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// Copyright (c) 2010 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 "app/tween.h"
#include <math.h>
#if defined(OS_WIN)
#include <float.h>
#endif
#include "gfx/rect.h"
// static
double Tween::CalculateValue(Tween::Type type, double state) {
DCHECK_GE(state, 0);
DCHECK_LE(state, 1);
switch (type) {
case EASE_IN:
return pow(state, 2);
case EASE_IN_OUT:
if (state < 0.5)
return pow(state * 2, 2) / 2.0;
return 1.0 - (pow((state - 1.0) * 2, 2) / 2.0);
case FAST_IN_OUT:
return (pow(state - 0.5, 3) + 0.125) / 0.25;
case LINEAR:
return state;
case EASE_OUT_SNAP:
state = 0.95 * (1.0 - pow(1.0 - state, 2));
break;
case EASE_OUT:
return 1.0 - pow(1.0 - state, 2);
case ZERO:
return 0;
}
NOTREACHED();
return state;
}
// static
double Tween::ValueBetween(double value, double start, double target) {
return start + (target - start) * value;
}
// static
int Tween::ValueBetween(double value, int start, int target) {
if (start == target)
return start;
double delta = static_cast<double>(target - start);
if (delta < 0)
delta--;
else
delta++;
#if defined(OS_WIN)
return start + static_cast<int>(value * _nextafter(delta, 0));
#else
return start + static_cast<int>(value * nextafter(delta, 0));
#endif
}
// static
gfx::Rect Tween::ValueBetween(double value,
const gfx::Rect& start_bounds,
const gfx::Rect& target_bounds) {
return gfx::Rect(ValueBetween(value, start_bounds.x(), target_bounds.x()),
ValueBetween(value, start_bounds.y(), target_bounds.y()),
ValueBetween(value, start_bounds.width(),
target_bounds.width()),
ValueBetween(value, start_bounds.height(),
target_bounds.height()));
}
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