[mutter] clutter/stage: Add view scale support on read_pixels()

[Jonas Ådahl <jadahl src gnome org>]

commit 412d5685bac1ac0e3e142b94dad88d269e9ad8d6
Author: Marco Trevisan (Treviño) <mail 3v1n0 net>
Date:   Fri Jan 26 13:39:44 2018 +0100

    clutter/stage: Add view scale support on read_pixels()
    
    https://bugzilla.gnome.org/show_bug.cgi?id=765011
    https://gitlab.gnome.org/GNOME/mutter/merge_requests/3

 clutter/clutter/clutter-stage.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)
---
diff --git a/clutter/clutter/clutter-stage.c b/clutter/clutter/clutter-stage.c
index c39753f51..1eea5b305 100644
--- a/clutter/clutter/clutter-stage.c
+++ b/clutter/clutter/clutter-stage.c
@@ -2944,6 +2944,9 @@ clutter_stage_read_pixels (ClutterStage *stage,
   cairo_region_t *clip;
   cairo_rectangle_int_t clip_rect;
   CoglFramebuffer *framebuffer;
+  float view_scale;
+  float pixel_width;
+  float pixel_height;
   uint8_t *pixels;
 
   g_return_val_if_fail (CLUTTER_IS_STAGE (stage), NULL);
@@ -2986,10 +2989,15 @@ clutter_stage_read_pixels (ClutterStage *stage,
   cogl_push_framebuffer (framebuffer);
   clutter_stage_do_paint_view (stage, view, &clip_rect);
 
-  pixels = g_malloc0 (clip_rect.width * clip_rect.height * 4);
+  view_scale = clutter_stage_view_get_scale (view);
+  pixel_width = roundf (clip_rect.width * view_scale);
+  pixel_height = roundf (clip_rect.height * view_scale);
+
+  pixels = g_malloc0 (pixel_width * pixel_height * 4);
   cogl_framebuffer_read_pixels (framebuffer,
-                                clip_rect.x, clip_rect.y,
-                                clip_rect.width, clip_rect.height,
+                                clip_rect.x * view_scale,
+                                clip_rect.y * view_scale,
+                                pixel_width, pixel_height,
                                 COGL_PIXEL_FORMAT_RGBA_8888,
                                 pixels);