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