cc/animation/scrollbar_animation_controller.cc

   1 // Copyright 2014 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.h"
   6
   7 #include <algorithm>
   8
   9 #include "base/time/time.h"
  10 #include "cc/trees/layer_tree_impl.h"
  11
  12 namespace cc {
  13
  14 ScrollbarAnimationController::ScrollbarAnimationController(
  15     LayerImpl* scroll_layer,
  16     ScrollbarAnimationControllerClient* client,
  17     base::TimeDelta delay_before_starting,
  18     base::TimeDelta resize_delay_before_starting,
  19     base::TimeDelta duration)
  20     : scroll_layer_(scroll_layer),
  21       client_(client),
  22       delay_before_starting_(delay_before_starting),
  23       resize_delay_before_starting_(resize_delay_before_starting),
  24       duration_(duration),
  25       is_animating_(false),
  26       currently_scrolling_(false),
  27       scroll_gesture_has_scrolled_(false),
  28       weak_factory_(this) {
  29 }
  30
  31 ScrollbarAnimationController::~ScrollbarAnimationController() {
  32   if (is_animating_)
  33     client_->StopAnimatingScrollbarAnimationController(this);
  34 }
  35
  36 void ScrollbarAnimationController::Animate(base::TimeTicks now) {
  37   if (!is_animating_)
  38     return;
  39
  40   if (last_awaken_time_.is_null())
  41     last_awaken_time_ = now;
  42
  43   float progress = AnimationProgressAtTime(now);
  44   RunAnimationFrame(progress);
  45 }
  46
  47 float ScrollbarAnimationController::AnimationProgressAtTime(
  48     base::TimeTicks now) {
  49   base::TimeDelta delta = now - last_awaken_time_;
  50   float progress = delta.InSecondsF() / duration_.InSecondsF();
  51   return std::max(std::min(progress, 1.f), 0.f);
  52 }
  53
  54 void ScrollbarAnimationController::DidScrollBegin() {
  55   currently_scrolling_ = true;
  56 }
  57
  58 void ScrollbarAnimationController::DidScrollUpdate(bool on_resize) {
  59   StopAnimation();
  60   delayed_scrollbar_fade_.Cancel();
  61
  62   // As an optimization, we avoid spamming fade delay tasks during active fast
  63   // scrolls.  But if we're not within one, we need to post every scroll update.
  64   if (!currently_scrolling_)
  65     PostDelayedAnimationTask(on_resize);
  66   else
  67     scroll_gesture_has_scrolled_ = true;
  68 }
  69
  70 void ScrollbarAnimationController::DidScrollEnd() {
  71   if (scroll_gesture_has_scrolled_) {
  72     PostDelayedAnimationTask(false);
  73     scroll_gesture_has_scrolled_ = false;
  74   }
  75
  76   currently_scrolling_ = false;
  77 }
  78
  79 void ScrollbarAnimationController::PostDelayedAnimationTask(bool on_resize) {
  80   base::TimeDelta delay =
  81       on_resize ? resize_delay_before_starting_ : delay_before_starting_;
  82   delayed_scrollbar_fade_.Reset(
  83       base::Bind(&ScrollbarAnimationController::StartAnimation,
  84                  weak_factory_.GetWeakPtr()));
  85   client_->PostDelayedScrollbarAnimationTask(delayed_scrollbar_fade_.callback(),
  86                                              delay);
  87 }
  88
  89 void ScrollbarAnimationController::StartAnimation() {
  90   delayed_scrollbar_fade_.Cancel();
  91   is_animating_ = true;
  92   last_awaken_time_ = base::TimeTicks();
  93   client_->StartAnimatingScrollbarAnimationController(this);
  94 }
  95
  96 void ScrollbarAnimationController::StopAnimation() {
  97   is_animating_ = false;
  98   client_->StopAnimatingScrollbarAnimationController(this);
  99 }
 100
 101 }  // namespace cc