We changed plans from moving web worker compatible code to shared/
to enforcing layers using core/, common/, ui/ and public/. This
change moves files back from the shared/ dir to clean up the
codebase.
Part of #1507
I did a bunch of testing of various ansi escape codes (including
italics) with all three char atlas implementations (none, static,
dynamic), with and without `drawBoldTextInBrightColors`, and with and
without `enableBold` to test all of the edge cases that I could.
It turns out that `glyph.char.charCodeAt(0)` isn't equivalent to the
character's actual code because of utf-16 garbage, so this adds
`glyph.code` to the `glyph` object so that we can use the `code` value,
and don't need to regenerate it.
- We need to make a clone of this array, because ColorManager mutates
it.
- We only want to compare the first 16 colors instead of all 256, since
only the first 16 will ever change. In DynamicCharAtlas, we can pull
the additional colors from DEFAULT_ANSI_COLORS.
I tested this out by loading the demo and changing the theme a few
times.
This limits the amount of damage a pathological program can cause in
thrashing the LRU cache.
I ran the script described here:
https://github.com/xtermjs/xterm.js/pull/1327#issuecomment-374003960
Without this patch, the entire output would get drawn in one frame that
took about 140 ms to draw. With this patch, it takes about 60 ms. It's
still nowhere as good as the static or none atlas implementations, but
it's not terrible, like it was.
This should have minimal impact on real-world applications: it'll just
take a little longer for the atlas to warm up.
The implementation is a little hacky, since it involves throwing some
code into TextRenderLayer that violates the separation of concerns, but
we can clean this up later.
Pros:
- The code is simpler.
- AA rendering is consistent between cached and uncached characters.
- No long requires parsing color values to determine the alpha, which
means that we no longer depend on #rrggbbaa color value support.
Cons:
- We're drawing without SPAA in some cases where we could be.
Addresses this comment:
https://github.com/xtermjs/xterm.js/pull/1327#discussion_r176109332
Drawing to a ctx with `{alpha: true}` causes the canvas API (on chrome
at least) to switch to grayscale AA, instead of RGB subpixel AA.
This fixes it by drawing to a ctx that's using `{alpha: false}` when
posisble, and switching to a ctx that's using `{alpha: true}` only when
we have to.
There were two bugs:
- We need to clear the background of _tmpCtx instead of just drawing on
top if the background color is transparent.
- We should set the background to fully transparent if it's partially
transparent, to avoid drawing the transparent background twice.
Nothing actually cares about the return value, so we can avoid depending
on `Promise` by not returning a promise.
This should make this work for IE11 (though I haven't tested that).
I tried this in Chrome and Firefox to test both codepaths (ImageBitmap
and HTMLCanvasElement).
Daniel Imms
Daniel Imms
Jeff Principe
Benjamin Woodruff