Added code to hook low-level keyboard events on 2K/XP/Vista.

The hook is only installed if in full-screen mode.
Filters out the left and right Windows keys to avoid accidentally dropping
out of full-screen mode.
If Tux Paint is deliberately switched to the background (using ALT-TAB, say)
the Windows keys function as normal until Tux Paint is the active
application again.

src/tuxpaint.c

@@ -6842,6 +6842,14 @@ static void setup(int argc, char *argv[])
     }
   }
 
+#ifdef _WIN32
+  if (fullscreen)
+  {
+    InstallKeyboardHook();
+    SetActivationState(1);
+  }
+#endif
+
   
   setup_language(getfilename(argv[0]), &button_label_y_nudge);
   im_init(&im_data, get_current_language());
@@ -14812,6 +14820,10 @@ void play_slideshow(int * selected, int num_selected, char * dirname,
 	    next = 1;
 	    done = 1;
 	  }
+          else if (event.type == SDL_ACTIVEEVENT)
+          {
+            handle_active(&event);
+          }
 	  else if (event.type == SDL_KEYDOWN)
 	  {
 	    key = event.key.keysym.sym;
@@ -16169,6 +16181,12 @@ static void handle_active(SDL_Event * event)
 	SDL_Flip(screen);
     }
   }
+#ifdef _WIN32
+  if (event->active.state & SDL_APPINPUTFOCUS|SDL_APPACTIVE)
+  {
+    SetActivationState(event->active.gain);
+  }
+#endif
 }
 
 

src/win32_print.c

@@ -589,3 +589,56 @@ char *get_temp_fname(const char *const name)
   return strdup(f);
 }
 
+/*
+ * Nasty low-level hook into the keyboard. 2K/XP/Vista only.
+ */
+
+static HHOOK g_hKeyboardHook = NULL;
+static int   g_bWindowActive = 0;
+
+LRESULT CALLBACK LowLevelKeyboardProc(int nCode, WPARAM wParam, LPARAM lParam)
+{
+  int bEatKeystroke = 0;
+  KBDLLHOOKSTRUCT *p = (KBDLLHOOKSTRUCT*)lParam;
+
+  if (nCode < 0 || nCode != HC_ACTION)
+    return CallNextHookEx(g_hKeyboardHook, nCode, wParam, lParam); 
+ 
+  switch (wParam) 
+  {
+    case WM_KEYDOWN:  
+    case WM_KEYUP:    
+    {
+      bEatKeystroke = g_bWindowActive && ((p->vkCode == VK_LWIN) || (p->vkCode == VK_RWIN));
+      break;
+    }
+  }
+ 
+  if(bEatKeystroke)
+    return 1;
+  return CallNextHookEx(g_hKeyboardHook, nCode, wParam, lParam);
+}
+
+int InstallKeyboardHook(void)
+{
+  if (g_hKeyboardHook)
+    return -1;
+  g_hKeyboardHook = SetWindowsHookEx(WH_KEYBOARD_LL, LowLevelKeyboardProc, GetModuleHandle(NULL), 0);
+  return g_hKeyboardHook ? 0 : -2;
+}
+
+int RemoveKeyboardHook(void)
+{
+  if (!g_hKeyboardHook)
+    return -1;
+  UnhookWindowsHookEx(g_hKeyboardHook);
+  g_hKeyboardHook = NULL;
+  return 0;
+}
+
+void SetActivationState(int state)
+{
+  g_bWindowActive = state;
+}
+
+

src/win32_print.h

@@ -24,4 +24,9 @@ extern char *GetDefaultSaveDir(const char *suffix);
 extern char *GetSystemFontDir(void);
 extern char *get_temp_fname(const char *const name);
 
+/* keyboard hooking functions */
+extern int  InstallKeyboardHook(void);
+extern int  RemoveKeyboardHook(void);
+extern void SetActivationState(int state);
+
 #endif