Combine resize events for each pipeline and process when layout is idle

src/components/main/constellation.rs

@@ -3,7 +3,6 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use compositing::{CompositorChan, SetIds, SetLayerClipRect};
-use script::dom::event::ResizeEvent;
 
 use std::cell::Cell;
 use std::comm;
@@ -18,7 +17,7 @@ use servo_msg::constellation_msg::{InitLoadUrlMsg, LoadIframeUrlMsg, LoadUrlMsg}
 use servo_msg::constellation_msg::{Msg, NavigateMsg, NavigationType, IFrameUnsandboxed};
 use servo_msg::constellation_msg::{PipelineId, RendererReadyMsg, ResizedWindowMsg, SubpageId};
 use servo_msg::constellation_msg;
-use script::script_task::{SendEventMsg, ResizeInactiveMsg, ExecuteMsg};
+use script::script_task::{ResizeMsg, ResizeInactiveMsg, ExecuteMsg};
 use servo_net::image_cache_task::{ImageCacheTask, ImageCacheTaskClient};
 use servo_net::resource_task::ResourceTask;
 use servo_net::resource_task;
@@ -409,9 +408,10 @@ impl Constellation {
                         subpage id. This should not be possible.") == subpage_id {
                         child_frame_tree.rect = Some(rect.clone());
                         let Rect { size: Size2D { width, height }, _ } = rect;
-                        pipeline.script_chan.send(SendEventMsg(pipeline.id.clone(),
+                        pipeline.script_chan.send(ResizeMsg(pipeline.id.clone(), Size2D {
-                                                               ResizeEvent(width as uint,
+                            width:  width  as uint,
-                                                                           height as uint))); 
+                            height: height as uint
+                        }));
                         self.compositor_chan.send(SetLayerClipRect(pipeline.id, rect));
                         already_sent.insert(pipeline.id.clone());
                         break;
@@ -720,9 +720,7 @@ impl Constellation {
     fn handle_resized_window_msg(&mut self, new_size: Size2D<uint>) {
         let mut already_seen = HashSet::new();
         for &@FrameTree { pipeline: pipeline, _ } in self.current_frame().iter() {
-            let Size2D { width, height } = new_size;
+            pipeline.script_chan.send(ResizeMsg(pipeline.id.clone(), new_size));
-            pipeline.script_chan.send(SendEventMsg(pipeline.id.clone(),
-                                                   ResizeEvent(width, height)));
             already_seen.insert(pipeline.id.clone());
         }
         for frame_tree in self.navigation_context.previous.iter()

src/components/script/script_task.rs

@@ -63,6 +63,8 @@ pub enum ScriptMsg {
     NavigateMsg(NavigationDirection),
     /// Sends a DOM event.
     SendEventMsg(PipelineId, Event_),
+    /// Window resized.  Sends a DOM event eventually, but first we combine events.
+    ResizeMsg(PipelineId, Size2D<uint>),
     /// Fires a JavaScript timeout.
     FireTimerMsg(PipelineId, ~TimerData),
     /// Notifies script that reflow is finished.
@@ -128,6 +130,9 @@ pub struct Page {
     url: Option<(Url, bool)>,
 
     next_subpage_id: SubpageId,
+
+    /// Pending resize event, if any.
+    resize_event: Option<Size2D<uint>>
 }
 
 pub struct PageTree {
@@ -152,6 +157,7 @@ impl PageTree {
                 js_info: None,
                 url: None,
                 next_subpage_id: SubpageId(0),
+                resize_event: None,
             },
             inner: ~[],
         }
@@ -406,7 +412,7 @@ impl ScriptTask {
     /// Starts the script task. After calling this method, the script task will loop receiving
     /// messages on its port.
     pub fn start(&mut self) {
-        while self.handle_msg() {
+        while self.handle_msgs() {
             // Go on...
         }
     }
@@ -440,9 +446,49 @@ impl ScriptTask {
         }
     }
 
-    /// Handles an incoming control message.
+    /// Handle incoming control messages.
-    fn handle_msg(&mut self) -> bool {
+    fn handle_msgs(&mut self) -> bool {
-        match self.port.recv() {
+        // Handle pending resize events.
+        // Gather them first to avoid a double mut borrow on self.
+        let mut resizes = ~[];
+        for page in self.page_tree.iter() {
+            // Only process a resize if layout is idle.
+            if page.layout_join_port.is_none() {
+                match page.resize_event.take() {
+                    Some(size) => resizes.push((page.id, size)),
+                    None => ()
+                }
+            }
+        }
+
+        for (id, Size2D { width, height }) in resizes.move_iter() {
+            self.handle_event(id, ResizeEvent(width, height));
+        }
+
+        // Store new resizes, and gather all other events.
+        let mut sequential = ~[];
+        loop {
+            // Receive at least one message so we don't spinloop.
+            let event = self.port.recv();
+            match event {
+                ResizeMsg(id, size) => {
+                    let page = self.page_tree.find(id).expect("resize sent to nonexistent pipeline").page;
+                    page.resize_event = Some(size);
+                }
+                _ => {
+                    sequential.push(event);
+                }
+            }
+
+            // Break if there are no more messages.
+            if !self.port.peek() {
+                break;
+            }
+        }
+
+        // Process the gathered events.
+        for msg in sequential.move_iter() {
+            match msg {
                 // TODO(tkuehn) need to handle auxiliary layouts for iframes
                 AttachLayoutMsg(new_layout_info) => self.handle_new_layout(new_layout_info),
                 LoadMsg(id, url) => self.load(id, url),
@@ -455,8 +501,11 @@ impl ScriptTask {
                 ExitMsg => {
                     self.handle_exit_msg();
                     return false
+                },
+                ResizeMsg(*) => fail!("should have handled ResizeMsg already"),
             }
         }
+
         true
     }