关于键盘触发事件和屏幕触发事件的问题
当在自定义View或者做游戏的时候,我们常常会用到键盘触发事件和屏幕触发事件!在自定义的View里的键盘触发事件(比如:onKeyDown(int keyCode, KeyEvent event))和屏幕触发事件(onTouchEvent(MotionEvent event))和activity里的键盘触发事件(比如:onKeyDown(int keyCode, KeyEvent event))和屏幕触发事件(onTouchEvent(MotionEvent event))是怎么样交互的呢?是怎样的一个运行原理呢?下面来看看:
1、屏幕触发事件:哪个activity或者视图,控件在最上层就最先触发这个控件里的屏幕触发事件,返回值如果是默认或者false就会一层一层的往下传递!如果返回值是true,则在执行完动作之后不会往下传递!
2、键盘触发事件:这个原理和屏幕触发事件差不多,但是不同的时,在没有设置控件处于焦点时,一般按键盘里的按键触发的是activity里的键盘触发事件(比如:onKeyDown(int keyCode, KeyEvent event))。
下面来举个例子:
比如在做游戏的时候,我们经常自定义视图,我们一般都喜欢和使用触发本视图(GameView)里的键盘触发事件和屏幕触发事件,但是比如:onKeyDown(int keyCode, KeyEvent event)),一般我们按键盘的时候直接触发的是activity里的键盘触发事件,怎样让它直接触发(GameView)里的键盘触发事件呢?
第一种方法:
例子1:
package net.loonggg.project; import android.app.Activity; import android.os.Bundle; import android.view.KeyEvent; import android.view.MotionEvent; public class MainActivity extends Activity { private GameView gameView; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); gameView = new GameView(this); setContentView(gameView); } @Override public boolean onKeyDown(int keyCode, KeyEvent event) { System.out.println("MainActivity:" + " keyCode:" + keyCode + " evnet:" + event); return super.onKeyDown(keyCode, event); } @Override public boolean onTouchEvent(MotionEvent event) { System.out.println("MainActivity:" + " event:" + event + " x:" + event.getX() + " y:" + event.getY()); return super.onTouchEvent(event); } } package net.loonggg.project; import android.content.Context; import android.graphics.Canvas; import android.graphics.Color; import android.graphics.Paint; import android.view.KeyEvent; import android.view.MotionEvent; import android.view.View; public class GameView extends View { private Paint paint; private int pointX; private int pointY; public GameView(Context context) { super(context); // 设置GameView获得焦点 this.setFocusable(true); paint = new Paint(); paint.setColor(Color.YELLOW); Thread t = new Thread(new MyThread()); t.start(); } @Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); canvas.drawCircle(pointX, pointY, 15, paint); } class MyThread implements Runnable { @Override public void run() { while (true) { try { Thread.sleep(3000); pointY = pointY + 10; pointX = pointX + 10; if (pointX > 200) { break; } } catch (InterruptedException e) { e.printStackTrace(); } GameView.this.postInvalidate(); } } } @Override public boolean onKeyDown(int keyCode, KeyEvent event) { System.out.println("GameView:" + " keyCode:" + keyCode + " evnet:" + event); //此事件不会传播出去 return true; } @Override public boolean onTouchEvent(MotionEvent event) { System.out.println("GameView:" + " event:" + event + " x:" + event.getX() + " y:" + event.getY()); //此事件不会传播出去 return true; } }
第二种方法:
package net.loonggg.project; import android.app.Activity; import android.os.Bundle; import android.view.KeyEvent; import android.view.MotionEvent; public class MainActivity extends Activity { private GameView gameView; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); gameView = new GameView(this); setContentView(gameView); } @Override public boolean onKeyDown(int keyCode, KeyEvent event) { System.out.println("MainActivity:" + " keyCode:" + keyCode + " evnet:" + event); //把事件传递给gameView gameView.onKeyDown(keyCode, event); return super.onKeyDown(keyCode, event); } @Override public boolean onTouchEvent(MotionEvent event) { System.out.println("MainActivity:" + " event:" + event + " x:" + event.getX() + " y:" + event.getY()); //把事件传递给gameView gameView.onTouchEvent(event); return super.onTouchEvent(event); } } package net.loonggg.project; import android.content.Context; import android.graphics.Canvas; import android.graphics.Color; import android.graphics.Paint; import android.view.KeyEvent; import android.view.MotionEvent; import android.view.View; public class GameView extends View { private Paint paint; private int pointX; private int pointY; public GameView(Context context) { super(context); paint = new Paint(); paint.setColor(Color.YELLOW); Thread t = new Thread(new MyThread()); t.start(); } @Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); canvas.drawCircle(pointX, pointY, 15, paint); } class MyThread implements Runnable { @Override public void run() { while (true) { try { Thread.sleep(3000); pointY = pointY + 10; pointX = pointX + 10; if (pointX > 200) { break; } } catch (InterruptedException e) { e.printStackTrace(); } GameView.this.postInvalidate(); } } } @Override public boolean onKeyDown(int keyCode, KeyEvent event) { System.out.println("GameView:" + " keyCode:" + keyCode + " evnet:" + event); return super.onKeyDown(keyCode, event); } @Override public boolean onTouchEvent(MotionEvent event) { System.out.println("GameView:" + " event:" + event + " x:" + event.getX() + " y:" + event.getY()); return super.onTouchEvent(event); } }
在这里,推荐使用第二种方法,因为第一种方法有的模拟器不能够使用!