[gtk/wip/chergert/glproto] improve damage rect calculation

[Christian Hergert <chergert src gnome org>]

commit b769e586ae1b2830982fc2da8f2cd6808a4ffd59
Author: Christian Hergert <chergert redhat com>
Date:   Thu Feb 18 17:55:24 2021 -0800

    improve damage rect calculation
    
    this appears to also be off in the gl renderer, in that it was comparing
    damage w/ scale factor applied to one without. This fixes that so we can
    fix our calculation when doing animated popovers.

 gsk/next/gskglrenderer.c | 20 ++++++++------------
 1 file changed, 8 insertions(+), 12 deletions(-)
---
diff --git a/gsk/next/gskglrenderer.c b/gsk/next/gskglrenderer.c
index 6d9fa3fc13..b49e3c75f7 100644
--- a/gsk/next/gskglrenderer.c
+++ b/gsk/next/gskglrenderer.c
@@ -150,25 +150,21 @@ get_render_region (GdkSurface   *surface,
   const cairo_region_t *damage;
   GdkRectangle whole_surface;
   GdkRectangle extents;
-  float scale_factor;
 
   g_assert (GDK_IS_SURFACE (surface));
   g_assert (GDK_IS_GL_CONTEXT (context));
 
-  scale_factor = gdk_surface_get_scale_factor (surface);
-
   whole_surface.x = 0;
   whole_surface.y = 0;
-  whole_surface.width = gdk_surface_get_width (surface) * scale_factor;
-  whole_surface.height = gdk_surface_get_height (surface) * scale_factor;
+  whole_surface.width = gdk_surface_get_width (surface);
+  whole_surface.height = gdk_surface_get_height (surface);
 
+  /* Damage does not have scale factor applied. so we can compare
+   * it to whole surface which also doesn'th have scale factor applied.
+   */
   damage = gdk_draw_context_get_frame_region (GDK_DRAW_CONTEXT (context));
 
-  /* NULL means everything in this case, and ensures that we
-   * don't setup any complicated clips for full scene redraw.
-   */
-  if (damage == NULL ||
-      cairo_region_contains_rectangle (damage, &whole_surface) == CAIRO_REGION_OVERLAP_IN)
+  if (cairo_region_contains_rectangle (damage, &whole_surface) == CAIRO_REGION_OVERLAP_IN)
     return NULL;
 
   /* If the extents match the full-scene, do the same as above */
@@ -176,7 +172,7 @@ get_render_region (GdkSurface   *surface,
   if (gdk_rectangle_equal (&extents, &whole_surface))
     return NULL;
 
-  /* Draw clipped to the bounding-box of the region */
+  /* Draw clipped to the bounding-box of the region. */
   return cairo_region_create_rectangle (&extents);
 }
 
@@ -206,7 +202,7 @@ gsk_next_renderer_render (GskRenderer          *renderer,
   gdk_gl_context_make_current (self->context);
   gdk_draw_context_begin_frame (GDK_DRAW_CONTEXT (self->context), update_area);
 
-  /* Must be called *after* gdk_draw_context_begin_frame() */
+  /* Must be called *AFTER* gdk_draw_context_begin_frame() */
   render_region = get_render_region (surface, self->context);
 
   gsk_next_driver_begin_frame (self->driver, self->command_queue);