Scroll Customization Prototype (Not for review, WIP)

Source/core/page/scrolling/ScrollState.h

+// Copyright 2014 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 ScrollState_h
+#define ScrollState_h
+
+#include "bindings/core/v8/ExceptionState.h"
+#include "bindings/core/v8/ScriptWrappable.h"
+#include "core/dom/Element.h"
+#include "wtf/Vector.h"
+
+namespace blink {
+
+class ScrollState final : public GarbageCollectedFinalized<ScrollState>, public ScriptWrappable {
+    DEFINE_WRAPPERTYPEINFO();
+
+public:
+    static ScrollState* create(
+        double deltaX, double deltaY, double deltaGranularity, double velocityX,
+        double velocityY, bool inInertialPhase, bool isEnding, bool fromUserInput = false,
+        bool shouldPropagate = true);
+
+    virtual ~ScrollState();
+
+    void consumeDelta(double x, double y, ExceptionState&);
+    void distributeToScrollChainDescendant();
+
+    // Positive when scrolling left.
+    double deltaX() const { return m_deltaX; }
+    // Positive when scrolling up.
+    double deltaY() const { return m_deltaY; }
+    // Indicates the smallest delta the input device can produce. 0 for unquantized inputs.
+    double deltaGranularity() const { return m_deltaGranularity; }
+    // Positive if moving right.
+    double velocityX() const { return m_velocityX; }
+    // Positive if moving down.
+    double velocityY() const { return m_velocityY; }
+    // True for events dispatched after the users's gesture has finished.
+    bool inInertialPhase() const { return m_inInertialPhase; }
+    // True if this is the last event for this scroll.
+    bool isEnding() const { return m_isEnding; }
+    // True if this scroll is the direct result of user input.
+    bool fromUserInput() const { return m_fromUserInput; }
+    // True if this scroll is allowed to bubble upwards.
+    bool shouldPropagate() const { return m_shouldPropagate; }
+
+    // FIXME - indicate which of these are exposed.
+    void consumeDeltaNative(double x, double y);
+
+    void setScrollChain(WillBeHeapVector<RefPtrWillBeMember<Element>> scrollChain)
+    {
+        m_scrollChain = scrollChain;
+    }
+
+    void setCurrentNativeScrollingElement(Element* element)
+    {
+        m_currentNativeScrollingElement = element;
+    }
+
+    Element* currentNativeScrollingElement() const
+    {
+        return m_currentNativeScrollingElement;
+    }
+
+    void setScrollLockedToElement(bool scrollLockedToElement)
+    {
+        m_scrollLockedToElement = scrollLockedToElement;
+    }
+
+    bool scrollLockedToElement() const { return m_scrollLockedToElement; }
+
+    bool fullyConsumed() const
+    {
+        return !m_deltaX && !m_deltaY && !m_isEnding;
+    }
+
+    void trace(Visitor* visitor)
+    {
+        visitor->trace(m_scrollChain);
+    }
+
+private:
+    ScrollState();
+    ScrollState(double deltaX, double deltaY, double deltaGranularity,
+        double velocityX, double velocityY, bool inInertialPhase, bool isEnding, bool fromUserInput, bool shouldPropagate);
+
+    double m_deltaX;
+    double m_deltaY;
+    double m_deltaGranularity;
+    double m_velocityX;
+    double m_velocityY;
+    bool m_inInertialPhase;
+    bool m_isEnding;
+    bool m_fromUserInput;
+
+    WillBeHeapVector<RefPtrWillBeMember<Element>> m_scrollChain;
+
+    // The last element to respond to a scroll, or null if none exists.
+    Element* m_currentNativeScrollingElement;
+    bool m_scrollLockedToElement;
+    bool m_shouldPropagate;
+};
+
+} // namespace blink
+
+#endif // ScrollState_h