Android - flip image in xml

I want to flip image for button's background in xml. I've seen example how to do it, but it was programmatically way: http://xjaphx.wordpress.com/2011/06/26/image-processing-image-flipping-mirroring. Anyway, I have a xml file (button_left_state.xml) like below :

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">  
<item android:state_pressed="true" >
    <rotate android:fromDegrees="180.0" android:toDegrees="180.0" 
    android:pivotX="50%" android:pivotY="50%" android:drawable="@drawable/buttonrightpressed" />    
</item>    

<item>
  <rotate android:fromDegrees="180.0" android:toDegrees="0.0" 
    android:pivotX="50%" android:pivotY="50%" android:drawable="@drawable/buttonright"/>
</item>   
</selector>

But this code just rotate image to 180 degrees. Is it possible to flip image in xml?

Use the scale attributes in ImageView

android:scaleX="-1" //To flip horizontally or
android:scaleY="-1" //To flip vertically

Here's a very short and easy to understand solution.

Add this to the imageView:

 android:rotationX="180"

This will flip the imageView horizontally (left<->right).

For vertically, put this:

android:rotationY="180"

Example:

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:gravity="center"
    android:orientation="vertical" >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="original image:"/>

    <ImageView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@drawable/test"/>

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="flip horizontally :"/>

    <ImageView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:rotationY="180"
        android:src="@drawable/test"/>

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="flip vertically:"/>

    <ImageView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:rotationX="180"
        android:src="@drawable/test"/>

</LinearLayout>

And the result (image taken from a JNI library that I've made, that can do it via JNI) :