123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778 |
- // Copyright (c) 2012 The Chromium Authors. All rights reserved.
- // Use of this source code is governed by a BSD-style license that can be
- // found in the LICENSE file.
- #include "ui/views/animation/scroll_animator.h"
- #include <algorithm>
- #include <cmath>
- #include "base/check.h"
- #include "ui/gfx/animation/slide_animation.h"
- namespace {
- constexpr float kDefaultAcceleration = -1500.0f; // in pixels per second^2
- // Assumes that d0 == 0.0f
- float GetPosition(float v0, float a, float t) {
- float max_t = -v0 / a;
- if (t > max_t)
- t = max_t;
- return t * (v0 + 0.5f * a * t);
- }
- float GetDelta(float v0, float a, float t1, float t2) {
- return GetPosition(v0, a, t2) - GetPosition(v0, a, t1);
- }
- } // namespace
- namespace views {
- ScrollAnimator::ScrollAnimator(ScrollDelegate* delegate)
- : delegate_(delegate), acceleration_(kDefaultAcceleration) {
- DCHECK(delegate);
- }
- ScrollAnimator::~ScrollAnimator() {
- Stop();
- }
- void ScrollAnimator::Start(float velocity_x, float velocity_y) {
- if (acceleration_ >= 0.0f)
- acceleration_ = kDefaultAcceleration;
- float v = std::max(fabs(velocity_x), fabs(velocity_y));
- last_t_ = 0.0f;
- velocity_x_ = velocity_x * velocity_multiplier_;
- velocity_y_ = velocity_y * velocity_multiplier_;
- duration_ = -v / acceleration_; // in seconds
- animation_ = std::make_unique<gfx::SlideAnimation>(this);
- animation_->SetSlideDuration(base::Seconds(duration_));
- animation_->Show();
- }
- void ScrollAnimator::Stop() {
- velocity_x_ = velocity_y_ = last_t_ = duration_ = 0.0f;
- animation_.reset();
- }
- void ScrollAnimator::AnimationEnded(const gfx::Animation* animation) {
- Stop();
- delegate_->OnFlingScrollEnded();
- }
- void ScrollAnimator::AnimationProgressed(const gfx::Animation* animation) {
- float t = static_cast<float>(animation->GetCurrentValue()) * duration_;
- float a_x = velocity_x_ > 0 ? acceleration_ : -acceleration_;
- float a_y = velocity_y_ > 0 ? acceleration_ : -acceleration_;
- float dx = GetDelta(velocity_x_, a_x, last_t_, t);
- float dy = GetDelta(velocity_y_, a_y, last_t_, t);
- last_t_ = t;
- delegate_->OnScroll(dx, dy);
- }
- void ScrollAnimator::AnimationCanceled(const gfx::Animation* animation) {
- Stop();
- }
- } // namespace views
|