server: Map region to the window DPI in redraw_region().

server/region.c

@@ -724,6 +724,18 @@ void mirror_region( const rectangle_t *client_rect, struct region *region )
 }
 
 
+/* scale a region for a given dpi factor */
+void scale_region( struct region *region, unsigned int dpi_from, unsigned int dpi_to )
+{
+    rectangle_t *rect, *end;
+
+    if (!region->num_rects) return;
+    for (rect = region->rects, end = rect + region->num_rects; rect < end; rect++)
+        scale_dpi_rect( rect, dpi_from, dpi_to );
+    scale_dpi_rect( &region->extents, dpi_from, dpi_to );
+}
+
+
 /* make a copy of a region; returns dst or NULL on error */
 struct region *copy_region( struct region *dst, const struct region *src )
 {

server/user.h

@@ -135,6 +135,7 @@ extern int is_region_empty( const struct region *region );
 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 );
+extern void scale_region( struct region *region, unsigned int dpi_from, unsigned int dpi_to );
 extern struct region *copy_region( struct region *dst, const struct region *src );
 extern struct region *intersect_region( struct region *dst, const struct region *src1,
                                         const struct region *src2 );

server/window.c

@@ -649,6 +649,15 @@ static void map_dpi_rect( struct window *win, rectangle_t *rect, unsigned int fr
     scale_dpi_rect( rect, from, to );
 }
 
+/* map a region between different DPI scaling levels */
+static void map_dpi_region( struct window *win, struct region *region, unsigned int from, unsigned int to )
+{
+    if (!from) from = get_monitor_dpi( win );
+    if (!to) to = get_monitor_dpi( win );
+    if (from == to) return;
+    scale_region( region, from, to );
+}
+
 /* check if window and all its ancestors are visible */
 static int is_visible( const struct window *win )
 {
@@ -1388,7 +1397,7 @@ static void validate_parents( struct window *child )
 /* add/subtract a region (in client coordinates) to the update region of the window */
 static void redraw_window( struct window *win, struct region *region, int frame, unsigned int flags )
 {
-    struct region *tmp;
+    struct region *child_rgn, *tmp;
     struct window *child;
 
     if (flags & RDW_INVALIDATE)
@@ -1450,11 +1459,19 @@ static void redraw_window( struct window *win, struct region *region, int frame,
     LIST_FOR_EACH_ENTRY( child, &win->children, struct window, entry )
     {
         if (!(child->style & WS_VISIBLE)) continue;
-        if (!rect_in_region( tmp, &child->window_rect )) continue;
-        offset_region( tmp, -child->client_rect.left, -child->client_rect.top );
-        redraw_window( child, tmp, 1, flags );
-        offset_region( tmp, child->client_rect.left, child->client_rect.top );
+        if (!(child_rgn = create_empty_region())) continue;
+        if (copy_region( child_rgn, tmp ))
+        {
+            map_dpi_region( child, child_rgn, win->dpi, child->dpi );
+            if (rect_in_region( child_rgn, &child->window_rect ))
+            {
+                offset_region( child_rgn, -child->client_rect.left, -child->client_rect.top );
+                redraw_window( child, child_rgn, 1, flags );
+            }
+        }
+        free_region( child_rgn );
     }
+
     free_region( tmp );
 }