camera2でライト ON / OFF

地味にハマったシリーズ。。。

CONTROL_AE_MODE と FLASH_MODE をセットしてあげる必要がある。
あと最後に capture を呼ぶのを忘れずに！！

HogeCamera.kt

    fun updateFlash(isFlash: Boolean) {
        // previewRequestBuilder → CaptureRequest.Builder
        // previewRequest        → CaptureRequest
        // captureSession        → CameraCaptureSession
        // captureCallback       → CameraCaptureSession.CaptureCallback
        // backgroundHandler    → Handler
        previewRequestBuilder.set(CaptureRequest.CONTROL_AE_MODE, CaptureRequest.CONTROL_AE_MODE_ON)
        if (isFlash) {
            previewRequestBuilder.set(CaptureRequest.FLASH_MODE, CaptureRequest.FLASH_MODE_TORCH)
        } else {
            previewRequestBuilder.set(CaptureRequest.FLASH_MODE, CaptureRequest.FLASH_MODE_OFF)
        }
        previewRequest = previewRequestBuilder.build()

        try {
            captureSession.capture(previewRequest, captureCallback, backgroundHandler)
        } catch (e: CameraAccessException) {
            e.printStackTrace()
        }
    }