[mutter/gbsneto/window-screencast-fixes: 3/7] window-actor: Clip before translate when blitting

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit 1e529ac5d012b1381c20ce961b53ec5162187d9b
Author: Georges Basile Stavracas Neto <georges stavracas gmail com>
Date:   Mon Mar 16 19:55:16 2020 -0300

    window-actor: Clip before translate when blitting
    
    cogl_framebuffer_push_rectangle_clip() acts on the current modelview
    matrix. That means the result of clipping then translating will be
    different of the result of translating then clipping.
    
    What we want for window screencasting is the former, not the latter.
    Move the translation code (and associated) to after clipping.
    
    Fixes: https://gitlab.gnome.org/GNOME/mutter/issues/1097
    
    https://gitlab.gnome.org/GNOME/mutter/merge_requests/1129

 src/compositor/meta-window-actor.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)
---
diff --git a/src/compositor/meta-window-actor.c b/src/compositor/meta-window-actor.c
index 225f57ddc..3495e229e 100644
--- a/src/compositor/meta-window-actor.c
+++ b/src/compositor/meta-window-actor.c
@@ -1295,13 +1295,9 @@ meta_window_actor_blit_to_framebuffer (MetaScreenCastWindow *screen_cast_window,
   if (width == 0 || height == 0)
     return FALSE;
 
-  cogl_framebuffer_push_matrix (framebuffer);
-
   cogl_color_init_from_4ub (&clear_color, 0, 0, 0, 0);
   cogl_framebuffer_clear (framebuffer, COGL_BUFFER_BIT_COLOR, &clear_color);
   cogl_framebuffer_orthographic (framebuffer, 0, 0, width, height, 0, 1.0);
-  cogl_framebuffer_scale (framebuffer, resource_scale, resource_scale, 1);
-  cogl_framebuffer_translate (framebuffer, -x, -y, 0);
 
   meta_rectangle_scale_double (bounds, resource_scale,
                                META_ROUNDING_STRATEGY_GROW,
@@ -1318,12 +1314,16 @@ meta_window_actor_blit_to_framebuffer (MetaScreenCastWindow *screen_cast_window,
                                         scaled_clip.x + scaled_clip.width,
                                         scaled_clip.y + scaled_clip.height);
 
+  cogl_framebuffer_push_matrix (framebuffer);
+  cogl_framebuffer_scale (framebuffer, resource_scale, resource_scale, 1);
+  cogl_framebuffer_translate (framebuffer, -x, -y, 0);
+
   paint_context = clutter_paint_context_new_for_framebuffer (framebuffer);
   clutter_actor_paint (actor, paint_context);
   clutter_paint_context_destroy (paint_context);
 
-  cogl_framebuffer_pop_clip (framebuffer);
   cogl_framebuffer_pop_matrix (framebuffer);
+  cogl_framebuffer_pop_clip (framebuffer);
 
   return TRUE;
 }