ViewExpandAnimation.java

package com.bestapp.yikuair.anim;

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

public class ViewExpandAnimation extends Animation {

	private View mAnimationView = null;
	private LayoutParams mViewLayoutParams = null;
	private int mStart = 0;
	private int mEnd = 0;
	
	public ViewExpandAnimation(View view){
		animationSettings(view, 500);
	}

	public ViewExpandAnimation(View view, int duration){
		animationSettings(view, duration);
	}
	
	private void animationSettings(View view, int duration){
		setDuration(duration);
		mAnimationView = view;
		mViewLayoutParams = (LayoutParams) view.getLayoutParams();
		mStart = mViewLayoutParams.bottomMargin;
		mEnd = (mStart == 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){
			mViewLayoutParams.bottomMargin = mStart + (int) ((mEnd - mStart) * interpolatedTime);
			// invalidate
			mAnimationView.requestLayout();
		}else{
			mViewLayoutParams.bottomMargin = mEnd;
			mAnimationView.requestLayout();
			if(mEnd != 0){
				mAnimationView.setVisibility(View.GONE);
			}
		}
	}
}