Configurator

Ideas behind this library:

breakdown UI logic into small reusable components
let view model construct and control them
allow Activity, Fragment or RecyclerView use them
make them reactive and lifecycle-aware

Building blocks

Configurator is simply an interface:

interface Configurator<T> {
    fun configure(target: T)
    fun reset(target: T)
}

Target T is not constrained: it can be a View, a ViewBinding or anything else depending on your needs.

Reactive Configurator implements RequiresCoroutineScope and defined as abstract CoroutineConfigurator<T> (only Flow is supported atm).

Working with RecyclerView

To use configurator in RecyclerView, first make it an AdapterEntry (or subclass either AdapterBasicConfigurator<T> or AdapterCoroutineConfigurator<T>):

interface AdapterEntry {
    val viewType: Int
    val contentId: Int
    val contentHash: Int
}

where viewType is a unique constant identifiying the view (could be R.layout.id or any other final constant). contentId and contentHash are used by DiffCallback.

Basic configurator for RecyclerView can look like the following:

@GenerateViewHolder
class RowConfigurator(
    override val contentId: Int,
    private val text: String
) : AdapterBasicConfigurator<TextView>() {

    override val viewType: Int = VIEW_TYPE_TEXT
    override val contentHash: Int = text.hashCode()

    override fun onConfigure(target: TextView) {
        target.text = text
    }
}

As you might have noticed, configurator is annotated with GenerateViewHolder annotation.

Generate view holder

Although library provides basic implementation for a RecyclerView.ViewHolder - ConfiguratorViewHolder - it requires to write some boilerplate code to create a viewholder for each configurator. So you can use GenerateViewHolderto generate this boilerplate:

public class RowViewHolder(
  view: TextView
) : ConfiguratorViewHolder<TextView, RowConfigurator>(view, view) {
  public class Factory : BasicViewHolder.Factory {
    public override val viewType: Int = 0 // value of VIEW_TYPE_TEXT

    public override fun create(parent: ViewGroup): BasicViewHolder {
      val view = TextView(parent.context)
      return RowViewHolder(view)
    }
  }
}

Then you register ViewHolder.Factory in adapter and its ready to go:

// view model
val items = listOf(
    RowConfigurator(0, "Row 0"),
    RowConfigurator(1, "Row 1"),
    RowConfigurator(2, "Row 2")
)

// screen
val adapter = RecyclerViewAdapter()
adapter.register(RowViewHolder.Factory())
adapter.reload(viewModel.items)

recyclerView.adapter = adapter

Please see the complete example in the sample app.

Working with ViewGroup

Similarly, it is possible to use configurators to configure child views of some layout. It can be done using ViewGroupAdapter and same GenerateViewHolder annotation, but with a special type:

@GenerateViewHolder(type = ViewHolderType.VIEW_GROUP)
class RowConfigurator

Then tie everything together:

val adapter = LinearLayoutAdapter()
adaper.register(RowViewHolder.Factory())
adapter.reload(viewModel.items)

adapter.attach(linearLayout)

What else

There is built-in support for Paging 3 library.

Artifacts

// core
implementation "com.github.sdelaysam.configurator-android:core:$latest_version"

// adapter for RecyclerView
implementation "com.github.sdelaysam.configurator-android:adapter-recyclerview:$latest_version"

// adapter for ViewGroup
implementation "com.github.sdelaysam.configurator-android:adapter-viewgroup:$latest_version"

// adapter for Paging3
implementation "com.github.sdelaysam.configurator-android:adapter-paging:$latest_version"

// annotation processor (requires 'kotlin-kapt' plugin)
implementation "com.github.sdelaysam.configurator-android:processor:$latest_version"
kapt "com.github.sdelaysam.configurator-android:processor:$latest_version"

License

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

   http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.

sdelaysam / configurator-android