如何在viewmodel中将imageview与drawable进行数据绑定？

Question

Binding Adapter:

@BindingAdapter("src")
fun loadImage(imageView: ImageView, src: Any) {

    if (src is Int || src is String || src is Drawable) {
        Glide.with(imageView.context).load(src).into(imageView)
    }
}

Imageview in xml:

<androidx.appcompat.widget.AppCompatImageView
    android:layout_width="200dp"
    android:layout_height="300dp"
    app:src="@{model.image}" />

View model:

val image = MutableLiveData<Drawable>()

init {
    // image.value = How to initialize this?
}

Scenario:
I want to bind imageview with drawable received from server. I want to set a placeholder drawable till the image is obtained from server.

Error for the above code:

java.lang.IllegalArgumentException: Parameter specified as non-null is null: method kotlin.jvm.internal.Intrinsics.checkParameterIsNotNull, parameter src

Note: 1. Please provide a solution which follows MVVM. (No context in viewmodel)

Answer 1

You can set the placeholder in Glide, instead of handling that in your ViewModel . Just the following line should serve your purpose.

Glide.with(imageView.context).load(src).placeholder(R.drawable.placeholder).into(imageView)

See the documentation here .

Answer 2

Extending @Reaz Murshed's idea and after refering Android Binding Adapter Docs , I created a binding adapter for all imageview's. (All imageview's need not have the same placeholder)

Binding Adapter:

@BindingAdapter(value = ["src", "placeholderImage"], requireAll = false)
fun loadImage(imageView: ImageView, src: Int?, placeholderImage: Drawable?) {
    if (placeholderImage != null) {
        Glide.with(imageView.context).load(src).placeholder(placeholderImage).into(imageView)
    } else {
        Glide.with(imageView.context).load(src).into(imageView)
    }
}

@BindingAdapter(value = ["src", "placeholderImage"], requireAll = false)
fun loadImage(imageView: ImageView, src: String?, placeholderImage: Drawable?) {
    if (placeholderImage != null) {
        Glide.with(imageView.context).load(src).placeholder(placeholderImage).into(imageView)
    } else {
        Glide.with(imageView.context).load(src).into(imageView)
    }
}

@BindingAdapter(value = ["src", "placeholderImage"], requireAll = false)
fun loadImage(imageView: ImageView, src: Drawable?, placeholderImage: Drawable?) {
    if (placeholderImage != null) {
        Glide.with(imageView.context).load(src).placeholder(placeholderImage).into(imageView)
    } else {
        Glide.with(imageView.context).load(src).into(imageView)
    }
}

XML:

<androidx.appcompat.widget.AppCompatImageView
    android:layout_width="200dp"
    android:layout_height="300dp"
    app:placeholderImage="@{@drawable/kids_ethnic_1}"
    app:src="@{model.image}" />

If needed we can add other methods to make placeholder of Int or other datatype as required.