scenario:
* position a wrapped line on screen
* search for the word immediately after the point of wrapping
Before this commit the word would be highlighted twice:
- at the end of the first screen line
- at the start of the second screen line
Now it shows up at the right place.
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.
This is a violation of an existing rule in Manual_tests.md. The
following command weakly suggests there aren't any others:
grep ':sub(' *.lua |grep pos
A code editor is unlikely to need support for extremely long lines. And
that kind of scroll is jarring anyway in a code editor. We don't read
code like a novel, and less scroll per page implies more scrolling work.
I'd gotten rid of this functionality and the test for it [1] back in the
spokecone fork, but only took out the test when first pulling it into
the source editor.
[1] test_pagedown_often_shows_start_of_wrapping_line
This doesn't affect this fork directly, but it's a bad idea to assume
the _app_ is always going to be doing just what a particular subsystem
(here, the text editor in edit.lua+text.lua) is doing.
I think all we need to maintain is the populate_screen_line_starting_pos
array. It's easy to render screen lines one by one from it, and we'll
only ever construct one additional screen line at a time.
I'd hoped to delete other calls to Text.populate_screen_line_starting_pos,
but it turns out we need to update it when editing sometimes. Give up on
that for now; it's a no-op if not needed.