Data binding: How pass Context in xml to method?

Question

Android Studio 3.0.

Here my custom method:

public static int getTileWidthDpInScreen(Context context) {
    // some code here
    return tileWidthDp;
}

here my xml file with data binding code :

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools">

    <data>

        <import type="com.myproject.android.customer.util.GUIUtil" />

    </data>

    <android.support.constraint.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <ImageView
            android:id="@+id/imageViewPhoto"
            android:layout_width="@{GUIUtil.getTileWidthDpInScreen()}"
            android:layout_height="@dimen/preview_image_height"
            android:scaleType="centerCrop"
            app:layout_constraintLeft_toLeftOf="parent"
            app:layout_constraintRight_toRightOf="parent"
            app:layout_constraintTop_toTopOf="parent" />       


    </android.support.constraint.ConstraintLayout>

</layout>

And as result I get error:

e: java.lang.IllegalStateException: failed to analyze: android.databinding.tool.util.LoggedErrorException: Found data binding errors.
data binding error msg:cannot find method getTileWidthDpInScreen() in class com.myproject.android.customer.util.GUIUtil

This error because I'm not pass context in method getTileWidthDpInScreen().

How I get context in xml and pass it in method: getTileWidthDpInScreen()?

Answer 1

The Android documentation say :

A special variable named context is generated for use in binding expressions as needed. The value for context is the Context object from the root View's getContext() method. The context variable is overridden by an explicit variable declaration with that name.

So the solution is : android:layout_width="@{GUIUtil.getTileWidthDpInScreen(context)}

Answer 2

You just have to import <import type="android.content.Context" /> in your xml data imports.

Then, you can access context for your databinding simply with context.

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android">

    <data>
        <import type="android.content.Context" />

        <import type="com.myproject.android.customer.util.GUIUtil" />
    </data>

    <androidx.constraintlayout.widget.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <ImageView
            android:id="@+id/imageViewPhoto"
            android:layout_width="@{GUIUtil.getTileWidthDpInScreen(context)}"
            android:layout_height="@dimen/preview_image_height"
            android:scaleType="centerCrop"
            app:layout_constraintLeft_toLeftOf="parent"
            app:layout_constraintRight_toRightOf="parent"
            app:layout_constraintTop_toTopOf="parent" />

    </androidx.constraintlayout.widget.ConstraintLayout>
</layout>