When `printimage` is invoked without `-w` or `-h`, we now preserve the
aspect ratio of each input image when scaling it to fit in the window.
A new flag `-i` ignores the aspect ratio, recovering the old behavior
when neither `-w` nor `-h` is passed. When `-i` is passed alongside
exactly one of `-w` or `-h`, the other dimension is just taken from the
window size, ignoring aspect ratio.
We also unconditionally print a newline between images to prevent them
from overlapping.
wchargin-branch: printimage-fit
wchargin-source: 4c2cfcffe9ce1a3b30c0ff051e3c6a2c166ae1c7
We now rewrite the binary image at runtime on Windows and XNU to change
mov %fs:0,%reg instructions to use %gs instead. There's also simpler
threading API introduced by this change and it's called _spawn() and
_join(), which has replaced most clone() usage.
The patch in #469 was buggy for images where the start of a row matched
the end of the previous row. We don't re-issue the `setbgfg` ANSI codes
when we think that the color hasn't changed. But by sending an `\e[0m`
sequence at the end of the line without updating `bg` or `fg`, we
desynced `bg` and `fg` from the actual ANSI state. Now, we simply follow
that line-terminating `\e[0m` with another `setbgfg` call.
This bug was visible in images with a constant-color matte border:
![Screenshot of `printimage` output before and after this commit when
run on `lemurs.png` and `lemursborder.png`, where `lemursborder.png` has
a thick blue border around the outside of the image. Both versions look
fine for `lemurs.png`. For `lemursborder.png`, the "before" version has
a chess board pattern for the left border (except for the first row) and
the bottom border. The "after" version looks correct.][ss]
[ss]: https://user-images.githubusercontent.com/4317806/178120511-c1b89348-2376-4bf2-a2d3-8723d2663bd4.png
Fixes: 85aecbda67 ("ttyraster: reset ANSI attributes after each line (#469)")
wchargin-branch: ttyraster-restore-each-line
wchargin-source: 621a788cfa0a87ce360e142a6004e325cca70caa
