Scroll Customization Prototype (Not for review, WIP)

Source/core/page/scrolling/ScrollState.cpp

+// 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.
+
+#include "config.h"
+#include "core/page/scrolling/ScrollState.h"
+
+#include "core/dom/Element.h"
+#include "core/dom/ExceptionCode.h"
+
+namespace blink {
+
+ScrollState* ScrollState::create(double deltaX, double deltaY, double deltaGranularity,
+    double velocityX, double velocityY, bool inInertialPhase, bool isEnding,
+    bool fromUserInput, bool shouldPropagate)
+{
+    return new ScrollState(
+        deltaX, deltaY, deltaGranularity, velocityX, velocityY,
+        inInertialPhase, isEnding, fromUserInput, shouldPropagate);
+}
+
+ScrollState::ScrollState(double deltaX, double deltaY, double deltaGranularity,
+    double velocityX, double velocityY, bool inInertialPhase, bool isEnding,
+    bool fromUserInput, bool shouldPropagate)
+    : m_deltaX(deltaX)
+    , m_deltaY(deltaY)
+    , m_deltaGranularity(deltaGranularity)
+    , m_velocityX(velocityX)
+    , m_velocityY(velocityY)
+    , m_inInertialPhase(inInertialPhase)
+    , m_isEnding(isEnding)
+    , m_fromUserInput(fromUserInput)
+    , m_shouldPropagate(shouldPropagate)
+{
+}
+
+ScrollState::~ScrollState()
+{
+}
+
+void ScrollState::consumeDelta(double x, double y, ExceptionState& exceptionState)
+{
+    if ((m_deltaX > 0 && 0 > x) || (m_deltaX < 0 && 0 < x) || (m_deltaY > 0 && 0 > y) || (m_deltaY < 0 && 0 < y)) {
+        exceptionState.throwDOMException(InvalidModificationError, "Can't increase delta using consumeDelta");
+    } else if (fabs(x) > fabs(m_deltaX) || fabs(y) > fabs(m_deltaY)) {
+        exceptionState.throwDOMException(InvalidModificationError, "Can't change direction of delta using consumeDelta");
+    }
+    consumeDeltaNative(x, y);
+}
+
+void ScrollState::distributeToScrollChainDescendant()
+{
+    if (m_scrollChain.isEmpty())
+        return;
+    Element* element = m_scrollChain[0].get();
+    m_scrollChain.remove(0);
+    element->callDistributeScroll(this);
+}
+
+void ScrollState::consumeDeltaNative(double x, double y)
+{
+    m_deltaX -= x;
+    m_deltaY -= y;
+
+    if (x || y)
+        m_scrollLockedToElement = true;
+}
+
+} // namespace blink