clutter/stage-view: Move fb viewport and projection setting to here

The stage would fetch the front framebuffer and set the viewport and
projection matrix, but if we are going to more than one front buffer,
that won't work, so let the stage just pass the viewport and projection
matrix to the view and have the view deal with the framebuffer(s).

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

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

@@ -27,11 +27,20 @@ gboolean clutter_stage_view_is_dirty_viewport (ClutterStageView *view);
 void clutter_stage_view_set_dirty_viewport (ClutterStageView *view,
                                             gboolean          dirty);
 
+void clutter_stage_view_set_viewport (ClutterStageView *view,
+                                      float             x,
+                                      float             y,
+                                      float             width,
+                                      float             height);
+
 gboolean clutter_stage_view_is_dirty_projection (ClutterStageView *view);
 
 void clutter_stage_view_set_dirty_projection (ClutterStageView *view,
                                               gboolean          dirty);
 
+void clutter_stage_view_set_projection (ClutterStageView *view,
+                                        const CoglMatrix *matrix);
+
 void clutter_stage_view_add_redraw_clip (ClutterStageView            *view,
                                          const cairo_rectangle_int_t *clip);
 

clutter/clutter/clutter-stage-view.c

@@ -363,6 +363,22 @@ clutter_stage_view_set_dirty_viewport (ClutterStageView *view,
   priv->dirty_viewport = dirty;
 }
 
+void
+clutter_stage_view_set_viewport (ClutterStageView *view,
+                                 float             x,
+                                 float             y,
+                                 float             width,
+                                 float             height)
+{
+  ClutterStageViewPrivate *priv =
+    clutter_stage_view_get_instance_private (view);
+  CoglFramebuffer *framebuffer;
+
+  priv->dirty_viewport = FALSE;
+  framebuffer = clutter_stage_view_get_framebuffer (view);
+  cogl_framebuffer_set_viewport (framebuffer, x, y, width, height);
+}
+
 gboolean
 clutter_stage_view_is_dirty_projection (ClutterStageView *view)
 {
@@ -382,6 +398,19 @@ clutter_stage_view_set_dirty_projection (ClutterStageView *view,
   priv->dirty_projection = dirty;
 }
 
+void
+clutter_stage_view_set_projection (ClutterStageView *view,
+                                   const CoglMatrix *matrix)
+{
+  ClutterStageViewPrivate *priv =
+    clutter_stage_view_get_instance_private (view);
+  CoglFramebuffer *framebuffer;
+
+  priv->dirty_projection = FALSE;
+  framebuffer = clutter_stage_view_get_framebuffer (view);
+  cogl_framebuffer_set_projection_matrix (framebuffer, matrix);
+}
+
 void
 clutter_stage_view_get_offscreen_transformation_matrix (ClutterStageView *view,
                                                         CoglMatrix       *matrix)

clutter/clutter/clutter-stage.c

@@ -3147,7 +3147,6 @@ _clutter_stage_maybe_setup_viewport (ClutterStage     *stage,
                                      ClutterStageView *view)
 {
   ClutterStagePrivate *priv = stage->priv;
-  CoglFramebuffer *fb = clutter_stage_view_get_framebuffer (view);
 
   if (clutter_stage_view_is_dirty_viewport (view))
     {
@@ -3174,19 +3173,14 @@ _clutter_stage_maybe_setup_viewport (ClutterStage     *stage,
       viewport_y = roundf (priv->viewport[1] * fb_scale - viewport_offset_y);
       viewport_width = roundf (priv->viewport[2] * fb_scale);
       viewport_height = roundf (priv->viewport[3] * fb_scale);
-      cogl_framebuffer_set_viewport (fb,
+
+      clutter_stage_view_set_viewport (view,
                                        viewport_x, viewport_y,
                                        viewport_width, viewport_height);
-
-      clutter_stage_view_set_dirty_viewport (view, FALSE);
     }
 
   if (clutter_stage_view_is_dirty_projection (view))
-    {
+    clutter_stage_view_set_projection (view, &priv->projection);
-      cogl_framebuffer_set_projection_matrix (fb, &priv->projection);
-
-      clutter_stage_view_set_dirty_projection (view, FALSE);
-    }
 }
 
 #undef _DEG_TO_RAD