Android Theme drawable doesn't work with Color Drawable (Bug?)

Question

So I'm trying to make a selector that uses a theme-based color as its background. Following the instructions from this SO answer, I first define my color drawable in res/values/colors.xml:

<color name="selected">#FFF7C9</color>

Then I define an attribute in res/values/attrs.xml:

<attr name="drawable_selected" format="reference" />

and then in my theme, I set attribute to my color drawable (res/values/styles.xml):

<style name="AppThemeWhite" parent="AppTheme">
    <item name="drawable_selected">@color/selected</item>
</style>

finally, I reference the attribute in my selector (res/drawable/selected_background):

<selector>
    <item android:state_activated="true" android:drawable="?drawable_selected" />
    <item android:drawable="@android:color/transparent" />
</selector>

When I run this, I get an error Binary XML file line #2: Error inflating class <unknown> when trying to inflate the class that uses the selector. However, when I change the selector's state_activated to reference the drawable directly using android:drawable="@color/selected", it works.

Is this a bug, or am I doing something wrong?

EDIT

If I add a color attribute (res/values/attrs.xml)

<attr name="selected_color" format="color" />

and define the color in my theme (res/values/styles.xml)

<item name="selected_color">#FFF7C9</item>

I can change the color drawable to change based on them (res/values/colors.xml)

<color name="selected">?selected_color</color>

and reference the drawable directly using android:drawable="@color/selected in my selector. However, this causes a crash as well! And changing the color drawable back to a hardcoded value of #FFF7C9 fixes it. It seems this whole theming system is pretty broken...

Answer 1

Reason

Yeah, referencing custom theme attributes from drawable (or colors) doesn't work on Android currently.

Here you can see more details about the issue that was reported long time ago: https://code.google.com/p/android/issues/detail?id=26251

As you can see they have finally resolved it in Android L release, but anywhere lower than L such referencing will fail.

Solution

To work around this issue you need to do something like that:

<selector>
    <item android:state_activated="true" android:drawable="@color/selected" />
    <item android:drawable="@android:color/transparent" />
</selector>

where @color/selected is defined as at the beginning of your post:

<color name="selected">#FFF7C9</color>