java - 当我在 Android 中将事件从 View 传输到按钮时，为什么 requestLayout() 不调用 onLayout()？

Question

我试图将事件从一个 View 转移到另一个按钮。当用户在特定条件下触摸 View 时，我想将事件传输到按钮。在 onTouchEvent 内的按钮中，我调用了 requestLayout()。当我单击按钮时会调用此 requestLayout()，但当我将事件从 View 传输到按钮时不会调用 requestLayout()。 This是我对上一个问题的后续问题。

/// MaintActivity.java
package com.example.mylayout;

import android.app.Activity; 
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;

public class MainActivity extends Activity {


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);


        setContentView(R.layout.activity_main);     

    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
           return true;
        }
        return super.onOptionsItemSelected(item);
    }
}

//--------activity_main.xml

<com.example.mylayout.MyViewGroup
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <com.example.mylayout.MyView 
    android:id="@+id/myview"  
    android:layout_height="match_parent"
    android:layout_width="match_parent"
    android:background="@color/green">
    </com.example.mylayout.MyView>

    <com.example.mylayout.MyButton
    android:id="@+id/mybutton"
    android:layout_height="wrap_content"
    android:layout_width="wrap_content"
    android:text="@string/Next"
    android:background="@color/red">
    </com.example.mylayout.MyButton>

</com.example.mylayout.MyViewGroup>

//--------MyViewGroup-------- 包 com.example.mylayout;

import android.content.Context;
import android.util.AttributeSet;
import android.view.View;
import android.view.ViewGroup;

public class MyViewGroup extends ViewGroup{



    public MyViewGroup(Context context) {
        super(context);
        // TODO Auto-generated constructor stub
    }

    public MyViewGroup(Context context, AttributeSet attrs) {
        this(context, attrs, 0);

    }

    public MyViewGroup(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {

       int count = getChildCount();

       for (int i = 0; i < count; i++) {
           final View child = getChildAt(i);

       }

       setMeasuredDimension(widthMeasureSpec, heightMeasureSpec);
   }

   @Override
   protected void onLayout(boolean arg0, int arg1, int arg2, int arg3, int arg4) {
       // TODO Auto-generated method stub
       System.out.println("I am from MyViewGroup:onLayout");
       for(int i = 0; i < getChildCount(); i++){
           final View child = getChildAt(i);

           if(i == 0)child.layout(0,0,800,800);
           if(i == 1)child.layout(10,10, 200, 200);
       }
   }

}

//----------------我的 View --------

package com.example.mylayout;

import android.content.Context;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;

public class MyView extends View{

    MyButton objbutton;

    public MyView(Context context) {
        // TODO Auto-generated constructor stub
        super(context);

        objbutton = new MyButton(context);
    }

    public MyView(Context context, AttributeSet attrs) {
        super(context, attrs);
        objbutton = new MyButton(context, attrs);
        // TODO Auto-generated constructor stu
    }

    @Override
    public boolean dispatchTouchEvent(MotionEvent event) {
        System.out.println("I am from MyView: dispatchTouchEvent");
        objbutton.dispatchTouchEvent(event);

        return false;
   }

//--------我的按钮----

package com.example.mylayout;

import android.content.Context;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.widget.Button;

public class MyButton extends Button{

    public MyButton(Context context) {
        // TODO Auto-generated constructor stub
        super(context);

    }

    public MyButton(Context context, AttributeSet attrs) {
        super(context, attrs);
        // TODO Auto-generated constructor stu
    }

    @Override
    public boolean dispatchTouchEvent(MotionEvent event) {
        System.out.println("I am from MyButton: dispatchTouchEvent");
        requestLayout();
        return super.dispatchTouchEvent(event);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        System.out.println("I am from MyButton: dispatchTouchEvent");
        requestLayout();
        return true;
    }

    void printme(){
        System.out.println("I am from MyButton: printme ..");
    }

Answer 1

来自评论:

根据您的粘贴，看起来您正在 MyView 中创建一个全新的 MyButton 实例。它不知道您在布局 xml 中包含的 MyButton。与其这样做，不如在 MyView 中创建一个 setter，然后通过 findViewById() 从 MainActivity 将其传入。

像这样:

package com.example.mylayout;

import android.content.Context;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;

public class MyView extends View {

    private MyButton objbutton;

    public MyView(Context context) {
        // TODO Auto-generated constructor stub
        super(context);
    }

    public void setMyButton(MyButton myButton) {
        objbutton = myButton;
    }

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

    @Override
    public boolean dispatchTouchEvent(MotionEvent event) {
        System.out.println("I am from MyView: dispatchTouchEvent");
        if(objbutton != null)
            objbutton.dispatchTouchEvent(event);
        return false;
    }

}