Bug 918288 - Modify the SetTargetAPZC API to take an array of targets for multiple touch points. r=botond

gfx/layers/apz/src/APZCTreeManager.cpp

@@ -721,11 +721,7 @@ APZCTreeManager::GetTouchInputBlockAPZC(const MultiTouchInput& aEvent,
   apzc = GetTargetAPZC(aEvent.mTouches[0].mScreenPoint, aOutHitResult);
   for (size_t i = 1; i < aEvent.mTouches.Length(); i++) {
     nsRefPtr<AsyncPanZoomController> apzc2 = GetTargetAPZC(aEvent.mTouches[i].mScreenPoint, aOutHitResult);
-    apzc = CommonAncestor(apzc.get(), apzc2.get());
-    APZCTM_LOG("Using APZC %p as the common ancestor\n", apzc.get());
-    // For now, we only ever want to do pinching on the root APZC for a given layers id. So
-    // when we find the common ancestor of multiple points, also walk up to the root APZC.
-    apzc = RootAPZCForLayersId(apzc);
+    apzc = GetMultitouchTarget(apzc, apzc2);
     APZCTM_LOG("Using APZC %p as the root APZC for multi-touch\n", apzc.get());
   }
 
@@ -960,9 +956,16 @@ APZCTreeManager::ContentReceivedTouch(uint64_t aInputBlockId,
 
 void
 APZCTreeManager::SetTargetAPZC(uint64_t aInputBlockId,
-                               const ScrollableLayerGuid& aGuid)
+                               const nsTArray<ScrollableLayerGuid>& aTargets)
 {
-  nsRefPtr<AsyncPanZoomController> target = GetTargetAPZC(aGuid);
+  nsRefPtr<AsyncPanZoomController> target = nullptr;
+  if (aTargets.Length() > 0) {
+    target = GetTargetAPZC(aTargets[0]);
+  }
+  for (size_t i = 1; i < aTargets.Length(); i++) {
+    nsRefPtr<AsyncPanZoomController> apzc2 = GetTargetAPZC(aTargets[i]);
+    target = GetMultitouchTarget(target, apzc2);
+  }
   mInputQueue->SetConfirmedTargetApzc(aInputBlockId, target);
 }
 
@@ -1556,7 +1559,17 @@ APZCTreeManager::GetApzcToGeckoTransform(const AsyncPanZoomController *aApzc) co
 }
 
 already_AddRefed<AsyncPanZoomController>
-APZCTreeManager::CommonAncestor(AsyncPanZoomController* aApzc1, AsyncPanZoomController* aApzc2)
+APZCTreeManager::GetMultitouchTarget(AsyncPanZoomController* aApzc1, AsyncPanZoomController* aApzc2) const
+{
+  nsRefPtr<AsyncPanZoomController> apzc = CommonAncestor(aApzc1, aApzc2);
+  // For now, we only ever want to do pinching on the root APZC for a given layers id. So
+  // when we find the common ancestor of multiple points, also walk up to the root APZC.
+  apzc = RootAPZCForLayersId(apzc);
+  return apzc.forget();
+}
+
+already_AddRefed<AsyncPanZoomController>
+APZCTreeManager::CommonAncestor(AsyncPanZoomController* aApzc1, AsyncPanZoomController* aApzc2) const
 {
   MonitorAutoLock lock(mTreeLock);
   nsRefPtr<AsyncPanZoomController> ancestor;
@@ -1602,7 +1615,7 @@ APZCTreeManager::CommonAncestor(AsyncPanZoomController* aApzc1, AsyncPanZoomCont
 }
 
 already_AddRefed<AsyncPanZoomController>
-APZCTreeManager::RootAPZCForLayersId(AsyncPanZoomController* aApzc)
+APZCTreeManager::RootAPZCForLayersId(AsyncPanZoomController* aApzc) const
 {
   MonitorAutoLock lock(mTreeLock);
   nsRefPtr<AsyncPanZoomController> apzc = aApzc;

gfx/layers/apz/src/APZCTreeManager.h

@@ -219,11 +219,13 @@ public:
    * where the initial input event of the block hit a dispatch-to-content region
    * but is safe to call for all input blocks. This function should always be
    * invoked on the controller thread.
-   * In the case where the input block has no target, or the target is not a
-   * scrollable frame, |aGuid.mScrollId| should be set to FrameMetrics::
-   * NULL_SCROLL_ID.
+   * The different elements in the array of targets correspond to the targets
+   * for the different touch points. In the case where the touch point has no
+   * target, or the target is not a scrollable frame, the target's |mScrollId|
+   * should be set to FrameMetrics::NULL_SCROLL_ID.
    */
-  void SetTargetAPZC(uint64_t aInputBlockId, const ScrollableLayerGuid& aGuid);
+  void SetTargetAPZC(uint64_t aInputBlockId,
+                     const nsTArray<ScrollableLayerGuid>& aTargets);
 
   /**
    * Updates any zoom constraints contained in the <meta name="viewport"> tag.
@@ -404,8 +406,9 @@ private:
   AsyncPanZoomController* GetAPZCAtPoint(AsyncPanZoomController* aApzc,
                                          const gfx::Point& aHitTestPoint,
                                          HitTestResult* aOutHitResult);
-  already_AddRefed<AsyncPanZoomController> CommonAncestor(AsyncPanZoomController* aApzc1, AsyncPanZoomController* aApzc2);
-  already_AddRefed<AsyncPanZoomController> RootAPZCForLayersId(AsyncPanZoomController* aApzc);
+  already_AddRefed<AsyncPanZoomController> GetMultitouchTarget(AsyncPanZoomController* aApzc1, AsyncPanZoomController* aApzc2) const;
+  already_AddRefed<AsyncPanZoomController> CommonAncestor(AsyncPanZoomController* aApzc1, AsyncPanZoomController* aApzc2) const;
+  already_AddRefed<AsyncPanZoomController> RootAPZCForLayersId(AsyncPanZoomController* aApzc) const;
   already_AddRefed<AsyncPanZoomController> GetTouchInputBlockAPZC(const MultiTouchInput& aEvent,
                                                                   HitTestResult* aOutHitResult);
   nsEventStatus ProcessTouchInput(MultiTouchInput& aInput,

gfx/tests/gtest/TestAsyncPanZoomController.cpp

@@ -2485,7 +2485,9 @@ TEST_F(APZEventRegionsTester, HitRegionImmediateResponse) {
   // Now let's do that again, but simulate a main-thread response
   uint64_t inputBlockId = 0;
   Tap(manager, 10, 110, time, 100, nullptr, &inputBlockId);
-  manager->SetTargetAPZC(inputBlockId, left->GetGuid());
+  nsTArray<ScrollableLayerGuid> targets;
+  targets.AppendElement(left->GetGuid());
+  manager->SetTargetAPZC(inputBlockId, targets);
   while (mcc->RunThroughDelayedTasks());    // this runs the tap event
   check.Call("Tapped on left this time");
 }