Formula Editor in GNU Emacs

 

 


Here's a simple formula editor using SVG for quick note taking in GNU Emacs. Presently, it's a single line editor. You can use arrow keys to move around, Shift+arrow keys for selection and backspace for deleting characters. Use Ctrl + x prefix for special actions like grouping (g), fractions (f) and exponents (e).

(require 'formula)
 
M-x formula-mode

Code:

https://gitlab.com/atamariya/emacs/-/blob/dev/lisp/svg.el
https://gitlab.com/atamariya/emacs/-/blob/dev/lisp/formula.el
 

How it works?

In the video, an event loop is started in the scratch buffer. All the edit operations update text and text property in a temporary buffer, say a.txt. Based on this information, in-memory SVG DOM is updated. Ultimately, the display engine updates the view with this SVG image.

Comments

Post a Comment

Popular posts from this blog

GNU Emacs as a Comic Book Reader

Image
  Comics are available in digital format as a collection of images in a compressed ZIP or RAR file (.cbz or .cbr file extension respectively). These can be enjoyed in GNU Emacs with full access to image viewing capabilities using keybindings.   # Make sure you have unrar installed for CBR files # apt install unrar   (require 'arc2-mode)   (setq archive-summarize-files-fn 'archive-summarize-files-as-thumb)     Note: The archive-mode is capable of displaying the list of files in an archive; though it depends on external tools for extraction. For JPG and PNG, Emacs can resize the image without external convertor (ie. imagemagick). However, some menu options for image transformations in image-mode might not be available. Use the following patch for image-mode.el . @@ -460,16 +460,16 @@ image-mode-map       :help "Show image as hex"]      "--"      ["Fit to Window Height" image-transform-fit-to-...
Read more

HTML Renderer (Emacs)

Image
  Emacs: A non-intrusive browser An Elisp implementation of HTML rendering using SVG. The browser functionality is an extension of eww . For Javascript, you can use either NodeJS or QuickJS as a JS interpreter . Developer Note: The entry point is shr-render.   Table Colspan example Rowspan example Sample Table <html>   <body>     <table border="1">       <tr bgcolor="#9acd32">         <th style="text-align:left">Title</th>         <th style="text-align:left">Artist</th>       </tr>       <tr>         <td>Empire Burlesque</td>         <td>Bob Dylan</td>       </tr>     </table>   </body> </html...
Read more

Mozilla Readability in GNU Emacs

Image
  Output using Readability (left) and original eww (right)   Mozilla Readability is a standalone version of the readability library used for Firefox Reader View . A simple hack to eww can bring the same feature in GNU Emacs. ( Note: eww already has a readable mode. This is just an alternative. Updated the post to reflect the same.)   - Install NodeJS   - Install npm modules. npm install @mozilla/readability jsdom   - Create a file readability.js with following content. Note the file location. var { Readability } = require('@mozilla/readability'); var { JSDOM } = require('jsdom'); var fs = require("fs"); var str = fs.readFileSync(process.stdin.fd).toString(); var doc = new JSDOM(str); var reader = new Readability(doc.window.document); var article = reader.parse(); console.log(article.content);     - Modify the following function to use the file location noted above . Evaluate the function. (defun mozilla-readability (start end)   (shell-command-o...
Read more