When we receive an XTGETTCAP query, where the capability is not
correctly hex encoded, ignore it.
Before this patch, we echo:ed it back to the TTY inside an error
resonse.
Images with an aspect ratio of 1:1 are by far the most common (though
not the default).
It makes a lot of sense, performance wise, to special case
them.
Specifically, the sixel_add() function benefits greatly from this, as
it is the inner most, most heavily executed function when parsing a
sixel image.
sixel_add_many() also benefits, since allows us to drop a
multiplication. Since sixel_add_many() always called first (no other
call sites call sixel_add() directly), this has a noticeable effect on
performance.
Another thing that helps (though not as much), and not specifically
with AR 1:1 images, is special casing DECGRI a bit.
Up until now, it simply updated the current sixel parameter value. The
problem is that the default parameter value is 0. But, a value of 0
should be treated as 1. By adding a special ‘repeat_count’ variable to
the sixel struct, we can initialize it to ‘1’ when we see DECGRI, and
then simply overwrite it as the parameter value gets updated. This
allows us to drop an if..else when emitting the sixel.
If a request handler doesn’t define its own put() handler, simply drop
all DCS parameter data. This way, we won’t end up allocating
potentially large buffers for unsupported/unimplemented DCS requests.
Closes#959
This could be triggered by running, for example:
printf '\033P$qrxyz\033\\'
...which would cause a memcmp() of 4 bytes on a 2 byte string literal.
Fixes: #960
This patch adds support for DECRQSS (request Selection or Setting),
for the following sub-queries:
* DECSTBM Set Top and Bottom Margins
* SGR Set Graphic Rendition
* DECSCUSR Set Cursor Style
Closes#798
Having the builtin terminfo DB as a table, with one entry per
capability/value pair was ineffective memory-wise - we ended up adding
~20K to the final binary size.
This patch changes the internal representation from a table, to a
single NULL-separated (and NULL-terminated) char array:
cap1-name \0 cap1-value \0 cap2-name \0 cap2-value \0
The capabilities are still sorted; to lookup a capability we need to
scan from the beginning until we either find a match, or until the
capabilities from the DB sort higher (lexicographically) than the
searched-for capability.
The terminfo char array is 3.3K - more better than before.
We emit one DCS reply for each queried capability (like Kitty, but
unlike XTerm), as this allows us to a) not skip any capabilities in
the query, and b) reply with correct success/fail flag for each
capability.
We do not batch the entire reply - as soon as the reply for _one_
capability is done, we write it to the PTY.
Closes#846
When P2=1, empty pixels are transparent.
This patch also changes the behavior of P2=0|2, from setting empty
pixels to the default background color, to instead use the *current*
background color.
To implement this, a couple of changes are needed:
* Sixel pixels always use alpha=1.0, except for *empty* cells when
P2=1 (i.e. transparent pixels).
* The renderer draws sixels with the OVER operator, instead of the SRC
operator.
* The renderer *must* now render the cells beneath the sixel. As an
optimization, this is only done for sixels where P2=1. I.e. for
fully opaque sixels, there’s no need to render the cells beneath.
The sixel renderer isn’t yet hooked into the multi-threaded
renderer. This means *rows* (not just the cells) beneath
maybe-transparent sixels are rendered single-threaded.
Closes#391.
Take ‘\E(#0’ for example - this is *not* the same as ‘\E(0’.
Up until now, foot has however treated them as the same escape,
because the handler for ‘\E(0’ didn’t verify there weren’t any _other_
private characters present.
Fix this by turning the ‘private’ array into a single 4-byte
integer. This allows us to match *all* privates with a single
comparison.
Private characters are added to the LSB first, and MSB last. This
means we can check for single privates in pretty much the same way as
before:
switch (term->vt.private) {
case ‘?’:
...
break;
}
Checking for two (or more) is much uglier, but foot only supports
a *single* escape with two privates, and no escapes with three or
more:
switch (term->vt.private) {
case 0x243f: /* ‘?$’ */
...
break;
}
The ‘clear’ action remains simple (and fast), with a single write
operation.
Collecting privates is potentially _slightly_ more complex than
before; we now need mask and compare, instead of simply comparing,
when checking how many privates we already have.
We _could_ add a counter, which would make collecting privates easier,
but this would add an additional write to the ‘clean’ action which is
really bad since it’s in the hot path.
This implements basic parsing of sixel data. Lots of limitations and
temporary solutions as this is still work-in-progress:
* Maximum image size hardcoded to 800x800
* No HLS color format support
* Image is always rendered at 0x0 in the terminal
Add data structure to term->vt. This structure tracks the free-form
data that is passed-through, and the handler to call at the end.
Intermediates and parameters are collected by the normal VT
parser. Then, when we enter the passthrough state, we call dcs_hook().
This function checks the intermediate(s) and parameters, and selects
the appropriate unhook handler (and optionally does some execution
already).
In passthrough mode, we simply append strings to an internal
buffer. This might have to be changed in the future, if we need to
support a DCS that needs to execute as we go.
In unhook (i.e. when the DCS is terminated), we execute the unhook
handler.
As a proof-of-concept, handlers for BSU/ESU (Begin/End Synchronized
Update) has been added (but are left unimplemented).
