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A Pure Elm Text Editor

This package offers a pure Elm text editor. It relies heavily on prior work of Martin Janiczek and Sidney Nemzer. It is a pleasure to acknowledge their work. I would also like to acknowldge the work of Anton-4 who cleaned up the codebase, running elm-analyse on it, fixed a variety of bugs, and wrote the small-demo app to facilitate further development. Many thanks!

After a time away from this code (other things called!) I am now back at work with a first order of business to make it possible to edit large files without the app slowing to a crawl. As a test document, I am using Darwin's Origin of the Species, which weighs in at over 15,000 lines. Even with a file this large, the app is quite snappy.

The approach taken is for the editor to "see" only a small window into the full array of lines of text. That window is currently initialized in EditorModel.init at 300 lines, about ten times the number of lines visible in the editor of smalldemo.

It is important to distinguish between the viewport and the window. The former consists of what is visible, while the latter populates the scene defines what can be visible without moving the window in the document from which it is derived.

When the user clicks on a line that is near the upper or lower boundary of the window, the window and viewport are both adjusted so that (a) there is plenty of text above/below the viewport boundaries, and so that (b) the cursor does not appear to move.

Once the windowing system is working satisfactorily, I'll move back to working on other issues, including many annoying bugs and infelicities. Regarding the windowing system, I've done some preliminary work on making the window into the full text update itself as the user scroll, so that the user never runs out of text. This currently works if the user scrolls say, on a mac by by moving the cursor with track pad. For the scroll bars, I think I need some sort of subscription to the y-coordinate of the viewport.

There will be real documentation at some point. For now, if you want to use the package, the best way is to see how it is used in the demo app.

The demo contains both "in-editor" features and hooks for using it in a host app, e.g., syncing the source and rendered text for various markup languages.

Bugs and whatnot

I appreciate feedback. Please post issues, feature requests, comments as an issue on Github. Or contact me on gmail at jxxcarlson.

The Demo

Live version here!

The editor lives in the left-hand window of the demo app. You can write text there in either

  • a dialect of Markdown (Markdown/Math) that can handle equations written in LaTeX and can render SVG images as in the example.

  • or MiniLaTeX, a subset of LaTeX

The source text will be rendered on the fly to Html, as you will see in the right-hand window.

Installation

cd ./demo
npm install
npm start

Notes

  • The present package, jxxcarlson/elm-editor, supersedes jxxcarlson/elm-text-editor. Better to use this one!

  • Im plannng on a Vim mode, but have made just a barebones start on this.

  • Under consideration: an Electron version. I know nothing about doing this, so if anyone wants lend a helping hand, that would be great.