server: Correctly expose composited parent window and its child on position change.

dlls/user32/tests/msg.c

@@ -9303,7 +9303,7 @@ static void subtest_swp_paint_regions_( int line, int wrap_toplevel, LPCSTR pare
             else
             {
                 todo_wine_if( EqualRect( &rect_old, &rect_new ) ? is_zorder_redraw :
-                              ((extest->style & WS_CLIPCHILDREN) == 0 || is_composited) )
+                              ((extest->style & WS_CLIPCHILDREN) == 0 && !is_composited) )
                 ok( !!rgn_ok, "Parent update region shall match expected region\n" );
             }
 
@@ -9366,7 +9366,7 @@ static void subtest_swp_paint_regions_( int line, int wrap_toplevel, LPCSTR pare
             else
             {
                 todo_wine_if( EqualRect( &rect_old, &rect_new ) ? is_zorder_redraw :
-                              ((extest->style & WS_CLIPCHILDREN) == 0 || is_composited) )
+                              ((extest->style & WS_CLIPCHILDREN) == 0 && !is_composited) )
                 ok( !!rgn_ok, "Child update region shall match expected region\n" );
             }
 

server/class.c

@@ -141,6 +141,11 @@ int is_hwnd_message_class( struct window_class *class )
     return (!class->local && class->atom == find_global_atom( NULL, &name ));
 }
 
+int get_class_style( struct window_class *class )
+{
+    return class->style;
+}
+
 atom_t get_class_atom( struct window_class *class )
 {
     return class->base_atom;

server/region.c

@@ -684,6 +684,23 @@ int is_region_empty( const struct region *region )
 }
 
 
+/* checks if two regions are identical */
+int is_region_equal( const struct region *region1, const struct region *region2 )
+{
+    int i;
+
+    if (region1->num_rects != region2->num_rects) return 0;
+    if (region1->num_rects == 0) return 1;
+    if (!is_rect_equal( &region1->extents, &region2->extents )) return 0;
+    for (i = 0; i < region1->num_rects; i++)
+    {
+        if (!is_rect_equal( &region1->rects[i], &region2->rects[i] )) return 0;
+    }
+
+    return 1;
+}
+
+
 /* get the extents rect of a region */
 void get_region_extents( const struct region *region, rectangle_t *rect )
 {

server/user.h

@@ -132,6 +132,7 @@ extern rectangle_t *get_region_data( const struct region *region, data_size_t ma
 extern rectangle_t *get_region_data_and_free( struct region *region, data_size_t max_size,
                                               data_size_t *total_size );
 extern int is_region_empty( const struct region *region );
+extern int is_region_equal( const struct region *region1, const struct region *region2 );
 extern void get_region_extents( const struct region *region, rectangle_t *rect );
 extern void offset_region( struct region *region, int x, int y );
 extern void mirror_region( const rectangle_t *client_rect, struct region *region );
@@ -175,6 +176,7 @@ extern struct window_class *grab_class( struct process *process, atom_t atom,
 extern void release_class( struct window_class *class );
 extern int is_desktop_class( struct window_class *class );
 extern int is_hwnd_message_class( struct window_class *class );
+extern int get_class_style( struct window_class *class );
 extern atom_t get_class_atom( struct window_class *class );
 extern client_ptr_t get_class_client_ptr( struct window_class *class );
 
@@ -191,6 +193,13 @@ extern void close_process_desktop( struct process *process );
 extern void set_thread_default_desktop( struct thread *thread, struct desktop *desktop, obj_handle_t handle );
 extern void release_thread_desktop( struct thread *thread, int close );
 
+/* checks if two rectangles are identical */
+static inline int is_rect_equal( const rectangle_t *rect1, const rectangle_t *rect2 )
+{
+    return (rect1->left == rect2->left && rect1->right == rect2->right &&
+            rect1->top == rect2->top && rect1->bottom == rect2->bottom);
+}
+
 static inline int is_rect_empty( const rectangle_t *rect )
 {
     return (rect->left >= rect->right || rect->top >= rect->bottom);

server/window.c

@@ -789,6 +789,21 @@ int is_window_transparent( user_handle_t window )
     return (win->ex_style & (WS_EX_LAYERED|WS_EX_TRANSPARENT)) == (WS_EX_LAYERED|WS_EX_TRANSPARENT);
 }
 
+static int is_window_using_parent_dc( struct window *win )
+{
+    return (win->style & (WS_POPUP|WS_CHILD)) == WS_CHILD && (get_class_style( win->class ) & CS_PARENTDC) != 0;
+}
+
+static int is_window_composited( struct window *win )
+{
+    return (win->ex_style & WS_EX_COMPOSITED) != 0 && !is_window_using_parent_dc(win);
+}
+
+static int is_parent_composited( struct window *win )
+{
+    return win->parent && is_window_composited( win->parent );
+}
+
 /* check if point is inside the window, and map to window dpi */
 static int is_point_in_window( struct window *win, int *x, int *y, unsigned int dpi )
 {
@@ -1712,12 +1727,23 @@ static struct region *expose_window( struct window *win, const rectangle_t *old_
                                      struct region *old_vis_rgn )
 {
     struct region *new_vis_rgn, *exposed_rgn;
+    int is_composited = is_parent_composited( win );
 
     if (!(new_vis_rgn = get_visible_region( win, DCX_WINDOW ))) return NULL;
 
+    if (is_composited &&
+        is_rect_equal( old_window_rect, &win->window_rect ) &&
+        is_region_equal( old_vis_rgn, new_vis_rgn ))
+    {
+        free_region( new_vis_rgn );
+        return NULL;
+    }
+
     if ((exposed_rgn = create_empty_region()))
     {
-        if (subtract_region( exposed_rgn, new_vis_rgn, old_vis_rgn ) && !is_region_empty( exposed_rgn ))
+        if ((is_composited ? union_region( exposed_rgn, new_vis_rgn, old_vis_rgn )
+                           : subtract_region( exposed_rgn, new_vis_rgn, old_vis_rgn )) &&
+            !is_region_empty( exposed_rgn ))
         {
             /* make it relative to the new client area */
             offset_region( exposed_rgn, win->window_rect.left - win->client_rect.left,
@@ -1736,7 +1762,8 @@ static struct region *expose_window( struct window *win, const rectangle_t *old_
         offset_region( new_vis_rgn, win->window_rect.left - old_window_rect->left,
                        win->window_rect.top - old_window_rect->top  );
 
-        if ((win->parent->style & WS_CLIPCHILDREN) ?
+        if (is_composited ? union_region( new_vis_rgn, old_vis_rgn, new_vis_rgn ) :
+            (win->parent->style & WS_CLIPCHILDREN) ?
             subtract_region( new_vis_rgn, old_vis_rgn, new_vis_rgn ) :
             xor_region( new_vis_rgn, old_vis_rgn, new_vis_rgn ))
         {