werf - mouse driven text editor

Werf is mouse driven experimental text editor inspired by Acme, text editor from the Plan 9 from Bell Labs.

Requirements

libX11, libcairo, libfreetype, libfontconfig

Compile with GNU or BSD make. Uses C11 only for anonymous structs as rest is C99.

Features and non-features

• Mouse driven
• Simple integration with shell
• UTF-8 only
• Unlimited undo
• Uses proportional font by default
• No syntax highlighting
• No text wrapping yet
• Can't save yet...

Keybindings

• Default X input method for text entry.
• Enter for new line.
• Same as in WIMP interfaces:
  • Arrows
  • Home/End
  • Page Up/Down
  • Backspace/Delete

Will be removed or changed:

• F2 - undo
• F3 - redo

Command toolbars

Toolbar is a place for commands that can be applied to selection or the file as a whole. It is divided in two sections. First is for pinned commands and is by default populated by a few built-in commands. Second is for ad-hoc commands. It starts with "..." - a space where new command can be issued. On the right side of "..." is a list of previously issued non-pinned commands. The list is filtered while typing.

There are two such toolbars: selection and top toolbar.

Selection toolbar

Text can be selected with mouse (left click and drag). After text is selected and LMB is released selection-toolbar is shown. Toolbar does not overlap the text it splits it. Toolbar appears between lines bordering with selection start or end just under mouse pointer.

Default pinned commands: Cut, Copy, Paste, Delete, Find, Open, Exec.

Top toolbar

Top toolbar is for commands related more to the file as a whole. Default pinned commands: Save, Open, Undo, Redo, Paste, Find.

Commands

Most edit actions are done through commands. Commands can act as simple filters - getting selection content from standard input and replacing it by giving standard output. Except for built-in commands commands are run with sh -c.

• left click - execute command
• double click - edit command and select word under pointer
• triple click - edit command and select whole command line
• middle click - append space and clipboard contents to command and execute it

Built-in commands

Built-in commands names are capitalized in CamelCase style.

Available built-in commands:

• Save [filename]
• Open [filename]
• Cut
• Copy
• Paste
• Delete
• Undo
• Redo
• Find [regex]

Command pipes

Commands have more options where to read from or write to a file. They are spawned with additional pipes that are exposed by environmental variables thanks to /dev/fd mechanism.

Available pipes:

• WERF_CONTROL_W - control pipe

Control pipe

Command can request special behavior from editor through control pipe (WERF_CONTROL_W). Control pipe expects available command name with new line at the end.

Available control commands:

• ReadOnly - disregard changes to selection

It is also available as a simple command wrapper:

$ cat cmd/ReadOnly
#!/bin/sh
echo ReadOnly >> "$werf_control_w"
exec "$@"

• disregard - selection is read only, disregard writes to selection - rename to ReadOnly
• finish - finish as soon as write off selection is done, probably can be removed, as with jobs toolbar it would not have much use

TODO

Now

• top toolbar
  • Save
  • Load
• Find command
  • WERF_AFTER_SELECTION_R - wrap around end?
  • WERF_BEFORE_SELECTION_R - wrap around begin?
  • WERF_HIGHLIGHT_W
    • maybe fold to control pipe? same thing for range?
    • Highlight 12 0 13 0 # highlight whole line 12
• single poll loop (also for command execution)
• command issuing

Internal

• proper marking of dirty caches
• optimize array grow strategy
• use arrays in buckets for line and lines?
• memory optimization
  • use uint32_t instead of size_t?
  • intrusive array: put nmemb and amemb before payload
• split backend/frontend for ssh tunneling

Presentation

• cursor blinking
• implement a bit of material design (shadows, but not animation)
• limit direct use of Xlib to only necessary parts?
  • use SDL?
  • draw text to single alpha channel
  • disable subpixel hinting
  • it seems that SDL_Texture does not support single channel pixel formats

Simpler

• load from stdin and save to stdout
• right click to show selection toolbar
• save undo buffer as mmapped file like vim's swap files
• double click to select word, triple to select line
• extending selection: handles or shift+click
• tab while selected - increase indentation level
• proper tab stops
• keeping indentation level (copy leading white space)
• mark white space at the end of the line
• detect and distinguish indentation style?
  • detect if tabs or spaces are used for indentation
  • mark not matching indentation

Later

• Jobs toolbar - shows running and exited commands
  • display standard error and exit code
  • Kill running command
  • Issue subcommands to running command (i.e. Next/Previous for Find)
  • show cursor for running job in text
    • backspace/delete the cursor to kill
• WERF_BEFORE_SELECTION_W
• WERF_AFTER_SELECTION_W
• Command pinning - drag and drop before "..."
• Scrollable toolbars
• multiview and multifile
• completion for:
  • command line
  • editing
• line wrapping
• smooth scrolling
• drag and drop:
  • selection as text
  • files as filenames
• visual scroll bar
  • with outline?
  • external process?
• built-in commands as multicall binary (symlinks to werf)
• shell mode
  • interactive shell
  • partial implementation of VT100 emulation?
• syntax highlighting?
• line numbers?

After 1.0

• touch events
• elastic tabs?
• undo/redo as external command?