ui/gfx/animation/slide_animation.cc

   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
  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
  28 SlideAnimation::~SlideAnimation() {
  29 }
  30
  31 void SlideAnimation::Reset() {
  32   Reset(0);
  33 }
  34
  35 void SlideAnimation::Reset(double value) {
  36   Stop();
  37   showing_ = static_cast<bool>(value == 1);
  38   value_current_ = value;
  39 }
  40
  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
  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
  85 void SlideAnimation::SetSlideDuration(int duration) {
  86   slide_duration_ = duration;
  87 }
  88
  89 double SlideAnimation::GetCurrentValue() const {
  90   return value_current_;
  91 }
  92
  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