Android 之两点抚摸技术

package mobile.android.multi.touch;import android.os.Bundle;import android.app.Activity;import android.util.Log;import android.view.Menu;import android.view.MotionEvent;public class MultiTouchActivity extends Activity{	@Override	protected void onCreate(Bundle savedInstanceState)	{		super.onCreate(savedInstanceState);		setContentView(R.layout.activity_multi_touch);	}	@Override	public boolean onTouchEvent(MotionEvent event)	{				if (event.getPointerCount() == 2)		{			if (event.getAction() == MotionEvent.ACTION_MOVE)			{				int historySize = event.getHistorySize();				if (historySize == 0)					return true;				float currentY1 = event.getY(0);				float currentY2 = event.getY(1);				float historyY1 = event.getHistoricalY(0, historySize - 1);				float historyY2 = event.getHistoricalY(1, historySize - 1);				float distance = Math.abs(currentY1 - currentY2);				float historyDistance = Math.abs(historyY1 - historyY2);				if (distance > historyDistance)				{					Log.d("status", "放大" +historySize);				}				else if (distance < historyDistance)				{					Log.d("status", "缩小"+historySize);				}				else				{					Log.d("status", "移动"+historySize);				}			}		}		return true;	}}