为了加强点击、拖动响应事件,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down时触发
boolean onDoubleTapEvent(MotionEvent e)
解释:双击的第二下down和up都会触发,可用e.getAction()区分。
boolean onDown(MotionEvent e)
解释: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Touch down后过一会没有滑动先触发onShowPress再是onLongPress。
所以Touch down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
创建手势监听对象:
package com.sun.gesturetest; import android.util.Log; import android.view.GestureDetector.SimpleOnGestureListener; import android.view.MotionEvent; public class MyGestureListener extends SimpleOnGestureListener { private static final String TAG = "MyGestureListener"; public MyGestureListener() { } /** * 双击的第二下Touch down时触发 * @param e * @return */ @Override public boolean onDoubleTap(MotionEvent e) { Log.i(TAG, "onDoubleTap : " + e.getAction()); return super.onDoubleTap(e); } /** * 双击的第二下 down和up都会触发,可用e.getAction()区分。 * @param e * @return */ @Override public boolean onDoubleTapEvent(MotionEvent e) { Log.i(TAG, "onDoubleTapEvent : " + e.getAction()); return super.onDoubleTapEvent(e); } /** * down时触发 * @param e * @return */ @Override public boolean onDown(MotionEvent e) { Log.i(TAG, "onDown : " + e.getAction()); return super.onDown(e); } /** * Touch了滑动一点距离后,up时触发。 * @param e1 * @param e2 * @param velocityX * @param velocityY * @return */ @Override public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) { Log.i(TAG, "onFling e1 : " + e1.getAction() + ", e2 : " + e2.getAction() + ", distanceX : " + velocityX + ", distanceY : " + velocityY); return super.onFling(e1, e2, velocityX, velocityY); } /** * Touch了不移动一直 down时触发 * @param e */ @Override public void onLongPress(MotionEvent e) { Log.i(TAG, "onLongPress : " + e.getAction()); super.onLongPress(e); } /** * Touch了滑动时触发。 * @param e1 * @param e2 * @param distanceX * @param distanceY * @return */ @Override public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) { Log.i(TAG, "onScroll e1 : " + e1.getAction() + ", e2 : " + e2.getAction() + ", distanceX : " + distanceX + ", distanceY : " + distanceY); return super.onScroll(e1, e2, distanceX, distanceY); } /** * Touch了还没有滑动时触发 * @param e */ @Override public void onShowPress(MotionEvent e) { Log.i(TAG, "onShowPress : " + e.getAction()); super.onShowPress(e); } @Override public boolean onSingleTapConfirmed(MotionEvent e) { Log.i(TAG, "onSingleTapConfirmed : " + e.getAction()); return super.onSingleTapConfirmed(e); } @Override public boolean onSingleTapUp(MotionEvent e) { Log.i(TAG, "onSingleTapUp : " + e.getAction()); return super.onSingleTapUp(e); } }
在Activity中onTouchEvent(MotionEvent event)方法中设置手势:
package com.sun.gesturetest; import android.os.Bundle; import android.app.Activity; import android.view.GestureDetector; import android.view.Menu; import android.view.MotionEvent; public class MainActivity extends Activity { private GestureDetector mDetector; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); mDetector = new GestureDetector(this, new MyGestureListener()); } @Override public boolean onTouchEvent(MotionEvent event) { return mDetector.onTouchEvent(event); } @Override public boolean onCreateOptionsMenu(Menu menu) { getMenuInflater().inflate(R.menu.activity_main, menu); return true; } }
或者在自定义View中设置手势:
package com.sun.gesturetest; import android.content.Context; import android.util.AttributeSet; import android.view.GestureDetector; import android.view.MotionEvent; import android.view.View; public class GestureView extends View { private GestureDetector mDetector; public GestureView(Context context, AttributeSet set) { super(context, set); mDetector = new GestureDetector(context, new MyGestureListener()); setLongClickable(true); this.setOnTouchListener(new OnTouchListener() { @Override public boolean onTouch(View v, MotionEvent event) { return mDetector.onTouchEvent(event); } }); } }
在View中设置手势有两点需要注意:
1:View必须设置longClickable为true,否则手势识别无法正确工作,只会返回Down, Show, Long三种手势。
2:必须在View的onTouchListener中调用手势识别,而不能像Activity一样重载onTouchEvent,否则同样手势识别无法正确工作。