DataBinding / ViewBinding

Setup

Add the katalog-androidview package.

dependencies {
    implementation("com.moriatsushi.katalog:katalog:`LATEST_VERSION`")
    implementation("com.moriatsushi.katalog:katalog-androidview:`LATEST_VERSION`")
}

Examples

To add a DataBinding / ViewBinding, use the binding method. Pass an inflate method reference to the factory parameter. If you omit the name, the Binding class name will be used.

res/layout/sample.xml

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

    <TextView
        android:layout_gravity="center"
        android:text="Hello, World"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

</FrameLayout>

binding(
    factory = SampleBinding::inflate,
    name = "Binding Sample"
)

By default, wrap_content is used for both width and height. You can change the size of the View by setting the layoutParams.

res/layout/sample.xml

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:background="#FF0000"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <TextView
        android:layout_gravity="center"
        android:text="Hello, World"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />
</FrameLayout>

binding(
    factory = SampleBinding::inflate,
    name = "Binding Sample",
    layoutParams = MATCH_WIDTH_WRAP_HEIGHT
)

The following four options are available.

• WARP_WIDTH_WRAP_HEIGHT - It is default.
• MATCH_WIDTH_WRAP_HEIGHT
• WRAP_WIDTH_WRAP_HEIGHT
• MATCH_WIDTH_MATCH_HEIGHT

You can also specify a number directly. Note that the value is in pixels.

res/layout/sample.xml

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:background="#FF0000"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <TextView
        android:layout_gravity="center"
        android:text="Hello, World"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />
</FrameLayout>

binding(
    factory = SampleBinding::inflate,
    name = "Binding Sample",
    layoutParams = ViewGroup.LayoutParams(600, 300)
)

The Binding parameters can be set in the lambda expression.

res/layout/sample.xml

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

    <data>

        <variable
            name="text"
            type="String" />
    </data>

    <FrameLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <TextView
            android:layout_gravity="center"
            android:text="@{text}"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" />
    </FrameLayout>
</layout>

binding(
    factory = SampleBinding::inflate,
    name = "Binding Sample"
) { binding ->
    binding.text = "Hello, World"
}

It is also possible to use LiveData and StateFlow in DataBinding. Don't forget to pass the LifecycleOwner to the Binding class.

SampleViewModel.kt

class SampleViewModel {
    private val _count = MutableLiveData(0)
    val count: LiveData<Int> = _count

    fun handleClick() {
        _count.value = (_count.value!! + 1) % 10
    }
}

res/layout/sample.xml

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

    <data>

        <variable
            name="viewModel"
            type="com.moriatsushi.katalog.android_sample.SampleViewModel" />
    </data>

    <FrameLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <TextView
            android:onClick="@{() -> viewModel.handleClick()}"
            android:layout_gravity="center"
            android:text="@{viewModel.count.toString()}"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" />
    </FrameLayout>
</layout>

binding(
    factory = SampleBinding::inflate,
    name = "Counter"
) { binding ->
    binding.viewModel = SampleViewModel()
    binding.lifecycleOwner = lifecycleOwner
}

Parameters

name	description
factory	Passes a reference to the Binding's inflation method.
name	The UI Component name. If you omit this, the Binding class name will be used.
layoutParams	Specifies the size of the View. By default, wrap_content is used for both width and height.
update	Set the Binding parameters. Inside the lambda expression, you can access activity, context, and lifecycleOwner. This is optional.