GestureDetector（手勢識別器） ### （1）手勢交互過程原理： A.觸屏一剎那，觸發 MotionEvent事件； B.上述事件被 OnTouchListenter 監聽，在 nTouch() 中獲得 MotionEvent對象； C.GestureDetector 轉發MotionEvent對象至 OnGestureListenter； D.OnGestureListenter 獲得該對象，根據該對象封裝的信息作出合適的反饋； ### （2）MotionEvent： 1）、用于封裝手勢等動作事件； 2）、內部封裝用于記錄橫軸和縱軸坐標的屬性X和Y； GestureDetector： 1）、識別各種手勢； OnGestureListenter： 1）、手勢交互的監聽接口，其提供多個抽象方法； 2）、根據GestureDetector的手勢識別結果調用相對應的方法； ### （3）GestureDetector工作原理： 1)、GestureDetector.OnGestureListener接口 onDown(MotionEvent e)：——單擊 Notified when a tap occurs with the down MotionEvent that triggered it. onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY)：——滑動 Notified of a fling event when it occurs with the initial on down MotionEvent and the matching up MotionEvent. onLongPress(MotionEvent e)：——長按 Notified when a long press occurs with the initial on down MotionEvent that trigged it. onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY)：——滾動 Notified when a scroll occurs with the initial on down MotionEvent and the current move MotionEvent. onShowPress(MotionEvent e)：——短按 The user has performed a down MotionEvent and not performed a move or up yet. onSingleTapUp(MotionEvent e)：——抬起 Notified when a tap occurs with the up MotionEvent that triggered it.? 2)、GestureDetector.OnDoubleTapListener接口 onDoubleTap(MotionEvent e)：——雙擊** Notified when a double-tap occurs. onDoubleTapEvent(MotionEvent e)：——雙擊按下和抬起各觸發一次 Notified when an event within a double-tap gesture occurs, including the down, move, and up events. onSingleTapConfirmed(MotionEvent e)：——單擊確認（即很快的按下并抬起，但并不連續點擊第二下） Notified when a single-tap occurs. 3）、GestureDetector.SimpleOnGestureListener類 其實我們并不需要處理上面所有手勢。問了方便起見，Android提供了另外一個類SimpleOnGestureListener。它實現了如上接口，我們只需要繼承SimpleOnGestureListener類，然后重載感興趣的手勢。?implements?[GestureDetector.OnGestureListener](http://developer.android.com/reference/android/view/GestureDetector.OnGestureListener.html)?[GestureDetector. OnDoubleTapListener](http://developer.android.com/reference/android/view/GestureDetector.OnDoubleTapListener.html)[GestureDetector. OnContextClickListener](http://developer.android.com/reference/android/view/GestureDetector.OnContextClickListener.html)。A convenience class to extend when you only want to listen for a subset of all the gestures. This implements all methods in ?the ?`[GestureDetector.OnGestureListener](http://developer.android.com/reference/android/view/GestureDetector.OnGestureListener.html)`, ?`[GestureDetector.OnDoubleTapListener](http://developer.android.com/reference/android/view/GestureDetector.OnDoubleTapListener.html)`, and`[GestureDetector.OnContextClickListener](http://developer.android.com/reference/android/view/GestureDetector.OnContextClickListener.html)`?but does nothing and return`false`?for all applicable methods. ~~~ public class MainActivity extends Activity { private ImageView imageView; private GestureDetector mygestureDetector; // 繼承SimpleOnGestureListener類，然后重載感興趣的手勢。 class MyGestureListenter extends SimpleOnGestureListener { @Override // 重載滑動手勢 public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) { if (e1.getX() - e2.getX() > 50) { Toast.makeText(MainActivity.this, "從右往左滑動", Toast.LENGTH_SHORT) .show(); } else if (e2.getX() - e1.getX() > 50) { Toast.makeText(MainActivity.this, "從左往右滑動", Toast.LENGTH_SHORT) .show(); } return super.onFling(e1, e2, velocityX, velocityY); } } @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); /* * GestureDetector工作原理 * 1、當接收到用戶觸摸消息時，將消息交給GestureDetector加工； * 2、通過設置監聽器獲得GestureDetector處理后的手勢； * 3、GestureDetector提供兩個監聽器： * A.OnGestureListenter：處理單擊類消息； * B.OnDoubleTapListenter：處理雙擊類消息； */ imageView = (ImageView) findViewById(R.id.img); mygestureDetector = new GestureDetector(new MyGestureListenter()); // MotionEvent——》setOnTouchListener捕獲 // ——》onTouch中GestureDetector對象將監聽事件轉發給MyGestureListenter(extends SimpleOnGestureListener) // ——》MyGestureListenter類中實現了要重載的手勢 imageView.setOnTouchListener(new OnTouchListener() { @Override // 可以捕獲觸摸屏幕發生的Event public boolean onTouch(View v, MotionEvent event) { // TODO Auto-generated method stub mygestureDetector.onTouchEvent(event); // 轉發event事件，轉發給MyGestureListenter(extends SimpleOnGestureListener) return false; } }); } //消除沖突 /*@Override public boolean dispatchTouchEvent(MotionEvent ev) { // TODO Auto-generated method stub if(mygestureDetector!=null){ if(mygestureDetector.onTouchEvent(ev)){ return true; } } return super.dispatchTouchEvent(ev); }*/ //必須重寫onTouchEvent方法，onFling才生效 @Override public boolean onTouchEvent(MotionEvent event) { // TODO Auto-generated method stub return mygestureDetector.onTouchEvent(event); } } ~~~ 為了讓onFling才生效，必須重寫onTouchEvent方法！