Data Binding with theme attributes

Question

I am trying out the new Android Databinding Library and I wanted to set the background color of ToolBar using a binding. By default the color should be colorPrimary (from the theme).

Before I was using DataBinding, my toolBar looked like

 <android.support.v7.widget.Toolbar         android:id="@+id/mainToolbar"         android:layout_width="match_parent"         android:layout_height="?attr/actionBarSize"         android:background="?attr/colorPrimary"         /> 

After adding a binding, I wanted to set its background to colorPrimary if no color is bound - I'm using ternary operator for this (as mentioned in the guide) - but it causes an error, as theme attributes also have a "?" operator before their names. The compiler thinks I'm starting a new ternary operation.

<data>     <variable name="toolBarBackgroundColor" type="int"/> </data> ... <android.support.v7.widget.Toolbar         android:id="@+id/mainToolbar"         android:layout_width="match_parent"         android:layout_height="?attr/actionBarSize"         android:background="@{toolBarBackgroundColor!=0? toolBarBackgroundColor: ?attr/colorPrimary }"         /> 

So is there a way I can access theme attributes inside a binding operation? Thanks!

Edit

I know I can get the colorPrimary attribute programmatically and bind it through java code. But I'm just wondering if there's an Xml-based solution for this or not.

Answer 1

The answer is a bit late, but maybe it helps someone.

For accessing theme attributes in data binding, you can use this:

(imagine that clickable is Boolean variable)

android:background="@{clickable ? android.R.attr.selectableItemBackground : android.R.color.transparent}" 

No additional binding adapters or another things needed.