How to center layout inside of Android Dialog?

Question

I am trying to create a custom Dialog, and have its content centered, but it is always ending up left-aligned. Here is aboutdialog.xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
  xmlns:a="http://schemas.android.com/apk/res/android"
  a:orientation="vertical"
  a:id="@+id/AboutDialogLayout" 
  a:layout_width="fill_parent" 
  a:layout_height="fill_parent" 
  a:layout_gravity="center_horizontal" 
  a:gravity="center_horizontal">

    <ImageView a:id="@+id/imageView1" 
               a:src="@drawable/pricebook" 
               a:layout_height="wrap_content" 
               a:layout_width="wrap_content"/>
    <TextView a:layout_height="wrap_content"         
              a:textAppearance="?android:attr/textAppearanceLarge" 
              a:id="@+id/textView1" 
              a:text="Price Book" 
              a:layout_width="wrap_content"/>
    <TextView a:layout_height="wrap_content" 
              a:id="@+id/textView2" 
              a:layout_width="wrap_content" 
              a:text="foo"/>
</LinearLayout>

And my (relevant) code:

Dialog d = new Dialog(this);
d.setContentView(R.layout.aboutdialog);
d.setTitle(R.string.app_name);

What am I missing here? Thanks for the assistance.

Image:

Answer 1

try to edit to this: a:layout_gravity="center_horizontal|center_vertical"
OR
use Relative_Layout and align linear layout to center of parent with fill_parent for Relative wrap_content for Linear.

although it is worked with me on center