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      1 // Copyright (c) 2012 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 "ui/base/animation/tween.h"
      6 
      7 #include <math.h>
      8 
      9 #if defined(OS_WIN)
     10 #include <float.h>
     11 #endif
     12 
     13 #include "base/logging.h"
     14 
     15 namespace ui {
     16 
     17 // static
     18 double Tween::CalculateValue(Tween::Type type, double state) {
     19   DCHECK_GE(state, 0);
     20   DCHECK_LE(state, 1);
     21 
     22   switch (type) {
     23     case EASE_IN:
     24       return pow(state, 2);
     25 
     26     case EASE_IN_2:
     27       return pow(state, 4);
     28 
     29     case EASE_IN_OUT:
     30       if (state < 0.5)
     31         return pow(state * 2, 2) / 2.0;
     32       return 1.0 - (pow((state - 1.0) * 2, 2) / 2.0);
     33 
     34     case FAST_IN_OUT:
     35       return (pow(state - 0.5, 3) + 0.125) / 0.25;
     36 
     37     case LINEAR:
     38       return state;
     39 
     40     case EASE_OUT_SNAP:
     41       state = 0.95 * (1.0 - pow(1.0 - state, 2));
     42       return state;
     43 
     44     case EASE_OUT:
     45       return 1.0 - pow(1.0 - state, 2);
     46 
     47     case SMOOTH_IN_OUT:
     48       return sin(state);
     49 
     50     case ZERO:
     51       return 0;
     52   }
     53 
     54   NOTREACHED();
     55   return state;
     56 }
     57 
     58 // static
     59 double Tween::ValueBetween(double value, double start, double target) {
     60   return start + (target - start) * value;
     61 }
     62 
     63 // static
     64 int Tween::ValueBetween(double value, int start, int target) {
     65   if (start == target)
     66     return start;
     67   double delta = static_cast<double>(target - start);
     68   if (delta < 0)
     69     delta--;
     70   else
     71     delta++;
     72 #if defined(OS_WIN)
     73   return start + static_cast<int>(value * _nextafter(delta, 0));
     74 #else
     75   return start + static_cast<int>(value * nextafter(delta, 0));
     76 #endif
     77 }
     78 
     79 // static
     80 gfx::Rect Tween::ValueBetween(double value,
     81                               const gfx::Rect& start_bounds,
     82                               const gfx::Rect& target_bounds) {
     83   return gfx::Rect(ValueBetween(value, start_bounds.x(), target_bounds.x()),
     84                    ValueBetween(value, start_bounds.y(), target_bounds.y()),
     85                    ValueBetween(value, start_bounds.width(),
     86                                 target_bounds.width()),
     87                    ValueBetween(value, start_bounds.height(),
     88                                 target_bounds.height()));
     89 }
     90 
     91 // static
     92 gfx::Transform Tween::ValueBetween(double value,
     93                                    const gfx::Transform& start_transform,
     94                                    const gfx::Transform& end_transform) {
     95   if (value >= 1.0)
     96     return end_transform;
     97   if (value <= 0.0)
     98     return start_transform;
     99 
    100   gfx::Transform to_return = end_transform;
    101   to_return.Blend(start_transform, value);
    102 
    103   return to_return;
    104 }
    105 
    106 }  // namespace ui
    107