Bug 1243547 - Route scroll position adjusting for surface shifting directly to APZC. r=rbarker

gfx/layers/apz/src/APZCTreeManager.cpp

@@ -1267,6 +1267,16 @@ APZCTreeManager::CancelAnimation(const ScrollableLayerGuid &aGuid)
   }
 }
 
+void
+APZCTreeManager::AdjustScrollForSurfaceShift(const ScreenPoint& aShift)
+{
+  MonitorAutoLock lock(mTreeLock);
+  RefPtr<AsyncPanZoomController> apzc = FindRootContentOrRootApzc();
+  if (apzc) {
+    apzc->AdjustScrollForSurfaceShift(aShift);
+  }
+}
+
 void
 APZCTreeManager::ClearTree()
 {
@@ -1742,6 +1752,33 @@ APZCTreeManager::FindRootContentApzcForLayersId(uint64_t aLayersId) const
   return resultNode ? resultNode->GetApzc() : nullptr;
 }
 
+AsyncPanZoomController*
+APZCTreeManager::FindRootContentOrRootApzc() const
+{
+  mTreeLock.AssertCurrentThreadOwns();
+
+  // Note: this is intended to find the same "root" that would be found
+  // by AsyncCompositionManager::ApplyAsyncContentTransformToTree inside
+  // the MOZ_ANDROID_APZ block. That is, it should find the RCD node if there
+  // is one, or the root APZC if there is not.
+  // Since BreadthFirstSearch is a pre-order search, we first do a search for
+  // the RCD, and then if we don't find one, we do a search for the root APZC.
+  HitTestingTreeNode* resultNode = BreadthFirstSearch(mRootNode.get(),
+      [](HitTestingTreeNode* aNode) {
+        AsyncPanZoomController* apzc = aNode->GetApzc();
+        return apzc && apzc->IsRootContent();
+      });
+  if (resultNode) {
+    return resultNode->GetApzc();
+  }
+  resultNode = BreadthFirstSearch(mRootNode.get(),
+      [](HitTestingTreeNode* aNode) {
+        AsyncPanZoomController* apzc = aNode->GetApzc();
+        return (apzc != nullptr);
+      });
+  return resultNode ? resultNode->GetApzc() : nullptr;
+}
+
 /* The methods GetScreenToApzcTransform() and GetApzcToGeckoTransform() return
    some useful transformations that input events may need applied. This is best
    illustrated with an example. Consider a chain of layers, L, M, N, O, P, Q, R. Layer L

gfx/layers/apz/src/APZCTreeManager.h

@@ -261,6 +261,14 @@ public:
    */
   void CancelAnimation(const ScrollableLayerGuid &aGuid);
 
+  /**
+   * Adjusts the root APZC to compensate for a shift in the surface. See the
+   * documentation on AsyncPanZoomController::AdjustScrollForSurfaceShift for
+   * some more details. This is only currently needed due to surface shifts
+   * caused by the dynamic toolbar on Android.
+   */
+  void AdjustScrollForSurfaceShift(const ScreenPoint& aShift);
+
   /**
    * Calls Destroy() on all APZC instances attached to the tree, and resets the
    * tree back to empty. This function may be called multiple times during the
@@ -450,6 +458,7 @@ private:
                                          HitTestResult* aOutHitResult);
   AsyncPanZoomController* FindRootApzcForLayersId(uint64_t aLayersId) const;
   AsyncPanZoomController* FindRootContentApzcForLayersId(uint64_t aLayersId) const;
+  AsyncPanZoomController* FindRootContentOrRootApzc() const;
   already_AddRefed<AsyncPanZoomController> GetMultitouchTarget(AsyncPanZoomController* aApzc1, AsyncPanZoomController* aApzc2) const;
   already_AddRefed<AsyncPanZoomController> CommonAncestor(AsyncPanZoomController* aApzc1, AsyncPanZoomController* aApzc2) const;
   already_AddRefed<AsyncPanZoomController> GetTouchInputBlockAPZC(const MultiTouchInput& aEvent,

gfx/layers/apz/src/AsyncPanZoomController.cpp

@@ -2639,6 +2639,19 @@ void AsyncPanZoomController::ShareFrameMetricsAcrossProcesses() {
   mSharingFrameMetricsAcrossProcesses = true;
 }
 
+void AsyncPanZoomController::AdjustScrollForSurfaceShift(const ScreenPoint& aShift)
+{
+  ReentrantMonitorAutoEnter lock(mMonitor);
+  CSSPoint adjustment =
+    ViewAs<ParentLayerPixel>(aShift, PixelCastJustification::ScreenIsParentLayerForRoot)
+    / mFrameMetrics.GetZoom();
+  APZC_LOG("%p adjusting scroll position by %s for surface shift\n",
+    this, Stringify(adjustment).c_str());
+  mFrameMetrics.ScrollBy(adjustment);
+  ScheduleCompositeAndMaybeRepaint();
+  UpdateSharedCompositorFrameMetrics();
+}
+
 void AsyncPanZoomController::ScrollBy(const CSSPoint& aOffset) {
   mFrameMetrics.ScrollBy(aOffset);
 }

gfx/layers/apz/src/AsyncPanZoomController.h

@@ -315,6 +315,15 @@ public:
    */
   void CancelAnimation(CancelAnimationFlags aFlags = Default);
 
+  /**
+   * Adjusts the scroll position to compensate for a shift in the surface, such
+   * that the content appears to remain visually in the same position. i.e. if
+   * the surface moves up by 10 screenpixels, the scroll position should also
+   * move up by 10 pixels so that what used to be at the top of the surface is
+   * now 10 pixels down the surface.
+   */
+  void AdjustScrollForSurfaceShift(const ScreenPoint& aShift);
+
   /**
    * Clear any overscroll on this APZC.
    */

mobile/android/base/java/org/mozilla/gecko/gfx/GeckoLayerClient.java

@@ -226,7 +226,7 @@ class GeckoLayerClient implements LayerView.Listener, PanZoomTarget
         }
         mViewportMetrics = mViewportMetrics.setViewportSize(width, height);
         if (scrollChange != null) {
-            mViewportMetrics = mViewportMetrics.offsetViewportByAndClamp(scrollChange.x, scrollChange.y);
+            mViewportMetrics = mPanZoomController.adjustScrollForSurfaceShift(mViewportMetrics, scrollChange);
         }
 
         if (mGeckoIsReady) {

mobile/android/base/java/org/mozilla/gecko/gfx/JavaPanZoomController.java

@@ -1467,4 +1467,9 @@ class JavaPanZoomController
     public void setOverscrollHandler(final Overscroll handler) {
         mOverscroll = handler;
     }
+
+    @Override
+    public ImmutableViewportMetrics adjustScrollForSurfaceShift(ImmutableViewportMetrics aMetrics, PointF aShift) {
+        return aMetrics.offsetViewportByAndClamp(aShift.x, aShift.y);
+    }
 }

mobile/android/base/java/org/mozilla/gecko/gfx/NativePanZoomController.java

@@ -184,6 +184,15 @@ class NativePanZoomController extends JNIObject implements PanZoomController {
         }
     }
 
+    @WrapForJNI(stubName = "AdjustScrollForSurfaceShift")
+    private native void adjustScrollForSurfaceShift(float aX, float aY);
+
+    @Override // PanZoomController
+    public ImmutableViewportMetrics adjustScrollForSurfaceShift(ImmutableViewportMetrics aMetrics, PointF aShift) {
+        adjustScrollForSurfaceShift(aShift.x, aShift.y);
+        return aMetrics;
+    }
+
     @WrapForJNI(allowMultithread = true)
     private void updateOverscrollVelocity(final float x, final float y) {
         if (mOverscroll != null) {

mobile/android/base/java/org/mozilla/gecko/gfx/PanZoomController.java

@@ -51,4 +51,6 @@ public interface PanZoomController {
     public void setOverscrollHandler(final Overscroll controller);
 
     public void setIsLongpressEnabled(boolean isLongpressEnabled);
+
+    public ImmutableViewportMetrics adjustScrollForSurfaceShift(ImmutableViewportMetrics aMetrics, PointF aShift);
 }

mobile/android/chrome/content/browser.js

@@ -6044,8 +6044,10 @@ var ViewportHandler = {
       let scrollChange = JSON.parse(aData);
       let windowUtils = window.QueryInterface(Ci.nsIInterfaceRequestor).getInterface(Ci.nsIDOMWindowUtils);
       windowUtils.setNextPaintSyncId(scrollChange.id);
-      let win = BrowserApp.selectedTab.browser.contentWindow;
+      if (!AppConstants.MOZ_ANDROID_APZ) {
-      win.scrollBy(scrollChange.x, scrollChange.y);
+        let win = BrowserApp.selectedTab.browser.contentWindow;
+        win.scrollBy(scrollChange.x, scrollChange.y);
+      }
     }
   },
 

widget/android/GeneratedJNINatives.h

@@ -274,6 +274,10 @@ class NativePanZoomController::Natives : public mozilla::jni::NativeImpl<NativeP
 public:
     static constexpr JNINativeMethod methods[] = {
 
+        mozilla::jni::MakeNativeMethod<NativePanZoomController::AdjustScrollForSurfaceShift_t>(
+                mozilla::jni::NativeStub<NativePanZoomController::AdjustScrollForSurfaceShift_t, Impl>
+                ::template Wrap<&Impl::AdjustScrollForSurfaceShift>),
+
         mozilla::jni::MakeNativeMethod<NativePanZoomController::DisposeNative_t>(
                 mozilla::jni::NativeStub<NativePanZoomController::DisposeNative_t, Impl>
                 ::template Wrap<&Impl::DisposeNative>),

widget/android/GeneratedJNIWrappers.cpp

@@ -1442,6 +1442,9 @@ auto LayerView::updateZoomedView(mozilla::jni::Object::Param a0) -> void
 
 constexpr char NativePanZoomController::name[];
 
+constexpr char NativePanZoomController::AdjustScrollForSurfaceShift_t::name[];
+constexpr char NativePanZoomController::AdjustScrollForSurfaceShift_t::signature[];
+
 constexpr char NativePanZoomController::Destroy_t::name[];
 constexpr char NativePanZoomController::Destroy_t::signature[];
 

widget/android/GeneratedJNIWrappers.h

@@ -3981,6 +3981,23 @@ public:
 protected:
     NativePanZoomController(jobject instance) : Class(instance) {}
 
+public:
+    struct AdjustScrollForSurfaceShift_t {
+        typedef NativePanZoomController Owner;
+        typedef void ReturnType;
+        typedef void SetterType;
+        typedef mozilla::jni::Args<
+                float,
+                float> Args;
+        static constexpr char name[] = "adjustScrollForSurfaceShift";
+        static constexpr char signature[] =
+                "(FF)V";
+        static const bool isStatic = false;
+        static const bool isMultithreaded = false;
+        static const mozilla::jni::ExceptionMode exceptionMode =
+                mozilla::jni::ExceptionMode::ABORT;
+    };
+
 public:
     struct Destroy_t {
         typedef NativePanZoomController Owner;

widget/android/nsWindow.cpp

@@ -490,6 +490,23 @@ public:
         }
     }
 
+    void AdjustScrollForSurfaceShift(float aX, float aY)
+    {
+        MOZ_ASSERT(AndroidBridge::IsJavaUiThread());
+
+        MutexAutoLock lock(mWindowLock);
+        if (!mWindow) {
+            // We already shut down.
+            return;
+        }
+
+        RefPtr<APZCTreeManager> controller = mWindow->mAPZC;
+        if (controller) {
+            controller->AdjustScrollForSurfaceShift(
+                ScreenPoint(aX, aY));
+        }
+    }
+
     void SetIsLongpressEnabled(bool aIsLongpressEnabled)
     {
         MOZ_ASSERT(AndroidBridge::IsJavaUiThread());