Make a child view match the width of a parent scrollview

Question

I have a horizontal scrollview with many EditText children. I want each of these children to be the same width of the visible area of the parent scrollview. Is this possible in XML?

Answer 1

You can do it writing a small helper class:

We are creating a very small class that extends EditText called FullWidthEditText like this:

package com.YOURPACKAGENAME;

import android.content.Context;
import android.util.AttributeSet;
import android.view.View;
import android.widget.EditText;
import android.widget.HorizontalScrollView;

public class FullWidthEditText extends EditText {
    public FullWidthEditText(Context context) { super(context);}    
    public FullWidthEditText(Context context, AttributeSet attrs) { super(context, attrs); }
    public FullWidthEditText(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); }

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

        View parentScrollView=((View)(getParent().getParent()));

        if (parentScrollView!=null) {
            // check the container of the container is an HorizontallScrollView
            if (parentScrollView instanceof HorizontalScrollView) {
                // Yes it is, so change width to HSV's width
                widthMeasureSpec=parentScrollView.getMeasuredWidth();
            }
        }
        setMeasuredDimension(widthMeasureSpec, heightMeasureSpec);
    }
}

Now you have this class created, you can use it in your XML just like a normal EditText:

<?xml version="1.0" encoding="utf-8"?>
<HorizontalScrollView xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/horizontalScrollView1"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:background="#ffff0000" >

    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="30dp"
        android:layout_marginRight="5dp"
        android:orientation="horizontal" >

        <com.YOURPACKAGENAME.FullWidthEditText
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:id="@+id/yourEditTextId">
        </com.YOURPACKAGENAME.FullWidthEditText>

        <com.YOURPACKAGENAME.FullWidthEditText
            android:layout_width="wrap_content"
            android:layout_height="match_parent" >
        </com.YOURPACKAGENAME.FullWidthEditText>
        .
        .
        .
    </LinearLayout>
</HorizontalScrollView>

You can also create it programmatically, add handlers, listeners, change text, findViewById ... etc ... just like a normal EditText.

 EditText editText=new EditText(context);
 FullWidthEditText fullWidthEditText=new FullWidthEditText(context);

• Note that this solution works for any other Widget as well. If you need ie. a full-width button, just change extends EditText for extends Button and you got it.

• You can easily customize the size, the key line is: widthMeasureSpec=parentScrollView.getMeasuredWidth(); so you can ie. make full width minus 10 or 20px, make half width, etc.

Hope it helps !