I was surprised there was no way to adjust the backlight brightness out of the box for the official 7″ LCD (except for the command line obviously) so I made this widget to accomplish it.

Files available at my github: https://github.com/CactusProjects/rpi-brightness-widget/upload

First of all LCD brightness can be adjusted in the terminal using:

sudo sh -c 'echo "100" > /sys/class/backlight/rpi_backlight/brightness'

The range is 0-255 but nothing seems to happen after 200, if even get a little dimmer so my widget scales from 0-200. Put the .py & .png files in /home/pi/code directory. Put the .desktop file on your desktop. Make the files executable by:

cd /
chmod +x /home/pi/code/brightness_ex.py
chmod +x /home/pi/Desktop/brightness.desktop

The Desktop shortcut will work now but there was an annoying warning every time opening the file asking if wanted to execute the file in terminal etc., I got rid of it by opening the file manager, Go to Edit/Preferences/General, Check box for “Don’t ask options on launch executable file”

Now we have a shortcut that opens up the app to adjust the brightness but I wanted a taskbar shortcut:

Copy the .desktop file into the below two locations: (thanks to https://www.raspberrypi.org/forums/viewtopic.php?t=132072 for guidance on this)

cp /home/pi/Desktop/brightness.desktop /usr/share/raspi-ui-overides/applications/
cp /home/pi/Desktop/brightness.desktop /usr/share/applications/

Open /home/pi/.config/lxpanel/LXDE-pi/panels/panel and add the below code:

nano /home/pi/.config/lxpanel/LXDE-pi/panels/panel

    Button {
      id=brightness.desktop
    }

Restart GUI without a full reboot:

 lxpanelctl restart && openbox --restart

All done, the shortcut should now be on the taskbar. Delete the desktop shortcut if not needed.

One improvement left to do would be to have the widget automatically set maybe 50% brightness in the event it was accidentally set to 0 previously.