//package com.android.item.util;

import android.content.Context;
import android.graphics.Matrix;
import android.util.AttributeSet;
import android.util.Log;
import android.view.View;
import android.view.animation.Transformation;
import android.widget.Gallery;

/**
 * 实现鱼眼效果的Gallery
 * @author ZhangZy
 *
 */
public class FisheyeEffectsGallery extends Gallery
{

	public FisheyeEffectsGallery(Context context)
	{
		super(context);

	}

	public FisheyeEffectsGallery(Context context, AttributeSet attrs)
	{
		super(context, attrs);
	}
	
	public FisheyeEffectsGallery(Context context, AttributeSet attrs, int defStyle)
	{
		 super(context, attrs, defStyle);
	}
	
	
	/*
	 * （译者注： setStaticTransformationsEnabled这个属性设成 true的时候每次 viewGroup(看
	 * Gallery的源码就可以看到它是从 ViewGroup间接继承过来的 )在重新画它的 child的时候都会促发
	 * getChildStaticTransformation这个函数
	 */
	@Override
	protected boolean getChildStaticTransformation(View child, Transformation t)
	{
		t.clear();
		t.setTransformationType(Transformation.TYPE_MATRIX);
		
		Matrix matrix = t.getMatrix();
		float px=child.getWidth() / 2;
		float py=child.getHeight() / 2;
		float sx = (getWidth()-Math.abs(getCenterOfCoverflow()-getCenterOfView(child)))*1f/getWidth();
//		Log.w(getClass().getSimpleName(), "sx="+sx+",Coverflow="+getCenterOfCoverflow()+",child="+getCenterOfView(child)+",getWidth()="+getWidth());
//缩放比例的限制
		sx = sx<0.8f?0.8f:sx;
		float sy = sx;
		matrix.postScale(sx, sy, px,py );

//		return super.getChildStaticTransformation(child, t);
		return true;
	}

	/* Gallery的中心点 */
	private int getCenterOfCoverflow()
	{
		return (getWidth() - getPaddingLeft() - getPaddingRight()) / 2 + getPaddingLeft();
	}

	/* view的中心点 */
	private static int getCenterOfView(View view)
	{
		return view.getLeft() + view.getWidth() / 2;
	}

}