src/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/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   if (!scroll_layer_->scrollbars())
 116     return;
 117
 118   LayerImpl::ScrollbarSet* scrollbars = scroll_layer_->scrollbars();
 119   for (LayerImpl::ScrollbarSet::iterator it = scrollbars->begin();
 120        it != scrollbars->end();
 121        ++it) {
 122     ScrollbarLayerImplBase* scrollbar = *it;
 123     if (scrollbar->is_overlay_scrollbar())
 124       scrollbar->SetOpacity(opacity);
 125   }
 126 }
 127
 128 }  // namespace cc