server: Crop the invalidate region against the rectangles of all parents.

dlls/user32/tests/msg.c

@@ -5824,6 +5824,12 @@ static void test_paint_messages(void)
     SetRectRgn( hrgn, 30, 30, 40, 40 );
     check_update_rgn( hchild, hrgn );
 
+    /* invalidated region is cropped by the parent rects */
+    SetRect( &rect, 0, 0, 50, 50 );
+    RedrawWindow( hchild, &rect, 0, RDW_INVALIDATE | RDW_ERASE );
+    SetRectRgn( hrgn, 30, 30, 50, 50 );
+    check_update_rgn( hchild, hrgn );
+
     DestroyWindow( hparent );
     ok(!IsWindow(hchild), "child must be destroyed with its parent\n");
     flush_sequence();

server/window.c

@@ -1036,23 +1036,27 @@ static int get_window_visible_rect( struct window *win, rectangle_t *rect, int f
 /* and converted from client to window coordinates. Helper for (in)validate_window. */
 static struct region *crop_region_to_win_rect( struct window *win, struct region *region, int frame )
 {
-    struct region *tmp = create_empty_region();
+    rectangle_t rect;
+    struct region *tmp;
 
-    if (!tmp) return NULL;
+    if (!get_window_visible_rect( win, &rect, frame )) return NULL;
+    if (!(tmp = create_empty_region())) return NULL;
+    set_region_rect( tmp, &rect );
 
-    /* get bounding rect in client coords */
-    if (frame) set_region_rect( tmp, &win->window_rect );
-    else set_region_client_rect( tmp, win );
-    if (!is_desktop_window(win))
-        offset_region( tmp, -win->client_rect.left, -win->client_rect.top );
+    if (region)
+    {
+        /* map it to client coords */
+        offset_region( tmp, win->window_rect.left - win->client_rect.left,
+                       win->window_rect.top - win->client_rect.top );
 
         /* intersect specified region with bounding rect */
-    if (region && !intersect_region( tmp, region, tmp )) goto done;
+        if (!intersect_region( tmp, region, tmp )) goto done;
         if (is_region_empty( tmp )) goto done;
 
-    /* map it to window coords */
+        /* map it back to window coords */
         offset_region( tmp, win->client_rect.left - win->window_rect.left,
                        win->client_rect.top - win->window_rect.top );
+    }
     return tmp;
 
 done: