自定义ViewGroup（二）

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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, "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_DOWN11-15 05:32:35.202 1584-1584/com.xiey94.view E/MyLinearLayout: onInterceptTouchEvent ACTION_DOWN11-15 05:32:35.202 1584-1584/com.xiey94.view E/MyButton: dispatchTouchEvent ACTION_DOWN11-15 05:32:35.202 1584-1584/com.xiey94.view E/MyButton: onTouch ACTION_DOWN11-15 05:32:35.202 1584-1584/com.xiey94.view E/MyButton: onTouchEvent ACTION_DOWN11-15 05:32:35.314 1584-1584/com.xiey94.view E/MyLinearLayout: dispatchTouchEvent ACTION_MOVE11-15 05:32:35.314 1584-1584/com.xiey94.view E/MyLinearLayout: onInterceptTouchEvent ACTION_MOVE11-15 05:32:35.314 1584-1584/com.xiey94.view E/MyButton: dispatchTouchEvent ACTION_MOVE11-15 05:32:35.314 1584-1584/com.xiey94.view E/MyButton: onTouch ACTION_MOVE11-15 05:32:35.314 1584-1584/com.xiey94.view E/MyButton: onTouchEvent ACTION_MOVE11-15 05:32:35.426 1584-1584/com.xiey94.view E/MyLinearLayout: dispatchTouchEvent ACTION_UP11-15 05:32:35.426 1584-1584/com.xiey94.view E/MyLinearLayout: onInterceptTouchEvent ACTION_UP11-15 05:32:35.426 1584-1584/com.xiey94.view E/MyButton: dispatchTouchEvent ACTION_UP11-15 05:32:35.426 1584-1584/com.xiey94.view E/MyButton: onTouch ACTION_UP11-15 05:32:35.426 1584-1584/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
这里写图片描述

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！

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