HeightEvaluator.java

package com.alorma.github.ui.animations;

import android.animation.IntEvaluator;
import android.view.View;
import android.view.ViewGroup;

public class HeightEvaluator extends IntEvaluator {

  private View v;
  private boolean expand;

  public HeightEvaluator(View v, boolean expand) {
    this.v = v;
    this.expand = expand;
  }

  @Override
  public Integer evaluate(float fraction, Integer startValue, Integer endValue) {
    int num = super.evaluate(fraction, startValue, endValue);
    ViewGroup.LayoutParams params = v.getLayoutParams();
    params.height = (int) ((expand ? endValue : startValue) * (expand ? fraction : 1 - fraction));
    v.setLayoutParams(params);
    return num;
  }
}