[Update: After I wrote this, I found out that Google's
Digital Wellbeing app has a built-in Grayscale feature. Ugh.]
Grayscale via Digital Wellbeing
Digital Wellbeing: https://www.androidpolice.com/2018/09/06/digital-wellbeing-update-adds-grayscale-tile-app-drawer-icon/
Monochromacy via Tiles
Toggling colour / monochrome on an Android phone is a much bigger pain than it needs to be but once the instructions are all in one place, it's worth the five minutes it takes to complete.
Pay $1 and nstall Tiles
Open Tiles and scroll down to
Tile visibilityon. Edit Quick Settings and add the
Write secure settings permission. It will complain, saying the app doesn't have this authority and you need to grant it using Android Platform Tools.
Install Android Platform Tools. On a Mac:
brew cask install android-platform-tools
...for Linux and Windows, follow the instructions on the Tiles support wiki: https://github.com/TilesOrganization/support/wiki/How-to-use-ADB-to-grant-permissions
- Plug your phone into your computer with a USB cable and use ADB to override the secure settings permission:
adb devices # => this will poke your phone and your phone will ask you to give `USB Debugging` permission to your computer; allow this adb shell pm grant com.rascarlo.quick.settings.tiles android.permission.WRITE_SECURE_SETTINGS # => no news is good news; this command has no output if it worked correctly adb shell dumpsys package com.rascarlo.quick.settings.tiles | grep WRITE_SECURE_SETTINGS # => you should see `android.permission.WRITE_SECURE_SETTINGS: granted=true`
Write secure settings permissionagain. You'll get the same pop-up but it should toggle the setting this time.
Try your new Monochromacy quick setting!