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感謝android中國開發者的眾多先驅,本文主要內容來自于總結,一小部分是自己的體會。主要參考文章為:
http://www.williamhua.com/2009/04/23/android-touchscreen-gesture-recogniton/
http://goro.iteye.com/blog/402163
Android Touch Screen 與傳統Click Touch Screen不同,會有一些手勢(Gesture),例如Fling,Scroll等等。這些Gesture會使用戶體驗大大提升。Android中的Gesture識別(detector)是通過GestureDetector.OnGestureListener接口實現的。
首先,Android事件處理機制是基于Listener實現的,比如觸摸屏相關的事件,就是通過onTouchListener實現;
其次,所有View的子類都可以通過setOnTouchListener()、setOnKeyListener()等方法來添加對某一類事件的Listener;
第三,Listener一般會以Interface的方式來提供,其中包含一個或多個abstract方法,我們需要實現這些方法來完成onTouch()、onKey()等操作。這樣,程序便可以在特定的事件被dispatch到該view的時候,通過callback函數給予適當的響應。
1. Touch Screen Click舉例
Java代碼
public class MyGesture extends Activity implements OnTouchListener { public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); TextView tv = (TextView) findViewById(R.id.tv); tv.setOnTouchListener(this); } public boolean onTouch(View v, MotionEvent event) { Toast.makeText(this, "Touch Touch", Toast.LENGTH_SHORT).show(); return false; } } [java] view plain copy print ?
public class MyGesture extends Activity implements OnTouchListener { public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); TextView tv = (TextView) findViewById(R.id.tv); tv.setOnTouchListener(this); } public boolean onTouch(View v, MotionEvent event) { Toast.makeText(this, "Touch Touch", Toast.LENGTH_SHORT).show(); return false; } } public class MyGesture extends Activity implements OnTouchListener { public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); TextView tv = (TextView) findViewById(R.id.tv); tv.setOnTouchListener(this); } public boolean onTouch(View v, MotionEvent event) { Toast.makeText(this, "Touch Touch", Toast.LENGTH_SHORT).show(); return false; } }
我們可以通過MotionEvent的getAction()方法來獲取Touch事件的類型,包括 ACTION_DOWN(按下觸摸屏), ACTION_MOVE(按下觸摸屏后移動受力點), ACTION_UP(松開觸摸屏)和ACTION_CANCEL(不會由用戶直接觸發)。借助對于用戶不同操作的判斷,結合getRawX()、getRawY()、getX()和getY()等方法來獲取坐標后,我們可以實現諸如拖動某一個按鈕,拖動滾動條等功能。
2. 回到今天的重點,當我們捕捉到Touch操作的時候,如何識別出用戶的Gesture?這里我們需要GestureDetector.OnGestureListener接口的幫助,代碼如下:
Java代碼
public class MyGesture extends Activity implements OnTouchListener, OnGestureListener { private GestureDetector mGestureDetector; public MyGesture() { mGestureDetector = new GestureDetector(this); } public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); TextView tv = (TextView) findViewById(R.id.tv); tv.setOnTouchListener(this); tv.setFocusable(true); tv.setClickable(true); tv.setLongClickable(true); mGestureDetector.setIsLongpressEnabled(true); } /* * 在onTouch()方法中,我們調用GestureDetector的onTouchEvent()方法,將捕捉到的MotionEvent交給GestureDetector * 來分析是否有合適的callback函數來處理用戶的手勢 */ public boolean onTouch(View v, MotionEvent event) { return mGestureDetector.onTouchEvent(event); } // 用戶輕觸觸摸屏,由1個MotionEvent ACTION_DOWN觸發 public boolean onDown(MotionEvent arg0) { Log.i("MyGesture", "onDown"); Toast.makeText(this, "onDown", Toast.LENGTH_SHORT).show(); return true; } /* * 用戶輕觸觸摸屏,尚未松開或拖動,由一個1個MotionEvent ACTION_DOWN觸發 * 注意和onDown()的區別,強調的是沒有松開或者拖動的狀態 */ public void onShowPress(MotionEvent e) { Log.i("MyGesture", "onShowPress"); Toast.makeText(this, "onShowPress", Toast.LENGTH_SHORT).show(); } // 用戶(輕觸觸摸屏后)松開,由一個1個MotionEvent ACTION_UP觸發 public boolean onSingleTapUp(MotionEvent e) { Log.i("MyGesture", "onSingleTapUp"); Toast.makeText(this, "onSingleTapUp", Toast.LENGTH_SHORT).show(); return true; } // 用戶按下觸摸屏、快速移動后松開,由1個MotionEvent ACTION_DOWN, 多個ACTION_MOVE, 1個ACTION_UP觸發 public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) { Log.i("MyGesture", "onFling"); Toast.makeText(this, "onFling", Toast.LENGTH_LONG).show(); return true; } // 用戶按下觸摸屏,并拖動,由1個MotionEvent ACTION_DOWN, 多個ACTION_MOVE觸發 public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) { Log.i("MyGesture", "onScroll"); Toast.makeText(this, "onScroll", Toast.LENGTH_LONG).show(); return true; } // 用戶長按觸摸屏,由多個MotionEvent ACTION_DOWN觸發 public void onLongPress(MotionEvent e) { Log.i("MyGesture", "onLongPress"); Toast.makeText(this, "onLongPress", Toast.LENGTH_LONG).show(); } } [java] view plain copy print ?
public class MyGesture extends Activity implements OnTouchListener, OnGestureListener { private GestureDetector mGestureDetector; public MyGesture() { mGestureDetector = new GestureDetector(this); } public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); TextView tv = (TextView) findViewById(R.id.tv); tv.setOnTouchListener(this); tv.setFocusable(true); tv.setClickable(true); tv.setLongClickable(true); mGestureDetector.setIsLongpressEnabled(true); } /* * 在onTouch()方法中,我們調用GestureDetector的onTouchEvent()方法,將捕捉到的MotionEvent交給GestureDetector * 來分析是否有合適的callback函數來處理用戶的手勢 */ public boolean onTouch(View v, MotionEvent event) { return mGestureDetector.onTouchEvent(event); } // 用戶輕觸觸摸屏,由1個MotionEvent ACTION_DOWN觸發 public boolean onDown(MotionEvent arg0) { Log.i("MyGesture", "onDown"); Toast.makeText(this, "onDown", Toast.LENGTH_SHORT).show(); return true; } /* * 用戶輕觸觸摸屏,尚未松開或拖動,由一個1個MotionEvent ACTION_DOWN觸發 * 注意和onDown()的區別,強調的是沒有松開或者拖動的狀態 */ public void onShowPress(MotionEvent e) { Log.i("MyGesture", "onShowPress"); Toast.makeText(this, "onShowPress", Toast.LENGTH_SHORT).show(); } // 用戶(輕觸觸摸屏后)松開,由一個1個MotionEvent ACTION_UP觸發 public boolean onSingleTapUp(MotionEvent e) { Log.i("MyGesture", "onSingleTapUp"); Toast.makeText(this, "onSingleTapUp", Toast.LENGTH_SHORT).show(); return true; } // 用戶按下觸摸屏、快速移動后松開,由1個MotionEvent ACTION_DOWN, 多個ACTION_MOVE, 1個ACTION_UP觸發 public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) { Log.i("MyGesture", "onFling"); Toast.makeText(this, "onFling", Toast.LENGTH_LONG).show(); return true; } // 用戶按下觸摸屏,并拖動,由1個MotionEvent ACTION_DOWN, 多個ACTION_MOVE觸發 public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) { Log.i("MyGesture", "onScroll"); Toast.makeText(this, "onScroll", Toast.LENGTH_LONG).show(); return true; } // 用戶長按觸摸屏,由多個MotionEvent ACTION_DOWN觸發 public void onLongPress(MotionEvent e) { Log.i("MyGesture", "onLongPress"); Toast.makeText(this, "onLongPress", Toast.LENGTH_LONG).show(); } } public class MyGesture extends Activity implements OnTouchListener, OnGestureListener { private GestureDetector mGestureDetector; public MyGesture() { mGestureDetector = new GestureDetector(this); } public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); TextView tv = (TextView) findViewById(R.id.tv); tv.setOnTouchListener(this); tv.setFocusable(true); tv.setClickable(true); tv.setLongClickable(true); mGestureDetector.setIsLongpressEnabled(true); } /* * 在onTouch()方法中,我們調用GestureDetector的onTouchEvent()方法,將捕捉到的MotionEvent交給GestureDetector * 來分析是否有合適的callback函數來處理用戶的手勢 */ public boolean onTouch(View v, MotionEvent event) { return mGestureDetector.onTouchEvent(event); } // 用戶輕觸觸摸屏,由1個MotionEvent ACTION_DOWN觸發 public boolean onDown(MotionEvent arg0) { Log.i("MyGesture", "onDown"); Toast.makeText(this, "onDown", Toast.LENGTH_SHORT).show(); return true; } /* * 用戶輕觸觸摸屏,尚未松開或拖動,由一個1個MotionEvent ACTION_DOWN觸發 * 注意和onDown()的區別,強調的是沒有松開或者拖動的狀態 */ public void onShowPress(MotionEvent e) { Log.i("MyGesture", "onShowPress"); Toast.makeText(this, "onShowPress", Toast.LENGTH_SHORT).show(); } // 用戶(輕觸觸摸屏后)松開,由一個1個MotionEvent ACTION_UP觸發 public boolean onSingleTapUp(MotionEvent e) { Log.i("MyGesture", "onSingleTapUp"); Toast.makeText(this, "onSingleTapUp", Toast.LENGTH_SHORT).show(); return true; } // 用戶按下觸摸屏、快速移動后松開,由1個MotionEvent ACTION_DOWN, 多個ACTION_MOVE, 1個ACTION_UP觸發 public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) { Log.i("MyGesture", "onFling"); Toast.makeText(this, "onFling", Toast.LENGTH_LONG).show(); return true; } // 用戶按下觸摸屏,并拖動,由1個MotionEvent ACTION_DOWN, 多個ACTION_MOVE觸發 public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) { Log.i("MyGesture", "onScroll"); Toast.makeText(this, "onScroll", Toast.LENGTH_LONG).show(); return true; } // 用戶長按觸摸屏,由多個MotionEvent ACTION_DOWN觸發 public void onLongPress(MotionEvent e) { Log.i("MyGesture", "onLongPress"); Toast.makeText(this, "onLongPress", Toast.LENGTH_LONG).show(); } }
3. Fling事件的處理代碼:除了第一個觸發Fling的ACTION_DOWN和最后一個ACTION_MOVE中包含的坐標等信息外,我們還可以根據用戶在X軸或者Y軸上的移動速度作為條件。比如下面的代碼中我們就在用戶移動超過100個像素,且X軸上每秒的移動速度大于200像素時才進行處理。
Java代碼
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) { // 參數解釋: // e1:第1個ACTION_DOWN MotionEvent // e2:最后一個ACTION_MOVE MotionEvent // velocityX:X軸上的移動速度,像素/秒 // velocityY:Y軸上的移動速度,像素/秒 // 觸發條件 : // X軸的坐標位移大于FLING_MIN_DISTANCE,且移動速度大于FLING_MIN_VELOCITY個像素/秒 final int FLING_MIN_DISTANCE = 100, FLING_MIN_VELOCITY = 200; if (e1.getX() - e2.getX() > FLING_MIN_DISTANCE && Math.abs(velocityX) > FLING_MIN_VELOCITY) { // Fling left Log.i("MyGesture", "Fling left"); Toast.makeText(this, "Fling Left", Toast.LENGTH_SHORT).show(); } else if (e2.getX() - e1.getX() > FLING_MIN_DISTANCE && Math.abs(velocityX) > FLING_MIN_VELOCITY) { // Fling right Log.i("MyGesture", "Fling right"); Toast.makeText(this, "Fling Right", Toast.LENGTH_SHORT).show(); } return false; } [java] view plain copy print ?
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) { // 參數解釋: // e1:第1個ACTION_DOWN MotionEvent // e2:最后一個ACTION_MOVE MotionEvent // velocityX:X軸上的移動速度,像素/秒 // velocityY:Y軸上的移動速度,像素/秒 // 觸發條件 : // X軸的坐標位移大于FLING_MIN_DISTANCE,且移動速度大于FLING_MIN_VELOCITY個像素/秒 final int FLING_MIN_DISTANCE = 100, FLING_MIN_VELOCITY = 200; if (e1.getX() - e2.getX() > FLING_MIN_DISTANCE && Math.abs(velocityX) > FLING_MIN_VELOCITY) { // Fling left Log.i("MyGesture", "Fling left"); Toast.makeText(this, "Fling Left", Toast.LENGTH_SHORT).show(); } else if (e2.getX() - e1.getX() > FLING_MIN_DISTANCE && Math.abs(velocityX) > FLING_MIN_VELOCITY) { // Fling right Log.i("MyGesture", "Fling right"); Toast.makeText(this, "Fling Right", Toast.LENGTH_SHORT).show(); } return false; } public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) { // 參數解釋: // e1:第1個ACTION_DOWN MotionEvent // e2:最后一個ACTION_MOVE MotionEvent // velocityX:X軸上的移動速度,像素/秒 // velocityY:Y軸上的移動速度,像素/秒 // 觸發條件 : // X軸的坐標位移大于FLING_MIN_DISTANCE,且移動速度大于FLING_MIN_VELOCITY個像素/秒 final int FLING_MIN_DISTANCE = 100, FLING_MIN_VELOCITY = 200; if (e1.getX() - e2.getX() > FLING_MIN_DISTANCE && Math.abs(velocityX) > FLING_MIN_VELOCITY) { // Fling left Log.i("MyGesture", "Fling left"); Toast.makeText(this, "Fling Left", Toast.LENGTH_SHORT).show(); } else if (e2.getX() - e1.getX() > FLING_MIN_DISTANCE && Math.abs(velocityX) > FLING_MIN_VELOCITY) { // Fling right Log.i("MyGesture", "Fling right"); Toast.makeText(this, "Fling Right", Toast.LENGTH_SHORT).show(); } return false; }
這個例子中,tv.setLongClickable(true )是必須的,因為 只有這樣,view才能夠處理不同于Tap(輕觸)的hold(即ACTION_MOVE,或者多個ACTION_DOWN),我們同樣可以通過layout定義中的android:longClickable來做到這一點。
4. SimpleOnGestureListener
Java代碼
public class MyGesture extends Activity implements OnTouchListener { private GestureDetector mGestureDetector; public MyGesture() { mGestureDetector = new GestureDetector(new MySimpleGesture()); } public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); TextView tv = (TextView) findViewById(R.id.tv); tv.setOnTouchListener(this); tv.setFocusable(true); tv.setClickable(true); tv.setLongClickable(true); } public boolean onTouch(View v, MotionEvent event) { if (event.getAction() == MotionEvent.ACTION_UP) { Log.i("MyGesture", "MotionEvent.ACTION_UP"); } return mGestureDetector.onTouchEvent(event); } // SimpleOnGestureListener implements GestureDetector.OnDoubleTapListener, GestureDetector.OnGestureListener private class MySimpleGesture extends SimpleOnGestureListener { // 雙擊的第二下Touch down時觸發 public boolean onDoubleTap(MotionEvent e) { Log.i("MyGesture", "onDoubleTap"); return super.onDoubleTap(e); } // 雙擊的第二下Touch down和up都會觸發,可用e.getAction()區分 public boolean onDoubleTapEvent(MotionEvent e) { Log.i("MyGesture", "onDoubleTapEvent"); return super.onDoubleTapEvent(e); } // Touch down時觸發 public boolean onDown(MotionEvent e) { Log.i("MyGesture", "onDown"); return super.onDown(e); } // Touch了滑動一點距離后,up時觸發 public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) { Log.i("MyGesture", "onFling"); return super.onFling(e1, e2, velocityX, velocityY); } // Touch了不移動一直Touch down時觸發 public void onLongPress(MotionEvent e) { Log.i("MyGesture", "onLongPress"); super.onLongPress(e); } // Touch了滑動時觸發 public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) { Log.i("MyGesture", "onScroll"); return super.onScroll(e1, e2, distanceX, distanceY); } /* * Touch了還沒有滑動時觸發 * (1)onDown只要Touch Down一定立刻觸發 * (2)Touch Down后過一會沒有滑動先觸發onShowPress再觸發onLongPress * So: Touch Down后一直不滑動,onDown -> onShowPress -> onLongPress這個順序觸發。 */ public void onShowPress(MotionEvent e) { Log.i("MyGesture", "onShowPress"); super.onShowPress(e); } /* * 兩個函數都是在Touch Down后又沒有滑動(onScroll),又沒有長按(onLongPress),然后Touch Up時觸發 * 點擊一下非常快的(不滑動)Touch Up: onDown->onSingleTapUp->onSingleTapConfirmed * 點擊一下稍微慢點的(不滑動)Touch Up: onDown->onShowPress->onSingleTapUp->onSingleTapConfirmed */ public boolean onSingleTapConfirmed(MotionEvent e) { Log.i("MyGesture", "onSingleTapConfirmed"); return super.onSingleTapConfirmed(e); } public boolean onSingleTapUp(MotionEvent e) { Log.i("MyGesture", "onSingleTapUp"); return super.onSingleTapUp(e); } } }
轉載于:https://my.oschina.net/caikezhan/blog/52038
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