Bug 795567 - Part 5: Add zoom prevention based on the touch-action value. r=kats

gfx/layers/ipc/AsyncPanZoomController.cpp

@@ -758,6 +758,11 @@ nsEventStatus AsyncPanZoomController::OnTouchCancel(const MultiTouchInput& aEven
 
 nsEventStatus AsyncPanZoomController::OnScaleBegin(const PinchGestureInput& aEvent) {
   APZC_LOG("%p got a scale-begin in state %d\n", this, mState);
+
+  if (!TouchActionAllowZoom()) {
+    return nsEventStatus_eIgnore;
+  }
+
   if (!mZoomConstraints.mAllowZoom) {
     return nsEventStatus_eConsumeNoDefault;
   }
@@ -1726,6 +1731,22 @@ void AsyncPanZoomController::CheckContentResponse() {
   }
 }
 
+bool AsyncPanZoomController::TouchActionAllowZoom() {
+  if (!mTouchActionPropertyEnabled) {
+    return true;
+  }
+
+  // Pointer events specification implies all touch points to allow zoom
+  // to perform it.
+  for (size_t i = 0; i < mAllowedTouchBehaviors.Length(); i++) {
+    if (!(mAllowedTouchBehaviors[i] & AllowedTouchBehavior::ZOOM)) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
 AsyncPanZoomController::TouchBehaviorFlags
 AsyncPanZoomController::GetTouchBehavior(uint32_t touchIndex) {
   if (touchIndex < mAllowedTouchBehaviors.Length()) {

gfx/layers/ipc/AsyncPanZoomController.h

@@ -538,6 +538,11 @@ private:
                                  was not set yet. we still need to abort animations. */
   };
 
+  /*
+   * Returns whether current touch behavior values allow zooming.
+   */
+  bool TouchActionAllowZoom();
+
   /*
    * Returns allowed touch behavior from the mAllowedTouchBehavior array.
    * In case apzc didn't receive touch behavior values within the timeout