学步园

MotionEvent中定义了基本事件，View中定义了一些简单事件的处理接口，GestureDetector拓展了View中的事件接口，提供了一些复杂事件的接口。框架接口(API)的好处是框架已经帮我们定义好了为什么onDoubleClick表示双击事件，而我们只需要直接使用即可。下面通过实例说明如何使用GestureDetector类实现复杂事件。

package com.sean.gesturetest;

import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.view.GestureDetector;
import android.view.GestureDetector.OnGestureListener;
import android.view.MotionEvent;
import android.widget.Toast;

public class MainActivity extends Activity {

	private GestureDetector gesture;
	CharSequence onDown = "onDown Event";
	CharSequence onFling = "onFling Event";
	CharSequence onLongPress = "onLongPress Event";
	CharSequence onScroll = "onScroll Event";
	CharSequence onShowPress = "onShowPress Event";
	CharSequence onSingleTapUp = "onSingleTapUp Event";
	private Context mContext = this;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		gesture = new GestureDetector(this, new myGestureListener() {

		});
	}

	@Override
	public boolean onTouchEvent(MotionEvent event) {
		// TODO Auto-generated method stub
		return gesture.onTouchEvent(event);
	}

	private class myGestureListener implements OnGestureListener {

		@Override
		public boolean onDown(MotionEvent e) {
			// TODO Auto-generated method stub
			Toast.makeText(mContext, onDown, Toast.LENGTH_SHORT).show();
			return false;
		}

		@Override
		public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,
				float velocityY) {
			// TODO Auto-generated method stub
			Toast.makeText(mContext, onFling, Toast.LENGTH_SHORT).show();
			return false;
		}

		@Override
		public void onLongPress(MotionEvent e) {
			// TODO Auto-generated method stub
			Toast.makeText(mContext, onLongPress, Toast.LENGTH_SHORT).show();
		}

		@Override
		public boolean onScroll(MotionEvent e1, MotionEvent e2,
				float distanceX, float distanceY) {
			// TODO Auto-generated method stub
			Toast.makeText(mContext, onScroll, Toast.LENGTH_SHORT).show();
			return false;
		}

		@Override
		public void onShowPress(MotionEvent e) {
			// TODO Auto-generated method stub
			Toast.makeText(mContext, onShowPress, Toast.LENGTH_SHORT).show();
		}

		@Override
		public boolean onSingleTapUp(MotionEvent e) {
			// TODO Auto-generated method stub
			Toast.makeText(mContext, onSingleTapUp, Toast.LENGTH_SHORT).show();
			return false;
		}
	}
}