1 // Copyright 2013 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/scroll_offset_animation_curve.h" 6 7 #include <algorithm> 8 #include <cmath> 9 10 #include "base/logging.h" 11 #include "cc/animation/timing_function.h" 12 #include "ui/gfx/animation/tween.h" 13 14 const double kDurationDivisor = 60.0; 15 16 namespace cc { 17 18 scoped_ptr<ScrollOffsetAnimationCurve> ScrollOffsetAnimationCurve::Create( 19 gfx::Vector2dF target_value, 20 scoped_ptr<TimingFunction> timing_function) { 21 return make_scoped_ptr( 22 new ScrollOffsetAnimationCurve(target_value, timing_function.Pass())); 23 } 24 25 ScrollOffsetAnimationCurve::ScrollOffsetAnimationCurve( 26 gfx::Vector2dF target_value, 27 scoped_ptr<TimingFunction> timing_function) 28 : target_value_(target_value), 29 duration_(0.0), 30 timing_function_(timing_function.Pass()) {} 31 32 ScrollOffsetAnimationCurve::~ScrollOffsetAnimationCurve() {} 33 34 void ScrollOffsetAnimationCurve::SetInitialValue(gfx::Vector2dF initial_value) { 35 initial_value_ = initial_value; 36 37 // The duration of a scroll animation depends on the size of the scroll. 38 // The exact relationship between the size and the duration isn't specified 39 // by the CSSOM View smooth scroll spec and is instead left up to user agents 40 // to decide. The calculation performed here will very likely be further 41 // tweaked before the smooth scroll API ships. 42 float delta_x = std::abs(target_value_.x() - initial_value_.x()); 43 float delta_y = std::abs(target_value_.y() - initial_value_.y()); 44 float max_delta = std::max(delta_x, delta_y); 45 duration_ = std::sqrt(max_delta)/kDurationDivisor; 46 } 47 48 gfx::Vector2dF ScrollOffsetAnimationCurve::GetValue(double t) const { 49 if (t <= 0) 50 return initial_value_; 51 52 if (t >= duration_) 53 return target_value_; 54 55 double progress = timing_function_->GetValue(t / duration_); 56 return gfx::Vector2dF(gfx::Tween::FloatValueBetween( 57 progress, initial_value_.x(), target_value_.x()), 58 gfx::Tween::FloatValueBetween( 59 progress, initial_value_.y(), target_value_.y())); 60 } 61 62 double ScrollOffsetAnimationCurve::Duration() const { 63 return duration_; 64 } 65 66 AnimationCurve::CurveType ScrollOffsetAnimationCurve::Type() const { 67 return ScrollOffset; 68 } 69 70 scoped_ptr<AnimationCurve> ScrollOffsetAnimationCurve::Clone() const { 71 scoped_ptr<TimingFunction> timing_function( 72 static_cast<TimingFunction*>(timing_function_->Clone().release())); 73 scoped_ptr<ScrollOffsetAnimationCurve> curve_clone = 74 Create(target_value_, timing_function.Pass()); 75 curve_clone->initial_value_ = initial_value_; 76 curve_clone->duration_ = duration_; 77 return curve_clone.PassAs<AnimationCurve>(); 78 } 79 80 } // namespace cc 81
