Auto merge of #5936 - pcwalton:fast-resize, r=jdm

2.1x improvement on resizing on Reddit.

r? @jdm

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components/layout/layout_task.rs

@@ -884,11 +884,8 @@ impl LayoutTask {
             }
         }
         if needs_reflow {
-            match self.try_get_layout_root(*node) {
+            if let Some(mut flow) = self.try_get_layout_root(*node) {
-                None => {}
+                LayoutTask::reflow_all_nodes(&mut *flow);
-                Some(mut flow) => {
-                    LayoutTask::reflow_all_nodes(&mut *flow);
-                }
             }
         }
 
@@ -899,28 +896,30 @@ impl LayoutTask {
                                                                          &self.url,
                                                                          data.reflow_info.goal);
 
-        // Recalculate CSS styles and rebuild flows and fragments.
+        if node.is_dirty() || node.has_dirty_descendants() || rw_data.stylist.is_dirty() {
-        profile(time::ProfilerCategory::LayoutStyleRecalc,
+            // Recalculate CSS styles and rebuild flows and fragments.
-                self.profiler_metadata(),
+            profile(time::ProfilerCategory::LayoutStyleRecalc,
-                self.time_profiler_chan.clone(),
+                    self.profiler_metadata(),
-                || {
+                    self.time_profiler_chan.clone(),
-            // Perform CSS selector matching and flow construction.
+                    || {
-            let rw_data = &mut *rw_data;
+                // Perform CSS selector matching and flow construction.
-            match rw_data.parallel_traversal {
+                let rw_data = &mut *rw_data;
-                None => {
+                match rw_data.parallel_traversal {
-                    sequential::traverse_dom_preorder(*node, &shared_layout_context);
+                    None => {
+                        sequential::traverse_dom_preorder(*node, &shared_layout_context);
+                    }
+                    Some(ref mut traversal) => {
+                        parallel::traverse_dom_preorder(*node, &shared_layout_context, traversal);
+                    }
                 }
-                Some(ref mut traversal) => {
+            });
-                    parallel::traverse_dom_preorder(*node, &shared_layout_context, traversal);
-                }
-            }
-        });
 
-        // Retrieve the (possibly rebuilt) root flow.
+            // Retrieve the (possibly rebuilt) root flow.
-        rw_data.root_flow = Some(self.get_layout_root((*node).clone()));
+            rw_data.root_flow = Some(self.get_layout_root((*node).clone()));
 
-        // Kick off animations if any were triggered.
+            // Kick off animations if any were triggered.
-        animation::process_new_animations(&mut *rw_data, self.id);
+            animation::process_new_animations(&mut *rw_data, self.id);
+        }
 
         // Perform post-style recalculation layout passes.
         self.perform_post_style_recalc_layout_passes(&data.reflow_info,

components/script/dom/window.rs

@@ -490,6 +490,7 @@ pub trait WindowHelpers {
     fn init_browser_context(self, doc: JSRef<Document>, frame_element: Option<JSRef<Element>>);
     fn load_url(self, href: DOMString);
     fn handle_fire_timer(self, timer_id: TimerId);
+    fn force_reflow(self, goal: ReflowGoal, query_type: ReflowQueryType, reason: ReflowReason);
     fn reflow(self, goal: ReflowGoal, query_type: ReflowQueryType, reason: ReflowReason);
     fn join_layout(self);
     fn layout(&self) -> &LayoutRPC;
@@ -566,24 +567,19 @@ impl<'a> WindowHelpers for JSRef<'a, Window> {
         *self.browser_context.borrow_mut() = None;
     }
 
-    /// Reflows the page if it's possible to do so and the page is dirty. This method will wait
+    /// Reflows the page unconditionally. This method will wait for the layout thread to complete
-    /// for the layout thread to complete (but see the `TODO` below). If there is no window size
+    /// (but see the `TODO` below). If there is no window size yet, the page is presumed invisible
-    /// yet, the page is presumed invisible and no reflow is performed.
+    /// and no reflow is performed.
     ///
     /// TODO(pcwalton): Only wait for style recalc, since we have off-main-thread layout.
-    fn reflow(self, goal: ReflowGoal, query_type: ReflowQueryType, reason: ReflowReason) {
+    fn force_reflow(self, goal: ReflowGoal, query_type: ReflowQueryType, reason: ReflowReason) {
         let document = self.Document().root();
         let root = document.r().GetDocumentElement().root();
         let root = match root.r() {
             Some(root) => root,
             None => return,
         };
-
         let root: JSRef<Node> = NodeCast::from_ref(root);
-        if query_type == ReflowQueryType::NoQuery && !root.get_has_dirty_descendants() {
-            debug!("root has no dirty descendants; avoiding reflow (reason {:?})", reason);
-            return
-        }
 
         let window_size = match self.window_size.get() {
             Some(window_size) => window_size,
@@ -642,6 +638,28 @@ impl<'a> WindowHelpers for JSRef<'a, Window> {
         }
     }
 
+    /// Reflows the page if it's possible to do so and the page is dirty. This method will wait
+    /// for the layout thread to complete (but see the `TODO` below). If there is no window size
+    /// yet, the page is presumed invisible and no reflow is performed.
+    ///
+    /// TODO(pcwalton): Only wait for style recalc, since we have off-main-thread layout.
+    fn reflow(self, goal: ReflowGoal, query_type: ReflowQueryType, reason: ReflowReason) {
+        let document = self.Document().root();
+        let root = document.r().GetDocumentElement().root();
+        let root = match root.r() {
+            Some(root) => root,
+            None => return,
+        };
+
+        let root: JSRef<Node> = NodeCast::from_ref(root);
+        if query_type == ReflowQueryType::NoQuery && !root.get_has_dirty_descendants() {
+            debug!("root has no dirty descendants; avoiding reflow (reason {:?})", reason);
+            return
+        }
+
+        self.force_reflow(goal, query_type, reason)
+    }
+
     // FIXME(cgaebel): join_layout is racey. What if the compositor triggers a
     // reflow between the "join complete" message and returning from this
     // function?

components/script/script_task.rs

@@ -820,7 +820,7 @@ impl ScriptTask {
                 let window = inner_page.window().root();
                 if window.r().set_page_clip_rect_with_new_viewport(rect) {
                     let page = get_page(page, id);
-                    self.force_reflow(&*page, ReflowReason::Viewport);
+                    self.rebuild_and_force_reflow(&*page, ReflowReason::Viewport);
                 }
                 return;
             }
@@ -884,7 +884,7 @@ impl ScriptTask {
 
         let needed_reflow = page.set_reflow_status(false);
         if needed_reflow {
-            self.force_reflow(&*page, ReflowReason::CachedPageNeededReflow);
+            self.rebuild_and_force_reflow(&*page, ReflowReason::CachedPageNeededReflow);
         }
 
         let window = page.window().root();
@@ -1200,8 +1200,8 @@ impl ScriptTask {
         self.compositor.borrow_mut().scroll_fragment_point(pipeline_id, LayerId::null(), point);
     }
 
-    /// Reflows non-incrementally.
+    /// Reflows non-incrementally, rebuilding the entire layout tree in the process.
-    fn force_reflow(&self, page: &Page, reason: ReflowReason) {
+    fn rebuild_and_force_reflow(&self, page: &Page, reason: ReflowReason) {
         let document = page.document().root();
         document.r().dirty_all_nodes();
         let window = window_from_node(document.r()).root();
@@ -1322,7 +1322,9 @@ impl ScriptTask {
         let page = get_page(&self.root_page(), pipeline_id);
         let window = page.window().root();
         window.r().set_window_size(new_size);
-        self.force_reflow(&*page, ReflowReason::WindowResize);
+        window.r().force_reflow(ReflowGoal::ForDisplay,
+                                ReflowQueryType::NoQuery,
+                                ReflowReason::WindowResize);
 
         let document = page.document().root();
         let fragment_node = window.r().steal_fragment_name()

components/style/selector_matching.rs

@@ -251,6 +251,10 @@ impl Stylist {
 
         shareable
     }
+
+    pub fn is_dirty(&self) -> bool {
+        self.is_dirty
+    }
 }
 
 struct PerOriginSelectorMap {