Turning on flashlight and camera that does not support flash simultaneously in Android

Question

I'm writing a highly specialized application for the Kyocera E6820 that requires the device's wide angle camera and the flashlight to be on simultaneously.

I'm using the Camera2 Android API . The problem is that by default the wide angle camera doesn't support flash, so if I try to turn on the flashlight and the wide angle camera at the same time by doing the following:

mPreviewRequestBuilder.set(CaptureRequest.FLASH_MODE, CaptureRequest.FLASH_MODE_TORCH);
mPreviewRequest = mPreviewRequestBuilder.build();
mCaptureSession.setRepeatingRequest(mPreviewRequest, mCaptureCallback, mBackgroundHandler);

I get an error that says:

W/LegacyRequestMapper: mapAeAndFlashMode - Ignore flash.mode == TORCH;camera does not support it

I tried to get around this by turning on the flash using the regular rear facing camera (which does support flash) without opening it by doing the following:

manager.openCamera(wideAngleCameraID, mStateCallback, mBackgroundHandler);
manager.setTorchMode(rearFacingCameraID, true);

However, it didn't work, and I got this message:

W/System.err: android.hardware.camera2.CameraAccessException: The system-wide limit for number of open cameras has been reached, and more camera devices cannot be opened until previous instances are closed.

I can get the normal rear facing camera and the flashlight to go on simultaneously, but no such luck with the wide angle.

Does anyone know a potential way around this problem? I've already looked through this post but didn't find anything useful. Since this is such a specialized application it is not out of the question to do something like rooting the phone or talking directly to the device's LED drivers, but I would need to know where to start. Any direction or help would be appreciated.

Answer 1

For anyone viewing, I found the answer after looking at this forum discussion . For me, the brightness value was located in the

/sys/class/leds/led:torch_0

directory. After rooting the phone, I was able to manipulate the value by invoking an adb command using the process given here .