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// Copyright 2013 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 "cc/animation/scroll_offset_animation_curve.h"
#include <algorithm>
#include <cmath>
#include "base/logging.h"
#include "cc/animation/timing_function.h"
#include "cc/base/time_util.h"
#include "ui/gfx/animation/tween.h"
using DurationBehavior = cc::ScrollOffsetAnimationCurve::DurationBehavior;
const double kConstantDuration = 9.0;
const double kDurationDivisor = 60.0;
const double kInverseDeltaRampStartPx = 120.0;
const double kInverseDeltaRampEndPx = 480.0;
const double kInverseDeltaMinDuration = 6.0;
const double kInverseDeltaMaxDuration = 12.0;
const double kInverseDeltaSlope =
(kInverseDeltaMinDuration - kInverseDeltaMaxDuration) /
(kInverseDeltaRampEndPx - kInverseDeltaRampStartPx);
const double kInverseDeltaOffset =
kInverseDeltaMaxDuration - kInverseDeltaRampStartPx * kInverseDeltaSlope;
namespace cc {
namespace {
const double kEpsilon = 0.01f;
static float MaximumDimension(const gfx::Vector2dF& delta) {
return std::abs(delta.x()) > std::abs(delta.y()) ? delta.x() : delta.y();
}
static base::TimeDelta SegmentDuration(const gfx::Vector2dF& delta,
DurationBehavior behavior) {
double duration = kConstantDuration;
switch (behavior) {
case DurationBehavior::CONSTANT:
duration = kConstantDuration;
break;
case DurationBehavior::DELTA_BASED:
duration = std::sqrt(std::abs(MaximumDimension(delta)));
break;
case DurationBehavior::INVERSE_DELTA:
duration = std::min(
std::max(kInverseDeltaOffset +
std::abs(MaximumDimension(delta)) * kInverseDeltaSlope,
kInverseDeltaMinDuration),
kInverseDeltaMaxDuration);
break;
default:
NOTREACHED();
}
return base::TimeDelta::FromMicroseconds(duration / kDurationDivisor *
base::Time::kMicrosecondsPerSecond);
}
static scoped_ptr<TimingFunction> EaseOutWithInitialVelocity(double velocity) {
// Clamp velocity to a sane value.
velocity = std::min(std::max(velocity, -1000.0), 1000.0);
// Based on EaseInOutTimingFunction::Create with first control point scaled.
const double x1 = 0.42;
const double y1 = velocity * x1;
return CubicBezierTimingFunction::Create(x1, y1, 0.58, 1);
}
} // namespace
scoped_ptr<ScrollOffsetAnimationCurve> ScrollOffsetAnimationCurve::Create(
const gfx::ScrollOffset& target_value,
scoped_ptr<TimingFunction> timing_function,
DurationBehavior duration_behavior) {
return make_scoped_ptr(new ScrollOffsetAnimationCurve(
target_value, std::move(timing_function), duration_behavior));
}
ScrollOffsetAnimationCurve::ScrollOffsetAnimationCurve(
const gfx::ScrollOffset& target_value,
scoped_ptr<TimingFunction> timing_function,
DurationBehavior duration_behavior)
: target_value_(target_value),
timing_function_(std::move(timing_function)),
duration_behavior_(duration_behavior),
has_set_initial_value_(false) {}
ScrollOffsetAnimationCurve::~ScrollOffsetAnimationCurve() {}
void ScrollOffsetAnimationCurve::SetInitialValue(
const gfx::ScrollOffset& initial_value) {
initial_value_ = initial_value;
has_set_initial_value_ = true;
total_animation_duration_ = SegmentDuration(
target_value_.DeltaFrom(initial_value_), duration_behavior_);
}
bool ScrollOffsetAnimationCurve::HasSetInitialValue() const {
return has_set_initial_value_;
}
gfx::ScrollOffset ScrollOffsetAnimationCurve::GetValue(
base::TimeDelta t) const {
base::TimeDelta duration = total_animation_duration_ - last_retarget_;
t -= last_retarget_;
if (t <= base::TimeDelta())
return initial_value_;
if (t >= duration)
return target_value_;
double progress = timing_function_->GetValue(TimeUtil::Divide(t, duration));
return gfx::ScrollOffset(
gfx::Tween::FloatValueBetween(
progress, initial_value_.x(), target_value_.x()),
gfx::Tween::FloatValueBetween(
progress, initial_value_.y(), target_value_.y()));
}
base::TimeDelta ScrollOffsetAnimationCurve::Duration() const {
return total_animation_duration_;
}
AnimationCurve::CurveType ScrollOffsetAnimationCurve::Type() const {
return SCROLL_OFFSET;
}
scoped_ptr<AnimationCurve> ScrollOffsetAnimationCurve::Clone() const {
scoped_ptr<TimingFunction> timing_function(
static_cast<TimingFunction*>(timing_function_->Clone().release()));
scoped_ptr<ScrollOffsetAnimationCurve> curve_clone =
Create(target_value_, std::move(timing_function), duration_behavior_);
curve_clone->initial_value_ = initial_value_;
curve_clone->total_animation_duration_ = total_animation_duration_;
curve_clone->last_retarget_ = last_retarget_;
curve_clone->has_set_initial_value_ = has_set_initial_value_;
return std::move(curve_clone);
}
static double VelocityBasedDurationBound(gfx::Vector2dF old_delta,
double old_normalized_velocity,
double old_duration,
gfx::Vector2dF new_delta) {
double old_delta_max_dimension = MaximumDimension(old_delta);
double new_delta_max_dimension = MaximumDimension(new_delta);
// If we are already at the target, stop animating.
if (std::abs(new_delta_max_dimension) < kEpsilon)
return 0;
// Guard against division by zero.
if (std::abs(old_delta_max_dimension) < kEpsilon ||
std::abs(old_normalized_velocity) < kEpsilon) {
return std::numeric_limits<double>::infinity();
}
// Estimate how long it will take to reach the new target at our present
// velocity, with some fudge factor to account for the "ease out".
double old_true_velocity =
old_normalized_velocity * old_delta_max_dimension / old_duration;
double bound = (new_delta_max_dimension / old_true_velocity) * 2.5f;
// If bound < 0 we are moving in the opposite direction.
return bound < 0 ? std::numeric_limits<double>::infinity() : bound;
}
void ScrollOffsetAnimationCurve::UpdateTarget(
double t,
const gfx::ScrollOffset& new_target) {
gfx::ScrollOffset current_position =
GetValue(base::TimeDelta::FromSecondsD(t));
gfx::Vector2dF old_delta = target_value_.DeltaFrom(initial_value_);
gfx::Vector2dF new_delta = new_target.DeltaFrom(current_position);
double old_duration =
(total_animation_duration_ - last_retarget_).InSecondsF();
double old_normalized_velocity = timing_function_->Velocity(
(t - last_retarget_.InSecondsF()) / old_duration);
// Use the velocity-based duration bound when it is less than the constant
// segment duration. This minimizes the "rubber-band" bouncing effect when
// old_normalized_velocity is large and new_delta is small.
double new_duration =
std::min(SegmentDuration(new_delta, duration_behavior_).InSecondsF(),
VelocityBasedDurationBound(old_delta, old_normalized_velocity,
old_duration, new_delta));
if (new_duration < kEpsilon) {
// We are already at or very close to the new target. Stop animating.
target_value_ = new_target;
total_animation_duration_ = base::TimeDelta::FromSecondsD(t);
return;
}
// TimingFunction::Velocity gives the slope of the curve from 0 to 1.
// To match the "true" velocity in px/sec we must adjust this slope for
// differences in duration and scroll delta between old and new curves.
double new_normalized_velocity =
old_normalized_velocity * (new_duration / old_duration) *
(MaximumDimension(old_delta) / MaximumDimension(new_delta));
initial_value_ = current_position;
target_value_ = new_target;
total_animation_duration_ = base::TimeDelta::FromSecondsD(t + new_duration);
last_retarget_ = base::TimeDelta::FromSecondsD(t);
timing_function_ = EaseOutWithInitialVelocity(new_normalized_velocity);
}
} // namespace cc