Apply window gravity for border width changes

Together with the previous changes, this also fixes the initial positions for
metacity's test-gravity.c.

Signed-off-by: Uli Schlachter <psychon@znc.in>

objects/client.c

@@ -128,6 +128,7 @@
 
 static area_t titlebar_get_area(client_t *c, client_titlebar_t bar);
 static drawable_t *titlebar_get_drawable(lua_State *L, client_t *c, int cl_idx, client_titlebar_t bar);
+static void client_resize_do(client_t *c, area_t geometry, bool force_notice);
 
 /** Collect a client.
  * \param L The Lua VM state.
@@ -466,6 +467,24 @@ client_focus_refresh(void)
                         win, globalconf.timestamp);
 }
 
+static void
+border_width_callback(client_t *c, uint16_t old_width, uint16_t new_width)
+{
+    if(c->size_hints.flags & XCB_ICCCM_SIZE_HINT_P_WIN_GRAVITY)
+    {
+        area_t geometry = c->geometry;
+        int16_t diff = new_width - old_width;
+        int16_t diff_x = 0, diff_y = 0;
+        xwindow_translate_for_gravity(c->size_hints.win_gravity,
+                                      diff, diff, diff, diff,
+                                      &diff_x, &diff_y);
+        geometry.x += diff_x;
+        geometry.y += diff_y;
+        /* force_notice = true -> inform client about changes */
+        client_resize_do(c, geometry, true);
+    }
+}
+
 static void
 client_update_properties(lua_State *L, int cidx, client_t *c)
 {
@@ -537,6 +556,7 @@ client_manage(xcb_window_t w, xcb_get_geometry_reply_t *wgeom, xcb_get_window_at
 
     client_t *c = client_new(L);
     xcb_screen_t *s = globalconf.screen;
+    c->border_width_callback = (void (*) (void *, uint16_t, uint16_t)) border_width_callback;
 
     /* consider the window banned */
     c->isbanned = true;

objects/window.c

@@ -178,6 +178,7 @@ void
 window_set_border_width(lua_State *L, int idx, int width)
 {
     window_t *window = luaA_checkudata(L, idx, &window_class);
+    uint16_t old_width = window->border_width;
 
     if(width == window->border_width || width < 0)
         return;
@@ -189,6 +190,9 @@ window_set_border_width(lua_State *L, int idx, int width)
 
     window->border_width = width;
 
+    if(window->border_width_callback)
+        (*window->border_width_callback)(window, old_width, width);
+
     luaA_object_emit_signal(L, idx, "property::border_width", 0);
 }
 

objects/window.h

@@ -67,7 +67,9 @@ typedef enum
     /** Border width */ \
     uint16_t border_width; \
     /** The window type */ \
-    window_type_t type;
+    window_type_t type; \
+    /** The border width callback */ \
+    void (*border_width_callback)(void *, uint16_t old, uint16_t new);
 
 /** Window structure */
 typedef struct