Android 手势识别类 ( 一 ) GestureDetector 基本介绍

为了加强鼠标响应事件，Android提供了GestureDetector手势识别类。通过GestureDetector.OnGestureListener来获取当前被触发的操作手势（Single Tap Up、Show Press、Long Press、Scroll、Down、Fling），具体包括以下几种：

boolean  onDoubleTap(MotionEvent e)
解释：双击的第二下Touch down时触发
boolean  onDoubleTapEvent(MotionEvent e)
解释：双击的第二下Touch down和up都会触发，可用e.getAction()区分。
boolean  onDown(MotionEvent e)
解释：Touch down时触发
boolean  onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY)
解释：Touch了滑动一点距离后，up时触发。
void  onLongPress(MotionEvent e)
解释：Touch了不移动一直Touch down时触发
boolean  onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY)
解释：Touch了滑动时触发。
void  onShowPress(MotionEvent e)
解释：Touch了还没有滑动时触发
（与onDown，onLongPress比较
onDown只要Touch down一定立刻触发。
而Touchdown后过一会没有滑动先触发onShowPress再是onLongPress。
所以Touchdown后一直不滑动，onDown->onShowPress->onLongPress这个顺序触发。

boolean  onSingleTapConfirmed(MotionEvent e)
boolean  onSingleTapUp(MotionEvent e)
解释：上面这两个函数都是在touch down后又没有滑动（onScroll），又没有长按（onLongPress），然后Touchup时触发。

点击一下非常快的（不滑动）Touchup：
onDown->onSingleTapUp->onSingleTapConfirmed
点击一下稍微慢点的（不滑动）Touchup：
onDown->onShowPress->onSingleTapUp->onSingleTapConfirmed

使用GestureDetector需要在View中重写onTouchEvent事件，例如：

GestureDetector mGesture = null;
@Override
    public boolean onTouch(View v, MotionEvent event)
    {
        // TODO Auto-generated method stub
        return mGesture.onTouchEvent(event);
    }

 详细的测试例子如下：

package com.jiubang.android.gesturetest;

import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.view.GestureDetector;
import android.view.MotionEvent;
import android.view.View;
import android.view.GestureDetector.SimpleOnGestureListener;
import android.view.View.OnTouchListener;
import android.widget.Button;

public class GestureActivity extends Activity
            implements OnTouchListener
{
    private Button mButton = null;
    GestureDetector mGesture = null;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        Log.i("TEST", "onCreate");
        mButton = (Button)findViewById(R.id.button1);
        mButton.setOnTouchListener(this);
        mGesture = new GestureDetector(this, new GestureListener());
    }

    @Override
    public boolean onTouch(View v, MotionEvent event)
    {
        // TODO Auto-generated method stub
        return mGesture.onTouchEvent(event);
    }

    class GestureListener extends SimpleOnGestureListener
    {

        @Override
        public boolean onDoubleTap(MotionEvent e)
        {
            // TODO Auto-generated method stub
            Log.i("TEST", "onDoubleTap");
            return super.onDoubleTap(e);
        }

        @Override
        public boolean onDown(MotionEvent e)
        {
            // TODO Auto-generated method stub
            Log.i("TEST", "onDown");
            return super.onDown(e);
        }

        @Override
        public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,
                float velocityY)
        {
            // TODO Auto-generated method stub
            Log.i("TEST", "onFling:velocityX = " + velocityX + " velocityY" + velocityY);
            return super.onFling(e1, e2, velocityX, velocityY);
        }

        @Override
        public void onLongPress(MotionEvent e)
        {
            // TODO Auto-generated method stub
            Log.i("TEST", "onLongPress");
            super.onLongPress(e);
        }

        @Override
        public boolean onScroll(MotionEvent e1, MotionEvent e2,
                float distanceX, float distanceY)
        {
            // TODO Auto-generated method stub
            Log.i("TEST", "onScroll:distanceX = " + distanceX + " distanceY = " + distanceY);
            return super.onScroll(e1, e2, distanceX, distanceY);
        }

        @Override
        public boolean onSingleTapUp(MotionEvent e)
        {
            // TODO Auto-generated method stub
            Log.i("TEST", "onSingleTapUp");
            return super.onSingleTapUp(e);
        }

    }
}

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