How can I use my custom image view with DataBinding in Android?

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android android-custom-view android-databinding android-jetpack kotlin

How can I use my custom image view with DataBinding in Android?

发布于 2020-04-20 10:51:06

So I checked this codelab by Google for creating a custom view RatioImageView in Android. It simply extends the ImageView and overrides the OnMeasure() method according to device's viewport's aspect ratio. The code for the same is:

class RatioImageView @JvmOverloads constructor(
    context: Context,
    attrs: AttributeSet? = null,
    defStyleAttr: Int = 0
): ImageView(context, attrs, defStyleAttr) {

    private val VP_HEIGHT = Resources.getSystem().displayMetrics.heightPixels
    private val VP_WIDTH = Resources.getSystem().displayMetrics.widthPixels
    private val HWR: Float = VP_HEIGHT.toFloat()/VP_WIDTH.toFloat() //height to width ratio


    override fun onMeasure(widthMeasureSpec: Int, heightMeasureSpec: Int) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec)
        setMeasuredDimension(MeasureSpec.getSize(widthMeasureSpec),(MeasureSpec.getSize(widthMeasureSpec)*HWR).toInt())
    }
}

Then I am using this in ListItem view as:

<?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">

    <data>

    </data>

    <androidx.constraintlayout.widget.ConstraintLayout
        android:orientation="vertical"
        android:layout_width="match_parent"
        android:layout_height="0dp">

        <com.example.myapp.RatioImageView
            android:id="@+id/target"
            android:layout_width="match_parent"
            android:layout_height="0dp"
            android:contentDescription="image holder"
            android:scaleType="centerCrop"
            android:background="#757575"
            app:layout_constraintTop_toTopOf="parent"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintDimensionRatio="9:16" />

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

Then in the Adapter, I am using DataBinding to update the views with content as follows:

override fun onBindViewHolder(holder: HomeItemHolder, position: Int) {
        holder.binding.apply {

              //loadImage() is an extension function added to ImageView class
              target.loadImage(UiUtil.getCustomUrl(photos[position].urls.fullImage, height, width))
       
            root.setOnClickListener {
                handleClick(position)
            }
        }
}

During building, it shows the following error:

Cannot access class 'RatioImageView'. Check your module classpath for missing or conflicting dependencies

i.e. for the line in which target.loadImage(...) is written in OnBindViewHolder()

Also, if I don't use DataBinding for the root layout, then it works fine.

So the question is what needs to be added to RatioImageView? To make it work with DataBinding, considering that here I don't require an XML layout to be associated with the View class.

Here's the onCreateViewHolder()

override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): HomeItemHolder {
        return HomeItemHolder(ItemPhotoListLayoutBinding.inflate(LayoutInflater.from(parent.context)))
    }

And below is the ViewHolder class:

inner class HomeItemHolder (val binding: ItemPhotoListLayoutBinding):
        RecyclerView.ViewHolder(binding.root) {
    }

Also here is the repo in case my code is missing something over here: https://github.com/prafullmishra/CustomImageView

Questioner

Lincoln

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How can I use my custom image view with DataBinding in Android?

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