複数のカメラ ストリームを同時に使用する

val session: CameraCaptureSession = ...  // from CameraCaptureSession.StateCallback

// You will use the preview capture template for the combined streams
// because it is optimized for low latency; for high-quality images, use
// TEMPLATE_STILL_CAPTURE, and for a steady frame rate use TEMPLATE_RECORD.
val requestTemplate = CameraDevice.TEMPLATE_PREVIEW
val combinedRequest = session.device.createCaptureRequest(requestTemplate)

// Link the Surface targets with the combined request.
combinedRequest.addTarget(previewSurface)
combinedRequest.addTarget(imReaderSurface)

// In this basic case, the SurfaceView gets updated automatically. ImageReader
// has its own callback that you have to listen to in order to retrieve the
// frames so there is no need to set up a callback for the capture request.
session.setRepeatingRequest(combinedRequest.build(), null, null)
MultipleCameraStreamsSimultaneously.kt

val characteristics: CameraCharacteristics = ...
val supportedFormats = characteristics.get(
    CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP
)?.outputFormats
MultipleCameraStreamsSimultaneously.kt

val characteristics: CameraCharacteristics = ...
val outputFormat: Int = ...  // such as ImageFormat.JPEG
val sizes = characteristics.get(
    CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP
)?.getOutputSizes(outputFormat)
MultipleCameraStreamsSimultaneously.kt

val characteristics: CameraCharacteristics = ...
val targetClass: Class<T> = ...  // such as SurfaceView::class.java
val sizes = characteristics.get(
    CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP
)?.getOutputSizes(targetClass)
MultipleCameraStreamsSimultaneously.kt

fun <T> getMaximumOutputSize(
    characteristics: CameraCharacteristics,
    targetClass: Class<T>,
    format: Int? = null
): Size {
    val config = checkNotNull(
        characteristics.get(CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP)
    )

    // If image format is provided, use it to determine supported sizes; or else use target class.
    val allSizes = if (format == null)
        config.getOutputSizes(targetClass) else config.getOutputSizes(format)
    return allSizes.maxBy { it.height * it.width }
}
MultipleCameraStreamsSimultaneously.kt

/** Helper class used to pre-compute shortest and longest sides of a [Size] */
class SmartSize(width: Int, height: Int) {
    var size = Size(width, height)
    var long = max(size.width, size.height)
    var short = min(size.width, size.height)
    override fun toString() = "SmartSize(${long}x${short})"
}

/** Standard High Definition size for pictures and video */
val SIZE_1080P: SmartSize = SmartSize(1920, 1080)

/** Returns a [SmartSize] object for the given [Display] */
fun getDisplaySmartSize(display: Display): SmartSize {
    val outPoint = Point()
    display.getRealSize(outPoint)
    return SmartSize(outPoint.x, outPoint.y)
}

/**
 * Returns the largest available PREVIEW size. For more information, see:
 * https://d.android.com/reference/android/hardware/camera2/CameraDevice
 */
fun<T> getPreviewOutputSize(
        display: Display,
        characteristics: CameraCharacteristics,
        targetClass: Class<T>,
        format: Int? = null
): Size {

    // Find which is smaller: screen or 1080p
    val screenSize = getDisplaySmartSize(display)
    val hdScreen = screenSize.long >= SIZE_1080P.long || screenSize.short >= SIZE_1080P.short
    val maxSize = if (hdScreen) SIZE_1080P else screenSize

    // If image format is provided, use it to determine supported sizes; else use target class
    val config = characteristics.get(
            CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP)!!
    if (format == null)
        assert(StreamConfigurationMap.isOutputSupportedFor(targetClass))
    else
        assert(config.isOutputSupportedFor(format))
    val allSizes = if (format == null)
        config.getOutputSizes(targetClass) else config.getOutputSizes(format)

    // Get available sizes and sort them by area from largest to smallest
    val validSizes = allSizes
            .sortedWith(compareBy { it.height * it.width })
            .map { SmartSize(it.width, it.height) }.reversed()

    // Then, get the largest output size that is smaller or equal than our max size
    return validSizes.first { it.long <= maxSize.long && it.short <= maxSize.short }.size
}

val characteristics: CameraCharacteristics = ...

// Hardware level will be one of:
// - CameraCharacteristics.INFO_SUPPORTED_HARDWARE_LEVEL_LEGACY,
// - CameraCharacteristics.INFO_SUPPORTED_HARDWARE_LEVEL_EXTERNAL,
// - CameraCharacteristics.INFO_SUPPORTED_HARDWARE_LEVEL_LIMITED,
// - CameraCharacteristics.INFO_SUPPORTED_HARDWARE_LEVEL_FULL,
// - CameraCharacteristics.INFO_SUPPORTED_HARDWARE_LEVEL_3
val hardwareLevel = characteristics.get(
    CameraCharacteristics.INFO_SUPPORTED_HARDWARE_LEVEL
)
MultipleCameraStreamsSimultaneously.kt

val characteristics: CameraCharacteristics = ...
val context = this as Context // assuming you are inside of an activity

val surfaceViewSize = getPreviewOutputSize(
    context, characteristics, SurfaceView::class.java
)
val imageReaderSize = getPreviewOutputSize(
    context, characteristics, ImageReader::class.java, format = ImageFormat.YUV_420_888
)
MultipleCameraStreamsSimultaneously.kt

val surfaceView = findViewById<SurfaceView>(...)
surfaceView.holder.addCallback(object : SurfaceHolder.Callback {
    override fun surfaceCreated(holder: SurfaceHolder) {
        // You do not need to specify image format, and it will be considered of type PRIV.
        // Surface is now ready and you could use it as an output target for CameraSession.
    }
    // ...
})
MultipleCameraStreamsSimultaneously.kt

val frameBufferCount = 3 // just an example, depends on your usage of ImageReader
val imageReader = ImageReader.newInstance(
    imageReaderSize.width, imageReaderSize.height, ImageFormat.YUV_420_888,
    frameBufferCount
)
MultipleCameraStreamsSimultaneously.kt

imageReader.setOnImageAvailableListener({
    val frame = it.acquireNextImage()
    // Do something with "frame" here.
    it.close()
}, null)
MultipleCameraStreamsSimultaneously.kt