[FR] Tablet Support Meta Issue

[ChaosBlades]

This will serve as the meta issue for better tablet support in KlipperScreen.

I am creating this after seeing the Chris Riley video and then realizing that old x86/ARM tablets used off eBay can be had for as little as $50 in excellent condition. Most screens you can get to use with KlipperScreen are around that price. I am currently testing functionality with a Microsoft Surface Go 2 I got for $72 running Ubuntu Server.

I feel this is the next evolution of KlipperScreen. The cost is basically the same as getting a single high quality screen for a single printer and with this Tablet you can control as many printers as you want then just leave them all headless. But first KlipperScreen will need to support some extra features.

Will try to keep this updated with...

• What features need to be added
• What features are rejected and for what reason
• Workarounds until features are added
• General Progress or lack thereof
• Other Notes about getting this working

Biggest Issues

• No way to tell what the battery percentage is
• Auto Screen Brightness is not enabled by default
• Screen Brightness defaults to 100% resulting in unnecessary battery drain and increased risk of screen burn in
• Can't update Tablet OS or KlipperScreen on Tablet without installing klipper and moonraker which are otherwise not needed

Workarounds:

• View current battery percentage using the below command. May not work on raspbian.

 upower -i `upower -e | grep 'BAT'`

• OS and KlipperScreen updates will need to be performed manually via the package manager and KIAUH respectively.

Feature Requests:

• Battery Level indicator on Top Bar to the right of the clock that also shows when the tablet is charging
  • [FR] Host system Battery Status #1262
• Menu in Settings called Tablet that shows the following options
  • Option to enable/disable battery percentage on Battery Level indicator
  • Option to adjust Screen Brightness
  • Option to turn on/off Auto Brightness
  • Option to enable/disable Screen Auto Rotation
  • Option to lock Screen to Landscape or Portrait
  • Option to set different screen timeout when on battery vs wall power
• Option in Klipper Settings for 'Extra Small' Font Size
• Ability to perform Tablet OS and KlipperScreen on Tablet updates without needing to install klipper and moonraker
• KlipperScreen Audio alerts such as Print Finished, Temperature Reached, Error, etc

Other Notes:

• You will want to change the power button to suspend instead of power off. On Ubuntu you will want to sudo nano /etc/systemd/logind.conf then change the line #HandlePowerKey=poweroff to HandlePowerKey=suspend, save, exit, then sudo reboot.
• I did install Pop_OS on this Tablet and Auto Screen Brightness and Auto Screen Rotation were on by default. Can't seem to figure out how to enable these without installing an entire DE. Best guess is this is simply something KlipperScreen would need to implement as it is effectively running as the DE.
• Battery life is really good. On this Surface Go 2 at 80% battery I get 6.3 hours left with screen at 100% brightness and 41 hours remaining with screen off. With the tablet in Suspend it will obviously be even longer. This is even without TLP or auto-cpufeq install and all devices enabled in BIOS. With TLP 8.8 hours with screen on and 4 days with screen off.
• Ubuntu Server, Raspberry Pi OS lite, etc probably isn't going to have any kind of battery operated power saving functions turned on by default. Probably a good idea to install TLP or auto-cpufeq.
• Might save some extra battery by turning off extra devices like On-board Audio, Cameras, etc in BIOS.
• If it supports it and you plan on leaving your KlipperScreen Tablet plugged into the wall most of the time check the BIOS for a battery limit option to keep the device from staying at 100% battery all the time as this will degrade the battery life long term.