[mutter] clutter/stage: Pass redraw clip instead of extents when painting view

[Jonas Ådahl <jadahl src gnome org>]

commit c483b52d240136cf49b358cde2c0d2c0ed237e51
Author: Jonas Ådahl <jadahl gmail com>
Date:   Thu Feb 6 09:00:12 2020 +0100

    clutter/stage: Pass redraw clip instead of extents when painting view
    
    That's the struct we have ready, the callee can just call
    cairo_region_get_extents() if it only cares about the extents rectangle.
    
    https://gitlab.gnome.org/GNOME/mutter/merge_requests/1042

 clutter/clutter/clutter-stage-private.h         |  6 +--
 clutter/clutter/clutter-stage.c                 | 59 ++++++++++++++-----------
 clutter/clutter/clutter-stage.h                 |  5 ++-
 clutter/clutter/cogl/clutter-stage-cogl.c       | 39 +++-------------
 src/backends/meta-stage.c                       |  8 ++--
 src/tests/clutter/conform/actor-shader-effect.c |  1 +
 6 files changed, 50 insertions(+), 68 deletions(-)
---
diff --git a/clutter/clutter/clutter-stage-private.h b/clutter/clutter/clutter-stage-private.h
index 7a8429067..c8c1ef34a 100644
--- a/clutter/clutter/clutter-stage-private.h
+++ b/clutter/clutter/clutter-stage-private.h
@@ -36,9 +36,9 @@ typedef struct _ClutterStageQueueRedrawEntry ClutterStageQueueRedrawEntry;
 /* stage */
 ClutterStageWindow *_clutter_stage_get_default_window    (void);
 
-void                _clutter_stage_paint_view            (ClutterStage                *stage,
-                                                          ClutterStageView            *view,
-                                                          const cairo_rectangle_int_t *clip);
+void                clutter_stage_paint_view             (ClutterStage          *stage,
+                                                          ClutterStageView      *view,
+                                                          const cairo_region_t  *redraw_clip);
 
 void                _clutter_stage_emit_after_paint      (ClutterStage          *stage);
 
diff --git a/clutter/clutter/clutter-stage.c b/clutter/clutter/clutter-stage.c
index 25735c264..24930df70 100644
--- a/clutter/clutter/clutter-stage.c
+++ b/clutter/clutter/clutter-stage.c
@@ -144,8 +144,6 @@ struct _ClutterStagePrivate
   gpointer paint_data;
   GDestroyNotify paint_notify;
 
-  cairo_rectangle_int_t view_clip;
-
   int update_freeze_count;
 
   guint redraw_pending         : 1;
@@ -903,15 +901,18 @@ setup_view_for_pick_or_paint (ClutterStage                *stage,
 }
 
 static void
-clutter_stage_do_paint_view (ClutterStage                *stage,
-                             ClutterStageView            *view,
-                             const cairo_rectangle_int_t *clip)
+clutter_stage_do_paint_view (ClutterStage         *stage,
+                             ClutterStageView     *view,
+                             const cairo_region_t *redraw_clip)
 {
   ClutterPaintContext *paint_context;
+  cairo_rectangle_int_t clip_rect;
 
   paint_context = clutter_paint_context_new_for_view (view);
 
-  setup_view_for_pick_or_paint (stage, view, clip);
+  cairo_region_get_extents (redraw_clip, &clip_rect);
+  setup_view_for_pick_or_paint (stage, view, &clip_rect);
+
   clutter_actor_paint (CLUTTER_ACTOR (stage), paint_context);
   clutter_paint_context_destroy (paint_context);
 }
@@ -920,9 +921,9 @@ clutter_stage_do_paint_view (ClutterStage                *stage,
  * for picking or painting...
  */
 void
-_clutter_stage_paint_view (ClutterStage                *stage,
-                           ClutterStageView            *view,
-                           const cairo_rectangle_int_t *clip)
+clutter_stage_paint_view (ClutterStage         *stage,
+                          ClutterStageView     *view,
+                          const cairo_region_t *redraw_clip)
 {
   ClutterStagePrivate *priv = stage->priv;
 
@@ -931,15 +932,11 @@ _clutter_stage_paint_view (ClutterStage                *stage,
 
   COGL_TRACE_BEGIN_SCOPED (ClutterStagePaintView, "Paint (view)");
 
-  priv->view_clip = *clip;
-
   if (g_signal_has_handler_pending (stage, stage_signals[PAINT_VIEW],
                                     0, TRUE))
-    g_signal_emit (stage, stage_signals[PAINT_VIEW], 0, view);
+    g_signal_emit (stage, stage_signals[PAINT_VIEW], 0, view, redraw_clip);
   else
-    CLUTTER_STAGE_GET_CLASS (stage)->paint_view (stage, view);
-
-  priv->view_clip = (cairo_rectangle_int_t) { 0 };
+    CLUTTER_STAGE_GET_CLASS (stage)->paint_view (stage, view, redraw_clip);
 }
 
 void
@@ -1980,13 +1977,11 @@ clutter_stage_finalize (GObject *object)
 }
 
 static void
-clutter_stage_real_paint_view (ClutterStage     *stage,
-                               ClutterStageView *view)
+clutter_stage_real_paint_view (ClutterStage         *stage,
+                               ClutterStageView     *view,
+                               const cairo_region_t *redraw_clip)
 {
-  ClutterStagePrivate *priv = stage->priv;
-  const cairo_rectangle_int_t *clip = &priv->view_clip;
-
-  clutter_stage_do_paint_view (stage, view, clip);
+  clutter_stage_do_paint_view (stage, view, redraw_clip);
 }
 
 static void
@@ -2212,6 +2207,7 @@ clutter_stage_class_init (ClutterStageClass *klass)
    * ClutterStage::paint-view:
    * @stage: the stage that received the event
    * @view: a #ClutterStageView
+   * @redraw_clip: a #cairo_region_t with the redraw clip
    *
    * The ::paint-view signal is emitted before a #ClutterStageView is being
    * painted.
@@ -2226,8 +2222,9 @@ clutter_stage_class_init (ClutterStageClass *klass)
                   G_SIGNAL_RUN_LAST,
                   G_STRUCT_OFFSET (ClutterStageClass, paint_view),
                   NULL, NULL, NULL,
-                  G_TYPE_NONE, 1,
-                  CLUTTER_TYPE_STAGE_VIEW);
+                  G_TYPE_NONE, 2,
+                  CLUTTER_TYPE_STAGE_VIEW,
+                  G_TYPE_POINTER);
 
   /**
    * ClutterStage::presented: (skip)
@@ -2803,13 +2800,17 @@ clutter_stage_read_pixels (ClutterStage *stage,
                                       .height = height,
                                     });
   cairo_region_get_extents (clip, &clip_rect);
-  cairo_region_destroy (clip);
 
   if (clip_rect.width == 0 || clip_rect.height == 0)
-    return NULL;
+    {
+      cairo_region_destroy (clip);
+      return NULL;
+    }
 
   framebuffer = clutter_stage_view_get_framebuffer (view);
-  clutter_stage_do_paint_view (stage, view, &clip_rect);
+  clutter_stage_do_paint_view (stage, view, clip);
+
+  cairo_region_destroy (clip);
 
   view_scale = clutter_stage_view_get_scale (view);
   pixel_width = roundf (clip_rect.width * view_scale);
@@ -4449,8 +4450,12 @@ capture_view_into (ClutterStage          *stage,
 
   if (paint)
     {
+      cairo_region_t *region;
+
       _clutter_stage_maybe_setup_viewport (stage, view);
-      clutter_stage_do_paint_view (stage, view, rect);
+      region = cairo_region_create_rectangle (rect);
+      clutter_stage_do_paint_view (stage, view, region);
+      cairo_region_destroy (region);
     }
 
   view_scale = clutter_stage_view_get_scale (view);
diff --git a/clutter/clutter/clutter-stage.h b/clutter/clutter/clutter-stage.h
index 5910e6140..11f2e8716 100644
--- a/clutter/clutter/clutter-stage.h
+++ b/clutter/clutter/clutter-stage.h
@@ -84,8 +84,9 @@ struct _ClutterStageClass
   gboolean (* delete_event) (ClutterStage *stage,
                              ClutterEvent *event);
 
-  void (* paint_view) (ClutterStage     *stage,
-                       ClutterStageView *view);
+  void (* paint_view) (ClutterStage         *stage,
+                       ClutterStageView     *view,
+                       const cairo_region_t *redraw_clip);
 
   /*< private >*/
   /* padding for future expansion */
diff --git a/clutter/clutter/cogl/clutter-stage-cogl.c b/clutter/clutter/cogl/clutter-stage-cogl.c
index 590061234..ec9e746bc 100644
--- a/clutter/clutter/cogl/clutter-stage-cogl.c
+++ b/clutter/clutter/cogl/clutter-stage-cogl.c
@@ -576,29 +576,12 @@ offset_scale_and_clamp_region (const cairo_region_t *region,
 static void
 paint_stage (ClutterStageCogl *stage_cogl,
              ClutterStageView *view,
-             cairo_region_t   *fb_clip_region)
+             cairo_region_t   *redraw_clip)
 {
   ClutterStage *stage = stage_cogl->wrapper;
-  cairo_rectangle_int_t clip_rect;
-  cairo_rectangle_int_t paint_rect;
-  cairo_rectangle_int_t view_rect;
-  graphene_rect_t rect;
-  float fb_scale;
-
-  clutter_stage_view_get_layout (view, &view_rect);
-  fb_scale = clutter_stage_view_get_scale (view);
-
-  cairo_region_get_extents (fb_clip_region, &clip_rect);
-
-  _clutter_util_rect_from_rectangle (&clip_rect, &rect);
-  scale_and_clamp_rect (&rect, 1.0f / fb_scale, &paint_rect);
-  _clutter_util_rectangle_offset (&paint_rect,
-                                  view_rect.x,
-                                  view_rect.y,
-                                  &paint_rect);
 
   _clutter_stage_maybe_setup_viewport (stage, view);
-  _clutter_stage_paint_view (stage, view, &paint_rect);
+  clutter_stage_paint_view (stage, view, redraw_clip);
 
   clutter_stage_view_after_paint (view);
 }
@@ -863,6 +846,7 @@ clutter_stage_cogl_redraw_view (ClutterStageWindow *stage_window,
 
               /* Update the redraw clip region with the extra damage. */
               cairo_region_union (stage_cogl->redraw_clip, view_damage);
+              cairo_region_union (redraw_clip, view_damage);
 
               cairo_region_destroy (view_damage);
 
@@ -939,7 +923,7 @@ clutter_stage_cogl_redraw_view (ClutterStageWindow *stage_window,
           cogl_framebuffer_push_region_clip (fb, fb_clip_region);
         }
 
-      paint_stage (stage_cogl, view, fb_clip_region);
+      paint_stage (stage_cogl, view, redraw_clip);
 
       cogl_framebuffer_pop_clip (fb);
 
@@ -971,24 +955,13 @@ clutter_stage_cogl_redraw_view (ClutterStageWindow *stage_window,
                                               scissor_rect.width,
                                               scissor_rect.height);
 
-          paint_stage (stage_cogl, view, fb_clip_region);
+          paint_stage (stage_cogl, view, redraw_clip);
 
           cogl_framebuffer_pop_clip (fb);
         }
       else
         {
-          cairo_rectangle_int_t clip;
-          cairo_region_t *view_region;
-
-          clip = (cairo_rectangle_int_t) {
-            .x = 0,
-            .y = 0,
-            .width = ceilf (view_rect.width * fb_scale),
-            .height = ceilf (view_rect.height * fb_scale)
-          };
-          view_region = cairo_region_create_rectangle (&clip);
-          paint_stage (stage_cogl, view, view_region);
-          cairo_region_destroy (view_region);
+          paint_stage (stage_cogl, view, redraw_clip);
         }
     }
 
diff --git a/src/backends/meta-stage.c b/src/backends/meta-stage.c
index 478c60f33..4df6a4261 100644
--- a/src/backends/meta-stage.c
+++ b/src/backends/meta-stage.c
@@ -209,15 +209,17 @@ meta_stage_paint (ClutterActor        *actor,
 }
 
 static void
-meta_stage_paint_view (ClutterStage     *stage,
-                       ClutterStageView *view)
+meta_stage_paint_view (ClutterStage         *stage,
+                       ClutterStageView     *view,
+                       const cairo_region_t *redraw_clip)
 {
   MetaStage *meta_stage = META_STAGE (stage);
 
   notify_watchers_for_mode (meta_stage, view, META_STAGE_WATCH_BEFORE_PAINT);
 
   meta_stage->current_view = view;
-  CLUTTER_STAGE_CLASS (meta_stage_parent_class)->paint_view (stage, view);
+  CLUTTER_STAGE_CLASS (meta_stage_parent_class)->paint_view (stage, view,
+                                                             redraw_clip);
 
   notify_watchers_for_mode (meta_stage, view, META_STAGE_WATCH_AFTER_PAINT);
 }
diff --git a/src/tests/clutter/conform/actor-shader-effect.c b/src/tests/clutter/conform/actor-shader-effect.c
index 58d0a30b7..a2cea6d46 100644
--- a/src/tests/clutter/conform/actor-shader-effect.c
+++ b/src/tests/clutter/conform/actor-shader-effect.c
@@ -232,6 +232,7 @@ get_pixel (CoglFramebuffer *fb,
 static void
 view_painted_cb (ClutterStage     *stage,
                  ClutterStageView *view,
+                 cairo_region_t   *redraw_clip,
                  gpointer          data)
 {
   CoglFramebuffer *fb = clutter_stage_view_get_framebuffer (view);