Code editor widget

[aivarannamaa]

It looks like Toga currently lacks a widget for building a code editor.

GTK has GtkSourceView, Cocoa has NSTextView, WinForms probably can use RichEditControl. I haven't use any of these but I assume they all have different capabilities so that it would be hard to create a common interface for these.

wxWidgets seems to use Scintilla on all platfroms: https://docs.wxwidgets.org/3.0/group__group__class__stc.html

Do you see any technical obstacles for bringing Scintilla into Toga? Or would it be better or easier to create a common interface over the native widgets? Another alternative?

[freakboy3742]

You're correct that Toga doesn't have a code editing widget at present. We'd like to add one, but it's not on our immediate roadmap; our focus at present is on getting the core widget set in place.

I haven't looked into Scintilla in particular, but it may be possible to use it; the fact that it seems to have separate builds for macOS, and GTK is a promising start. The windows code is win32, which isn't directly compatible (Toga uses Winforms), but might be usable.

There are 3 major impediments that I can see:

• Scintilla doesn't support iOS, Android or Web as a deployment platform, so implementations for those platforms will need to be written.
• Scintilla's project management is... archaic. A Sourceforge project with version control on Mercurial doesn't exactly put forward the facade of a project that cares about it's development community
• It's written in C++. This means there are binary artefacts, which means you're going to hit binary distribution problems. These are reasonably solvable on macOS and Windows, because those platforms have binary ABI stability; but distribution on Linux will be a mess. It also means that if a problem is found, the Toga audience isn't well positioned to contribute bug fixes.

These problems might be solvable; at least on the first point, a "desktop only" editor would be a big start.

Another (more extreme) approach would be to use Scintilla as "inspiration", and reproduce the implementation in Python. That would make the code a lot more compatible with Toga; although there might be performance issues.

And, of course, another option still would be to use a different widget as the starting point. I've come across a couple (https://github.com/coteditor/CotEditor https://github.com/Microsoft/monaco-editor https://ace.c9.io https://github.com/CodeEditApp/CodeEdit and more) over the years; but I haven't done a comprehensive audit to work out if any of them are viable as a starting point for a Toga code widget. At least 2 of these projects (Monaco and Ace) are web-based, so you get cross-platform (including mobile) for free; you just have to work out how to embed it in a web page.

[aivarannamaa]

Thanks for this insight!