[gtk+/gtk-2-24] win32: Report ScrollDC update region directly

[Alexander Larsson <alexl src gnome org>]

commit ea66a8a580ad496dc375ce6afeb2ee29f585a7fb
Author: Alexander Larsson <alexl redhat com>
Date:   Wed Apr 10 14:25:26 2013 +0200

    win32: Report ScrollDC update region directly
    
    Rather than set the window update region and repaint this region
    when we get a WM_PAINT we just directly add it to the update
    region. No need to roundtrip via win32.
    
    This lets us also make sure we do this drawing in the same update
    cycle. This seems especially important on Win7, because ScrollDC
    seems to act kind of weird there, not using bitblt in areas where
    it seemingly could, which makes scrolling look really flashy.
    
    http://bugzilla.gnome.org/show_bug-cgi?id=674051

 gdk/win32/gdkdrawable-win32.c |   23 +++++++++++++++--------
 1 files changed, 15 insertions(+), 8 deletions(-)
---
diff --git a/gdk/win32/gdkdrawable-win32.c b/gdk/win32/gdkdrawable-win32.c
index b8a30b0..14d9f45 100644
--- a/gdk/win32/gdkdrawable-win32.c
+++ b/gdk/win32/gdkdrawable-win32.c
@@ -1560,21 +1560,28 @@ blit_inside_drawable (HDC                   hdc,
        * scrolling a window that is partially obscured by another window. For
        * example, GIMP's toolbox being over the editor window. */
 
-      RECT scrollRect, emptyRect;
+      RECT emptyRect, clipRect;
       HRGN updateRgn;
+      GdkRegion *update_region;
 
-      scrollRect.left = MIN (xsrc, xdest);
-      scrollRect.top = MIN (ysrc, ydest);
-      scrollRect.right = MAX (xsrc + width + 1, xdest + width + 1);
-      scrollRect.bottom = MAX (ysrc + height + 1, ydest + height + 1);
+      clipRect.left = xdest;
+      clipRect.top = ydest;
+      clipRect.right = xdest + width;
+      clipRect.bottom = ydest + height;
 
       SetRectEmpty (&emptyRect);
       updateRgn = CreateRectRgnIndirect (&emptyRect);
 
-      if (!ScrollDC (hdc, xdest - xsrc, ydest - ysrc, &scrollRect, NULL, updateRgn, NULL))
+      if (!ScrollDC (hdc, xdest - xsrc, ydest - ysrc, NULL, &clipRect, updateRgn, NULL))
         WIN32_GDI_FAILED ("ScrollDC");
-      else if (!InvalidateRgn (src->handle, updateRgn, FALSE))
-        WIN32_GDI_FAILED ("InvalidateRgn");
+      else
+       {
+         GdkDrawable *wrapper = src->wrapper;
+         update_region = _gdk_win32_hrgn_to_region (updateRgn);
+         if (!gdk_region_empty (update_region))
+           _gdk_window_invalidate_for_expose (GDK_WINDOW (wrapper), update_region);
+         gdk_region_destroy (update_region);
+       }
 
       if (!DeleteObject (updateRgn))
         WIN32_GDI_FAILED ("DeleteObject");