DeferredSurface.kt
/*
* Copyright 2023 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.camera.viewfinder.impl.surface
import android.view.Surface
import androidx.annotation.GuardedBy
import androidx.camera.impl.utils.Logger
import androidx.camera.impl.utils.futures.Futures.nonCancellationPropagating
import androidx.concurrent.futures.CallbackToFutureAdapter
import com.google.common.util.concurrent.ListenableFuture
/** A class for creating and tracking use of a [Surface] in an asynchronous manner. */
abstract class DeferredSurface : AutoCloseable {
private val lock = Any()
private val terminationFuture: ListenableFuture<Void?>
@GuardedBy("mLock") private var closed = false
@GuardedBy("mLock")
private var terminationCompleterInternal: CallbackToFutureAdapter.Completer<Void?>? = null
init {
terminationFuture =
CallbackToFutureAdapter.getFuture {
synchronized(lock) { terminationCompleterInternal = it }
"ViewfinderSurface-termination(" + this@DeferredSurface + ")"
}
}
fun getSurfaceAsync(): ListenableFuture<Surface> {
return provideSurfaceAsync()
}
fun getTerminationFutureAsync(): ListenableFuture<Void?> {
return nonCancellationPropagating(terminationFuture)
}
/**
* Close the surface.
*
* After closing, the underlying surface resources can be safely released by [SurfaceView] or
* [TextureView] implementation.
*/
override fun close() {
var terminationCompleter: CallbackToFutureAdapter.Completer<Void?>? = null
synchronized(lock) {
if (!closed) {
closed = true
terminationCompleter = terminationCompleterInternal
terminationCompleterInternal = null
Logger.d(TAG, "surface closed, closed=true $this")
}
}
if (terminationCompleter != null) {
terminationCompleter!!.set(null)
}
}
protected abstract fun provideSurfaceAsync(): ListenableFuture<Surface>
/**
* The exception that is returned by the ListenableFuture of [getSurfaceAsync] if the deferrable
* surface is unable to produce a [Surface].
*/
class SurfaceUnavailableException(message: String) : Exception(message)
companion object {
private const val TAG = "DeferredSurface"
}
}