AndroidViewBinding.kt
/*
* Copyright 2020 The Android Open Source Project
*
* 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.
*/
package androidx.compose.ui.viewinterop
import android.content.Context
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.compose.runtime.Composable
import androidx.compose.runtime.currentComposer
import androidx.compose.runtime.emit
import androidx.compose.ui.Modifier
import androidx.compose.ui.materialize
import androidx.compose.ui.node.UiApplier
import androidx.compose.ui.platform.ContextAmbient
import androidx.compose.ui.platform.DensityAmbient
import androidx.viewbinding.ViewBinding
/**
* Composes an Android layout resource in the presence of [ViewBinding]. The binding is obtained
* from the [bindingBlock] block, which will be called exactly once to obtain the [ViewBinding]
* to be composed, and it is also guaranteed to be invoked on the UI thread.
* Therefore, in addition to creating the [ViewBinding], the block can also be used
* to perform one-off initializations and [View] constant properties' setting.
* The [update] block can be run multiple times (on the UI thread as well) due to recomposition,
* and it is the right place to set [View] properties depending on state. When state changes,
* the block will be reexecuted to set the new properties. Note the block will also be ran once
* right after the [bindingBlock] block completes.
*
* @sample androidx.compose.ui.samples.AndroidViewBindingSample
*
* @param bindingBlock The block creating the [ViewBinding] to be composed.
* @param modifier The modifier to be applied to the layout.
* @param update The callback to be invoked after the layout is inflated.
*/
@Composable
fun <T : ViewBinding> AndroidViewBinding(
bindingBlock: (LayoutInflater, ViewGroup, Boolean) -> T,
modifier: Modifier = Modifier,
update: T.() -> Unit = {}
) {
val context = ContextAmbient.current
val materialized = currentComposer.materialize(modifier)
emit<ViewBindingHolder<T>, UiApplier>(
ctor = { ViewBindingHolder(context) },
update = {
set(Unit) { this.bindingBlock = bindingBlock }
set(materialized) { this.modifier = it }
set(DensityAmbient.current) { this.density = it }
set(update) { this.updateBlock = it }
}
)
}
@OptIn(InternalInteropApi::class)
internal class ViewBindingHolder<T : ViewBinding>(
context: Context
) : AndroidViewHolder(context) {
private var viewBinding: T? = null
set(value) {
field = value
if (value != null) {
view = value.root
}
}
internal var bindingBlock: ((LayoutInflater, ViewGroup, Boolean) -> T)? = null
set(value) {
field = value
if (value != null) {
val layoutParamsParent = (parent as? ViewGroup) ?: this
viewBinding = value(LayoutInflater.from(context), layoutParamsParent, false)
}
}
internal var updateBlock: (T) -> Unit = {}
set(value) {
field = value
update = { viewBinding?.apply(updateBlock) }
}
}