Very simple first Krita script, written because I wanted a ruler with marks on it (useful if you're copying a photo and trying to measure proportions in terms of "eye-width units" or some other convenient visual yardstick):
- if you're not in a layer named "Ruler", it selects a layer named "Ruler" and activates the Transform tool
- if you're in a layer named "Ruler", it switches back to whichever layer you were in previously, and activates whichever tool you were using previously
Copy toggle_ruler_layer.action into the folder ~/.local/share/krita/actions/ on your computer (you may need to create it), and the file toggle_ruler_layer.desktop and folder toggle_ruler_layer/ into the folder ~/.local/share/krita/pykrita/, then restart Krita.
By default it uses the keyboard shortcut Alt+Ctrl+Shift+R, go to "Settings" menu > "Configure Krita..." > "Keyboard Shortcuts" > "Action: Scripts / My Scripts / Toggle Ruler Layer" to change that.