clutter/stage-cogl: Use buffer age when view monitor is rotated

We failed to use the buffer age when monitors were rotated, as when they
are, we first composite to an offscreen framebuffer, then later again to
the onscreen. The buffer age checking happened on the offscreen, and an
offscreen being single buffered, they can't possible support buffer
ages.

Instead, move the buffer age check to check the actual onscreen
framebuffer. The offscreen to onscreen painting is still always full
frame, but that will be fixed in a later commit.

https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1237

clutter/clutter/clutter-stage-view-private.h

@@ -52,4 +52,10 @@ cairo_region_t * clutter_stage_view_take_redraw_clip (ClutterStageView *view);
 
 CoglScanout * clutter_stage_view_take_scanout (ClutterStageView *view);
 
+void clutter_stage_view_transform_rect_to_onscreen (ClutterStageView            *view,
+                                                    const cairo_rectangle_int_t *src_rect,
+                                                    int                          dst_width,
+                                                    int                          dst_height,
+                                                    cairo_rectangle_int_t       *dst_rect);
+
 #endif /* __CLUTTER_STAGE_VIEW_PRIVATE_H__ */

clutter/clutter/clutter-stage-view.c

@@ -166,6 +166,22 @@ clutter_stage_view_invalidate_offscreen_blit_pipeline (ClutterStageView *view)
   g_clear_pointer (&priv->offscreen_pipeline, cogl_object_unref);
 }
 
+void
+clutter_stage_view_transform_rect_to_onscreen (ClutterStageView            *view,
+                                               const cairo_rectangle_int_t *src_rect,
+                                               int                          dst_width,
+                                               int                          dst_height,
+                                               cairo_rectangle_int_t       *dst_rect)
+{
+  ClutterStageViewClass *view_class = CLUTTER_STAGE_VIEW_GET_CLASS (view);
+
+  return view_class->transform_rect_to_onscreen (view,
+                                                 src_rect,
+                                                 dst_width,
+                                                 dst_height,
+                                                 dst_rect);
+}
+
 static void
 paint_transformed_framebuffer (ClutterStageView *view,
                                CoglPipeline     *pipeline,
@@ -471,19 +487,6 @@ clutter_stage_view_take_redraw_clip (ClutterStageView *view)
   return g_steal_pointer (&priv->redraw_clip);
 }
 
-void
-clutter_stage_view_transform_to_onscreen (ClutterStageView *view,
-                                          gfloat           *x,
-                                          gfloat           *y)
-{
-  gfloat z = 0, w = 1;
-  CoglMatrix matrix;
-
-  clutter_stage_view_get_offscreen_transformation_matrix (view, &matrix);
-  cogl_matrix_get_inverse (&matrix, &matrix);
-  cogl_matrix_transform_point (&matrix, x, y, &z, &w);
-}
-
 static void
 clutter_stage_default_get_offscreen_transformation_matrix (ClutterStageView *view,
                                                            CoglMatrix       *matrix)

clutter/clutter/clutter-stage-view.h

@@ -43,6 +43,12 @@ struct _ClutterStageViewClass
 
   void (* get_offscreen_transformation_matrix) (ClutterStageView *view,
                                                 CoglMatrix       *matrix);
+
+  void (* transform_rect_to_onscreen) (ClutterStageView            *view,
+                                       const cairo_rectangle_int_t *src_rect,
+                                       int                          dst_width,
+                                       int                          dst_height,
+                                       cairo_rectangle_int_t       *dst_rect);
 };
 
 CLUTTER_EXPORT
@@ -56,11 +62,6 @@ CoglFramebuffer *clutter_stage_view_get_onscreen (ClutterStageView *view);
 CLUTTER_EXPORT
 void             clutter_stage_view_invalidate_offscreen_blit_pipeline (ClutterStageView *view);
 
-CLUTTER_EXPORT
-void             clutter_stage_view_transform_to_onscreen (ClutterStageView *view,
-                                                           gfloat           *x,
-                                                           gfloat           *y);
-
 CLUTTER_EXPORT
 float clutter_stage_view_get_scale (ClutterStageView *view);
 

clutter/clutter/cogl/clutter-stage-cogl.c

@@ -536,44 +536,25 @@ static cairo_region_t *
 transform_swap_region_to_onscreen (ClutterStageView *view,
                                    cairo_region_t   *swap_region)
 {
-  CoglFramebuffer *framebuffer;
+  CoglFramebuffer *onscreen = clutter_stage_view_get_onscreen (view);
-  cairo_rectangle_int_t layout;
-  gint width, height;
   int n_rects, i;
   cairo_rectangle_int_t *rects;
   cairo_region_t *transformed_region;
+  int width, height;
 
-  framebuffer = clutter_stage_view_get_onscreen (view);
+  width = cogl_framebuffer_get_width (onscreen);
-  clutter_stage_view_get_layout (view, &layout);
+  height = cogl_framebuffer_get_height (onscreen);
-
-  width = cogl_framebuffer_get_width (framebuffer);
-  height = cogl_framebuffer_get_height (framebuffer);
 
   n_rects = cairo_region_num_rectangles (swap_region);
   rects = g_newa (cairo_rectangle_int_t, n_rects);
   for (i = 0; i < n_rects; i++)
     {
-      gfloat x1, y1, x2, y2;
-
       cairo_region_get_rectangle (swap_region, i, &rects[i]);
-
+      clutter_stage_view_transform_rect_to_onscreen (view,
-      x1 = (float) rects[i].x / layout.width;
+                                                     &rects[i],
-      y1 = (float) rects[i].y / layout.height;
+                                                     width,
-      x2 = (float) (rects[i].x + rects[i].width) / layout.width;
+                                                     height,
-      y2 = (float) (rects[i].y + rects[i].height) / layout.height;
+                                                     &rects[i]);
-
-      clutter_stage_view_transform_to_onscreen (view, &x1, &y1);
-      clutter_stage_view_transform_to_onscreen (view, &x2, &y2);
-
-      x1 = floor (x1 * width);
-      y1 = floor (height - (y1 * height));
-      x2 = ceil (x2 * width);
-      y2 = ceil (height - (y2 * height));
-
-      rects[i].x = x1;
-      rects[i].y = y1;
-      rects[i].width = x2 - x1;
-      rects[i].height = y2 - y1;
     }
   transformed_region = cairo_region_create_rectangles (rects, n_rects);
 
@@ -598,6 +579,7 @@ clutter_stage_cogl_redraw_view (ClutterStageWindow *stage_window,
   ClutterStageViewCoglPrivate *view_priv =
     clutter_stage_view_cogl_get_instance_private (view_cogl);
   CoglFramebuffer *fb = clutter_stage_view_get_framebuffer (view);
+  CoglFramebuffer *onscreen = clutter_stage_view_get_onscreen (view);
   cairo_rectangle_int_t view_rect;
   gboolean is_full_redraw;
   gboolean use_clipped_redraw;
@@ -619,10 +601,10 @@ clutter_stage_cogl_redraw_view (ClutterStageWindow *stage_window,
   fb_height = cogl_framebuffer_get_height (fb);
 
   can_blit_sub_buffer =
-    cogl_is_onscreen (fb) &&
+    cogl_is_onscreen (onscreen) &&
     cogl_clutter_winsys_has_feature (COGL_WINSYS_FEATURE_SWAP_REGION);
 
-  has_buffer_age = cogl_is_onscreen (fb) && is_buffer_age_enabled ();
+  has_buffer_age = cogl_is_onscreen (onscreen) && is_buffer_age_enabled ();
 
   redraw_clip = clutter_stage_view_take_redraw_clip (view);
   if (G_UNLIKELY (clutter_paint_debug_flags & CLUTTER_DEBUG_PAINT_DAMAGE_REGION))
@@ -636,7 +618,7 @@ clutter_stage_cogl_redraw_view (ClutterStageWindow *stage_window,
 
   if (has_buffer_age)
     {
-      buffer_age = cogl_onscreen_get_buffer_age (COGL_ONSCREEN (fb));
+      buffer_age = cogl_onscreen_get_buffer_age (COGL_ONSCREEN (onscreen));
       if (!valid_buffer_age (view_cogl, buffer_age))
         {
           CLUTTER_NOTE (CLIPPING,
@@ -654,7 +636,7 @@ clutter_stage_cogl_redraw_view (ClutterStageWindow *stage_window,
     !is_full_redraw &&
     /* some drivers struggle to get going and produce some junk
      * frames when starting up... */
-    cogl_onscreen_get_frame_counter (COGL_ONSCREEN (fb)) > 3;
+    cogl_onscreen_get_frame_counter (COGL_ONSCREEN (onscreen)) > 3;
 
   if (use_clipped_redraw)
     {

src/backends/meta-renderer-view.c

@@ -34,6 +34,7 @@
 
 #include "backends/meta-renderer.h"
 #include "clutter/clutter-mutter.h"
+#include "compositor/region-utils.h"
 
 enum
 {
@@ -117,6 +118,25 @@ meta_renderer_view_setup_offscreen_blit_pipeline (ClutterStageView *view,
   cogl_pipeline_set_layer_matrix (pipeline, 0, &matrix);
 }
 
+static void
+meta_renderer_view_transform_rect_to_onscreen (ClutterStageView            *view,
+                                               const cairo_rectangle_int_t *src_rect,
+                                               int                          dst_width,
+                                               int                          dst_height,
+                                               cairo_rectangle_int_t       *dst_rect)
+{
+  MetaRendererView *renderer_view = META_RENDERER_VIEW (view);
+  MetaMonitorTransform inverted_transform;
+
+  inverted_transform =
+    meta_monitor_transform_invert (renderer_view->transform);
+  return meta_rectangle_transform (src_rect,
+                                   inverted_transform,
+                                   dst_width,
+                                   dst_height,
+                                   dst_rect);
+}
+
 static void
 meta_renderer_view_set_transform (MetaRendererView     *view,
                                   MetaMonitorTransform  transform)
@@ -181,6 +201,8 @@ meta_renderer_view_class_init (MetaRendererViewClass *klass)
     meta_renderer_view_setup_offscreen_blit_pipeline;
   view_class->get_offscreen_transformation_matrix =
     meta_renderer_view_get_offscreen_transformation_matrix;
+  view_class->transform_rect_to_onscreen =
+    meta_renderer_view_transform_rect_to_onscreen;
 
   object_class->get_property = meta_renderer_view_get_property;
   object_class->set_property = meta_renderer_view_set_property;