How do you repeat an image only vertically in android?

Is there a way to repeat an image only vertically in android? I've tried it like this:

<bitmap xmlns:android="http://schemas.android.com/apk/res/android"
    android:src="@drawable/asphalt_texture"
    android:tileMode="repeat"
    android:dither="true"/>

But it repeats both ways and I only want it repeated vertically, any ideas would be appreciated!