Creating a helper class for reversing timing functions.

Source/core/animation/CompositorAnimations.cpp

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 25 matching lines @@
 #include "core/rendering/RenderLayer.h"
 #include "core/rendering/RenderObject.h"
 #include "public/platform/Platform.h"
 #include "public/platform/WebAnimation.h"
 #include "public/platform/WebCompositorSupport.h"
 #include "public/platform/WebFloatAnimationCurve.h"
 #include "public/platform/WebFloatKeyframe.h"
 
 namespace WebCore {
 
+// -----------------------------------------------------------------------
+
+PassRefPtr<TimingFunction> CompositorAnimationsTimingFunctionReverser::reverse(const LinearTimingFunction* timefunc)
+{
+    return const_cast<LinearTimingFunction*>(timefunc);
+}
+
+PassRefPtr<TimingFunction> CompositorAnimationsTimingFunctionReverser::reverse(const CubicBezierTimingFunction* timefunc)
+{
+    switch (timefunc->subType()) {
+    case CubicBezierTimingFunction::EaseIn:
+        return CubicBezierTimingFunction::preset(CubicBezierTimingFunction::EaseOut);
+    case CubicBezierTimingFunction::EaseOut:
+        return CubicBezierTimingFunction::preset(CubicBezierTimingFunction::EaseIn);
+    case CubicBezierTimingFunction::EaseInOut:
+        return const_cast<CubicBezierTimingFunction*>(timefunc);
+    case CubicBezierTimingFunction::Ease: // Ease is not symmetrical
+    case CubicBezierTimingFunction::Custom:
+        // Flip the timing function in x. We also have to flip it in y to
+        // maintain the invariant that it runs from (0, 0) to (1, 1).

[Steve Block, 2013/11/06 06:06:23]

You can probably remove this, given the comment in the header

[mithro-old, 2013/11/07 00:56:59]

Done.

+        return CubicBezierTimingFunction::create(1 - timefunc->x2(), 1 - timefunc->y2(), 1 - timefunc->x1(), 1 - timefunc->y1());
+    default:
+        ASSERT_NOT_REACHED();
+    }
+}
+
+PassRefPtr<TimingFunction> CompositorAnimationsTimingFunctionReverser::reverse(const ChainedTimingFunction* timefunc)
+{
+    RefPtr<ChainedTimingFunction> reversed = ChainedTimingFunction::create();
+    for (size_t i = 0; i < timefunc->m_segments.size(); i++) {
+        size_t index = timefunc->m_segments.size() - i - 1;
+
+        RefPtr<TimingFunction> rtf = reverse(timefunc->m_segments[index].m_timingFunction.get());
+        reversed->appendSegment(1 - timefunc->m_segments[index].m_min, rtf.get());
+    }
+    return reversed;
+}
+
+PassRefPtr<TimingFunction> CompositorAnimationsTimingFunctionReverser::reverse(const TimingFunction* timefunc)
+{
+    switch (timefunc->type()) {
+    case TimingFunction::LinearFunction: {
+        const LinearTimingFunction* linear = static_cast<const LinearTimingFunction*>(timefunc);
+        return reverse(linear);
+    }
+    case TimingFunction::CubicBezierFunction: {
+        const CubicBezierTimingFunction* cubic = static_cast<const CubicBezierTimingFunction*>(timefunc);
+        return reverse(cubic);
+    }
+    case TimingFunction::ChainedFunction: {
+        const ChainedTimingFunction* chained = static_cast<const ChainedTimingFunction*>(timefunc);
+        return reverse(chained);
+    }
+
+    // Steps function can not be reversed.
+    case TimingFunction::StepsFunction:
+    default:
+        ASSERT_NOT_REACHED();
+    }
+}
+
+// -----------------------------------------------------------------------
+
+
 bool CompositorAnimations::isCandidateForCompositorAnimation(const Timing& timing, const AnimationEffect* effect)
 {
     // FIXME: Implement.
     ASSERT_NOT_REACHED();
     return false;
 }
 
 bool CompositorAnimations::canStartCompositorAnimation(const Element* element)
 {
     return element->renderer() && element->renderer()->compositingState() == PaintsIntoOwnBacking;
 }
 
 void CompositorAnimations::startCompositorAnimation(const Element* element, const Timing&, const AnimationEffect*, Vector<int>& startedAnimationIds)
 {
     // FIXME: Implement.
     ASSERT_NOT_REACHED();
 }
 
 void CompositorAnimations::cancelCompositorAnimation(const Element* element, int id)
 {
     // FIXME: Implement.
     ASSERT_NOT_REACHED();
 }
 
 }