Allow interpolation of background-size values with keywords in CSS Animations

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

+// Copyright 2016 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/SizeListPropertyFunctions.h"
+
+#include "core/style/ComputedStyle.h"
+
+namespace blink {
+
+static const FillLayer* getFillLayer(CSSPropertyID property, const ComputedStyle& style)
+{
+    switch (property) {
+    case CSSPropertyBackgroundSize:
+        return &style.backgroundLayers();
+    case CSSPropertyWebkitMaskSize:
+        return &style.maskLayers();
+    default:
+        NOTREACHED();
+        return nullptr;
+    }
+}
+
+static FillLayer* accessFillLayer(CSSPropertyID property, ComputedStyle& style)
+{
+    switch (property) {
+    case CSSPropertyBackgroundSize:
+        return &style.accessBackgroundLayers();
+    case CSSPropertyWebkitMaskSize:
+        return &style.accessMaskLayers();
+    default:
+        NOTREACHED();
+        return nullptr;
+    }
+}
+
+SizeList SizeListPropertyFunctions::getInitialSizeList(CSSPropertyID property)
+{
+    return getSizeList(property, ComputedStyle::initialStyle());
+}
+
+SizeList SizeListPropertyFunctions::getSizeList(CSSPropertyID property, const ComputedStyle& style)
+{
+    SizeList result;
+    for (const FillLayer* fillLayer = getFillLayer(property, style); fillLayer && fillLayer->isSizeSet(); fillLayer = fillLayer->next())

[Eric Willigers, 2016/08/31 01:47:06]

We stop when we hit a fillLayer with size not set, instead of skipping over. Is
that intentional?

[alancutter (OOO until 2018), 2016/09/05 07:44:27]

Yes. Unset/nullptr indicates the end of the list.

+        result.append(fillLayer->size());
+    return result;
+}
+
+void SizeListPropertyFunctions::setSizeList(CSSPropertyID property, ComputedStyle& style, SizeList& sizeList)
+{
+    FillLayer* fillLayer = accessFillLayer(property, style);
+    FillLayer* prev = nullptr;
+    for (const FillSize& size : sizeList) {
+        if (!fillLayer)
+            fillLayer = prev->ensureNext();
+        fillLayer->setSize(size);
+        prev = fillLayer;
+        fillLayer = fillLayer->next();
+    }
+    while (fillLayer) {
+        fillLayer->clearSize();
+        fillLayer = fillLayer->next();
+    }
+}
+
+} // namespace blink