Implement Msg::Status with serialized url upon mouseover

Credits for Mike Blumenkrantz (@zmike), I just rebased against trunk and
fixed the url serialization.

Fixes #6178.

components/compositing/compositor.rs

@@ -420,6 +420,10 @@ impl<Window: WindowMethods> IOCompositor<Window> {
                 self.scroll_fragment_to_point(pipeline_id, layer_id, point);
             }
 
+            (Msg::Status(message), ShutdownState::NotShuttingDown) => {
+                self.window.status(message);
+            }
+
             (Msg::LoadStart(back, forward), ShutdownState::NotShuttingDown) => {
                 self.window.load_start(back, forward);
             }

components/compositing/compositor_task.rs

@@ -199,6 +199,8 @@ pub enum Msg {
     ReturnUnusedNativeSurfaces(Vec<NativeSurface>),
     /// Collect memory reports and send them back to the given mem::ReportsChan.
     CollectMemoryReports(mem::ReportsChan),
+    /// A status message to be displayed by the browser chrome.
+    Status(Option<String>),
 }
 
 impl Debug for Msg {
@@ -229,6 +231,7 @@ impl Debug for Msg {
             Msg::HeadParsed => write!(f, "HeadParsed"),
             Msg::ReturnUnusedNativeSurfaces(..) => write!(f, "ReturnUnusedNativeSurfaces"),
             Msg::CollectMemoryReports(..) => write!(f, "CollectMemoryReports"),
+            Msg::Status(..) => write!(f, "Status"),
         }
     }
 }

components/compositing/constellation.rs

@@ -514,6 +514,10 @@ impl<LTF: LayoutTaskFactory, STF: ScriptTaskFactory> Constellation<LTF, STF> {
                 debug!("constellation got create-WebGL-paint-task message");
                 self.handle_create_webgl_paint_task_msg(&size, attributes, sender)
             }
+            ConstellationMsg::NodeStatus(message) => {
+                debug!("constellation got NodeStatus message");
+                self.compositor_proxy.send(CompositorMsg::Status(message));
+            }
         }
         true
     }

components/compositing/headless.rs

@@ -97,6 +97,7 @@ impl CompositorEventListener for NullCompositor {
             Msg::AssignPaintedBuffers(..) |
             Msg::ChangeRunningAnimationsState(..) |
             Msg::ScrollFragmentPoint(..) |
+            Msg::Status(..) |
             Msg::LoadStart(..) |
             Msg::LoadComplete(..) |
             Msg::ScrollTimeout(..) |

components/compositing/windowing.rs

@@ -107,6 +107,8 @@ pub trait WindowMethods {
     fn set_page_title(&self, title: Option<String>);
     /// Sets the load data for the current page.
     fn set_page_url(&self, url: Url);
+    /// Called when the browser chrome should display a status message.
+    fn status(&self, Option<String>);
     /// Called when the browser has started loading a frame.
     fn load_start(&self, back: bool, forward: bool);
     /// Called when the browser is done loading a frame.

components/msg/constellation_msg.rs

@@ -269,6 +269,8 @@ pub enum Msg {
     CreateWebGLPaintTask(Size2D<i32>,
                          GLContextAttributes,
                          IpcSender<Result<(IpcSender<CanvasMsg>, usize), String>>),
+    /// Status message to be displayed in the chrome, eg. a link URL on mouseover.
+    NodeStatus(Option<String>),
 }
 
 #[derive(Clone, Eq, PartialEq, Deserialize, Serialize)]

components/script/script_task.rs

@@ -21,6 +21,7 @@
 
 use document_loader::{LoadType, DocumentLoader, NotifierData};
 use dom::bindings::cell::DOMRefCell;
+use dom::bindings::codegen::Bindings::AttrBinding::AttrMethods;
 use dom::bindings::codegen::Bindings::DocumentBinding::{DocumentMethods, DocumentReadyState};
 use dom::bindings::codegen::InheritTypes::{ElementCast, EventTargetCast, NodeCast, EventCast};
 use dom::bindings::conversions::FromJSValConvertible;
@@ -88,7 +89,7 @@ use js::jsapi::{JS_GetRuntime, JS_SetGCCallback, JSGCStatus, JSAutoRequest, SetD
 use js::jsapi::{SetDOMProxyInformation, DOMProxyShadowsResult, HandleObject, HandleId, RootedValue};
 use js::jsval::UndefinedValue;
 use js::rust::Runtime;
-use url::Url;
+use url::{Url, UrlParser};
 
 use libc;
 use std::any::Any;
@@ -1532,11 +1533,48 @@ impl ScriptTask {
                 }
                 let page = get_page(&self.root_page(), pipeline_id);
                 let document = page.document();
+
+                let mut prev_mouse_over_targets: RootedVec<JS<Node>> = RootedVec::new();
+                for target in self.mouse_over_targets.borrow_mut().iter() {
+                    prev_mouse_over_targets.push(target.clone());
+                }
+
                 // We temporarily steal the list of targets over which the mouse is to pass it to
                 // handle_mouse_move_event() in a safe RootedVec container.
                 let mut mouse_over_targets = RootedVec::new();
                 std_mem::swap(&mut *self.mouse_over_targets.borrow_mut(), &mut *mouse_over_targets);
                 document.r().handle_mouse_move_event(self.js_runtime.rt(), point, &mut mouse_over_targets);
+
+                // Notify Constellation about anchors that are no longer mouse over targets.
+                for target in prev_mouse_over_targets.iter() {
+                    if !mouse_over_targets.contains(target) {
+                        if target.root().r().is_anchor_element() {
+                            let event = ConstellationMsg::NodeStatus(None);
+                            let ConstellationChan(ref chan) = self.constellation_chan;
+                            chan.send(event).unwrap();
+                            break;
+                        }
+                    }
+                }
+
+                // Notify Constellation about the topmost anchor mouse over target.
+                for target in mouse_over_targets.iter() {
+                    let target = target.root();
+                    if target.r().is_anchor_element() {
+                        let element = ElementCast::to_ref(target.r()).unwrap();
+                        let status = element.get_attribute(&ns!(""), &atom!("href"))
+                            .and_then(|href| {
+                                let value = href.r().Value();
+                                let url = document.r().url();
+                                UrlParser::new().base_url(&url).parse(&value).map(|url| url.serialize()).ok()
+                            });
+                        let event = ConstellationMsg::NodeStatus(status);
+                        let ConstellationChan(ref chan) = self.constellation_chan;
+                        chan.send(event).unwrap();
+                        break;
+                    }
+                }
+
                 std_mem::swap(&mut *self.mouse_over_targets.borrow_mut(), &mut *mouse_over_targets);
             }
 

ports/cef/window.rs

@@ -316,6 +316,9 @@ impl WindowMethods for Window {
         browser.downcast().favicons.borrow_mut().push(url.to_string().clone());
     }
 
+    fn status(&self, _: Option<String>) {
+    }
+
     fn load_start(&self, back: bool, forward: bool) {
         let browser = self.cef_browser.borrow();
         let browser = match *browser {

ports/glutin/window.rs

@@ -554,6 +554,9 @@ impl WindowMethods for Window {
     fn set_page_url(&self, _: Url) {
     }
 
+    fn status(&self, _: Option<String>) {
+    }
+
     fn load_start(&self, _: bool, _: bool) {
     }
 
@@ -778,6 +781,9 @@ impl WindowMethods for Window {
     fn set_favicon(&self, _: Url) {
     }
 
+    fn status(&self, _: Option<String>) {
+    }
+
     fn prepare_for_composite(&self, _width: usize, _height: usize) -> bool {
         true
     }

ports/gonk/src/window.rs

@@ -803,6 +803,9 @@ impl WindowMethods for Window {
     fn set_page_url(&self, _: Url) {
     }
 
+    fn status(&self, _: Option<String>) {
+    }
+
     fn load_start(&self, _: bool, _: bool) {
     }