Como repetir a imagem de plano de fundo de um aplicativo

Eu defini uma imagem de plano de fundo no meu aplicativo, mas a imagem de plano de fundo é pequena e quero que seja repetida e preencha a tela inteira. O que devo fazer?

<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:background="@drawable/bg"
    android:tileMode="repeat">

Ok, aqui está o que eu tenho no meu aplicativo. Ele inclui um hack para impedir que ListViews fiquem pretos durante a rolagem.

drawable / app_background.xml :

<?xml version="1.0" encoding="utf-8"?>
    <bitmap xmlns:android="http://schemas.android.com/apk/res/android"
        android:src="@drawable/actual_pattern_image"
        android:tileMode="repeat" />

values ​​/ styles.xml :

<?xml version="1.0" encoding="utf-8"?>
<resources>

  <style name="app_theme" parent="android:Theme">
    <item name="android:windowBackground">@drawable/app_background</item>
    <item name="android:listViewStyle">@style/TransparentListView</item>
    <item name="android:expandableListViewStyle">@style/TransparentExpandableListView</item>
  </style>

  <style name="TransparentListView" parent="@android:style/Widget.ListView">
    <item name="android:cacheColorHint">@android:color/transparent</item>
  </style>

  <style name="TransparentExpandableListView" parent="@android:style/Widget.ExpandableListView">
    <item name="android:cacheColorHint">@android:color/transparent</item>
  </style>

</resources>

AndroidManifest.xml :

//
<application android:theme="@style/app_theme">
//

Existe uma propriedade no xml drawable para fazer isso. android: tileMode = "repeat"

Consulte este site: http://androidforbeginners.blogspot.com/2010/06/how-to-tile-background-image-in-android.html

Aqui está uma implementação em java pura da repetição da imagem de plano de fundo:

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    Bitmap bmp = BitmapFactory.decodeResource(getResources(), R.drawable.bg_image);
    BitmapDrawable bitmapDrawable = new BitmapDrawable(bmp);
    bitmapDrawable.setTileModeXY(Shader.TileMode.REPEAT, Shader.TileMode.REPEAT);
    LinearLayout layout = new LinearLayout(this);
    layout.setBackgroundDrawable(bitmapDrawable);
}

Nesse caso, nossa imagem de plano de fundo teria que ser armazenada em res / drawable / bg_image.png.

Expandindo a resposta do plowman, aqui está a versão não preterida da alteração da imagem de plano de fundo com java.

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    Bitmap bmp = BitmapFactory.decodeResource(getResources(),
            R.drawable.texture);
    BitmapDrawable bitmapDrawable = new BitmapDrawable(getResources(),bmp);
    bitmapDrawable.setTileModeXY(Shader.TileMode.REPEAT,
            Shader.TileMode.REPEAT);
    setBackground(bitmapDrawable);
}

// Prepared By Muhammad Mubashir.
// 26, August, 2011.
// Chnage Back Ground Image of Activity.

package com.ChangeBg_01;

import com.ChangeBg_01.R;

import android.R.color;
import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.view.View;
import android.widget.ImageView;
import android.widget.TextView;

public class ChangeBg_01Activity extends Activity
{
    TextView tv;
    int[] arr = new int[2];
    int i=0;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        tv = (TextView)findViewById(R.id.tv);
        arr[0] = R.drawable.icon1;
        arr[1] = R.drawable.icon;

     // Load a background for the current screen from a drawable resource
        //getWindow().setBackgroundDrawableResource(R.drawable.icon1) ;

        final Handler handler=new Handler();
        final Runnable r = new Runnable()
        {
            public void run() 
            {
                //tv.append("Hello World");
                if(i== 2){
                    i=0;            
                }

                getWindow().setBackgroundDrawableResource(arr[i]);
                handler.postDelayed(this, 1000);
                i++;
            }
        };

        handler.postDelayed(r, 1000);
        Thread thread = new Thread()
        {
            @Override
            public void run() {
                try {
                    while(true) 
                    {
                        if(i== 2){
                            //finish();
                            i=0;
                        }
                        sleep(1000);
                        handler.post(r);
                        //i++;
                    }
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        };


    }
}

/*android:background="#FFFFFF"*/
/*
ImageView imageView = (ImageView) findViewById(R.layout.main);
imageView.setImageResource(R.drawable.icon);*/

// Now get a handle to any View contained 
// within the main layout you are using
/*        View someView = (View)findViewById(R.layout.main);

// Find the root view
View root = someView.getRootView();*/

// Set the color
/*root.setBackgroundColor(color.darker_gray);*/