Cleaning up PointerIdManager and add id re-mapping

third_party/WebKit/Source/core/events/PointerEventFactory.h

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef PointerEventFactory_h
+#define PointerEventFactory_h
+
+#include "core/CoreExport.h"
+#include "core/events/PointerEvent.h"
+#include "public/platform/WebPointerProperties.h"
+#include "wtf/Allocator.h"
+#include "wtf/HashMap.h"
+
+namespace blink {
+
+/**
+  Helper class for tracking the pointer ids for each type of PointerEvents.
+  Using id re-mapping at this layer, this class makes sure that regardless of the
+  domain of the id (i.e. in touch or pen) the corresponding pointer event will have
+  a unique id amongst all pointer events as per pointer events' specification.
+  This class intended to behave the same as existing browsers as much as possible
+  for compatibility reasons. Particularly it behaves very similar to MS Edge to have
+  pointer event ids generated by mouse always equal 1 and those that are generated
+  by touch and pen will have increasing ids from 2.
+*/
+class CORE_EXPORT PointerEventFactory {
+    DISALLOW_NEW();
+public:
+
+    PassRefPtrWillBeRawPtr<PointerEvent> create(const AtomicString& type,
+        const PlatformMouseEvent&, PassRefPtrWillBeRawPtr<Node> relatedTarget,
+        PassRefPtrWillBeRawPtr<AbstractView>);
+
+    PassRefPtrWillBeRawPtr<PointerEvent> create(const AtomicString& type,
+        const PlatformTouchPoint&, PlatformEvent::Modifiers,
+        const double width, const double height,
+        const double clientX, const double clientY);
+
+    PassRefPtrWillBeRawPtr<PointerEvent> createPointerCancel(const PlatformTouchPoint&);
+
+    PointerEventFactory();
+    ~PointerEventFactory();
+
+    // Clear all the existing ids.
+    void clear();
+    /*
+     * When a pointerEvent with a particular id is removed that id is considered
+     * free even though there might have been other PointerEvents that were
+     * generated with the same id before.
+     */
+    void remove(const PassRefPtrWillBeRawPtr<PointerEvent>);
+
+private:
+    typedef long MappedId;
+    typedef std::pair<int, int> IncomingId;
+
+    MappedId add(const IncomingId);
+    bool isPrimary(const MappedId) const;
+    void setIdAndType(PointerEventInit &, const WebPointerProperties &);
+
+    static const MappedId s_invalidId;
+    static const MappedId s_mouseId;
+
+    PointerEventFactory::MappedId m_currentId;
+    HashMap<IncomingId, MappedId, WTF::PairHash<int, int>, WTF::PairHashTraits<WTF::UnsignedWithZeroKeyHashTraits<int>, WTF::UnsignedWithZeroKeyHashTraits<int>>> m_idMapping;
+    HashMap<MappedId, IncomingId, WTF::IntHash<MappedId>, WTF::UnsignedWithZeroKeyHashTraits<MappedId>> m_idReverseMapping;
+    MappedId m_primaryId[static_cast<int>(WebPointerProperties::PointerType::LastEntry) + 1];
+    MappedId m_idCount[static_cast<int>(WebPointerProperties::PointerType::LastEntry) + 1];
+};
+
+} // namespace blink
+
+#endif // PointerEventFactory_h