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      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/time.h"
      8 #include "cc/layers/layer_impl.h"
      9 #include "cc/layers/scrollbar_layer_impl_base.h"
     10 
     11 namespace cc {
     12 
     13 scoped_ptr<ScrollbarAnimationControllerLinearFade>
     14 ScrollbarAnimationControllerLinearFade::Create(LayerImpl* scroll_layer,
     15                                                base::TimeDelta fadeout_delay,
     16                                                base::TimeDelta fadeout_length) {
     17   return make_scoped_ptr(new ScrollbarAnimationControllerLinearFade(
     18       scroll_layer, fadeout_delay, fadeout_length));
     19 }
     20 
     21 ScrollbarAnimationControllerLinearFade::ScrollbarAnimationControllerLinearFade(
     22     LayerImpl* scroll_layer,
     23     base::TimeDelta fadeout_delay,
     24     base::TimeDelta fadeout_length)
     25     : ScrollbarAnimationController(),
     26       scroll_layer_(scroll_layer),
     27       scroll_gesture_in_progress_(false),
     28       scroll_gesture_has_scrolled_(false),
     29       fadeout_delay_(fadeout_delay),
     30       fadeout_length_(fadeout_length) {}
     31 
     32 ScrollbarAnimationControllerLinearFade::
     33     ~ScrollbarAnimationControllerLinearFade() {}
     34 
     35 bool ScrollbarAnimationControllerLinearFade::IsAnimating() const {
     36   return !last_awaken_time_.is_null();
     37 }
     38 
     39 base::TimeDelta ScrollbarAnimationControllerLinearFade::DelayBeforeStart(
     40     base::TimeTicks now) const {
     41   if (now > last_awaken_time_ + fadeout_delay_)
     42     return base::TimeDelta();
     43   return fadeout_delay_ - (now - last_awaken_time_);
     44 }
     45 
     46 bool ScrollbarAnimationControllerLinearFade::Animate(base::TimeTicks now) {
     47   float opacity = OpacityAtTime(now);
     48   ApplyOpacityToScrollbars(opacity);
     49   if (!opacity)
     50     last_awaken_time_ = base::TimeTicks();
     51   return IsAnimating() && DelayBeforeStart(now) == base::TimeDelta();
     52 }
     53 
     54 void ScrollbarAnimationControllerLinearFade::DidScrollGestureBegin() {
     55   scroll_gesture_in_progress_ = true;
     56   scroll_gesture_has_scrolled_ = false;
     57 }
     58 
     59 void ScrollbarAnimationControllerLinearFade::DidScrollGestureEnd(
     60     base::TimeTicks now) {
     61   // The animation should not be triggered if no scrolling has occurred.
     62   if (scroll_gesture_has_scrolled_)
     63     last_awaken_time_ = now;
     64   scroll_gesture_has_scrolled_ = false;
     65   scroll_gesture_in_progress_ = false;
     66 }
     67 
     68 void ScrollbarAnimationControllerLinearFade::DidMouseMoveOffScrollbar(
     69     base::TimeTicks now) {
     70   // Ignore mouse move events.
     71 }
     72 
     73 bool ScrollbarAnimationControllerLinearFade::DidScrollUpdate(
     74     base::TimeTicks now) {
     75   ApplyOpacityToScrollbars(1.0f);
     76   // The animation should only be activated if the scroll updated occurred
     77   // programatically, outside the scope of a scroll gesture.
     78   if (scroll_gesture_in_progress_) {
     79     last_awaken_time_ = base::TimeTicks();
     80     scroll_gesture_has_scrolled_ = true;
     81     return false;
     82   }
     83 
     84   last_awaken_time_ = now;
     85   return true;
     86 }
     87 
     88 bool ScrollbarAnimationControllerLinearFade::DidMouseMoveNear(
     89     base::TimeTicks now, float distance) {
     90   // Ignore mouse move events.
     91   return false;
     92 }
     93 
     94 float ScrollbarAnimationControllerLinearFade::OpacityAtTime(
     95     base::TimeTicks now) {
     96   if (scroll_gesture_has_scrolled_)
     97     return 1.0f;
     98 
     99   if (last_awaken_time_.is_null())
    100     return 0.0f;
    101 
    102   base::TimeDelta delta = now - last_awaken_time_;
    103 
    104   if (delta <= fadeout_delay_)
    105     return 1.0f;
    106   if (delta < fadeout_delay_ + fadeout_length_) {
    107     return (fadeout_delay_ + fadeout_length_ - delta).InSecondsF() /
    108            fadeout_length_.InSecondsF();
    109   }
    110   return 0.0f;
    111 }
    112 
    113 void ScrollbarAnimationControllerLinearFade::ApplyOpacityToScrollbars(
    114     float opacity) {
    115   ScrollbarLayerImplBase* horizontal_scrollbar =
    116       scroll_layer_->horizontal_scrollbar_layer();
    117   if (horizontal_scrollbar)
    118     horizontal_scrollbar->SetOpacity(opacity);
    119 
    120   ScrollbarLayerImplBase* vertical_scrollbar =
    121       scroll_layer_->vertical_scrollbar_layer();
    122   if (vertical_scrollbar)
    123     vertical_scrollbar->SetOpacity(opacity);
    124 }
    125 
    126 }  // namespace cc
    127