From 7fc318a856a8c6148ab2a68cdbf989b7e6ae7117 Mon Sep 17 00:00:00 2001
From: Yves Rizoud <yrizoud@gmail.com>
Date: Wed, 15 Jul 2009 18:50:25 +0000
Subject: [PATCH] Experimental work on mouse locking with shift (issue 193).
 Consider unstable.

git-svn-id: svn://pulkomandy.tk/GrafX2/trunk@921 416bcca6-2ee7-4201-b75f-2eb2f807beb1
---
 input.c   | 21 ++++++++++++++++++---
 input.h   |  9 ++++++++-
 windows.c | 41 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 67 insertions(+), 4 deletions(-)

diff --git a/input.c b/input.c
index 6ffc6f07..34148178 100644
--- a/input.c
+++ b/input.c
@@ -31,7 +31,14 @@
 void Handle_window_resize(SDL_ResizeEvent event);
 void Handle_window_exit(SDL_QuitEvent event);
 
+// public Globals (available as extern)
+
 int Input_sticky_control = 0;
+int Snap_axis = 0;
+int Snap_axis_origin_X;
+int Snap_axis_origin_Y;
+
+// --
 
 byte Directional_up;
 byte Directional_up_right;
@@ -357,6 +364,14 @@ int Handle_key_press(SDL_KeyboardEvent event)
 
 int Release_control(int key_code, int modifier)
 {
+    int need_feedback = 0;
+
+    if (modifier == MOD_SHIFT)
+    {
+      // Disable "snap axis" mode
+      Snap_axis = 0;
+      need_feedback = 1;
+    }
 
     if((key_code && key_code == (Config_Key[SPECIAL_MOUSE_UP][0]&0x0FFF)) || (Config_Key[SPECIAL_MOUSE_UP][0]&modifier) ||
       (key_code && key_code == (Config_Key[SPECIAL_MOUSE_UP][1]&0x0FFF)) || (Config_Key[SPECIAL_MOUSE_UP][1]&modifier))
@@ -385,7 +400,7 @@ int Release_control(int key_code, int modifier)
         {
             Directional_click &= ~1;
             Input_new_mouse_K &= ~1;
-            return Move_cursor_with_constraints();
+            return Move_cursor_with_constraints() || need_feedback;
         }
     }
     if((key_code && key_code == (Config_Key[SPECIAL_CLICK_RIGHT][0]&0x0FFF)) || (Config_Key[SPECIAL_CLICK_RIGHT][0]&modifier) ||
@@ -395,14 +410,14 @@ int Release_control(int key_code, int modifier)
         {
             Directional_click &= ~2;
             Input_new_mouse_K &= ~2;
-            return Move_cursor_with_constraints();
+            return Move_cursor_with_constraints() || need_feedback;
         }
     }
   
     // Other keys don't need to be released : they are handled as "events" and procesed only once.
     // These clicks are apart because they need to be continuous (ie move while key pressed)
     // We are relying on "hardware" keyrepeat to achieve that.
-    return 0;
+    return need_feedback;
 }
 
 
diff --git a/input.h b/input.h
index 8a70ca8f..c6f68f23 100644
--- a/input.h
+++ b/input.h
@@ -46,4 +46,11 @@ void Set_mouse_position(void);
 /// is manipulating. The input system will reset it to zero 
 /// when mouse button is released, but it's the engine
 /// that will record and retrieve a real control ID.
-extern int Input_sticky_control;
\ No newline at end of file
+extern int Input_sticky_control;
+
+/// Allows locking movement to X or Y axis: 0=normal, 1=lock on next move, 2=locked horizontally, 3=locked vertically.
+extern int Snap_axis;
+/// For the :Snap_axis mode, sets the origin's point (in image coordinates)
+extern int Snap_axis_origin_X;
+/// For the :Snap_axis mode, sets the origin's point (in image coordinates)
+extern int Snap_axis_origin_Y;
diff --git a/windows.c b/windows.c
index b7b29291..c91cc862 100644
--- a/windows.c
+++ b/windows.c
@@ -32,6 +32,7 @@
 #include "misc.h"
 #include "sdlscreen.h"
 #include "errors.h"
+#include "input.h"
 
 // L'encapsulation tente une percée...ou un dernier combat.
 
@@ -1275,6 +1276,46 @@ void Compute_paintbrush_coordinates(void)
     Paintbrush_X=(((Paintbrush_X+(Snap_width>>1)-Snap_offset_X)/Snap_width)*Snap_width)+Snap_offset_X;
     Paintbrush_Y=(((Paintbrush_Y+(Snap_height>>1)-Snap_offset_Y)/Snap_height)*Snap_height)+Snap_offset_Y;
   }
+  
+  // Handling the snap axis mode, when shift is pressed.
+  switch (Current_operation)
+  {
+    // Operations that don't implement it
+    case OPERATION_LINE:
+      Snap_axis=0;
+      break;
+    // Operations that implement it
+    default:
+      if (Snap_axis==0 && (SDL_GetModState() & KMOD_SHIFT))
+      {
+        // Start "Snap axis" mode
+        Snap_axis=1;
+        Snap_axis_origin_X=Paintbrush_X;
+        Snap_axis_origin_Y=Paintbrush_Y;
+      } 
+  }
+
+  if (Snap_axis==1)
+  {
+    // Cursor moved
+    if (Paintbrush_X != Snap_axis_origin_X || Paintbrush_Y != Snap_axis_origin_Y)
+    {
+      if ((Paintbrush_X-Snap_axis_origin_X)*(Paintbrush_X-Snap_axis_origin_X) >
+          (Paintbrush_Y-Snap_axis_origin_Y)*(Paintbrush_Y-Snap_axis_origin_Y))
+      // Displacement was bigger on X axis: lock Y
+        Snap_axis=2;
+      else
+        Snap_axis=3;
+    }
+  }
+  if (Snap_axis==2)
+  {
+    Paintbrush_Y = Snap_axis_origin_Y;
+  }
+  else if (Snap_axis==3)
+  {
+    Paintbrush_X = Snap_axis_origin_X;
+  }
 }