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1 // Copyright (c) 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 "ui/gfx/animation/slide_animation.h"
6 
7 #include <math.h>
8 
9 namespace gfx {
10 
11 // How many frames per second to target.
12 static const int kDefaultFrameRateHz = 60;
13 
14 // How long animations should take by default.
15 static const int kDefaultDurationMs = 120;
16 
SlideAnimation(AnimationDelegate * target)17 SlideAnimation::SlideAnimation(AnimationDelegate* target)
18     : LinearAnimation(kDefaultFrameRateHz, target),
19       target_(target),
20       tween_type_(Tween::EASE_OUT),
21       showing_(false),
22       value_start_(0),
23       value_end_(0),
24       value_current_(0),
25       slide_duration_(kDefaultDurationMs) {
26 }
27 
~SlideAnimation()28 SlideAnimation::~SlideAnimation() {
29 }
30 
Reset()31 void SlideAnimation::Reset() {
32   Reset(0);
33 }
34 
Reset(double value)35 void SlideAnimation::Reset(double value) {
36   Stop();
37   showing_ = static_cast<bool>(value == 1);
38   value_current_ = value;
39 }
40 
Show()41 void SlideAnimation::Show() {
42   // If we're already showing (or fully shown), we have nothing to do.
43   if (showing_)
44     return;
45 
46   showing_ = true;
47   value_start_ = value_current_;
48   value_end_ = 1.0;
49 
50   // Make sure we actually have something to do.
51   if (slide_duration_ == 0) {
52     AnimateToState(1.0);  // Skip to the end of the animation.
53     return;
54   } else if (value_current_ == value_end_)  {
55     return;
56   }
57 
58   // This will also reset the currently-occurring animation.
59   SetDuration(static_cast<int>(slide_duration_ * (1 - value_current_)));
60   Start();
61 }
62 
Hide()63 void SlideAnimation::Hide() {
64   // If we're already hiding (or hidden), we have nothing to do.
65   if (!showing_)
66     return;
67 
68   showing_ = false;
69   value_start_ = value_current_;
70   value_end_ = 0.0;
71 
72   // Make sure we actually have something to do.
73   if (slide_duration_ == 0) {
74     AnimateToState(0.0);  // Skip to the end of the animation.
75     return;
76   } else if (value_current_ == value_end_) {
77     return;
78   }
79 
80   // This will also reset the currently-occurring animation.
81   SetDuration(static_cast<int>(slide_duration_ * value_current_));
82   Start();
83 }
84 
SetSlideDuration(int duration)85 void SlideAnimation::SetSlideDuration(int duration) {
86   slide_duration_ = duration;
87 }
88 
GetCurrentValue() const89 double SlideAnimation::GetCurrentValue() const {
90   return value_current_;
91 }
92 
AnimateToState(double state)93 void SlideAnimation::AnimateToState(double state) {
94   if (state > 1.0)
95     state = 1.0;
96 
97   state = Tween::CalculateValue(tween_type_, state);
98 
99   value_current_ = value_start_ + (value_end_ - value_start_) * state;
100 
101   // Implement snapping.
102   if (tween_type_ == Tween::EASE_OUT_SNAP &&
103       fabs(value_current_ - value_end_) <= 0.06)
104     value_current_ = value_end_;
105 
106   // Correct for any overshoot (while state may be capped at 1.0, let's not
107   // take any rounding error chances.
108   if ((value_end_ >= value_start_ && value_current_ > value_end_) ||
109       (value_end_ < value_start_ && value_current_ < value_end_)) {
110     value_current_ = value_end_;
111   }
112 }
113 
114 }  // namespace gfx
115