Cleaning up PointerIdManager and add id re-mapping

third_party/WebKit/Source/core/input/EventHandler.cpp

Index: third_party/WebKit/Source/core/input/EventHandler.cpp
diff --git a/third_party/WebKit/Source/core/input/EventHandler.cpp b/third_party/WebKit/Source/core/input/EventHandler.cpp
index 0f681c7c1dd8cc2472fcb137aeeebea4d98091ad..cbd4c6e33ffec5434d3abead6cd5159f41d4ffdc 100644
--- a/third_party/WebKit/Source/core/input/EventHandler.cpp
+++ b/third_party/WebKit/Source/core/input/EventHandler.cpp
@@ -1619,7 +1619,8 @@ bool EventHandler::dispatchPointerEvent(Node* target, const AtomicString& eventT
         return false;
 
     RefPtrWillBeRawPtr<PointerEvent> pointerEvent = PointerEvent::create(eventType, true,
-        mouseEvent, relatedTarget, m_frame->document()->domWindow());
+        mouseEvent, relatedTarget, m_frame->document()->domWindow(),
+        m_pointerIdManager.getPrimaryId(WebPointerProperties::PointerType::Mouse));
     target->dispatchEvent(pointerEvent.get());
     return pointerEvent->defaultPrevented() || pointerEvent->defaultHandled();
 }
@@ -3656,6 +3657,7 @@ void EventHandler::dispatchPointerEvents(const PlatformTouchEvent& event,
         const unsigned& pointerId = touchPoint.id();
         const PlatformTouchPoint::State pointState = touchPoint.state();
 
+
         if (pointState == PlatformTouchPoint::TouchStationary || !touchInfo.knownTarget)
             continue;
 
@@ -3663,22 +3665,24 @@ void EventHandler::dispatchPointerEvents(const PlatformTouchEvent& event,
             || pointState == PlatformTouchPoint::TouchCancelled;
         const WebPointerProperties::PointerType pointerType = touchPoint.pointerProperties().pointerType;
 
-        if (pointState == PlatformTouchPoint::TouchPressed)
-            m_pointerIdManager.add(pointerType, pointerId);
+        // The id gets added the first time we call add which should TouchPressed
+        // and the consecutive calls with the same GeneratedPointer will return the same MappedId.
+        const PointerIdManager::MappedId mappedId = m_pointerIdManager.add(PointerIdManager::GeneratedPointer(pointerType, pointerId));

[mustaq, 2015/11/20 20:13:53]

This looks good. One concern is that EventHandler now has to worry too much
about PE ids w/o really doing anything with it. The state maintained through
m_pointerIdManager is unavoidable, but at least GeneratedPointer could be hidden
inside PointerEvent.

What if you just pass a PointerIdManager reference to PointerEvent::create()
methods so that the id mapping invisible to EventHandler?

Am I right that in that case, users of PointerEvent would know nothing about
mapped ids, and therefore, would pass only raw int/unsigned ids to
PointerIdManager methods? PointerEvent will be the only user of mapped ids then.

[Navid Zolghadr, 2015/11/20 20:32:22]

Then maybe in this case we can change PointerIdManager to PointerEventManager
and the new class will play the role of a factory class for PointerEvent class.
So all the create methods from PointerEvent will be moved to PointerEventManager
and then this guarantees nobody can create PointerEvent directly and everybody
goes through PointerEventManager and this class makes sure all the ids and
everything is unique. Is this a better approach then?

 
         RefPtrWillBeRawPtr<PointerEvent> pointerEvent = PointerEvent::create(
             pointerEventNameForTouchPointState(pointState),
-            m_pointerIdManager.isPrimary(pointerType, pointerId),
+            m_pointerIdManager.isPrimary(mappedId),
             touchPoint, event.modifiers(),
             touchInfo.adjustedRadius.width(), touchInfo.adjustedRadius.height(),
-            touchInfo.adjustedPagePoint.x(), touchInfo.adjustedPagePoint.y());
+            touchInfo.adjustedPagePoint.x(), touchInfo.adjustedPagePoint.y(),
+            mappedId);
 
         touchInfo.touchTarget->dispatchEvent(pointerEvent.get());
         touchInfo.consumed = pointerEvent->defaultPrevented() || pointerEvent->defaultHandled();
 
         // Remove the released/cancelled id at the end to correctly determine primary id above.
         if (pointerReleasedOrCancelled)
-            m_pointerIdManager.remove(pointerType, pointerId);
+            m_pointerIdManager.remove(mappedId);
     }
 }
 
@@ -3706,7 +3710,7 @@ void EventHandler::sendPointerCancels(WillBeHeapVector<TouchInfo>& touchInfos)
             EventTypeNames::pointercancel, pointerEventInit);
         touchInfo.touchTarget->dispatchEvent(pointerEvent.get());
 
-        m_pointerIdManager.remove(WebPointerProperties::PointerType::Touch, pointerId);
+        m_pointerIdManager.remove(PointerIdManager::GeneratedPointer(WebPointerProperties::PointerType::Touch, pointerId));
     }
 }