CreateCaptureSession.kt

/**
* Begin a still image capture
*/

fun takePicture() {
        if (cameraDevice ==
                null) {
            Log.w(TAG, "Cannot capture image. Camera not initialized.")
            return
        }
        // Here, we create a CameraCaptureSession for capturing still images.
        try {
            cameraDevice.createCaptureSession(
                    listOf<Surface>(imageReader.getSurface()),
                    sessionCallback, null)
        } catch (cae: CameraAccessException) {
            Log.d(TAG, "access exception while preparing pic", cae)
        }
}

/**
 * Callback handling session state changes
 */
 
private val sessionCallback = object : CameraCaptureSession.StateCallback() {
        override fun onConfigured(cameraCaptureSession: CameraCaptureSession) {
            // The camera is already closed
            if (cameraDevice == null) {
                return
            }
            // When the session is ready, we start capture.
            captureSession = cameraCaptureSession
            triggerImageCapture()
        }

        override fun onConfigureFailed(cameraCaptureSession: CameraCaptureSession) {
            Log.w(TAG, "Failed to configure camera")
        }
    }