Thanks Alex Schroeder for reporting this crash. The scenario:
* Edit a file like say this repo's Readme.
* The second line is empty and there's a '+' to insert a drawing.
Click on that.
* Resize the window so just the first line of text and the drawing are
visible.
* Close the window.
* Reopen lines.love, it will reopen the same file.
* Click on the left margin to the left of the drawing.
Before this commit these steps yielded the following crash:
Error: bad argument #1 to 'len' (string expected, got nil)
text.lua:626: in function 'pos_at_end_of_screen_line'
edit.lua:298: in function 'mouse_press'
There were two distinct problems here:
1. State.screen_bottom1 is not required to point to a text line, it
could just as well be a drawing. I have been sloppy in handling that.
2. The bug was partially masked (the need to close and reopen the
window) by a second bug: inserting a drawing was not invalidating the
cache I save of starty coordinates for each line. (I've inserted and
deleted starty invalidations a few times in the past, but it looks
like I'd never had one in this particular location edit.draw before.)
How did these issues get missed for years?
- Even though I use lines.love on a daily basis, it turns out I don't
actually create line drawings all that often.
- When I do, I'm still living in files that are mostly text with only
an occasional drawing.
- I keep my windows fairly large.
Between these 3 patterns, the odds of running into a drawing as the
first or bottom-most line on the screen were fairly small. And then I
had to interact with it. I suspect I tend to interact with drawings
after centering them vertically.
---
Bug #1 in particular has some interesting past history.
* Near the start of the project, when I implemented line-wrapping I
started saving screen_bottom, the bottom-most line displayed on
screen. I did this so I could scroll down easily just by assigning
`screen_top = screen_bottom`. (On the other hand, scrolling up still
required some work. I should perhaps get rid of it and just compute
scrolls from scratch each time.)
* Also near the start of the project, I supported selecting text by a
complex state machine spanning keypress, mouse press and mouse
release:
mouse click (press and immediate release) moves cursor
mouse drag (press and much later release) creates selection
shift-click selects from current cursor to click location
shift-movement creates/grows a selection
* On 2023-06-01, inscript reported a bug. Opening a window with just a
little bit of text (lots of unused space in the window), selecting all
the text and then clicking below all the text would crash the editor.
To fix this I added code at the bottom of edit.mouse_press which
computed the final visible line+pos location and used that in the
cursor-move/text-selection state machine. It did this computation
based on.. screen_bottom. But I didn't notice that screen_bottom could
be a drawing (which has no pos). This commit's bug/regression was
created.
* On 2023-09-20, Matt Wynne encountered a crash which got me to realize
I need code at the bottom of edit.mouse_release symmetric to the code
at the bottom of edit.mouse_press. I still didn't notice that
screen_bottom could be a drawing.
So in fixing inscript's bug report, I introduced (at least) 2
regressions, because I either had no idea or quickly forgot that
screen_bottom could point at a drawing.
While I created regressions, the underlying mental bug feels new. I just
never focused on the fact that screen_bottom could point at a drawing.
This past history makes me suspicious of my mouse_press/mouse_release
code. I think I'm going to get rid of screen_bottom entirely as a
concept. I'll still have to be careful though about the remaining
locations and which of them are allowed to point at drawings:
- cursor and selection are not allowed to point at drawings
- screen_top and screen_bottom are allowed to point at drawings
I sometimes copy between these 4 location variables. Auditing shows no
gaps where cursor could ever end up pointing at a drawing. It's just
when I started using screen_bottom for a whole new purpose (in
the mouse_press/release state machine) that I went wrong.
I should also try getting rid of starty entirely. Is it _really_ needed
for a responsive editor? I think I introduced it back when I didn't know
what I was doing with LÖVE and was profligately creating text objects
willy-nilly just to compute widths.
Getting rid of these two fairly global bits of mutable state will
hopefully make lines much more robust when the next person tries it out
in 6 months :-/ X-(
Thanks everyone for the conversation around this bug:
https://merveilles.town/@akkartik/112567862542495637
---
Bug #2 has some complexity as well, and might lead to some follow-on
cleanup.
When I click on the button to insert a new drawing, the mouse_release
hook triggers and moves the cursor below the new drawing. This is
desirable, but I'd never noticed this happy accident. It stops working
when I invalidate starty for all lines (which gets recomputed and cached
for all visible lines on every frame).
Fixing this caused a couple of unit tests start crashing for 2 reasons
that required their own minor fixes:
- My emulated mouse press and release didn't have an intervening
frame and so mouse_release no longer receives starty. Now I've added
a call to edit.draw() between press and release.
This might actually bite someone for real someday, if they're
running on a slow computer or something like that. I've tried to
click really fast but I can't seem to put mouse_press and release in
the same frame (assuming 30 frames per second)
- My tests' window dimensions often violate my constraint that the
screen always have one line of text for showing the cursor. They're
unrealistically small or have a really wide aspect ratio (width 2x
of height). I suspect lines.love will itself crash in those
situations, but hopefully they're unrealistic. Hmm, I wonder what
would happen if someone maximized in a 16:9 screen, that's almost
2x.. Anyways, I've cleaned a couple of tests up, but might need to
fix up others at some point. I'd have to rejigger all my brittle
line-wrapping tests if I modify the screen width :-/ X-(
|
||
|---|---|---|
| LICENSE.txt | ||
| Manual_tests.md | ||
| MemoryReferenceInfo.lua.0 | ||
| MemoryReferenceInfo.lua.unused | ||
| README.md | ||
| app.lua | ||
| button.lua | ||
| colorize.lua | ||
| commands.lua | ||
| drawing.lua | ||
| drawing_tests.lua | ||
| edit.lua | ||
| file.lua | ||
| geom.lua | ||
| help.lua | ||
| icons.lua | ||
| json.lua | ||
| keychord.lua | ||
| log.lua | ||
| log_browser.lua | ||
| main.lua | ||
| nativefs.lua | ||
| reference.md | ||
| run.lua | ||
| run_tests.lua | ||
| search.lua | ||
| select.lua | ||
| source.lua | ||
| source_edit.lua | ||
| source_file.lua | ||
| source_select.lua | ||
| source_tests.lua | ||
| source_text.lua | ||
| source_text_tests.lua | ||
| source_undo.lua | ||
| test.lua | ||
| text.lua | ||
| text_tests | ||
| text_tests.lua | ||
| undo.lua | ||
README.md
Plain text with lines
An editor for plain text where you can also seamlessly insert line drawings. Designed above all to be easy to modify and give you early warning if your modifications break something.
http://akkartik.name/lines.html
Getting started
Install LÖVE. It's just a 5MB download, open-source and
extremely well-behaved. I'll assume below that you can invoke it using the
love command, but that might vary depending on your OS.
To run from the terminal, pass this directory to LÖVE, optionally with a file path to edit.
Alternatively, turn it into a .love file you can double-click on:
$ zip -r /tmp/lines.love *.lua
By default, lines.love reads/writes the file lines.txt in
a directory relative to this app.
To open a different file, drop it on the lines.love window.
Keyboard shortcuts
While editing text:
ctrl+fto find patterns within a filectrl+cto copy,ctrl+xto cut,ctrl+vto pastectrl+zto undo,ctrl+yto redoctrl+=to zoom in,ctrl+-to zoom out,ctrl+0to reset zoomalt+right/alt+leftto jump to the next/previous word, respectively- mouse drag or
shift+ movement to select text,ctrl+ato select all ctrl+eto modify the sources
For shortcuts while editing drawings, consult the online help. Either:
- hover on a drawing and hit
ctrl+h, or - click on a drawing to start a stroke and then press and hold
hto see your options at any point during a stroke.
lines.love has been exclusively tested so far with a US keyboard layout. If you use a different layout, please let me know if things worked, or if you found anything amiss: http://akkartik.name/contact
Known issues
-
No support yet for Unicode graphemes spanning multiple codepoints.
-
No support yet for right-to-left languages.
-
Undo/redo may be sluggish in large files. Large files may grow sluggish in other ways. lines.love works well in all circumstances with files under 50KB.
-
If you kill the process, say by force-quitting because things things get sluggish, you can lose data.
-
The text cursor will always stay on the screen. This can have some strange implications:
- A long series of drawings will get silently skipped when you hit page-down, until a line of text can be showed on screen.
- If there's no line of text at the top of the file, you may not be able to scroll back up to the top with page-up.
So far this app isn't really designed for drawing-heavy files. For now I'm targeting mostly-text files with a few drawings mixed in.
-
No clipping yet for drawings. In particular, circles/squares/rectangles and point labels can overflow a drawing.
-
If you ever see a crash when clicking on the mouse, it might be because a mouse press and release need to happen in separate frames. Try pressing and releasing more slowly and let me know if that helps or not. This is klunky, sorry.
-
Touchpads can drag the mouse pointer using a light touch or a heavy click. On Linux, drags using the light touch get interrupted when a key is pressed. You'll have to press down to drag.
-
Can't scroll while selecting text with mouse.
-
No scrollbars yet. That stuff is hard.
Mirrors and Forks
Updates to lines.love can be downloaded from the following mirrors in addition to the website above:
- https://git.sr.ht/~akkartik/lines.love
- https://repo.or.cz/lines.love.git
- https://tildegit.org/akkartik/lines.love
- https://git.merveilles.town/akkartik/lines.love
- https://git.tilde.institute/akkartik/lines.love
- https://codeberg.org/akkartik/lines.love
- https://github.com/akkartik/lines.love
- https://notabug.org/akkartik/lines.love
- https://pagure.io/lines.love
- https://nest.pijul.com/akkartik/lines.love (using the Pijul version control system)
Forks of lines.love are encouraged. If you show me your fork, I'll link to it here.
- https://github.com/akkartik/lines-polygon-experiment -- an experiment that
uses separate shortcuts for regular polygons.
ctrl+3for triangles,ctrl+4for squares, etc. - https://git.sr.ht/~akkartik/text.love -- a stripped down version without drawings; useful starting point for some forks
- https://git.sr.ht/~akkartik/pensieve.love -- a note-taking app on an infinite 2D surface. Still in development.
- https://git.sr.ht/~akkartik/capture.love -- a blank-slate mode for the note-taking app, so all the stuff pensieve.love puts on screen doesn't cause you to forget what you came to write down.
Associated tools
- https://codeberg.org/akkartik/lines2md exports lines.love files to Markdown and (non-editable) SVG.
- https://git.sr.ht/~akkartik/lines2html.love exports lines.love files to html and inline SVG.