Web Animations CSS: Support animation of background-position and background-image

Source/core/animation/css/CSSAnimatableValueFactory.cpp

Index: Source/core/animation/css/CSSAnimatableValueFactory.cpp
diff --git a/Source/core/animation/css/CSSAnimatableValueFactory.cpp b/Source/core/animation/css/CSSAnimatableValueFactory.cpp
index 373221847314d6ed53bf9a38258b7178e72a85cf..dfe9bd03842e92724f5d8fd9661e11487fd99ff9 100644
--- a/Source/core/animation/css/CSSAnimatableValueFactory.cpp
+++ b/Source/core/animation/css/CSSAnimatableValueFactory.cpp
@@ -39,6 +39,7 @@
 #include "core/animation/AnimatableLength.h"
 #include "core/animation/AnimatableLengthBox.h"
 #include "core/animation/AnimatableLengthSize.h"
+#include "core/animation/AnimatableRepeatable.h"
 #include "core/animation/AnimatableSVGLength.h"
 #include "core/animation/AnimatableSVGPaint.h"
 #include "core/animation/AnimatableShapeValue.h"
@@ -112,6 +113,46 @@ inline static PassRefPtr<AnimatableValue> createFromLengthSize(const LengthSize
         createFromLength(lengthSize.height(), style));
 }
 
+template<CSSPropertyID property>
+inline static PassRefPtr<AnimatableValue> createFromFillLayers(const FillLayer* fillLayer, const RenderStyle* style)
+{
+    ASSERT(fillLayer);
+    Vector<RefPtr<AnimatableValue> > values;
+    while (fillLayer) {

[dstockwell, 2013/10/09 23:15:07]

Hmm, yeah I guess there's a bit too much going on here.

Can we end up in a situation like this? [x-set, x-not-set, x-set]

If not, seems OK to not terminate the loop early. Otherwise I think there are
still a few ways to merge the switch statements and still exit, but its still
not going to be so great. I don't hate the function pointer version...

[alancutter (OOO until 2018), 2013/10/10 00:58:38]

Merged the switch statements using an if chain.

+        bool isSet;
+        switch (property) {
+        case CSSPropertyBackgroundImage:
+            isSet = fillLayer->isImageSet();
+            break;
+        case CSSPropertyBackgroundPositionX:
+            isSet = fillLayer->isXPositionSet();
+            break;
+        case CSSPropertyBackgroundPositionY:
+            isSet = fillLayer->isYPositionSet();
+            break;
+        default:
+            ASSERT_NOT_REACHED();
+        }
+        if (!isSet)
+            break;
+        switch (property) {
+        case CSSPropertyBackgroundImage:
+            values.append(AnimatableImage::create(fillLayer->image()));
+            break;
+        case CSSPropertyBackgroundPositionX:
+            values.append(createFromLength(fillLayer->xPosition(), style));
+            break;
+        case CSSPropertyBackgroundPositionY:
+            values.append(createFromLength(fillLayer->yPosition(), style));
+            break;
+        default:
+            ASSERT_NOT_REACHED();
+        }
+        fillLayer = fillLayer->next();
+    }
+    return AnimatableRepeatable::create(values);
+}
+
 PassRefPtr<AnimatableValue> CSSAnimatableValueFactory::createFromColor(CSSPropertyID property, const RenderStyle* style)
 {
     Color color = style->colorIncludingFallback(property, false);
@@ -137,6 +178,12 @@ PassRefPtr<AnimatableValue> CSSAnimatableValueFactory::create(CSSPropertyID prop
     switch (property) {
     case CSSPropertyBackgroundColor:
         return createFromColor(property, style);
+    case CSSPropertyBackgroundImage:
+        return createFromFillLayers<CSSPropertyBackgroundImage>(style->backgroundLayers(), style);
+    case CSSPropertyBackgroundPositionX:
+        return createFromFillLayers<CSSPropertyBackgroundPositionX>(style->backgroundLayers(), style);
+    case CSSPropertyBackgroundPositionY:
+        return createFromFillLayers<CSSPropertyBackgroundPositionY>(style->backgroundLayers(), style);
     case CSSPropertyBaselineShift:
         return AnimatableSVGLength::create(style->baselineShiftValue());
     case CSSPropertyBorderBottomColor: