ExpandAnimation.java

package com.dozuki.ifixit.ui.guide.create;

import android.view.View;
import android.view.animation.Animation;
import android.view.animation.Transformation;
import android.widget.LinearLayout.LayoutParams;

/**
 * This animation class is animating the expanding and reducing the size of a view.
 * The animation toggles between the Expand and Reduce, depending on the current state of the view
 * 
 * @author Udinic
 * 
 */
public class ExpandAnimation extends Animation {
   private View mAnimatedView;
   private LayoutParams mViewLayoutParams;
   private int mMarginStart, mMarginEnd;
   private boolean mIsVisibleAfter = false;
   private boolean mWasEndedAlready = false;

   /**
    * Initialize the animation
    * 
    * @param view
    *           The layout we want to animate
    * @param duration
    *           The duration of the animation, in ms
    */
   public ExpandAnimation(View view, int duration) {

      setDuration(duration);
      mAnimatedView = view;
      mViewLayoutParams = (LayoutParams) view.getLayoutParams();

      // decide to show or hide the view
      mIsVisibleAfter = (view.getVisibility() == View.VISIBLE);

      mMarginStart = mViewLayoutParams.bottomMargin;
      mMarginEnd = (mMarginStart == 0 ? (0 - view.getHeight()) : 0);

      view.setVisibility(View.VISIBLE);
   }

   @Override
   protected void applyTransformation(float interpolatedTime, Transformation t) {
      super.applyTransformation(interpolatedTime, t);

      if (interpolatedTime < 1.0f) {

         // Calculating the new bottom margin, and setting it
         mViewLayoutParams.bottomMargin = mMarginStart + (int) ((mMarginEnd - mMarginStart) * interpolatedTime);

         // Invalidating the layout, making us seeing the changes we made
         mAnimatedView.requestLayout();

         // Making sure we didn't run the ending before (it happens!)
      } else if (!mWasEndedAlready) {
         mViewLayoutParams.bottomMargin = mMarginEnd;
         mAnimatedView.requestLayout();

         if (mIsVisibleAfter) {
            mAnimatedView.setVisibility(View.GONE);
         }
         mWasEndedAlready = true;
      }
   }
}