cc/animation/scrollbar_animation_controller_linear_fade.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 "cc/animation/scrollbar_animation_controller_linear_fade.h"
   6
   7 #include "base/time.h"
   8 #include "cc/layers/layer_impl.h"
   9
  10 namespace cc {
  11
  12 scoped_ptr<ScrollbarAnimationControllerLinearFade>
  13 ScrollbarAnimationControllerLinearFade::Create(LayerImpl* scroll_layer,
  14                                                base::TimeDelta fadeout_delay,
  15                                                base::TimeDelta fadeout_length) {
  16   return make_scoped_ptr(new ScrollbarAnimationControllerLinearFade(
  17       scroll_layer, fadeout_delay, fadeout_length));
  18 }
  19
  20 ScrollbarAnimationControllerLinearFade::ScrollbarAnimationControllerLinearFade(
  21     LayerImpl* scroll_layer,
  22     base::TimeDelta fadeout_delay,
  23     base::TimeDelta fadeout_length)
  24     : ScrollbarAnimationController(),
  25       scroll_layer_(scroll_layer),
  26       scroll_gesture_in_progress_(false),
  27       fadeout_delay_(fadeout_delay),
  28       fadeout_length_(fadeout_length) {}
  29
  30 ScrollbarAnimationControllerLinearFade::
  31     ~ScrollbarAnimationControllerLinearFade() {}
  32
  33 bool ScrollbarAnimationControllerLinearFade::IsScrollGestureInProgress() const {
  34   return scroll_gesture_in_progress_;
  35 }
  36
  37 bool ScrollbarAnimationControllerLinearFade::IsAnimating() const {
  38   return !last_awaken_time_.is_null();
  39 }
  40
  41 base::TimeDelta ScrollbarAnimationControllerLinearFade::DelayBeforeStart(
  42     base::TimeTicks now) const {
  43   if (now > last_awaken_time_ + fadeout_delay_)
  44     return base::TimeDelta();
  45   return fadeout_delay_ - (now - last_awaken_time_);
  46 }
  47
  48 bool ScrollbarAnimationControllerLinearFade::Animate(base::TimeTicks now) {
  49   float opacity = OpacityAtTime(now);
  50   scroll_layer_->SetScrollbarOpacity(opacity);
  51   if (!opacity)
  52     last_awaken_time_ = base::TimeTicks();
  53   return IsAnimating() && DelayBeforeStart(now) == base::TimeDelta();
  54 }
  55
  56 void ScrollbarAnimationControllerLinearFade::DidScrollGestureBegin() {
  57   scroll_layer_->SetScrollbarOpacity(1.0f);
  58   scroll_gesture_in_progress_ = true;
  59   last_awaken_time_ = base::TimeTicks();
  60 }
  61
  62 void ScrollbarAnimationControllerLinearFade::DidScrollGestureEnd(
  63     base::TimeTicks now) {
  64   scroll_gesture_in_progress_ = false;
  65   last_awaken_time_ = now;
  66 }
  67
  68 void ScrollbarAnimationControllerLinearFade::DidProgrammaticallyUpdateScroll(
  69     base::TimeTicks now) {
  70   // Don't set scroll_gesture_in_progress_ as this scroll is not from a gesture
  71   // and we won't receive ScrollEnd.
  72   scroll_layer_->SetScrollbarOpacity(1.0f);
  73   last_awaken_time_ = now;
  74 }
  75
  76 float ScrollbarAnimationControllerLinearFade::OpacityAtTime(
  77     base::TimeTicks now) {
  78   if (scroll_gesture_in_progress_)
  79     return 1.0f;
  80
  81   if (last_awaken_time_.is_null())
  82     return 0.0f;
  83
  84   base::TimeDelta delta = now - last_awaken_time_;
  85
  86   if (delta <= fadeout_delay_)
  87     return 1.0f;
  88   if (delta < fadeout_delay_ + fadeout_length_) {
  89     return (fadeout_delay_ + fadeout_length_ - delta).InSecondsF() /
  90            fadeout_length_.InSecondsF();
  91   }
  92   return 0.0f;
  93 }
  94
  95 }  // namespace cc