GDK-Win32: Fixup, and cleanup WGL HDC handling

It turns out that the problem of the WGL window not drawing was due to
the fact that I messed up where I placed SwapBuffers() during the
conversion... doh:|

At the same time, stop storing the HDC in the GdkWin32GLContextWGL, but
instead always create it along the surface we created, so that it is ready
for use for operating with WGL when we are not dealing with "surfaceless"
contexts.  If we are dealing with "surfaceless" contexts, just use the
HDC of the dummy window that we created when we created the
Gdk(Win32)Display.

WGL contexts should now be in working order at this point.

gdk/win32/gdkglcontext-win32-wgl.c

@@ -46,8 +46,6 @@ struct _GdkWin32GLContextWGL
 {
   GdkWin32GLContext parent_instance;
 
-  HWND wgl_hwnd;
-  HDC wgl_hdc;
   HGLRC wgl_context;
   guint do_frame_sync : 1;
 };
@@ -70,8 +68,6 @@ gdk_win32_gl_context_wgl_dispose (GObject *gobject)
 
       wglDeleteContext (context_wgl->wgl_context);
       context_wgl->wgl_context = NULL;
-
-      ReleaseDC (context_wgl->wgl_hwnd, context_wgl->wgl_hdc);
     }
 
   G_OBJECT_CLASS (gdk_win32_gl_context_wgl_parent_class)->dispose (gobject);
@@ -84,8 +80,10 @@ gdk_win32_gl_context_wgl_end_frame (GdkDrawContext *draw_context,
   GdkGLContext *context = GDK_GL_CONTEXT (draw_context);
   GdkWin32GLContextWGL *context_wgl = GDK_WIN32_GL_CONTEXT_WGL (context);
   GdkSurface *surface = gdk_gl_context_get_surface (context);
-  GdkWin32Display *display = (GDK_WIN32_DISPLAY (gdk_gl_context_get_display (context)));
+  GdkWin32Display *display_win32 = (GDK_WIN32_DISPLAY (gdk_gl_context_get_display (context)));
   cairo_rectangle_int_t whole_window;
+  gboolean can_wait = display_win32->hasWglOMLSyncControl;
+  HDC hdc;
 
   GDK_DRAW_CONTEXT_CLASS (gdk_win32_gl_context_wgl_parent_class)->end_frame (draw_context, painted);
 
@@ -94,26 +92,31 @@ gdk_win32_gl_context_wgl_end_frame (GdkDrawContext *draw_context,
 
   gdk_profiler_add_mark (GDK_PROFILER_CURRENT_TIME, 0, "win32", "swap buffers");
 
-  gboolean can_wait = display->hasWglOMLSyncControl;
+  if (surface != NULL)
+    hdc = GDK_WIN32_SURFACE (surface)->hdc;
+  else
+    hdc = display_win32->dummy_context_wgl.hdc;
 
   if (context_wgl->do_frame_sync)
     {
+
       glFinish ();
 
       if (can_wait)
         {
           gint64 ust, msc, sbc;
 
-          wglGetSyncValuesOML (context_wgl->wgl_hdc, &ust, &msc, &sbc);
-          wglWaitForMscOML (context_wgl->wgl_hdc,
+          wglGetSyncValuesOML (hdc, &ust, &msc, &sbc);
+          wglWaitForMscOML (hdc,
                             0,
                             2,
                             (msc + 1) % 2,
                            &ust, &msc, &sbc);
         }
 
-      SwapBuffers (context_wgl->wgl_hdc);
     }
+
+  SwapBuffers (hdc);
 }
 
 static void
@@ -551,15 +554,9 @@ gdk_win32_gl_context_wgl_realize (GdkGLContext *context,
   compat_bit = gdk_gl_context_get_forward_compatible (context);
 
   if (surface != NULL)
-    {
-      hwnd = GDK_SURFACE_HWND (surface);
-      context_wgl->wgl_hdc = hdc = GetDC (hwnd);
-    }
+    hdc = GDK_WIN32_SURFACE (surface)->hdc;
   else
-    {
-      hwnd = display_win32->hwnd;
-      hdc = display_win32->dummy_context_wgl.hdc;
-    }
+    hdc = display_win32->dummy_context_wgl.hdc;
 
   /*
    * A legacy context cannot be shared with core profile ones, so this means we
@@ -642,13 +639,13 @@ gdk_win32_gl_context_wgl_make_current (GdkGLContext *context,
   GdkWin32GLContextWGL *context_wgl = GDK_WIN32_GL_CONTEXT_WGL (context);
   GdkDisplay *display = gdk_gl_context_get_display (context);
   GdkWin32Display *display_win32 = GDK_WIN32_DISPLAY (display);
-  GdkSurface *surface;
+  GdkSurface *surface = gdk_gl_context_get_surface (context);
   HDC hdc;
 
-  if (surfaceless)
+  if (surfaceless || surface == NULL)
     hdc = display_win32->dummy_context_wgl.hdc;
   else
-    hdc = context_wgl->wgl_hdc;
+    hdc = GDK_WIN32_SURFACE (surface)->hdc;
 
   if (!wglMakeCurrent (hdc, context_wgl->wgl_context))
     return FALSE;
@@ -656,7 +653,6 @@ gdk_win32_gl_context_wgl_make_current (GdkGLContext *context,
   if (!surfaceless && display_win32->hasWglEXTSwapControl)
     {
       gboolean do_frame_sync = FALSE;
-      GdkSurface *surface = gdk_gl_context_get_surface (context);
 
       /* If there is compositing there is no particular need to delay
        * the swap when drawing on the offscreen, rendering to the screen
@@ -696,12 +692,6 @@ gdk_win32_gl_context_wgl_init (GdkWin32GLContextWGL *wgl_context)
 {
 }
 
-void gdk_win32_gl_context_wgl_bind_surface (GdkWin32GLContextWGL *wgl_context,
-                                            GdkWin32Surface      *impl)
-{
-  wgl_context->wgl_hwnd = impl->handle;
-  wgl_context->wgl_hdc = GetDC (impl->handle);
-}
 
 /**
  * gdk_win32_display_get_wgl_version:

gdk/win32/gdksurface-win32.c

@@ -655,6 +655,7 @@ _gdk_win32_display_create_surface (GdkDisplay     *display,
                     impl);
 
   g_object_unref (frame_clock);
+  impl->hdc = GetDC (impl->handle);
 
   return surface;
 }