Matt Wynne pointed out that snap.love would crash when a node went off
screen. While debugging it I noticed that selection1 was being set when
it shouldn't be.
Turns out I introduced a bug when I fixed the inscript bug back in June
(commit 9656e13774). One invariant I want to preserve is: selection1
should be unset after a mouse click (press and release without
intervening drag). This invariant was violated in my bugfix back in
June. I was concerned only with selection back then, and I didn't
realize I was breaking the mouse click case (in a fairly subtle way; you
can have selection set, and when it's set identically to the cursor
everything looks the same).
I think there might still be an issue in snap.love after this fix. I
noticed screen_bottom1.pos was nil, and as far as I recall that should
never happen.
This is a backport of a bugfix in pensieve.love. It's not _technically_
a bug here in lines.love, but it seems worth establishing an
architectural invariant (or rather lack of invariant).
LÖVE's standard event loop performs the following sequence of operations
in a single frame:
* process events
* update
* draw
Ideally any mutations to global state happen during the first two
phases, while drawing includes no mutation.
However, there is a special case: `starty`, the top y coordinate for
each each line in the editor. This is used all over the place, and the
cheapest way to compute it is to simply save it while drawing.
However, draw by definition only updates `starty` for lines that are
drawn on screen. To avoid stale data on lines off screen, say after
scrolling, events often clear `starty` for all lines, leaving it to the
next draw phase to repopulate the right lines.
Sandwiched between the above two "however"s, the update phase needs to
gracefully handle `starty` being nil in the occasional frame right after
an event.
I think I've audited all our uses of `starty`, and this commit fixes the
only place that violates this rule.
All the Text functions assume the cursor is always on a text line. I was
violating that invariant.
* When scrolling up, I start the cursor at the top-most line below the
screen top.
* When scrolling down, I start the cursor at the top-most line below the
screen bottom.
I think it would feel slightly more natural for it to be the
bottom-most line above the screen bottom.
However, the Text functions maintain an invariant that the bottom-most
line in a buffer will be text. There's no such invariant for the
top-most line.
Earlier the ghost while drawing wouldn't quite match the final shape.
Now the math is identical in draw_pending_shape.
It's a little unfortunate that we have this duplication of formulae.
At least there are no other stray calls of App.mouse_x in
draw_pending_shape.
The drawing buttons are now absolutely positioned, which is a horrible
hack. But for just the source editor it seems good enough. The
alternative is to modify magic constants in all the tests :/
This is much easier to explain, and it also avoids errors like
forgetting to delete the save dir after editing sources in source dir.
One drawback: there's a little more risk of accidental data loss, either
because of bugs here or programmer mistakes. To mitigate this risk, put
your apps in a git repo and periodically `git commit`.
These are like versions in nativefs, but only support absolute paths.
I want to be thoughtful about the precise location at each call-site.
It's a little ugly that app.lua now has a dependency on file.lua. Or
source_file.lua for the source editor.
Error_message is a special global. It's set when the app (Current_app = 'run')
encounters an error and switches to the source editor, and cleared when
switching from source editor back to the app.