte green,byte blue);
 byte Best_color_perceptual(byte r,byte g,byte b);
 byte Best_color_perceptual_except(byte r,byte g,byte b, byte except);
+byte Best_color_perceptual_weighted(byte r,byte g,byte b, float weight);
 
 void Horizontal_XOR_line_zoom(short x_pos, short y_pos, short width);
 void Vertical_XOR_line_zoom(short x_pos, short y_pos, short height);