6eb6bb6017
Ding, dong... BUG=154451 Review URL: https://chromiumcodereview.appspot.com/11410021 git-svn-id: svn://svn.chromium.org/chrome/trunk/src@167071 0039d316-1c4b-4281-b951-d872f2087c98
145 lines
3.7 KiB
C++
145 lines
3.7 KiB
C++
// Copyright 2012 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#include "cc/timing_function.h"
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#include "third_party/skia/include/core/SkMath.h"
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// TODO(danakj) These methods come from SkInterpolator.cpp. When such a method
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// is available in the public Skia API, we should switch to using that.
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// http://crbug.com/159735
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namespace {
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// Dot14 has 14 bits for decimal places, and the remainder for whole numbers.
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typedef int Dot14;
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#define DOT14_ONE (1 << 14)
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#define DOT14_HALF (1 << 13)
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#define Dot14ToFloat(x) ((x) / 16384.f)
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static inline Dot14 Dot14Mul(Dot14 a, Dot14 b)
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{
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return (a * b + DOT14_HALF) >> 14;
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}
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static inline Dot14 EvalCubic(Dot14 t, Dot14 A, Dot14 B, Dot14 C)
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{
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return Dot14Mul(Dot14Mul(Dot14Mul(C, t) + B, t) + A, t);
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}
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static inline Dot14 PinAndConvert(SkScalar x)
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{
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if (x <= 0)
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return 0;
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if (x >= SK_Scalar1)
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return DOT14_ONE;
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return SkScalarToFixed(x) >> 2;
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}
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SkScalar SkUnitCubicInterp(SkScalar bx, SkScalar by, SkScalar cx, SkScalar cy, SkScalar value)
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{
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Dot14 x = PinAndConvert(value);
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if (x == 0) return 0;
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if (x == DOT14_ONE) return SK_Scalar1;
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Dot14 b = PinAndConvert(bx);
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Dot14 c = PinAndConvert(cx);
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// Now compute our coefficients from the control points.
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// t -> 3b
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// t^2 -> 3c - 6b
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// t^3 -> 3b - 3c + 1
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Dot14 A = 3 * b;
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Dot14 B = 3 * (c - 2 * b);
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Dot14 C = 3 * (b - c) + DOT14_ONE;
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// Now search for a t value given x.
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Dot14 t = DOT14_HALF;
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Dot14 dt = DOT14_HALF;
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for (int i = 0; i < 13; i++) {
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dt >>= 1;
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Dot14 guess = EvalCubic(t, A, B, C);
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if (x < guess)
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t -= dt;
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else
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t += dt;
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}
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// Now we have t, so compute the coefficient for Y and evaluate.
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b = PinAndConvert(by);
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c = PinAndConvert(cy);
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A = 3 * b;
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B = 3 * (c - 2 * b);
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C = 3 * (b - c) + DOT14_ONE;
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return SkFixedToScalar(EvalCubic(t, A, B, C) << 2);
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}
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} // anonymous namespace
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namespace cc {
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TimingFunction::TimingFunction()
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{
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}
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TimingFunction::~TimingFunction()
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{
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}
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double TimingFunction::duration() const
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{
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return 1.0;
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}
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scoped_ptr<CubicBezierTimingFunction> CubicBezierTimingFunction::create(double x1, double y1, double x2, double y2)
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{
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return make_scoped_ptr(new CubicBezierTimingFunction(x1, y1, x2, y2));
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}
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CubicBezierTimingFunction::CubicBezierTimingFunction(double x1, double y1, double x2, double y2)
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: m_x1(SkDoubleToScalar(x1))
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, m_y1(SkDoubleToScalar(y1))
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, m_x2(SkDoubleToScalar(x2))
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, m_y2(SkDoubleToScalar(y2))
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{
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}
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CubicBezierTimingFunction::~CubicBezierTimingFunction()
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{
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}
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float CubicBezierTimingFunction::getValue(double x) const
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{
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SkScalar value = SkUnitCubicInterp(m_x1, m_y1, m_x2, m_y2, x);
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return SkScalarToFloat(value);
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}
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scoped_ptr<AnimationCurve> CubicBezierTimingFunction::clone() const
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{
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return make_scoped_ptr(new CubicBezierTimingFunction(*this)).PassAs<AnimationCurve>();
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}
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// These numbers come from http://www.w3.org/TR/css3-transitions/#transition-timing-function_tag.
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scoped_ptr<TimingFunction> EaseTimingFunction::create()
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{
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return CubicBezierTimingFunction::create(0.25, 0.1, 0.25, 1).PassAs<TimingFunction>();
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}
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scoped_ptr<TimingFunction> EaseInTimingFunction::create()
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{
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return CubicBezierTimingFunction::create(0.42, 0, 1.0, 1).PassAs<TimingFunction>();
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}
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scoped_ptr<TimingFunction> EaseOutTimingFunction::create()
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{
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return CubicBezierTimingFunction::create(0, 0, 0.58, 1).PassAs<TimingFunction>();
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}
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scoped_ptr<TimingFunction> EaseInOutTimingFunction::create()
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{
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return CubicBezierTimingFunction::create(0.42, 0, 0.58, 1).PassAs<TimingFunction>();
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}
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} // namespace cc
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