cc/animation/timing_function.cc

   1 // Copyright 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "base/logging.h"
   6 #include "base/memory/scoped_ptr.h"
   7 #include "cc/animation/timing_function.h"
   8 #include "cc/base/math_util.h"
   9
  10 namespace cc {
  11
  12 TimingFunction::TimingFunction() {}
  13
  14 TimingFunction::~TimingFunction() {}
  15
  16 scoped_ptr<CubicBezierTimingFunction> CubicBezierTimingFunction::Create(
  17     double x1, double y1, double x2, double y2) {
  18   return make_scoped_ptr(new CubicBezierTimingFunction(x1, y1, x2, y2));
  19 }
  20
  21 CubicBezierTimingFunction::CubicBezierTimingFunction(double x1,
  22                                                      double y1,
  23                                                      double x2,
  24                                                      double y2)
  25     : bezier_(x1, y1, x2, y2) {}
  26
  27 CubicBezierTimingFunction::~CubicBezierTimingFunction() {}
  28
  29 float CubicBezierTimingFunction::GetValue(double x) const {
  30   return static_cast<float>(bezier_.Solve(x));
  31 }
  32
  33 float CubicBezierTimingFunction::Velocity(double x) const {
  34   return static_cast<float>(bezier_.Slope(x));
  35 }
  36
  37 void CubicBezierTimingFunction::Range(float* min, float* max) const {
  38   double min_d = 0;
  39   double max_d = 1;
  40   bezier_.Range(&min_d, &max_d);
  41   *min = static_cast<float>(min_d);
  42   *max = static_cast<float>(max_d);
  43 }
  44
  45 scoped_ptr<TimingFunction> CubicBezierTimingFunction::Clone() const {
  46   return make_scoped_ptr(new CubicBezierTimingFunction(*this));
  47 }
  48
  49 // These numbers come from
  50 // http://www.w3.org/TR/css3-transitions/#transition-timing-function_tag.
  51 scoped_ptr<TimingFunction> EaseTimingFunction::Create() {
  52   return CubicBezierTimingFunction::Create(0.25, 0.1, 0.25, 1.0);
  53 }
  54
  55 scoped_ptr<TimingFunction> EaseInTimingFunction::Create() {
  56   return CubicBezierTimingFunction::Create(0.42, 0.0, 1.0, 1.0);
  57 }
  58
  59 scoped_ptr<TimingFunction> EaseOutTimingFunction::Create() {
  60   return CubicBezierTimingFunction::Create(0.0, 0.0, 0.58, 1.0);
  61 }
  62
  63 scoped_ptr<TimingFunction> EaseInOutTimingFunction::Create() {
  64   return CubicBezierTimingFunction::Create(0.42, 0.0, 0.58, 1);
  65 }
  66
  67 scoped_ptr<StepsTimingFunction> StepsTimingFunction::Create(
  68     int steps,
  69     float steps_start_offset) {
  70   return make_scoped_ptr(new StepsTimingFunction(steps, steps_start_offset));
  71 }
  72
  73 StepsTimingFunction::StepsTimingFunction(int steps, float steps_start_offset)
  74     : steps_(steps), steps_start_offset_(steps_start_offset) {
  75   // Restrict it to CSS presets: step_start, step_end and step_middle.
  76   // See the Web Animations specification, 3.12.4. Timing in discrete steps.
  77   DCHECK(steps_start_offset_ == 0 || steps_start_offset_ == 1 ||
  78          steps_start_offset_ == 0.5);
  79 }
  80
  81 StepsTimingFunction::~StepsTimingFunction() {
  82 }
  83
  84 float StepsTimingFunction::GetValue(double t) const {
  85   const double steps = static_cast<double>(steps_);
  86   const double value = MathUtil::ClampToRange(
  87       std::floor((steps * t) + steps_start_offset_) / steps, 0.0, 1.0);
  88   return static_cast<float>(value);
  89 }
  90
  91 scoped_ptr<TimingFunction> StepsTimingFunction::Clone() const {
  92   return make_scoped_ptr(new StepsTimingFunction(*this));
  93 }
  94
  95 void StepsTimingFunction::Range(float* min, float* max) const {
  96   *min = 0.0f;
  97   *max = 1.0f;
  98 }
  99
 100 float StepsTimingFunction::Velocity(double x) const {
 101   return 0.0f;
 102 }
 103
 104 }  // namespace cc