Clip display list based on frame viewport

Instead of creating a display list for the entire page, only create one
for an area that expands around the viewport. On my machine this makes
incremental layout of http://timecube.com 50% faster.

1 files changed, 11 insertions, 3 deletions

diff --git a/components/script/script_task.rs b/components/script/script_task.rs
index b234efef6c3..5630a9763b9 100644
--- a/components/script/script_task.rs
+++ b/components/script/script_task.rs
@@ -40,9 +40,9 @@ use devtools_traits::{DevtoolScriptControlMsg, EvaluateJS, EvaluateJSReply, GetD
 use devtools_traits::{GetChildren, GetLayout};
 use script_traits::{CompositorEvent, ResizeEvent, ReflowEvent, ClickEvent, MouseDownEvent};
 use script_traits::{MouseMoveEvent, MouseUpEvent, ConstellationControlMsg, ScriptTaskFactory};
-use script_traits::{ResizeMsg, AttachLayoutMsg, LoadMsg, SendEventMsg, ResizeInactiveMsg};
-use script_traits::{ExitPipelineMsg, NewLayoutInfo, OpaqueScriptLayoutChannel, ScriptControlChan};
-use script_traits::{ReflowCompleteMsg, UntrustedNodeAddress};
+use script_traits::{ResizeMsg, AttachLayoutMsg, LoadMsg, ViewportMsg, SendEventMsg};
+use script_traits::{ResizeInactiveMsg, ExitPipelineMsg, NewLayoutInfo, OpaqueScriptLayoutChannel};
+use script_traits::{ScriptControlChan, ReflowCompleteMsg, UntrustedNodeAddress};
 use servo_msg::compositor_msg::{FinishedLoading, LayerId, Loading};
 use servo_msg::compositor_msg::{ScriptListener};
 use servo_msg::constellation_msg::{ConstellationChan, LoadCompleteMsg, LoadUrlMsg, NavigationDirection};
@@ -495,6 +495,13 @@ impl ScriptTask {
                     pending.push_all_move(node_addresses);
                     needs_reflow.insert(id);
                 }
+                FromConstellation(ViewportMsg(id, rect)) => {
+                    let mut page = self.page.borrow_mut();
+                    let inner_page = page.find(id).expect("Page rect message sent to nonexistent pipeline");
+                    if inner_page.set_page_clip_rect_with_new_viewport(rect) {
+                        needs_reflow.insert(id);
+                    }
+                }
                 _ => {
                     sequential.push(event);
                 }
@@ -530,6 +537,7 @@ impl ScriptTask {
                 FromConstellation(ReflowCompleteMsg(id, reflow_id)) => self.handle_reflow_complete_msg(id, reflow_id),
                 FromConstellation(ResizeInactiveMsg(id, new_size)) => self.handle_resize_inactive_msg(id, new_size),
                 FromConstellation(ExitPipelineMsg(id)) => if self.handle_exit_pipeline_msg(id) { return false },
+                FromConstellation(ViewportMsg(..)) => fail!("should have handled ViewportMsg already"),
                 FromScript(ExitWindowMsg(id)) => self.handle_exit_window_msg(id),
                 FromConstellation(ResizeMsg(..)) => fail!("should have handled ResizeMsg already"),
                 FromScript(XHRProgressMsg(addr, progress)) => XMLHttpRequest::handle_progress(addr, progress),