ElasticInterpolator.java :  » RSS » androidnews » vn » evolus » droidreader » interpolator » Android Open Source

package vn.evolus.droidreader.interpolator;

/*
 *
 * Open source under the BSD License. 
 * 
 * Copyright  2001 Robert Penner
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without modification, 
 * are permitted provided that the following conditions are met:
 * 
 * Redistributions of source code must retain the above copyright notice, this list of 
 * conditions and the following disclaimer.
 * Redistributions in binary form must reproduce the above copyright notice, this list 
 * of conditions and the following disclaimer in the documentation and/or other materials 
 * provided with the distribution.
 * 
 * Neither the name of the author nor the names of contributors may be used to endorse 
 * or promote products derived from this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY 
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
 * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED 
 * OF THE POSSIBILITY OF SUCH DAMAGE. 
 *
 */

import vn.evolus.droidreader.interpolator.EasingType.Type;
import android.view.animation.Interpolator;


public class ElasticInterpolator implements Interpolator {

  private Type type;
  private float amplitude;
  private float period;

  public ElasticInterpolator(Type type, float amplitude, float period) {
    this.type = type;
    this.amplitude = amplitude;
    this.period = period;
  }

  public float getInterpolation(float t) {
    if (type == Type.IN) {
      return in(t, amplitude, period);
    } else
    if (type == Type.OUT) {
      return out(t, amplitude, period);
    } else
    if (type == Type.INOUT) {
      return inout(t, amplitude, period);
    }
    return 0;
  }

  private float in(float t, float a, float p) {
    if (t == 0) {
      return 0;
    }
    if (t >= 1) {
      return 1;
    }
    if (p == 0) {
      p = 0.3f;
    }
    float s;
    if (a == 0 || a < 1) {
      a = 1;
      s = p / 4;
    }
    else {
      s = (float) (p/(2*Math.PI) * Math.asin(1/a));
    }
    return (float) (-(a*Math.pow(2,10*(t-=1)) * Math.sin((t-s)*(2*Math.PI)/p)));
  }

  private float out(float t, float a, float p) {
    if (t == 0) {
      return 0;
    }
    if (t >= 1) {
      return 1;
    }
    if (p == 0) {
      p = 0.3f;
    }
    float s;
    if (a == 0 || a < 1) {
      a = 1;
      s = p / 4;
    }
    else {
      s = (float) (p/(2*Math.PI) * Math.asin(1/a));
    }
    return (float) (a*Math.pow(2,-10*t) * Math.sin((t-s)*(2*Math.PI)/p) + 1);
  }
  
  private float inout(float t, float a, float p) {
    if (t == 0) {
      return 0;
    }
    if (t >= 1) {
      return 1;
    }
    if (p == 0) {
      p = .3f*1.5f;
    }
    float s;
    if (a == 0 || a < 1) {
      a = 1;
      s = p / 4;
    }
    else {
      s = (float) (p/(2*Math.PI) * Math.asin(1/a));
    }
    t *= 2;
    if (t < 1) {
      return (float) (-.5*(a*Math.pow(2,10*(t-=1)) * Math.sin((t-s)*(2*Math.PI)/p)));
    } else {
      return (float) (a*Math.pow(2,-10*(t-=1)) * Math.sin((t-s)*(2*Math.PI)/p)*.5 + 1);
    }
  }
}