Add a more general dragging thingy and use that to know when we
are dragging splits or the scroll thumb.
Fixup scrollbar math, which didn't account for whether the tabbar
was shown and which might cause the scroll thumb to jump around
on first drag (resolves#568)
The idea here is to make it a bit easier to do hit detection for UI
elements; today we've been duplicating position math between the render
and the mouse movement handlers, with both pieces of code knowing the
location of the UI element.
UIItem allows the render phase to record the position, which allows
the mouse phase to be a more independent lookup against the registered
elements.
This makes it easier to add more UI elements in the future.
Rather than using the configured initial window size, use the
size of the current tab to size the newly spawned tab.
refs: https://github.com/wez/wezterm/issues/920
If a cell contained a ligature, the math used to track where the
next quad was going to be placed could lose consistency with
the cluster/shaping information and result in offset glyphs.
This was most noticeable to me in tab titles in the tab bar;
my shell dotfiles append `-- something` to the title when a
command is launched, and the `--` is a ligature in my font.
I think I've also seen this mess up positioning in the notcurses
demo as well.
The solution is to take the cluster initial cell index rather
than trying to reverse engineer it from incomplete info.
A while back I made the line lengths lazily grown; the reduction
in memory was nice, and it helped with render performance for
really wide screens.
Unfortunately, it puts a bunch of reallocation into the hot path
of the parser and updating the terminal model when people run
the inevitable `cat giant-file.txt` benchmark.
This commit reinstates pre-allocating lines to match the physical
terminal width, and tweaks the code a bit to take advantage of
const Cell allocation and to avoid some clones (a really micro
optimization).
For simple graphemes, we can avoid subsequently calling
grapheme_column_width and cache that information in TeenyString.
Make blank TeenyString and Cell initializations const.
This size seems to be ~sweet spot for `time cat bigfile`, cutting the
time in half from the prior value. Making the buffer smaller doesn't
improve things, nor does making it bigger; this is balancing the latency
of applying the update to the model with the back-pressured parsing
latency.
The recent presentation logic needs to be tweaked to ensure that
we ignore presentation when we reach the fallback font, otherwise
we'll end up in a bad error stack and crash the program.
This commit annotates fonts with a boolean that indicates whether
we think it contains glyphs with emoji presentation, and then
passes the cluster.presentation field down to the shaper.
If the presentation doesn't match the current font in the fallback,
then it will be skipped until we exhaust its options.
`wezterm ls-fonts` also shows whether we think a font has emoji
presentation.
refs: #997
This replaces the slightly gnarly subpixel enabled blending in the
shader with Dual Source Blending, which is a technique where the
fragment shader can specify both the primary color (RGBA) as well
as an additional per-channel mask that can be used to alpha blend
with the destination.
This enables artifact-free alpha blending when used together
with a transparent window background.
refs: https://github.com/wez/wezterm/issues/932
