android - How to center vector drawable in layer-list without scaling

Question

I am attempting to use a VectorDrawable in a LayerList without scaling the vector. For example:

<layer-list>
    <item android:drawable="@color/grid_item_activated"/>
    <item android:gravity="center" android:drawable="@drawable/ic_check_white_48dp"/>
</layer-list>

The drawable ic_check_white_48dp id defined as:

<vector xmlns:android="http://schemas.android.com/apk/res/android"
        android:width="48dp"
        android:height="48dp"
        android:viewportWidth="24.0"
        android:viewportHeight="24.0">
    <path
        android:fillColor="#FFFFFFFF"
        android:pathData="M9,16.17L4.83,12l-1.42,1.41L9,19 21,7l-1.41,-1.41z"/>
</vector>

The desired effect is for the check icon to be centered in the layer drawable, without scaling. The issue is, the layer-list above causes the check icon to be scaled to fit the layer size.

I can produce the desired effect if I replace the vector drawable with PNGs for each density and modify the layer-list as such:

<layer-list>
    <item android:drawable="@color/grid_item_activated"/>
    <item>
        <bitmap android:gravity="center" android:src="@drawable/ic_check_white_48dp"/>
    </item>
</layer-list>

Is there any way I can do this using a VectorDrawable?

Answer 1

I ran into the same problem trying to center vectors drawables on a layered list.

I have a workaround, its not exactly the same but it works, you need to set a size for the entire drawable and add padding to the vector item:

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
    <item>
        <shape>
            <size android:height="120dp" android:width="120dp"/>
            <solid android:color="@color/grid_item_activated"/>
        </shape>
    </item>
    <item android:top="24dp"
          android:bottom="24dp"
          android:left="24dp"
          android:right="24dp"
          android:drawable="@drawable/ic_check_white_48dp"/>
</layer-list>

The size of the shape above sets the size of the entire drawable, 120dp in this example, the padding on the second item, 24dp in this example, centers the vector image.

Its not the same as using the gravity="center" but its working way of using vectors in API 21 and 22.