Remove SetLayerClipRect and add SetLayerOrigin

The constallation has accurate information about iframe layer origins,
but not their size.

components/compositing/compositor.rs

@@ -5,7 +5,7 @@
 use compositor_data::{CompositorData, DoesntWantScrollEvents, WantsScrollEvents};
 use compositor_task::{Msg, CompositorTask, Exit, ChangeReadyState, SetIds, LayerProperties};
 use compositor_task::{GetGraphicsMetadata, CreateOrUpdateRootLayer, CreateOrUpdateDescendantLayer};
-use compositor_task::{SetLayerClipRect, Paint, ScrollFragmentPoint, LoadComplete};
+use compositor_task::{SetLayerOrigin, Paint, ScrollFragmentPoint, LoadComplete};
 use compositor_task::{ShutdownComplete, ChangeRenderState, RenderMsgDiscarded};
 use constellation::SendableFrameTree;
 use events;
@@ -312,8 +312,8 @@ impl IOCompositor {
                     self.create_or_update_descendant_layer(layer_properties);
                 }
 
-                (Ok(SetLayerClipRect(pipeline_id, layer_id, new_rect)), NotShuttingDown) => {
-                    self.set_layer_clip_rect(pipeline_id, layer_id, new_rect);
+                (Ok(SetLayerOrigin(pipeline_id, layer_id, origin)), NotShuttingDown) => {
+                    self.set_layer_origin(pipeline_id, layer_id, origin);
                 }
 
                 (Ok(Paint(pipeline_id, epoch, replies)), NotShuttingDown) => {
@@ -558,17 +558,17 @@ impl IOCompositor {
         self.recomposite_if(needs_recomposite);
     }
 
-    fn set_layer_clip_rect(&mut self,
-                           pipeline_id: PipelineId,
-                           layer_id: LayerId,
-                           new_rect_in_page_coordinates: Rect<f32>) {
-        let new_rect_in_layer_coordinates =
-            self.convert_page_rect_to_layer_coordinates(new_rect_in_page_coordinates);
-        let new_rect_in_layer_coordinates = Rect::from_untyped(&new_rect_in_layer_coordinates);
-
+    fn set_layer_origin(&mut self,
+                        pipeline_id: PipelineId,
+                        layer_id: LayerId,
+                        new_origin: Point2D<f32>) {
+        let new_origin_in_device_coordinates = new_origin * self.device_pixels_per_page_px().get();
         match self.find_layer_with_pipeline_and_layer_id(pipeline_id, layer_id) {
-            Some(ref layer) => *layer.bounds.borrow_mut() = new_rect_in_layer_coordinates,
-            None => fail!("compositor received SetLayerClipRect for nonexistent layer"),
+            Some(ref layer) => {
+                layer.bounds.borrow_mut().origin =
+                    Point2D::from_untyped(&new_origin_in_device_coordinates)
+            }
+            None => fail!("Compositor received SetLayerOrigin for nonexistent layer"),
         };
 
         self.send_buffer_requests_for_all_layers();

components/compositing/compositor_task.rs

@@ -117,8 +117,6 @@ impl RenderListener for CompositorChan {
             } else {
                 self.chan.send(CreateOrUpdateDescendantLayer(layer_properties));
             }
-
-            self.chan.send(SetLayerClipRect(pipeline_id, metadata.id, layer_properties.rect));
         }
     }
 
@@ -167,8 +165,8 @@ pub enum Msg {
     /// Tells the compositor to create a descendant layer for a pipeline if necessary (i.e. if no
     /// layer with that ID exists).
     CreateOrUpdateDescendantLayer(LayerProperties),
-    /// Alerts the compositor that the specified layer's clipping rect has changed.
-    SetLayerClipRect(PipelineId, LayerId, Rect<f32>),
+    /// Alerts the compositor that the specified layer's origin has changed.
+    SetLayerOrigin(PipelineId, LayerId, Point2D<f32>),
     /// Scroll a page in a window
     ScrollFragmentPoint(PipelineId, LayerId, Point2D<f32>),
     /// Requests that the compositor paint the given layer buffer set for the given page size.

components/compositing/constellation.rs

@@ -2,7 +2,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-use compositor_task::{CompositorChan, LoadComplete, ShutdownComplete, SetLayerClipRect, SetIds};
+use compositor_task::{CompositorChan, LoadComplete, ShutdownComplete, SetLayerOrigin, SetIds};
 use std::collections::hashmap::{HashMap, HashSet};
 use geom::rect::{Rect, TypedRect};
 use geom::scale_factor::ScaleFactor;
@@ -507,9 +507,9 @@ impl<LTF: LayoutTaskFactory, STF: ScriptTaskFactory> Constellation<LTF, STF> {
                             initial_viewport: rect.size * ScaleFactor(1.0),
                             device_pixel_ratio: self.window_size.device_pixel_ratio,
                         }));
-                        self.compositor_chan.send(SetLayerClipRect(pipeline.id,
-                                                                   LayerId::null(),
-                                                                   rect.to_untyped()));
+                        self.compositor_chan.send(SetLayerOrigin(pipeline.id,
+                                                                 LayerId::null(),
+                                                                 rect.to_untyped().origin));
                     } else {
                         already_sent.insert(pipeline.id);
                     }

components/compositing/headless.rs

@@ -4,7 +4,7 @@
 
 use compositor_task::{Msg, Exit, ChangeReadyState, SetIds};
 use compositor_task::{GetGraphicsMetadata, CreateOrUpdateRootLayer, CreateOrUpdateDescendantLayer};
-use compositor_task::{SetLayerClipRect, Paint, ScrollFragmentPoint, LoadComplete};
+use compositor_task::{SetLayerOrigin, Paint, ScrollFragmentPoint, LoadComplete};
 use compositor_task::{ShutdownComplete, ChangeRenderState, RenderMsgDiscarded};
 
 use geom::scale_factor::ScaleFactor;
@@ -90,7 +90,7 @@ impl NullCompositor {
 
                 CreateOrUpdateRootLayer(..) |
                 CreateOrUpdateDescendantLayer(..) |
-                SetLayerClipRect(..) | Paint(..) |
+                SetLayerOrigin(..) | Paint(..) |
                 ChangeReadyState(..) | ChangeRenderState(..) | ScrollFragmentPoint(..) |
                 LoadComplete(..) | RenderMsgDiscarded(..) => ()
             }