[mutter] clutter/stage-cogl: Cleanup the code for scissor region calculation

[Marco Trevisan <marcotrevi src gnome org>]

commit 3d89b477577e54f1d77e424a03c241d51af260a4
Author: Marco Trevisan (Treviño) <mail 3v1n0 net>
Date:   Fri Mar 1 02:52:00 2019 +0100

    clutter/stage-cogl: Cleanup the code for scissor region calculation
    
    Ignore the subpixel compensation when this value isn't set, and directly
    set the passed rect.
    
    https://gitlab.gnome.org/GNOME/mutter/merge_requests/3

 clutter/clutter/cogl/clutter-stage-cogl.c | 26 +++++++-------------------
 1 file changed, 7 insertions(+), 19 deletions(-)
---
diff --git a/clutter/clutter/cogl/clutter-stage-cogl.c b/clutter/clutter/cogl/clutter-stage-cogl.c
index 7ab4b3823..af5acff02 100644
--- a/clutter/clutter/cogl/clutter-stage-cogl.c
+++ b/clutter/clutter/cogl/clutter-stage-cogl.c
@@ -551,31 +551,19 @@ calculate_scissor_region (cairo_rectangle_int_t *fb_clip_region,
                           int                    fb_height,
                           cairo_rectangle_int_t *out_scissor_rect)
 {
-  int scissor_x;
-  int scissor_y;
-  int scissor_width;
-  int scissor_height;
+  *out_scissor_rect = *fb_clip_region;
 
-  scissor_x = fb_clip_region->x;
-  scissor_y = fb_clip_region->y;
-  scissor_width = fb_clip_region->width;
-  scissor_height = fb_clip_region->height;
+  if (subpixel_compensation == 0)
+    return;
 
   if (fb_clip_region->x > 0)
-    scissor_x += subpixel_compensation;
+    out_scissor_rect->x += subpixel_compensation;
   if (fb_clip_region->y > 0)
-    scissor_y += subpixel_compensation;
+    out_scissor_rect->y += subpixel_compensation;
   if (fb_clip_region->x + fb_clip_region->width < fb_width)
-    scissor_width -= 2 * subpixel_compensation;
+    out_scissor_rect->width -= 2 * subpixel_compensation;
   if (fb_clip_region->y + fb_clip_region->height < fb_height)
-    scissor_height -= 2 * subpixel_compensation;
-
-  *out_scissor_rect = (cairo_rectangle_int_t) {
-    .x = scissor_x,
-    .y = scissor_y,
-    .width = scissor_width,
-    .height = scissor_height
-  };
+    out_scissor_rect->height -= 2 * subpixel_compensation;
 }
 
 static inline gboolean