scenario:
- create a long wrapping line
- tap past end of first screen line
Before this commit the cursor would be positioned not quite at the end
of the screen line but one character before. In effect there was no way
to position cursor at end of a wrapping line.
I'm not sure how this bug has lasted so long. It was introduced in
commit 8d3adfa36 back in June 2022, which was itself billed as a bugfix
for "clicking past end of screen line". But when I go back to it this
bug exists even back then. How did I miss it?! I wrote a test back then
-- and the test was wrong, has always been wrong.
This is all quite hacky. Many of my tests are unfortunately brittle to
changes in text rendering. Fortunately there's only one test that
currently requires a hacky special case (and a second test I tweaked
slightly to be more robust).
I can't think of a better approach. It doesn't help to standardize the
font, because version changes still come with changes to text-shaping
algorithms even if the font itself is unchanged. I could base all my
assertions on the widths of individual characters, but that would make
the tests much less readable and not express intent as clearly. So here
we are, with hopefully just a few hacky special cases (there might be a
few more as LÖVE v12 advances towards publication, and in further
versions).
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.
To fix this I have to first stop incrementally updating screen_bottom1
in the middle of a frame. Now it always has a good value from the end of
a frame.
I'm also running into some limitations in the test I'd ideally like to
write (that are documented in a comment), but I still get some sort of
automated test for this bugfix.
It's a hack:
- if you start selecting from below final line the start of the
selection is the most recent click even if it was forever ago
- (the crash we're currently fixing) if you start up and immediately
select all then click below final line => crash. recent_mouse was
never set.
- getting rid of it breaks no tests (except the crash we're currently
fixing)
Disquieting that none of my tests caught these. On the other hand, I
also haven't noticed any issues in practice. Perhaps cache invalidation
is often unnecessary.
The published version of lines.love was broken for almost an hour. The
cursor would render one position to the right of where it really is. To
fix it, this commit rolls back 26ba6e4e5a. There doesn't seem a good
way to test it.
I've been sloppy about this so far, and outside of tests I can't find
any examples where it matters, but it matters in a potential fork where
I'm rendering multiple columns of text.
It's unfortunate that my tests have this level of brittleness. What I'd
really like to assert in many of these changed lines is that the text
stays inside the margins and that more text would overflow margins.
Kartik K. Agaram