Can I change the LED intensity of an Android device?

问题

Is there a way to set the LED intensity that I desire? I know that to turn on the LED I use:

     p.setFlashMode(Camera.Parameters.FLASH_MODE_TORCH);
     mycam.setParameters(p);

But this code just turns on the LED. But is there a way to set different intensities to the LED for a stronger light or to reduce the light intensity?

回答1:

HTC has an alternative API that supports this, however it's only on HTC Sense devices, and as of Gingerbread they've changed the permissions so it's only for their Flashlight app, not third party ones (unless you use root).

But on 2.2 HTC devices you can use it by writing a string to /sys/devices/platform/flashlight.0/leds/flashlight/brightness. This controls if the LED is on and how bright it is. For maximum brightness write "128\n", half brightness write "64\n". Easy to test from adb shell:

echo "128" > /sys/devices/platform/flashlight.0/leds/flashlight/brightness

And finally turn it off by writing "0\n" there.

回答2:

Short answer is: NO.
Longer answer - maybe on some devices using undocumenterd calls / parameters. Supported flash modes, and their meanings (and behaviours) differ from device to device.

Your best option is to query supported flash modes, and hope they work as intented.

回答3:

Try to set different Flash Modes available for Camera parameters.

* FLASH_MODE_OFF
* FLASH_MODE_AUTO
* FLASH_MODE_ON
* FLASH_MODE_RED_EYE
* FLASH_MODE_TORCH

you can set Flash mode using setFlashMode() method.

This was just for camera back light. but if you want to change complete screen intensity. have a look at the example here.

回答4:

Try to find the code of this function:

private native final void native_setParameters(String params);

I beleive that you will find out if this is possible when you look through it.

Looking at the publics, it seems impossible

回答5:

I have tried this in my Samsung Galaxy S3 Mini. I have not tried on other devices.

Whenever i do this (while the led is ON):

public void changeIntensity()
{
    cam.stopPreview();
    cam.startPreview();
}

The LED rotates between 3 levels of intensity. It makes no sense, but it works.

来源：https://stackoverflow.com/questions/5970188/can-i-change-the-led-intensity-of-an-android-device