How to disable evil insert key in read only mode

Question

I want to disable evil insert key such as a, i, o in read-only mode (keep navigation key such as j and k), my idea is to disable these keys in local buffer when enabling read-only mode and enable these keys after disabling read-only mode.

There are two difficulties for me:

1. How to disable evil insert key.
2. How to execute code when enable/disable mode.

I notice there is evil-disable-insert-state-bindings variable. I try to set it to t in local buffer, but a, i keys still work.

I know I can use (add-hook 'read-only-mode-hook (lambda () (message "read-only-mode changed"))) to detect mode change, but I don't know how to distinguish enabling and disabling mode.

Answer 1

For read-only buffers, Evil provides the Evil specific motion-state (see here). You can configure the modes to open in that state by adding/removing the mode names to the list of evil-motion-state-modes.

If you are using Spacemacs then you can also use the evilified-state in a similar way (or when not using Spacemacs you could try https://github.com/mohsenil85/evil-evilified-state, I guess it works fine, but I have never tested it).

Alternatively, I think I would recommend to just use the very well designed evil-collection, although as a Spacemacs user I haven't used it much myself.