Add Emacs navigation key-bindings support

[janmejay]

Rebase and address review-comments on a very old abandoned change (PR#1039)

• add emacs-style navigation keymap support (similar to existing Vi keymap support)
• convert the checkboxes to a set of radio-buttons (one of the open review comments)

[janmejay]

@hluk did you have a chance to look at this?

[hluk]

@hluk did you have a chance to look at this?

Not yet. Thanks for the patch! Checking now.

[hluk]

Can you change this to use an enum? Something like:

enum class NavigationStyle {
    Default,
    Vi,
    Emacs
};

It would also mean that there is single method to set the navigation void setNavigationStyle(NavigationStyle style).

It would be best if the configuration value in appconfig.h has this type, but that might require some more refactoring. I could look into this later.

[janmejay]

@hluk I looked into this today. One way I can see of making this change (let me know if this is not really what you had in mind) is to make NavigationStyle a QVariant and then bind QGroupBox instead of individual QRadioButtons.

I'd have to overload the Option constructor to allow me to pass getter and setter lambdas because checkedId is not available as a property. This overload would be used for Option<NavigationStyle> instance.

The main problem is this is backwards incompatible with persisted settings. For anyone that has vi mode enabled at the moment would reset to Default when they upgrade.

We can try to migrate settings, but unless we introduce a new concept (say SettingsMigrator) the implementation won't be clean.

Let me know if this isn't what you had in mind.

[hluk]

I would prefer to keep the code simpler. I tried writing some conversion function for new enum option, but it did not work well and was unnecessarily complex (custom QMetaType conversion function).

Here is a simple solution: 2810029

The UI uses QComboBox with fixed values instead of a group of radio buttons - enum values and the items in the combo box must match.

It reuses the Config::vi option because I thought that it would convert the old false/true values so it would stay backwards-compatible. Unfortunately, that does not work. It would be good to figure this out, but I would avoid any complex migration code.

Another downside is that from CLI (copyq config vi ...) you would need to use values 0,1,2 instead of more reasonable strings (e.g. "vi"/"emacs").

[hluk]

I've solved the backwards-compatibility issue in: aba654f

But I'm not sure if I like the complexity of the solution 🙂 (diff from the previous version).