[metacity] window: parse _NET_WM_OPAQUE_REGION property

[Alberts Muktupāvels <muktupavels src gnome org>]

commit 339ce6a238ffdb9c67529869e8903e17f98480d5
Author: Alberts Muktupāvels <alberts muktupavels gmail com>
Date:   Mon Mar 6 11:20:56 2017 +0200

    window: parse _NET_WM_OPAQUE_REGION property
    
    https://git.gnome.org/browse/mutter/commit/?id=a613a55658c5717481e1f2d34987715d5f0a5ca4
    https://git.gnome.org/browse/mutter/commit/src/?id=39357fc242f6a02bab0af0176dc8d842b3d97020

 src/core/atomnames.h      |    1 +
 src/core/window-private.h |    3 ++
 src/core/window-props.c   |   79 +++++++++++++++++++++++++++++++++++++++++++++
 src/core/window.c         |    4 ++
 4 files changed, 87 insertions(+), 0 deletions(-)
---
diff --git a/src/core/atomnames.h b/src/core/atomnames.h
index 087d27a..6e14219 100644
--- a/src/core/atomnames.h
+++ b/src/core/atomnames.h
@@ -164,6 +164,7 @@ item(_NET_WM_ACTION_BELOW)
 item(_NET_WM_STATE_STICKY)
 item(_NET_WM_FULLSCREEN_MONITORS)
 item(_NET_WM_STATE_FOCUSED)
+item(_NET_WM_OPAQUE_REGION)
 item(_NET_RESTACK_WINDOW)
 item(_NET_WM_WINDOW_OPACITY)
 
diff --git a/src/core/window-private.h b/src/core/window-private.h
index e210270..65f98f9 100644
--- a/src/core/window-private.h
+++ b/src/core/window-private.h
@@ -343,6 +343,9 @@ struct _MetaWindow
   /* if non-NULL, the bounds of the window frame */
   cairo_region_t *frame_bounds;
 
+  /* if non-NULL, the opaque region _NET_WM_OPAQUE_REGION */
+  cairo_region_t *opaque_region;
+
   /* Note: can be NULL */
   GSList *struts;
 
diff --git a/src/core/window-props.c b/src/core/window-props.c
index 3366286..4007917 100644
--- a/src/core/window-props.c
+++ b/src/core/window-props.c
@@ -720,6 +720,79 @@ reload_wm_name (MetaWindow    *window,
 }
 
 static void
+meta_window_set_opaque_region (MetaWindow     *window,
+                               cairo_region_t *region)
+{
+  if (cairo_region_equal (window->opaque_region, region))
+    return;
+
+  g_clear_pointer (&window->opaque_region, cairo_region_destroy);
+
+  if (region != NULL)
+    window->opaque_region = cairo_region_reference (region);
+
+  meta_compositor_window_shape_changed (window->display->compositor, window);
+}
+
+static void
+reload_opaque_region (MetaWindow    *window,
+                      MetaPropValue *value,
+                      gboolean       initial)
+{
+  int nitems, nrects, rect_index, i;
+  gulong *region;
+  cairo_rectangle_int_t *rects;
+  cairo_region_t *opaque_region;
+
+  if (value->type == META_PROP_VALUE_INVALID)
+    {
+      meta_window_set_opaque_region (window, NULL);
+      return;
+    }
+
+  nitems = value->v.cardinal_list.n_cardinals;
+  region = value->v.cardinal_list.cardinals;
+
+  if (nitems % 4 != 0)
+    {
+      meta_verbose ("_NET_WM_OPAQUE_REGION does not have a list of 4-tuples.");
+      meta_window_set_opaque_region (window, NULL);
+      return;
+    }
+
+  /* empty region */
+  if (nitems == 0)
+    {
+      meta_window_set_opaque_region (window, NULL);
+      return;
+    }
+
+  nrects = nitems / 4;
+  rects = g_new (cairo_rectangle_int_t, nrects);
+  rect_index = i = 0;
+
+  while (i < nitems)
+    {
+      cairo_rectangle_int_t *rect;
+
+      rect = &rects[rect_index];
+
+      rect->x = region[i++];
+      rect->y = region[i++];
+      rect->width = region[i++];
+      rect->height = region[i++];
+
+      rect_index++;
+    }
+
+  opaque_region = cairo_region_create_rectangles (rects, nrects);
+  g_free (rects);
+
+  meta_window_set_opaque_region (window, opaque_region);
+  cairo_region_destroy (opaque_region);
+}
+
+static void
 reload_net_wm_state (MetaWindow    *window,
                      MetaPropValue *value,
                      gboolean       initial)
@@ -1715,6 +1788,12 @@ meta_display_init_window_prop_hooks (MetaDisplay *display)
       LOAD_INIT | INCLUDE_OR
     },
     {
+      display->atom__NET_WM_OPAQUE_REGION,
+      META_PROP_VALUE_CARDINAL_LIST,
+      reload_opaque_region,
+      LOAD_INIT | INCLUDE_OR
+    },
+    {
       display->atom__NET_WM_DESKTOP,
       META_PROP_VALUE_CARDINAL,
       reload_net_wm_desktop,
diff --git a/src/core/window.c b/src/core/window.c
index 7fd7928..5b14b20 100644
--- a/src/core/window.c
+++ b/src/core/window.c
@@ -528,6 +528,7 @@ meta_window_new (MetaDisplay    *display,
   window->disable_sync = FALSE;
   window->attached = FALSE;
   window->frame_bounds = NULL;
+  window->opaque_region = NULL;
 
   window->unmaps_pending = 0;
 
@@ -1274,6 +1275,9 @@ meta_window_free (MetaWindow  *window,
   if (window->frame_bounds)
     cairo_region_destroy (window->frame_bounds);
 
+  if (window->opaque_region)
+    cairo_region_destroy (window->opaque_region);
+
   meta_icon_cache_free (&window->icon_cache);
 
   g_free (window->sm_client_id);