src/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
  11 namespace cc {
  12
  13 ScrollbarAnimationController::ScrollbarAnimationController(
  14     ScrollbarAnimationControllerClient* client,
  15     base::TimeDelta delay_before_starting,
  16     base::TimeDelta resize_delay_before_starting,
  17     base::TimeDelta duration)
  18     : client_(client),
  19       delay_before_starting_(delay_before_starting),
  20       resize_delay_before_starting_(resize_delay_before_starting),
  21       duration_(duration),
  22       is_animating_(false),
  23       currently_scrolling_(false),
  24       scroll_gesture_has_scrolled_(false),
  25       weak_factory_(this) {
  26 }
  27
  28 ScrollbarAnimationController::~ScrollbarAnimationController() {
  29 }
  30
  31 void ScrollbarAnimationController::Animate(base::TimeTicks now) {
  32   if (!is_animating_)
  33     return;
  34
  35   if (last_awaken_time_.is_null())
  36     last_awaken_time_ = now;
  37
  38   float progress = AnimationProgressAtTime(now);
  39   RunAnimationFrame(progress);
  40
  41   if (is_animating_) {
  42     delayed_scrollbar_fade_.Cancel();
  43     client_->SetNeedsScrollbarAnimationFrame();
  44   }
  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     PostDelayedFade(on_resize);
  66   else
  67     scroll_gesture_has_scrolled_ = true;
  68 }
  69
  70 void ScrollbarAnimationController::DidScrollEnd() {
  71   if (scroll_gesture_has_scrolled_) {
  72     PostDelayedFade(false);
  73     scroll_gesture_has_scrolled_ = false;
  74   }
  75
  76   currently_scrolling_ = false;
  77 }
  78
  79 void ScrollbarAnimationController::PostDelayedFade(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_->PostDelayedScrollbarFade(delayed_scrollbar_fade_.callback(), delay);
  86 }
  87
  88 void ScrollbarAnimationController::StartAnimation() {
  89   delayed_scrollbar_fade_.Cancel();
  90   is_animating_ = true;
  91   last_awaken_time_ = base::TimeTicks();
  92   client_->SetNeedsScrollbarAnimationFrame();
  93 }
  94
  95 void ScrollbarAnimationController::StopAnimation() {
  96   is_animating_ = false;
  97 }
  98
  99 }  // namespace cc