Add additive animation support for CSS property background-position

third_party/WebKit/Source/core/animation/LengthListPropertyFunctions.cpp

Index: third_party/WebKit/Source/core/animation/LengthListPropertyFunctions.cpp
diff --git a/third_party/WebKit/Source/core/animation/LengthListPropertyFunctions.cpp b/third_party/WebKit/Source/core/animation/LengthListPropertyFunctions.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..904c14d1e01a162a0c3e36da238f89fd05f3f7dd
--- /dev/null
+++ b/third_party/WebKit/Source/core/animation/LengthListPropertyFunctions.cpp
@@ -0,0 +1,144 @@
+// 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.
+
+#include "core/animation/LengthListPropertyFunctions.h"
+
+#include "core/style/ComputedStyle.h"
+
+namespace blink {
+
+namespace {
+
+const FillLayer* getFillLayer(CSSPropertyID property, const ComputedStyle& style)
+{
+    switch (property) {
+    case CSSPropertyBackgroundPositionX:
+    case CSSPropertyBackgroundPositionY:
+        return &style.backgroundLayers();
+    case CSSPropertyWebkitMaskPositionX:
+    case CSSPropertyWebkitMaskPositionY:
+        return &style.maskLayers();
+    default:
+        ASSERT_NOT_REACHED();
+        return nullptr;
+    }
+}
+
+FillLayer* accessFillLayer(CSSPropertyID property, ComputedStyle& style)
+{
+    switch (property) {
+    case CSSPropertyBackgroundPositionX:
+    case CSSPropertyBackgroundPositionY:
+        return &style.accessBackgroundLayers();
+    case CSSPropertyWebkitMaskPositionX:
+    case CSSPropertyWebkitMaskPositionY:
+        return &style.accessMaskLayers();
+    default:
+        ASSERT_NOT_REACHED();
+        return nullptr;
+    }
+}
+
+struct FillLayerMethods {
+    FillLayerMethods(CSSPropertyID property)
+    {
+        switch (property) {
+        case CSSPropertyBackgroundPositionX:
+        case CSSPropertyWebkitMaskPositionX:
+            isSet = &FillLayer::isXPositionSet;
+            get = &FillLayer::xPosition;
+            set = &FillLayer::setXPosition;
+            clear = &FillLayer::clearXPosition;
+            break;
+        case CSSPropertyBackgroundPositionY:
+        case CSSPropertyWebkitMaskPositionY:
+            isSet = &FillLayer::isYPositionSet;
+            get = &FillLayer::yPosition;
+            set = &FillLayer::setYPosition;
+            clear = &FillLayer::clearYPosition;
+            break;
+        default:
+            ASSERT_NOT_REACHED();
+            isSet = nullptr;
+            get = nullptr;
+            set = nullptr;
+            clear = nullptr;
+            break;
+        }
+    }
+
+    bool (FillLayer::*isSet)() const;
+    const Length& (FillLayer::*get)() const;
+    void (FillLayer::*set)(const Length&);
+    void (FillLayer::*clear)();
+};
+
+} // namespace
+
+ValueRange LengthListPropertyFunctions::valueRange(CSSPropertyID property)
+{
+    switch (property) {
+    case CSSPropertyBackgroundPositionX:
+    case CSSPropertyBackgroundPositionY:
+    case CSSPropertyWebkitMaskPositionX:
+    case CSSPropertyWebkitMaskPositionY:
+        return ValueRangeAll;
+
+    case CSSPropertyStrokeDasharray:
+        return ValueRangeNonNegative;
+
+    default:
+        ASSERT_NOT_REACHED();
+        return ValueRangeAll;
+    }
+}
+
+Vector<Length> LengthListPropertyFunctions::getInitialLengthList(CSSPropertyID property)
+{
+    return getLengthList(property, *ComputedStyle::initialStyle());
+}
+
+Vector<Length> LengthListPropertyFunctions::getLengthList(CSSPropertyID property, const ComputedStyle& style)
+{
+    Vector<Length> result;
+
+    if (property == CSSPropertyStrokeDasharray) {
+        if (style.strokeDashArray())
+            result.appendVector(style.strokeDashArray()->vector());
+        return result;
+    }
+
+    const FillLayer* fillLayer = getFillLayer(property, style);
+    FillLayerMethods fillLayerMethods(property);
+    while (fillLayer && (fillLayer->*fillLayerMethods.isSet)()) {
+        result.append((fillLayer->*fillLayerMethods.get)());
+        fillLayer = fillLayer->next();
+    }
+    return result;
+}
+
+void LengthListPropertyFunctions::setLengthList(CSSPropertyID property, ComputedStyle& style, Vector<Length>&& lengthList)
+{
+    if (property == CSSPropertyStrokeDasharray) {
+        style.setStrokeDashArray(lengthList.isEmpty() ? nullptr : RefVector<Length>::create(std::move(lengthList)));
+        return;
+    }
+
+    FillLayer* fillLayer = accessFillLayer(property, style);
+    FillLayer* prev = nullptr;
+    FillLayerMethods fillLayerMethods(property);
+    for (size_t i = 0; i < lengthList.size(); i++) {
+        if (!fillLayer)
+            fillLayer = prev->ensureNext();
+        (fillLayer->*fillLayerMethods.set)(lengthList[i]);
+        prev = fillLayer;
+        fillLayer = fillLayer->next();
+    }
+    while (fillLayer) {
+        (fillLayer->*fillLayerMethods.clear)();
+        fillLayer = fillLayer->next();
+    }
+}
+
+} // namespace blink