Make flex-grow and flex-shrink interpolation continuous with 0

The current flex-grow and flex-shrink interpolation code will not smoothly
interpolate values with 0.
This patch removes this special behaviour as there is no specification text
justifying this behaviour.
Without this behaviour we can simplify the Constraint enum out of AnimatableDouble.

BUG=522817

Review URL: https://codereview.chromium.org/1300323003

git-svn-id: svn://svn.chromium.org/blink/trunk@201097 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/LayoutTests/animations/interpolation/flex-grow-interpolation.html

@@ -40,11 +40,18 @@ assertInterpolation({
   {at: 1.5, is: '2.5'},
 ]);
 
-assertNoInterpolation({
+assertInterpolation({
   property: 'flex-grow',
   from: 'initial',
   to: '2',
-});
+}, [
+  {at: -0.3, is: '0'},
+  {at: 0, is: '0'},
+  {at: 0.3, is: '0.6'},
+  {at: 0.6, is: '1.2'},
+  {at: 1, is: '2'},
+  {at: 1.5, is: '3'},
+]);
 
 assertInterpolation({
   property: 'flex-grow',
@@ -59,11 +66,18 @@ assertInterpolation({
   {at: 1.5, is: '1.5'},
 ]);
 
-assertNoInterpolation({
+assertInterpolation({
   property: 'flex-grow',
   from: 'unset',
   to: '2',
-});
+}, [
+  {at: -0.3, is: '0'},
+  {at: 0, is: '0'},
+  {at: 0.3, is: '0.6'},
+  {at: 0.6, is: '1.2'},
+  {at: 1, is: '2'},
+  {at: 1.5, is: '3'},
+]);
 
 assertInterpolation({
   property: 'flex-grow',
@@ -76,13 +90,21 @@ assertInterpolation({
   {at: 0.3, is: '1.3'},
   {at: 0.6, is: '1.6'},
   {at: 1, is: '2'},
-  {at: 1.5, is: '2.5'}
+  {at: 1.5, is: '2.5'},
 ]);
 
-assertNoInterpolation({
+assertInterpolation({
   property: 'flex-grow',
   from: '0',
   to: '1',
-});
+}, [
+  {at: -5, is: '0'},
+  {at: -0.3, is: '0'},
+  {at: 0, is: '0'},
+  {at: 0.3, is: '0.3'},
+  {at: 0.6, is: '0.6'},
+  {at: 1, is: '1'},
+  {at: 1.5, is: '1.5'},
+]);
 </script>
 </body>

third_party/WebKit/LayoutTests/animations/interpolation/flex-shrink-interpolation.html

@@ -74,13 +74,21 @@ assertInterpolation({
   {at: 0.3, is: '1.3'},
   {at: 0.6, is: '1.6'},
   {at: 1, is: '2'},
-  {at: 1.5, is: '2.5'}
+  {at: 1.5, is: '2.5'},
 ]);
 
-assertNoInterpolation({
+assertInterpolation({
   property: 'flex-shrink',
   from: '0',
   to: '1',
-});
+}, [
+  {at: -5, is: '0'},
+  {at: -0.3, is: '0'},
+  {at: 0, is: '0'},
+  {at: 0.3, is: '0.3'},
+  {at: 0.6, is: '0.6'},
+  {at: 1, is: '1'},
+  {at: 1.5, is: '1.5'},
+]);
 </script>
 </body>

third_party/WebKit/LayoutTests/transitions/flex-transitions-expected.txt

 PASS - "-webkit-flex" property for "row1" element at 0.2s saw something close to: 140,0,0
-PASS - "-webkit-flex" property for "column1" element at 0.2s saw something close to: 0,0,40
+PASS - "-webkit-flex" property for "column1" element at 0.2s saw something close to: 80,0,40
 PASS - "-webkit-flex" property for "negative1" element at 0.2s saw something close to: 100,100,60
-PASS - "-webkit-flex" property for "no-flex1" element at 0.2s saw something close to: 0,0,0
+PASS - "-webkit-flex" property for "no-flex1" element at 0.2s saw something close to: 80,0,0
 PASS - "-webkit-flex" property for "row1" element at 0.8s saw something close to: 260,0,0
-PASS - "-webkit-flex" property for "column1" element at 0.8s saw something close to: 0,0,160
+PASS - "-webkit-flex" property for "column1" element at 0.8s saw something close to: 20,0,160
 PASS - "-webkit-flex" property for "negative1" element at 0.8s saw something close to: 100,100,90
-PASS - "-webkit-flex" property for "no-flex1" element at 0.8s saw something close to: 0,0,0
+PASS - "-webkit-flex" property for "no-flex1" element at 0.8s saw something close to: 20,0,0
 

third_party/WebKit/LayoutTests/transitions/flex-transitions.html

@@ -58,13 +58,13 @@
     const expectedValues = [
       // [time, element-id, property, expected-value, tolerance]
       [0.2, 'row1',      '-webkit-flex', [140, 0,     0], 10],
-      [0.2, 'column1',   '-webkit-flex', [0,   0,    40], 10], // grow/shrink do not transition to/from zero
+      [0.2, 'column1',   '-webkit-flex', [80,  0,    40], 10],
       [0.2, 'negative1', '-webkit-flex', [100, 100,  60], 10],
-      [0.2, 'no-flex1',  '-webkit-flex', [0,   0,     0], 10], // grow/shrink do not transition to/from zero
+      [0.2, 'no-flex1',  '-webkit-flex', [80,  0,     0], 10],
       [0.8, 'row1',      '-webkit-flex', [260, 0,     0], 10],
-      [0.8, 'column1',   '-webkit-flex', [0,   0,   160], 10], // grow/shrink do not transition to/from zero
+      [0.8, 'column1',   '-webkit-flex', [20,  0,   160], 10],
       [0.8, 'negative1', '-webkit-flex', [100, 100,  90], 10],
-      [0.8, 'no-flex1',  '-webkit-flex', [0,   0,     0], 10], // grow/shrink do not transition to/from zero
+      [0.8, 'no-flex1',  '-webkit-flex', [20,  0,     0], 10],
     ];
 
     function setupTest()

third_party/WebKit/Source/core/animation/animatable/AnimatableDouble.cpp

@@ -36,18 +36,9 @@
 
 namespace blink {
 
-bool AnimatableDouble::usesDefaultInterpolationWith(const AnimatableValue* value) const
-{
-    const AnimatableDouble* other = toAnimatableDouble(value);
-    return (m_constraint == InterpolationIsNonContinuousWithZero) && (!m_number || !other->m_number);
-}
-
 PassRefPtrWillBeRawPtr<AnimatableValue> AnimatableDouble::interpolateTo(const AnimatableValue* value, double fraction) const
 {
     const AnimatableDouble* other = toAnimatableDouble(value);
-    ASSERT(m_constraint == other->m_constraint);
-    if ((m_constraint == InterpolationIsNonContinuousWithZero) && (!m_number || !other->m_number))
-        return defaultInterpolateTo(this, value, fraction);
     return AnimatableDouble::create(blend(m_number, other->m_number, fraction));
 }
 

third_party/WebKit/Source/core/animation/animatable/AnimatableDouble.h

@@ -40,14 +40,9 @@ class CORE_EXPORT AnimatableDouble final : public AnimatableValue {
 public:
     ~AnimatableDouble() override { }
 
-    enum Constraint {
-        Unconstrained,
-        InterpolationIsNonContinuousWithZero,
-    };
-
-    static PassRefPtrWillBeRawPtr<AnimatableDouble> create(double number, Constraint constraint = Unconstrained)
+    static PassRefPtrWillBeRawPtr<AnimatableDouble> create(double number)
     {
-        return adoptRefWillBeNoop(new AnimatableDouble(number, constraint));
+        return adoptRefWillBeNoop(new AnimatableDouble(number));
     }
 
     double toDouble() const { return m_number; }
@@ -56,19 +51,16 @@ public:
 
 protected:
     PassRefPtrWillBeRawPtr<AnimatableValue> interpolateTo(const AnimatableValue*, double fraction) const override;
-    bool usesDefaultInterpolationWith(const AnimatableValue*) const override;
 
 private:
-    AnimatableDouble(double number, Constraint constraint)
+    AnimatableDouble(double number)
         : m_number(number)
-        , m_constraint(constraint)
     {
     }
     AnimatableType type() const override { return TypeDouble; }
     bool equalTo(const AnimatableValue*) const override;
 
     double m_number;
-    Constraint m_constraint;
 };
 
 DEFINE_ANIMATABLE_VALUE_TYPE_CASTS(AnimatableDouble, isDouble());

third_party/WebKit/Source/core/animation/css/CSSAnimatableValueFactory.cpp

@@ -112,9 +112,9 @@ static PassRefPtrWillBeRawPtr<AnimatableValue> createFromLineHeight(const Length
     return createFromLength(length, style);
 }
 
-inline static PassRefPtrWillBeRawPtr<AnimatableValue> createFromDouble(double value, AnimatableDouble::Constraint constraint = AnimatableDouble::Unconstrained)
+inline static PassRefPtrWillBeRawPtr<AnimatableValue> createFromDouble(double value)
 {
-    return AnimatableDouble::create(value, constraint);
+    return AnimatableDouble::create(value);
 }
 
 inline static PassRefPtrWillBeRawPtr<AnimatableValue> createFromLengthBox(const LengthBox& lengthBox, const ComputedStyle& style)
@@ -379,9 +379,9 @@ PassRefPtrWillBeRawPtr<AnimatableValue> CSSAnimatableValueFactory::create(CSSPro
             style.svgStyle().fillPaintColor(), style.svgStyle().visitedLinkFillPaintColor(),
             style.svgStyle().fillPaintUri(), style.svgStyle().visitedLinkFillPaintUri());
     case CSSPropertyFlexGrow:
-        return createFromDouble(style.flexGrow(), AnimatableDouble::InterpolationIsNonContinuousWithZero);
+        return createFromDouble(style.flexGrow());
     case CSSPropertyFlexShrink:
-        return createFromDouble(style.flexShrink(), AnimatableDouble::InterpolationIsNonContinuousWithZero);
+        return createFromDouble(style.flexShrink());
     case CSSPropertyFlexBasis:
         return createFromLength(style.flexBasis(), style);
     case CSSPropertyFloodColor:
@@ -518,7 +518,9 @@ PassRefPtrWillBeRawPtr<AnimatableValue> CSSAnimatableValueFactory::create(CSSPro
     case CSSPropertyWebkitMaskSize:
         return createFromFillLayers<CSSPropertyWebkitMaskSize>(style.maskLayers(), style);
     case CSSPropertyPerspective:
-        return createFromDouble(style.perspective(), AnimatableDouble::InterpolationIsNonContinuousWithZero);
+        if (style.perspective() == 0)
+            return AnimatableUnknown::create(CSSPrimitiveValue::createIdentifier(CSSValueNone));
+        return createFromDouble(style.perspective());
     case CSSPropertyPerspectiveOrigin:
         return createFromLengthPoint(style.perspectiveOrigin(), style);
     case CSSPropertyShapeOutside:

third_party/WebKit/Source/core/css/resolver/AnimatedStyleBuilder.cpp

@@ -582,7 +582,7 @@ void AnimatedStyleBuilder::applyProperty(CSSPropertyID property, StyleResolverSt
         setOnFillLayers<CSSPropertyWebkitMaskSize>(style->accessMaskLayers(), value, state);
         return;
     case CSSPropertyPerspective:
-        style->setPerspective(clampTo<float>(toAnimatableDouble(value)->toDouble()));
+        style->setPerspective(value->isDouble() ? clampTo<float>(toAnimatableDouble(value)->toDouble()) : 0);
         return;
     case CSSPropertyPerspectiveOrigin:
         style->setPerspectiveOrigin(animatableValueToLengthPoint(value, state));