Bug 898580 - Metro mechanism for content to inform APZC about scroll events. Handles multi-APZC. r=bbondy, r=kats

browser/metro/base/content/apzc.js

@@ -46,11 +46,13 @@ var APZCObserver = {
       case 'TabOpen': {
         let browser = aEvent.originalTarget.linkedBrowser;
         browser.addEventListener("pageshow", this, true);
+        browser.messageManager.addMessageListener("scroll", this);
         break;
       }
       case 'TabClose': {
         let browser = aEvent.originalTarget.linkedBrowser;
-        browser.removeEventListener("pageshow", this);
+        browser.removeEventListener("pageshow", this, true);
+        browser.messageManager.removeMessageListener("scroll", this);
         break;
       }
     }
@@ -113,5 +115,16 @@ var APZCObserver = {
     } else if (aTopic == "apzc-handle-pan-end") {
       Util.dumpLn("APZC pan-end");
     }
+  },
+
+  receiveMessage: function(aMessage) {
+    let json = aMessage.json;
+    switch (aMessage.name) {
+      case "scroll": {
+        let data = json.viewId + " " + json.presShellId + " (" + json.scrollOffset.x + ", " + json.scrollOffset.y + ")";
+        Services.obs.notifyObservers(null, "scroll-offset-changed", data);
+        break;
+      }
+    }
   }
 };

browser/metro/base/content/bindings/browser.js

@@ -652,11 +652,7 @@ let ContentScroll =  {
         break;
 
       case "scroll": {
-        let doc = aEvent.target;
-        if (doc != content.document)
-          break;
-
-        this.sendScroll();
+        this.sendScroll(aEvent.target);
         break;
       }
 
@@ -683,13 +679,35 @@ let ContentScroll =  {
     }
   },
 
-  sendScroll: function sendScroll() {
-    let scrollOffset = this.getScrollOffset(content);
-    if (this._scrollOffset.x == scrollOffset.x && this._scrollOffset.y == scrollOffset.y)
-      return;
+  sendScroll: function sendScroll(target) {
+    let isRoot = false;
+    if (target instanceof Ci.nsIDOMDocument) {
+      var window = target.defaultView;
+      var scrollOffset = this.getScrollOffset(window);
+      var element = target.documentElement;
 
-    this._scrollOffset = scrollOffset;
-    sendAsyncMessage("scroll", scrollOffset);
+      if (target == content.document) {
+        if (this._scrollOffset.x == scrollOffset.x && this._scrollOffset.y == scrollOffset.y) {
+          return;
+        }
+        this._scrollOffset = scrollOffset;
+        isRoot = true;
+      }
+    } else {
+      var window = target.currentDoc.defaultView;
+      var scrollOffset = this.getScrollOffsetForElement(target);
+      var element = target;
+    }
+
+    let utils = window.QueryInterface(Ci.nsIInterfaceRequestor).getInterface(Ci.nsIDOMWindowUtils);
+    let presShellId = {};
+    utils.getPresShellId(presShellId);
+    let viewId = utils.getViewId(element);
+
+    sendAsyncMessage("scroll", { presShellId: presShellId.value,
+                                 viewId: viewId,
+                                 scrollOffset: scrollOffset,
+                                 isRoot: isRoot });
   }
 };
 

browser/metro/base/content/bindings/browser.xml

@@ -859,9 +859,11 @@
 
             switch (aMessage.name) {
               case "scroll":
+	        if (!json.isRoot)
+		  return;
                 if (!self.scrollSync)
                   return;
-                this.doScroll(json.x, json.y, 0);
+                this.doScroll(json.scrollOffset.x, json.scrollOffset.y, 0);
                 break;
            }
          },

widget/windows/winrt/MetroWidget.cpp

@@ -163,6 +163,7 @@ MetroWidget::MetroWidget() :
   mWnd(NULL),
   mMetroWndProc(NULL),
   mTempBasicLayerInUse(false),
+  mRootLayerTreeId(),
   nsWindowBase()
 {
   // Global initialization
@@ -271,6 +272,14 @@ MetroWidget::Destroy()
 
   nsCOMPtr<nsIWidget> kungFuDeathGrip(this);
 
+  if (ShouldUseAPZC()) {
+    nsresult rv;
+    nsCOMPtr<nsIObserverService> observerService = do_GetService("@mozilla.org/observer-service;1", &rv);
+    if (NS_SUCCEEDED(rv)) {
+      observerService->RemoveObserver(this, "scroll-offset-changed");
+    }
+  }
+
   RemoveSubclass();
   NotifyWindowDestroyed();
 
@@ -829,6 +838,13 @@ CompositorParent* MetroWidget::NewCompositorParent(int aSurfaceWidth, int aSurfa
   if (ShouldUseAPZC()) {
     CompositorParent::SetControllerForLayerTree(compositor->RootLayerTreeId(), this);
     MetroWidget::sAPZC = CompositorParent::GetAPZCTreeManager(compositor->RootLayerTreeId());
+    mRootLayerTreeId = compositor->RootLayerTreeId();
+
+    nsresult rv;
+    nsCOMPtr<nsIObserverService> observerService = do_GetService("@mozilla.org/observer-service;1", &rv);
+    if (NS_SUCCEEDED(rv)) {
+      observerService->AddObserver(this, "scroll-offset-changed", false);
+    }
   }
 
   return compositor;
@@ -1446,3 +1462,30 @@ MetroWidget::HandlePanEnd()
   LogFunction();
   MetroUtils::FireObserver("apzc-handle-pan-end", L"");
 }
+
+NS_IMETHODIMP
+MetroWidget::Observe(nsISupports *subject, const char *topic, const PRUnichar *data)
+{
+  NS_ENSURE_ARG_POINTER(topic);
+  if (!strcmp(topic, "scroll-offset-changed")) {
+    uint64_t scrollId;
+    int32_t presShellId;
+    CSSIntPoint scrollOffset;
+    int matched = sscanf(NS_LossyConvertUTF16toASCII(data).get(),
+                         "%llu %d (%d, %d)",
+                         &scrollId,
+                         &presShellId,
+                         &scrollOffset.x,
+                         &scrollOffset.y);
+    if (matched != 4) {
+      NS_WARNING("Malformed scroll-offset-changed message");
+      return NS_ERROR_UNEXPECTED;
+    }
+    if (MetroWidget::sAPZC) {
+      MetroWidget::sAPZC->UpdateScrollOffset(
+          ScrollableLayerGuid(mRootLayerTreeId, presShellId, scrollId),
+          scrollOffset);
+    }
+  }
+  return NS_OK;
+}

widget/windows/winrt/MetroWidget.h

@@ -46,7 +46,8 @@ class FrameworkView;
 } } }
 
 class MetroWidget : public nsWindowBase,
-                    public mozilla::layers::GeckoContentController
+                    public mozilla::layers::GeckoContentController,
+                    public nsIObserver
 {
   typedef mozilla::widget::WindowHook WindowHook;
   typedef mozilla::widget::TaskbarWindowPreview TaskbarWindowPreview;
@@ -55,6 +56,7 @@ class MetroWidget : public nsWindowBase,
   typedef ABI::Windows::UI::Core::IKeyEventArgs IKeyEventArgs;
   typedef ABI::Windows::UI::Core::ICharacterReceivedEventArgs ICharacterReceivedEventArgs;
   typedef mozilla::widget::winrt::FrameworkView FrameworkView;
+  typedef mozilla::layers::FrameMetrics FrameMetrics;
 
   static LRESULT CALLBACK
   StaticWindowProcedure(HWND aWnd, UINT aMsg, WPARAM aWParan, LPARAM aLParam);
@@ -65,6 +67,7 @@ public:
   virtual ~MetroWidget();
 
   NS_DECL_ISUPPORTS_INHERITED
+  NS_DECL_NSIOBSERVER
 
   static HWND GetICoreWindowHWND() { return sICoreHwnd; }
 
@@ -194,11 +197,11 @@ public:
   void RequestContentRepaintImplMainThread();
 
   // GeckoContentController interface impl
-  virtual void RequestContentRepaint(const mozilla::layers::FrameMetrics& aFrameMetrics);
+  virtual void RequestContentRepaint(const FrameMetrics& aFrameMetrics);
   virtual void HandleDoubleTap(const mozilla::CSSIntPoint& aPoint);
   virtual void HandleSingleTap(const mozilla::CSSIntPoint& aPoint);
   virtual void HandleLongTap(const mozilla::CSSIntPoint& aPoint);
-  virtual void SendAsyncScrollDOMEvent(mozilla::layers::FrameMetrics::ViewID aScrollId, const mozilla::CSSRect &aContentRect, const mozilla::CSSSize &aScrollableSize);
+  virtual void SendAsyncScrollDOMEvent(FrameMetrics::ViewID aScrollId, const mozilla::CSSRect &aContentRect, const mozilla::CSSSize &aScrollableSize);
   virtual void PostDelayedTask(Task* aTask, int aDelayMs);
   virtual void HandlePanBegin();
   virtual void HandlePanEnd();
@@ -243,6 +246,7 @@ protected:
   bool mTempBasicLayerInUse;
   Microsoft::WRL::ComPtr<mozilla::widget::winrt::MetroInput> mMetroInput;
   mozilla::layers::FrameMetrics mFrameMetrics;
+  uint64_t mRootLayerTreeId;
 
 public:
   static nsRefPtr<mozilla::layers::APZCTreeManager> sAPZC;