Just checking mouse.isDown works if the editor is the entirety of the
app, as is true in this fork. However, we often want to introduce other
widgets. We'd like tapping on them to not cause the selection to flash:
https://news.ycombinator.com/context?id=38404923&submission=38397715
The right architecture to enforce this is: have each layer of the UI
maintain its own state machine between mouse_press and mouse_release
events. And only check the state machine in the next level down rather
than lower layers or the bottommost layer of raw LÖVE.
This change needs to get backported to all the other forks. We want to
retain the ability to draw other UI elements in our apps, and that means
we can't always assume that a mouse press and mouse release will happen
together. Instead, each layer should manage its own state machine, and
only check for events from the immediately lower layer.
This idea generalizes commit c3cdbb52a.
Each one should provide a message that will show up within LÖVE. Stop
relying on nearby prints to the terminal.
I also found some unnecessary ones.
There is some potential here for performance regressions: the format()
calls will trigger whether or not the assertion fails, and cause
allocations. So far Lua's GC seems good enough to manage the load even
with Moby Dick, even in some situations that caused issues in the past
like undo.
Not quite ideal: the scrollbar computation only considers
screen_bottom1.line and not screen_bottom1.pos, and so it always assumes
the final line is at the bottom of the screen.
I'm making a deeper change here that I might come to regret. I want to
avoid creating new book-keeping for editor mutations, so I'm putting the
work of computing scrollbar data into clear_screen_line_cache. But that
implies the editor should never clear before updating data, and I caught
one place that wasn't true before. A better name helps avoid this in
future. Let's see how much toil this causes in resolving conflicts.
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)
Text.mouse_pos can sometimes set recent_mouse.time but not
recent_mouse.x/y. I'd assumed x/y is never nil in those situations, but
that's violated. It's most easily seen when typing C-a and then
clicking.
The bug has been spotted twice:
1. In snap.love, I selected text in one node, then another, and hit:
Error: text.lua:789: attempt to compare nil with number
stack traceback:
text.lua:789: in function 'lt1'
select.lua:19: in function 'clip_selection'
text.lua:32: in function 'draw'
edit.lua:117: in function 'draw'
[string "REPL"]:21: in function 'draw'
main.lua:152: in function 'draw'
app.lua:102: in function <app.lua:84>
[C]: in function 'xpcall'
app.lua:112: in function <app.lua:111>
[C]: in function 'xpcall'
Couldn't reproduce.
2. In text.love, inscript selected all text in a small buffer and then
clicked outside the text. And got:
Error: text.lua:784: attempt to compare nil with number
Traceback
[love "callbacks.lua"]:228: in function 'handler'
text.lua:784: in function 'lt1'
select.lua:19: in function 'clip_selection'
text.lua:27: in function 'draw'
edit.lua:117: in function 'draw'
run.lua:136: in function 'draw'
main.lua:148: in function 'draw'
app.lua:42: in function <app.lua:22>
[C]: in function 'xpcall'
This is reproducible, and also across forks.
Not sure where that idiom comes from or why strings work in some places
(auto-coercion?). I picked it up off some example apps. But
https://love2d.org/wiki/love.mouse.isDown says it should be an integer.
Kartik K. Agaram