diff options
Diffstat (limited to 'chromium/webkit/child/touch_fling_gesture_curve.cc')
| -rw-r--r-- | chromium/webkit/child/touch_fling_gesture_curve.cc | 163 |
1 files changed, 0 insertions, 163 deletions
diff --git a/chromium/webkit/child/touch_fling_gesture_curve.cc b/chromium/webkit/child/touch_fling_gesture_curve.cc deleted file mode 100644 index 91033dad07e..00000000000 --- a/chromium/webkit/child/touch_fling_gesture_curve.cc +++ /dev/null @@ -1,163 +0,0 @@ -// 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 "webkit/child/touch_fling_gesture_curve.h" - -#include <cmath> - -#include "base/debug/trace_event.h" -#include "base/logging.h" -#include "third_party/WebKit/public/platform/WebFloatPoint.h" -#include "third_party/WebKit/public/platform/WebFloatSize.h" -#include "third_party/WebKit/public/platform/WebGestureCurve.h" -#include "third_party/WebKit/public/platform/WebGestureCurveTarget.h" -#include "third_party/WebKit/public/platform/WebSize.h" - -using blink::WebFloatPoint; -using blink::WebFloatSize; -using blink::WebGestureCurve; -using blink::WebGestureCurveTarget; -using blink::WebSize; - -namespace { - -const char* kCurveName = "TouchFlingGestureCurve"; - -inline double position(double t, float* p) { - return p[0] * exp(-p[2] * t) - p[1] * t - p[0]; -} - -inline double velocity(double t, float* p) { - return -p[0] * p[2] * exp(-p[2] * t) - p[1]; -} - -inline double timeAtVelocity(double v, float* p) { - DCHECK(p[0]); - DCHECK(p[2]); - return -log((v + p[1]) / (-p[0] * p[2])) / p[2]; -} - -} // namespace - - -namespace webkit_glue { - -// This curve implementation is based on the notion of a single, absolute -// curve, which starts at a large velocity and smoothly decreases to -// zero. For a given input velocity, we find where on the curve this -// velocity occurs, and start the animation at this point---denoted by -// (time_offset_, position_offset_). -// -// This has the effect of automatically determining an animation duration -// that scales with input velocity, as faster initial velocities start -// earlier on the curve and thus take longer to reach the end. No -// complicated time scaling is required. -// -// Since the starting velocity is implicitly determined by our starting -// point, we only store the relative magnitude and direction of both -// initial x- and y-velocities, and use this to scale the computed -// displacement at any point in time. This guarantees that fling -// trajectories are straight lines when viewed in x-y space. Initial -// velocities that lie outside the max velocity are constrained to start -// at zero (and thus are implicitly scaled). -// -// The curve is modelled as a 4th order polynomial, starting at t = 0, -// and ending at t = curve_duration_. Attempts to generate -// position/velocity estimates outside this range are undefined. - -WebGestureCurve* TouchFlingGestureCurve::Create( - const WebFloatPoint& initial_velocity, - float p0, - float p1, - float p2, - const WebSize& cumulative_scroll) { - return new TouchFlingGestureCurve(initial_velocity, p0, p1, p2, - cumulative_scroll); -} - -TouchFlingGestureCurve::TouchFlingGestureCurve( - const WebFloatPoint& initial_velocity, - float alpha, - float beta, - float gamma, - const WebSize& cumulative_scroll) - : cumulative_scroll_(WebFloatSize(cumulative_scroll.width, - cumulative_scroll.height)) { - DCHECK(initial_velocity != WebFloatPoint()); - - coefficients_[0] = alpha; - coefficients_[1] = beta; - coefficients_[2] = gamma; - - // Curve ends when velocity reaches zero. - curve_duration_ = timeAtVelocity(0, coefficients_); - DCHECK(curve_duration_ > 0); - - float max_start_velocity = std::max(fabs(initial_velocity.x), - fabs(initial_velocity.y)); - - // Force max_start_velocity to lie in the range v(0) to v(curve_duration), - // and assume that the curve parameters define a monotonically decreasing - // velocity, or else bisection search may fail. - if (max_start_velocity > velocity(0, coefficients_)) - max_start_velocity = velocity(0, coefficients_); - - if (max_start_velocity < 0) - max_start_velocity = 0; - - // We keep track of relative magnitudes and directions of the - // velocity/displacement components here. - displacement_ratio_ = WebFloatPoint(initial_velocity.x / max_start_velocity, - initial_velocity.y / max_start_velocity); - - // Compute time-offset for start velocity. - time_offset_ = timeAtVelocity(max_start_velocity, coefficients_); - - // Compute curve position at offset time - position_offset_ = position(time_offset_, coefficients_); - TRACE_EVENT_ASYNC_BEGIN1("input", "GestureAnimation", this, "curve", - kCurveName); -} - -TouchFlingGestureCurve::~TouchFlingGestureCurve() { - TRACE_EVENT_ASYNC_END0("input", "GestureAnimation", this); -} - -bool TouchFlingGestureCurve::apply(double time, WebGestureCurveTarget* target) { - float displacement; - float speed; - if (time < 0) { - displacement = 0.f; - speed = 0.f; - } else if (time + time_offset_ < curve_duration_) { - displacement = - position(time + time_offset_, coefficients_) - position_offset_; - speed = velocity(time + time_offset_, coefficients_); - } else { - displacement = position(curve_duration_, coefficients_) - position_offset_; - speed = 0.f; - } - - // Keep track of integer portion of scroll thus far, and prepare increment. - WebFloatSize scroll(displacement * displacement_ratio_.x, - displacement * displacement_ratio_.y); - WebFloatSize scroll_increment(scroll.width - cumulative_scroll_.width, - scroll.height - cumulative_scroll_.height); - WebFloatSize scroll_velocity(speed * displacement_ratio_.x, - speed * displacement_ratio_.y); - cumulative_scroll_ = scroll; - - if (time + time_offset_ < curve_duration_ || - scroll_increment != WebFloatSize()) { - target->notifyCurrentFlingVelocity(scroll_velocity); - // scrollBy() could delete this curve if the animation is over, so don't - // touch any member variables after making that call. - target->scrollBy(scroll_increment); - return true; - } - - return false; -} - -} // namespace webkit_glue |