爲什麼requestLayout（）在Android中將事件從視圖轉移到按鈕時不調用onLayout（）？

Question

我正試圖將事件從一個視圖轉移到另一個按鈕。當用戶在特定條件下觸摸視圖時，我想將事件轉移到按鈕。在onTouchEvent中的按鈕中，我調用requestLayout（）。當我點擊該按鈕時，requestLayout（）被調用，但是當我將視圖中的事件轉移到按鈕時，requestLayout（）沒有被調用。 This是我對前一個問題的跟進問題。

/// 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。示例。 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); 
     } 
    } 

} 

// -------------- MyView的-------

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; 
    } 

}

// ----- --MyButton ----

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

從評論：

根據您的粘貼，它看起來像是在MyView內部創建了一個全新的MyButton實例。它不知道你已經包含在佈局xml中的MyButton。而不是這樣做，在MyView中創建一個setter並從MainActivity通過findViewById()傳遞它。

像這樣：

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; 
    } 

}