Styling Custom Views

Question

I have a few custom views in my Android project and I've added the relevant details to the attrs.xml file. And now I can implement my objects through XML. This works fine.

How do I style these elements? When I try to use my custom attributes in the styles.xml is get an error "No resource found that matches the given name:"

For using the custom views in normal xml developement I use xmlns:app="http://schemas.android.com/apk/res/bla.bla.bla". What is the correct for use in styles?

This is what my style looks like currently

<style name="Journey_DaySelect_Sunday">
    <item name="app:onImage">@drawable/day_sunday_selected</item>
    <item name="app:offImage">@drawable/day_sunday</item>
</style>

Answer 1

After more intensive searching on Google I gave up finding it answered elsewhere, and by chance tried using the absolute namespace of my generated R file it worked. May this solve all your problems.

USE THE NAMESPACE CONTAINING YOUR R FILE

<style name="Journey_DaySelect_Sunday" parent="Journey_DaySelect">
    <item name="AppZappy.NIRailAndBus:onImage">@drawable/day_sunday_selected</item>
    <item name="AppZappy.NIRailAndBus:offImage">@drawable/day_sunday</item>
</style>

Answer 2

For clarification, the item's name attribute should be the same as what is in the attrs.xml's declare-styleable name attribute + ":" + the attribute name.

For example:

attrs.xml:

<?xml version="1.0" encoding="utf-8"?>
<resources>  
    <declare-styleable name="com.chuck.norris">
        <attr name="actionBarTextColor" format="color"/>
    </declare-styleable> 
</resources>

style.xml:

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <style name="myNewStyle">
        <item name="android:textColor">#FFFF0000</item>
        <item name="com.chuck.norris:actionBarTextColor">#ffff0000</item>
    </style>
</resources>

You can then apply this style to all activities by using a theme in your manifest.xml file. Anywhere that a custom view exists that wants to use the "actionBarTextColor" attribute, you can then use the Java code:

TypedArray typedArray = context.obtainStyledAttributes(attrSet, R.styleable.com_chuck_norris);
COLOR_ACTION_BAR_TEXT = typedArray.getColor(R.styleable.com_chuck_norris_actionBarTextColor, 0xff0000ff);
typedArray.recycle();

I'm not sure why you cannot just define your schema in your style.xml file as was asked above, but it seems to be a limitation of style.xml.