自定义ViewGroup（二）

事件分发

自定义ViewGroup这块，不可能一直都是在测量和布置位置，那这样的布局没什么用，还得涉及到事件分发与拦截，哪些归父处理，哪些归子处理。

始终跟着大神走，还是看鸿洋大神的博客：Android ViewGroup事件分发机制

先自定义一个按钮：

public class MyButton extends AppCompatButton {

public static final String TAG = MyButton.class.getSimpleName();

public MyButton(Context context, AttributeSet attrs) {
super(context, attrs);
}

/**
* 触摸事件
*
* @param event
* @return
*/
@Override
public boolean onTouchEvent(MotionEvent event) {
int action = event.getAction();
switch (action) {
case MotionEvent.ACTION_DOWN:
Log.e(TAG, "onTouchEvent ACTION_DOWN");
break;
case MotionEvent.ACTION_MOVE:
Log.e(TAG, "onTouchEvent ACTION_MOVE");
break;
case MotionEvent.ACTION_UP:
Log.e(TAG, "onTouchEvent ACTION_UP");
break;
default:
break;
}
return super.onTouchEvent(event);
}

/**
* 分发事件
*
* @param event
* @return
*/
@Override
public boolean dispatchTouchEvent(MotionEvent event) {
int action = event.getAction();
switch (action) {
case MotionEvent.ACTION_DOWN:
Log.e(TAG,
4000
"dispatchTouchEvent ACTION_DOWN");
break;
case MotionEvent.ACTION_MOVE:
Log.e(TAG, "dispatchTouchEvent ACTION_MOVE");
break;
case MotionEvent.ACTION_UP:
Log.e(TAG, "dispatchTouchEvent ACTION_UP");
break;
default:
break;
}
return super.dispatchTouchEvent(event);
}
}

然后自定义一个LinearLayout:

public class MyLinearLayout extends LinearLayout {
public static final String TAG = MyLinearLayout.class.getSimpleName();

public MyLinearLayout(Context context, @Nullable AttributeSet attrs) {
super(context, attrs);
}

/**
* 分发
*/
@Override
public boolean dispatchTouchEvent(MotionEvent ev) {
int action = ev.getAction();
switch (action) {
case MotionEvent.ACTION_DOWN:
Log.e(TAG, "dispatchTouchEvent ACTION_DOWN");
break;
case MotionEvent.ACTION_MOVE:
Log.e(TAG, "dispatchTouchEvent ACTION_MOVE");
break;
case MotionEvent.ACTION_UP:
Log.e(TAG, "dispatchTouchEvent ACTION_UP");
break;

default:
break;
}
return super.dispatchTouchEvent(ev);
}

/**
* 触摸
*/
@Override
public boolean onTouchEvent(MotionEvent event) {

int action = event.getAction();

switch (action) {
case MotionEvent.ACTION_DOWN:
Log.e(TAG, "onTouchEvent ACTION_DOWN");
break;
case MotionEvent.ACTION_MOVE:
Log.e(TAG, "onTouchEvent ACTION_MOVE");
break;
case MotionEvent.ACTION_UP:
Log.e(TAG, "onTouchEvent ACTION_UP");
break;

default:
break;
}

return super.onTouchEvent(event);
}

/**
* 拦截
*/
@Override
public boolean onInterceptTouchEvent(MotionEvent ev) {

int action = ev.getAction();
switch (action) {
case MotionEvent.ACTION_DOWN:
Log.e(TAG, "onInterceptTouchEvent ACTION_DOWN");
break;
case MotionEvent.ACTION_MOVE:
Log.e(TAG, "onInterceptTouchEvent ACTION_MOVE");
break;
case MotionEvent.ACTION_UP:
Log.e(TAG, "onInterceptTouchEvent ACTION_UP");
break;

default:
break;
}

return super.onInterceptTouchEvent(ev);
}

@Override
public void requestDisallowInterceptTouchEvent(boolean disallowIntercept) {
Log.e(TAG, "requestDisallowInterceptTouchEvent");
super.requestDisallowInterceptTouchEvent(disallowIntercept);
}

然后在布局中引用：

<?xml version="1.0" encoding="utf-8"?>
<com.xiey94.view.viewgroup.MyLinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">

<com.xiey94.view.view.MyButton
android:id="@+id/btn"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="clcik"
android:textAllCaps="false" />

</com.xiey94.view.viewgroup.MyLinearLayout>

调用：

public class MainActivity extends AppCompatActivity {
protected static final String TAG = "MyButton";
private MyButton btn;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
btn = (MyButton) findViewById(R.id.btn);
btn.setOnTouchListener(new View.OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
int action = event.getAction();
switch (action) {
case MotionEvent.ACTION_DOWN:
Log.e(TAG, "onTouch ACTION_DOWN");
break;
case MotionEvent.ACTION_MOVE:
Log.e(TAG, "onTouch ACTION_MOVE");
break;
case MotionEvent.ACTION_UP:
Log.e(TAG, "onTouch ACTION_UP");
break;
default:
break;
}
return false;
}
});
}
}

触碰并移动后的打印如下：

11-15 05:32:35.202 1584-1584/com.xiey94.view E/MyLinearLayout: dispatchTouchEvent ACTION_DOWN
11-15 05:32:35.202 1584-1584/com.xiey94.view E/MyLinearLayout: onInterceptTouchEvent ACTION_DOWN
11-15 05:32:35.202 1584-1584/com.xiey94.view E/MyButton: dispatchTouchEvent ACTION_DOWN
11-15 05:32:35.202 1584-1584/com.xiey94.view E/MyButton: onTouch ACTION_DOWN
11-15 05:32:35.202 1584-1584/com.xiey94.view E/MyButton: onTouchEvent ACTION_DOWN
11-15 05:32:35.314 1584-1584/com.xiey94.view E/MyLinearLayout: dispatchTouchEvent ACTION_MOVE
11-15 05:32:35.314 1584-1584/com.xiey94.view E/MyLinearLayout: onInterceptTouchEvent ACTION_MOVE
11-15 05:32:35.314 1584-1584/com.xiey94.view E/MyButton: dispatchTouchEvent ACTION_MOVE
11-15 05:32:35.314 1584-1584/com.xiey94.view E/MyButton: onTouch ACTION_MOVE
11-15 05:32:35.314 1584-1584/com.xiey94.view E/MyButton: onTouchEvent ACTION_MOVE
11-15 05:32:35.426 1584-1584/com.xiey94.view E/MyLinearLayout: dispatchTouchEvent ACTION_UP
11-15 05:32:35.426 1584-1584/com.xiey94.view E/MyLinearLayout: onInterceptTouchEvent ACTION_UP
11-15 05:32:35.426 1584-1584/com.xiey94.view E/MyButton: dispatchTouchEvent ACTION_UP
11-15 05:32:35.426 1584-1584/com.xiey94.view E/MyButton: onTouch ACTION_UP
11-15 05:32:35.426 158
b289
4-1584/com.xiey94.view E/MyButton: onTouchEvent ACTION_UP

可以看出他们的调用顺序：

ViewGroup –>View

先调用ViewGroup的事件分发dispatchTouchEvent，然后拦截onInterceptTouchEvent，传到子View*（这里并没有拦截），View分发dispatchTouchEvent，然后View的onTouch，最后是View的onTouchEvent。

从这里可以看出，ViewGroup要比View多一个onInterceptTouchEvent，这也是它独有的特性；

这里并不解析源码，只是初步的了解一下它的分发机制，参考 一个Android群英传里的



1、ViewGroup拦截：1 –>6

2、ViewGroup不拦截，MyButton拦截并处理：1–>2–>3

3、ViewGroup不拦截，MyButton不拦截不处理：1–>2–>4

大的流程大概就是这样，至于源码的分析这种活，现在干不了，循序渐进吧！