cc/animation/scrollbar_animation_controller_thinning.cc

   1 // Copyright 2013 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_thinning.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 #include "cc/trees/layer_tree_impl.h"
  11
  12 namespace {
  13 const float kIdleThicknessScale = 0.4f;
  14 const float kIdleOpacity = 0.7f;
  15 const float kDefaultMouseMoveDistanceToTriggerAnimation = 25.f;
  16 }
  17
  18 namespace cc {
  19
  20 scoped_ptr<ScrollbarAnimationControllerThinning>
  21 ScrollbarAnimationControllerThinning::Create(
  22     LayerImpl* scroll_layer,
  23     ScrollbarAnimationControllerClient* client,
  24     base::TimeDelta delay_before_starting,
  25     base::TimeDelta resize_delay_before_starting,
  26     base::TimeDelta duration) {
  27   return make_scoped_ptr(new ScrollbarAnimationControllerThinning(
  28       scroll_layer, client, delay_before_starting, resize_delay_before_starting,
  29       duration));
  30 }
  31
  32 ScrollbarAnimationControllerThinning::ScrollbarAnimationControllerThinning(
  33     LayerImpl* scroll_layer,
  34     ScrollbarAnimationControllerClient* client,
  35     base::TimeDelta delay_before_starting,
  36     base::TimeDelta resize_delay_before_starting,
  37     base::TimeDelta duration)
  38     : ScrollbarAnimationController(scroll_layer,
  39                                    client,
  40                                    delay_before_starting,
  41                                    resize_delay_before_starting,
  42                                    duration),
  43       mouse_is_over_scrollbar_(false),
  44       mouse_is_near_scrollbar_(false),
  45       thickness_change_(NONE),
  46       opacity_change_(NONE),
  47       mouse_move_distance_to_trigger_animation_(
  48           kDefaultMouseMoveDistanceToTriggerAnimation) {
  49   ApplyOpacityAndThumbThicknessScale(kIdleOpacity, kIdleThicknessScale);
  50 }
  51
  52 ScrollbarAnimationControllerThinning::~ScrollbarAnimationControllerThinning() {
  53 }
  54
  55 void ScrollbarAnimationControllerThinning::RunAnimationFrame(float progress) {
  56   float opacity = OpacityAtAnimationProgress(progress);
  57   float thumb_thickness_scale =
  58       ThumbThicknessScaleAtAnimationProgress(progress);
  59   ApplyOpacityAndThumbThicknessScale(opacity, thumb_thickness_scale);
  60   client_->SetNeedsRedrawForScrollbarAnimation();
  61   if (progress == 1.f) {
  62     opacity_change_ = NONE;
  63     thickness_change_ = NONE;
  64     StopAnimation();
  65   }
  66 }
  67
  68 void ScrollbarAnimationControllerThinning::DidMouseMoveOffScrollbar() {
  69   mouse_is_over_scrollbar_ = false;
  70   mouse_is_near_scrollbar_ = false;
  71   opacity_change_ = DECREASE;
  72   thickness_change_ = DECREASE;
  73   StartAnimation();
  74 }
  75
  76 void ScrollbarAnimationControllerThinning::DidScrollUpdate(bool on_resize) {
  77   ScrollbarAnimationController::DidScrollUpdate(on_resize);
  78   ApplyOpacityAndThumbThicknessScale(
  79       1, mouse_is_near_scrollbar_ ? 1.f : kIdleThicknessScale);
  80
  81   if (!mouse_is_over_scrollbar_)
  82     opacity_change_ = DECREASE;
  83 }
  84
  85 void ScrollbarAnimationControllerThinning::DidMouseMoveNear(float distance) {
  86   bool mouse_is_over_scrollbar = distance == 0.0;
  87   bool mouse_is_near_scrollbar =
  88       distance < mouse_move_distance_to_trigger_animation_;
  89
  90   if (mouse_is_over_scrollbar == mouse_is_over_scrollbar_ &&
  91       mouse_is_near_scrollbar == mouse_is_near_scrollbar_)
  92     return;
  93
  94   if (mouse_is_over_scrollbar_ != mouse_is_over_scrollbar) {
  95     mouse_is_over_scrollbar_ = mouse_is_over_scrollbar;
  96     opacity_change_ = mouse_is_over_scrollbar_ ? INCREASE : DECREASE;
  97   }
  98
  99   if (mouse_is_near_scrollbar_ != mouse_is_near_scrollbar) {
 100     mouse_is_near_scrollbar_ = mouse_is_near_scrollbar;
 101     thickness_change_ = mouse_is_near_scrollbar_ ? INCREASE : DECREASE;
 102   }
 103
 104   StartAnimation();
 105 }
 106
 107 float ScrollbarAnimationControllerThinning::OpacityAtAnimationProgress(
 108     float progress) {
 109   if (opacity_change_ == NONE)
 110     return mouse_is_over_scrollbar_ ? 1.f : kIdleOpacity;
 111   float factor = opacity_change_ == INCREASE ? progress : (1.f - progress);
 112   float ret = ((1.f - kIdleOpacity) * factor) + kIdleOpacity;
 113   return ret;
 114 }
 115
 116 float ScrollbarAnimationControllerThinning::
 117     ThumbThicknessScaleAtAnimationProgress(float progress) {
 118   if (thickness_change_ == NONE)
 119     return mouse_is_near_scrollbar_ ? 1.f : kIdleThicknessScale;
 120   float factor = thickness_change_ == INCREASE ? progress : (1.f - progress);
 121   return ((1.f - kIdleThicknessScale) * factor) + kIdleThicknessScale;
 122 }
 123
 124 float ScrollbarAnimationControllerThinning::AdjustScale(
 125     float new_value,
 126     float current_value,
 127     AnimationChange animation_change) {
 128   if (animation_change == INCREASE && current_value > new_value)
 129     return current_value;
 130   if (animation_change == DECREASE && current_value < new_value)
 131     return current_value;
 132   return new_value;
 133 }
 134
 135 void ScrollbarAnimationControllerThinning::ApplyOpacityAndThumbThicknessScale(
 136     float opacity,
 137     float thumb_thickness_scale) {
 138   if (!scroll_layer_->scrollbars())
 139     return;
 140
 141   LayerImpl::ScrollbarSet* scrollbars = scroll_layer_->scrollbars();
 142   for (LayerImpl::ScrollbarSet::iterator it = scrollbars->begin();
 143        it != scrollbars->end(); ++it) {
 144     ScrollbarLayerImplBase* scrollbar = *it;
 145     if (scrollbar->is_overlay_scrollbar()) {
 146       float effectiveOpacity =
 147           scrollbar->CanScrollOrientation()
 148               ? AdjustScale(opacity, scrollbar->opacity(), opacity_change_)
 149               : 0;
 150
 151       scrollbar->SetOpacity(effectiveOpacity);
 152       scrollbar->SetThumbThicknessScaleFactor(AdjustScale(
 153           thumb_thickness_scale, scrollbar->thumb_thickness_scale_factor(),
 154           thickness_change_));
 155     }
 156   }
 157 }
 158
 159 }  // namespace cc