Set default colors to Android library

Question

So I have an Android library that I want others to be able to easily customize its color when using it. The problem is that the color is not just a single property (like the view background), but it's more like a theme color (the view background, the text color, the stroke for the button, etc...) so I'm not able to just pass it as a view attribute. So I ended up using a color reference and use it in styles, layout and drawables:

colors.xml:

<resources>
    <attr name="color" format="reference" />
</resources>

layout.xml:

<LinearLayout
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="?attr/color">
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textColor="?attr/color"/>
    <android.support.design.widget.TextInputLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:theme="@style/LibraryTheme.TextAppearance"/>
</LinearLayout>

styles.xml in library project:

<style name="LibraryTheme.TextAppearance">
    <item name="android:textColor">?attr/color</item>
    <item name="colorControlNormal">?attr/color</item>
    <item name="android:textColorHint">?attr/color</item>
    <item name="colorControlActivated">?attr/color</item>
    <item name="colorControlHighlight">?attr/color</item>
</style>

That works great, and when someone is using my lib he must declare the color he wants you use in his theme:

styles.xml in app project:

<style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
    <item name="color">@color/my_color</item>
</style>

The problem is this: I want to deliver this library with a default color scheme. It can be performed now with 2 options:

1. Declare my own theme with the default color sets and the user will need to inherit his theme from mine.
2. Put some default_color in my color.xml so that the user will be able to use that as the color in his theme.

The first one is really bad, because I can't force the user to use specific app theme (like AppCompact.Light). The second one is not that great either, because I want the user to be able to use the default seamlessly and I have a couple of colors in the theme that he needs to set.

Is there any other way that you think I will be able to let other users play with the colors easily?

Thanks.

Answer 1

The problem is that you are using a color reference, in your case I would use a regular color property- those can be overridden by the user in colors.xml.

So in you library project:

colors.xml:

<resources>
    <color name="color">#FFFFFF</color>
</resources>

layout.xml:

<LinearLayout
            android:orientation="vertical"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:background="@color/color">
            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:textColor="@color/color"/>
            <android.support.design.widget.TextInputLayout
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                app:theme="@style/LibraryTheme.TextAppearance"/>
</LinearLayout>

styles.xml:

<style name="LibraryTheme.TextAppearance">
    <item name="android:textColor">@color/color</item>
    <item name="colorControlNormal">@color/color</item>
    <item name="android:textColorHint">@color/color</item>
    <item name="colorControlActivated">@color/color</item>
    <item name="colorControlHighlight">@color/color</item>
</style>

And if the user wants to use different colors, he can declare his own color in his app's colors.xml:

<resources>
    <color name="color">#000000</color>
</resources>

Answer 2

I am not sure If I get the point correctly but I guess you have the following option:

Declare in your Strings.xml file something like this:

<!-- Colors-->
    <color name="color1">#55000000</color>
    <color name="color2">#FFFFFF</color>
    <color name="color3">#000000</color>

And then customize your template objects passing this reference. If the user wants to change all the app colors, he needs just to set new values in String.xml

  <TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:textColor="@color/color1"/>

Answer 3

I'd stick to option 1. As a theme is only a collection of attributes, I don't see how you "force" the user to inherit your theme - he only needs to supply the list of attributes, plus he has something working to start with...