[mutter] window-actor: Use actual image size for capture

[Jonas Ådahl <jadahl src gnome org>]

commit 3738579dd3239f110aba8c189d0cb0d8440ad61a
Author: Olivier Fourdan <ofourdan redhat com>
Date:   Tue Jan 22 10:22:27 2019 +0100

    window-actor: Use actual image size for capture
    
    Previously, the clipping rectangle passed to
    `meta_surface_actor_get_image()` was updated with the actual texture
    size, but recent changes in `meta_shaped_texture_get_image()` now keep
    the caller's clipping rectangle unchanged.
    
    The implementation of `meta_window_actor_capture_into()` was relying on
    the old behavior of updating the passed clipping rectangle, but now that
    it's kept unchanged, the actual clipping rectangle used to copy the data
    is wrong, which causes either a distorded image or worse, a crash of
    mutter.
    
    Use the resulting cairo image size to copy the data instead of the
    clipping rectangle to avoid the issue and get the expected size.
    
    Fixes: https://gitlab.gnome.org/GNOME/mutter/issues/442

 src/compositor/meta-window-actor.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)
---
diff --git a/src/compositor/meta-window-actor.c b/src/compositor/meta-window-actor.c
index c0a042aa1..20a22062f 100644
--- a/src/compositor/meta-window-actor.c
+++ b/src/compositor/meta-window-actor.c
@@ -1930,36 +1930,38 @@ meta_window_actor_capture_into (MetaScreenCastWindow *screen_cast_window,
   MetaWindowActorPrivate *priv =
     meta_window_actor_get_instance_private (window_actor);
   cairo_surface_t *image;
-  MetaRectangle clip_rect;
   uint8_t *cr_data;
   int cr_stride;
+  int cr_width;
+  int cr_height;
   int bpp = 4;
 
   if (meta_window_actor_is_destroyed (window_actor))
     return;
 
-  clip_rect = *bounds;
-  image = meta_surface_actor_get_image (priv->surface, &clip_rect);
+  image = meta_surface_actor_get_image (priv->surface, bounds);
   cr_data = cairo_image_surface_get_data (image);
+  cr_width = cairo_image_surface_get_width (image);
+  cr_height = cairo_image_surface_get_height (image);
   cr_stride = cairo_image_surface_get_stride (image);
 
-  if (clip_rect.width < bounds->width || clip_rect.height < bounds->height)
+  if (cr_width < bounds->width || cr_height < bounds->height)
     {
       uint8_t *src, *dst;
       src = cr_data;
       dst = data;
 
-      for (int i = 0; i < clip_rect.height; i++)
+      for (int i = 0; i < cr_height; i++)
         {
           memcpy (dst, src, cr_stride);
-          if (clip_rect.width < bounds->width)
+          if (cr_width < bounds->width)
             memset (dst + cr_stride, 0, (bounds->width * bpp) - cr_stride);
 
           src += cr_stride;
           dst += bounds->width * bpp;
         }
 
-      for (int i = clip_rect.height; i < bounds->height; i++)
+      for (int i = cr_height; i < bounds->height; i++)
         {
           memset (dst, 0, bounds->width * bpp);
           dst += bounds->width * bpp;
@@ -1967,7 +1969,7 @@ meta_window_actor_capture_into (MetaScreenCastWindow *screen_cast_window,
     }
   else
     {
-      memcpy (data, cr_data, clip_rect.height * cr_stride);
+      memcpy (data, cr_data, cr_height * cr_stride);
     }
 
   cairo_surface_destroy (image);