[mutter/gbsneto/window-screencast-fixes: 4/9] window-actor: Clip before translate when blitting

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

commit cdd27d0e53dbc8aa4e44506822492758d0a45296
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 fe6ea870a..143c5ac6b 100644
--- a/src/compositor/meta-window-actor.c
+++ b/src/compositor/meta-window-actor.c
@@ -1292,13 +1292,9 @@ meta_window_actor_blit_to_framebuffer (MetaScreenCastWindow *screen_cast_window,
 
   clutter_actor_get_position (actor, &x, &y);
 
-  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,
@@ -1315,12 +1311,16 @@ 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;
 }