How to Reference Style Attributes from a Drawable

How to reference style attributes from a drawable?

In my experience it is not possible to reference an attribute in an XML drawable.

In order to make your theme you need to:

• Create one XML drawable per theme.

• Include the needed color into you drawable directly with the @color tag or #RGB format.

  
  
  

Make an attribute for your drawable in attrs.xml.

<?xml version="1.0" encoding="utf-8"?>
<resources>
   <!-- Attributes must be lowercase as we want to use them for drawables -->
   <attr name="my_drawable" format="reference" />
</resources>

Add your drawable to your theme.xml.

<style name="MyTheme" parent="@android:style/Theme.NoTitleBar">
   <item name="my_drawable">@drawable/my_drawable</item>
</style>

Reference your drawable in your layout using your attribute.

<TextView android:background="?my_drawable" />

Use of attr reference in selector StateListDrawable

LayerDrawable flexibility on the use of either a ?attr or a drawable can be misleading. If you use the ?attr, it will try to set a custom theme attribute, but if you use a regular resource it will try to load a drawable entirely. Quoting from the LayerDrawable docs :

May be a reference to another resource, in the form "@[+][package:]type/name" or a theme attribute in the form "?[package:]type/name".

StateListDrawables only expect drawables to be references as such:

@[package:]drawable/filename

Notice how ?attr or type is omitted.

Reference : https://developer.android.com/guide/topics/resources/drawable-resource

How to reference colour attribute in drawable?

You might need to do the following to fix your problem:

1) Define 2 colors for each theme in your colors file:

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <color name="my_color_dark">#ff33B5E5</color>
    <color name="my_color_light">#ff355689</color>
</resources>

2) Create file res/values/attrs.xml with contents:

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <attr name="my_color" format="reference" />
</resources>

3) Assuming you have 2 themes in your styles.xml (Theme.dark and Theme.light) define:

<style name="Theme.dark" parent="@style/Theme.Sherlock">
    <item name="my_color">@color/my_color_dark</item>
</style>

<style name="Theme.light" parent="@style/Theme.Sherlock.Light">
    <item name="my_color">@color/my_color_light</item>
</style>

4) Use the color in a drawable:

<color android:color="?attr/my_color"/>

Hope this should fix your problem.

Unable to reference a color attribute in a drawable

res\values\attrs.xml

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

res\values\styles.xml

<style name="AppTheme.Dark" parent="android:Theme.Holo.Light.DarkActionBar">
    <item name="holo_blue_dark">@color/your_color</item>
</style>

res\values\colors.xml

<color name="your_color">#FF33B5E5</color>

And make sure you are using the theme AppTheme.Dark where you are using that attribute.

Drawable resource from custom attribute

See EdgarK's answer; it's better. (I can't delete this since it's the accepted answer)

Does this answer your question?

"You can use format="integer", the resource id of the drawable, and AttributeSet.getDrawable(...)."

(From https://stackoverflow.com/a/6108156/413254)

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