Inline Complex XML Resources

Certain resource types are a composition of multiple complex resources represented by XML files. One example is an animated vector drawable, which is a drawable resource encapsulating a vector drawable and an animation. This requires the use of at least three XML files.

res/drawable/avd.xml

<?xml version="1.0" encoding="utf-8"?>
<animated-vector xmlns:android="http://schemas.android.com/apk/res/android"
    android:drawable="@drawable/vectordrawable" >
    <target
        android:name="rotationGroup"
        android:animation="@anim/rotation" />
</animated-vector>

res/drawable/vectordrawable.xml

<?xml version="1.0" encoding="utf-8"?>
<vector xmlns:android="http://schemas.android.com/apk/res/android"
    android:height="64dp"
    android:width="64dp"
    android:viewportHeight="600"
    android:viewportWidth="600" >

   <group
        android:name="rotationGroup"
        android:pivotX="300.0"
        android:pivotY="300.0"
        android:rotation="45.0" >
        <path
            android:fillColor="#000000"
            android:pathData="M300,70 l 0,-70 70,70 0,0 -70,70z" />

   </group>
</vector>

res/anim/rotation.xml

<?xml version="1.0" encoding="utf-8"?>
<objectAnimator xmlns:android="http://schemas.android.com/apk/android"
    android:duration="6000"
    android:propertyName="rotation"
    android:valueFrom="0"

   android:valueTo="360" />

There are a lot of files here just to make a single animated vector drawable! If the vector drawable and animations are re-used elsewhere, this is the best way to implement an animated vector drawable. If they’re only ever used for this animated vector drawable, then there is a more compact way to implement them.

Using AAPT’s inline resource format, you can define all three resources in the same XML file. Since we’re making an animated vector drawable, we put the file under res/drawable/.

res/drawable/avd.xml

<?xml version="1.0" encoding="utf-8"?>
<animated-vector xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:aapt="http://schemas.android.com/aapt" >

    <aapt:attr name="android:drawable" >
        <vector
            android:height="64dp"
            android:width="64dp"
            android:viewportHeight="600"
            android:viewportWidth="600" >

           <group
                android:name="rotationGroup"
                android:pivotX="300.0"
                android:pivotY="300.0"
                android:rotation="45.0" >
                <path
                    android:fillColor="#000000"
                    android:pathData="M300,70 l 0,-70 70,70 0,0 -70,70z" />

           </group>
        </vector>
    <aapt:attr />

    <target android:name="rotationGroup">
        <aapt:attr name="android:animation" >
            <objectAnimator
                android:duration="6000"
                android:propertyName="rotation"
                android:valueFrom="0"

               android:valueTo="360" />
        <aapt:attr>
    </target>
</animated-vector>

The XML tag <aapt:attr > tells AAPT that the tag’s child shall be treated as a resource and extracted into its own resource file. The value in the attribute name specifies where to use the inline resource within the parent tag.

AAPT will generate resource files and names for all of the inline resources. Applications built using this inline format are compatible with all versions of Android.