Android事件传递和响应：TP和按键

        Android按键事件处理主要在View和Activity两个级别。和Touch事件相比，简单很多。按键事件的处理机制如下：
（1）默认情况下，如果没有View获得焦点，事件将传递给Activity处理。
（2）如果View获得焦点，事件首先传递到View的回调方法中（按键的回调用OnKeyListener，TP的回调用OnTouchListener）。view回调方法不处理的话返回false，事件继续传递到Activity处理。反之，处理了的话返回true，事件不会继续传递。

（3） 一个TP操作的实例

        通过TP操作activity上一个button控件，包括按下、划动、弹起三个操作，来区分出getX()与getRawX()的区别。两者都是获取屏幕坐标，但二者又有区别：getX()：是获取相对当前控件（View）的坐标；getRawX()：是获取相对显示屏幕左上角的坐标。

        JAVA代码如下，用的仍然是view中的interface：

public class MainActivity extends Activity implements OnTouchListener {private Button btn;  private int x = 0, y = 0;  private int rawX = 0, rawY = 0;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);btn = (Button) findViewById(R.id.btn);  btn.setOnTouchListener(this); }@Overridepublic boolean onTouch(View v, MotionEvent event) {// TODO Auto-generated method stubint eventaction = event.getAction();  switch (eventaction) { case MotionEvent.ACTION_DOWN:  x = (int) event.getX();  y = (int) event.getY();  rawX = (int) event.getRawX();  rawY = (int) event.getRawY();          Log.e("homer", "ACTION_DOWN x = " + x + "; y = " + y + "; rawX = " + rawX + "; rawY = " + rawY);  break;case MotionEvent.ACTION_MOVE:  x = (int) event.getX();  y = (int) event.getY();  rawX = (int) event.getRawX();  rawY = (int) event.getRawY();          Log.e("homer", "ACTION_MOVE x = " + x + "; y = " + y + "; rawX = " + rawX + "; rawY = " + rawY);  break;  case MotionEvent.ACTION_UP:  x = (int) event.getX();  y = (int) event.getY();  rawX = (int) event.getRawX();  rawY = (int) event.getRawY();          Log.e("homer", "ACTION_UP x = " + x + "; y = " + y + "; rawX = " + rawX + "; rawY = " + rawY);break; }return false;}}

操作TP的结果，就是如下LOG TRACE：

04-11 02:41:00.479: E/homer(589): ACTION_DOWN x = 15; y = 12; rawX = 107; rawY = 101
04-11 02:41:00.611: E/homer(589): ACTION_UP x = 15; y = 12; rawX = 107; rawY = 101
04-11 02:41:03.749: E/homer(589): ACTION_DOWN x = 13; y = 29; rawX = 105; rawY = 118
04-11 02:41:03.819: E/homer(589): ACTION_UP x = 13; y = 29; rawX = 105; rawY = 118
04-11 02:41:11.410: E/homer(589): ACTION_DOWN x = 44; y = 47; rawX = 136; rawY = 136
04-11 02:41:11.480: E/homer(589): ACTION_MOVE x = 51; y = 55; rawX = 143; rawY = 144
04-11 02:41:11.519: E/homer(589): ACTION_MOVE x = 72; y = 68; rawX = 164; rawY = 157
04-11 02:41:11.549: E/homer(589): ACTION_MOVE x = 112; y = 89; rawX = 204; rawY = 178
       总结：getX() 是表示Widget相对于自身左上角的x坐标，而getRawX()是表示相对于屏幕左上角的x坐标值（注意：这个屏幕左上角是手机屏幕左上角，不管activity是否有titleBar或是否全屏幕）； getY(),getRawY()一样的道理。

 

参考原文：http://orgcent.com/android-key-event-mechanism/

参考原文：http://blog.csdn.net/sunboy_2050/article/details/8757240