This represents an essentially complete rewrite of ncvisual and associated code. It had two major goals:
Improve the ncvisual API based off lessons learned, pursuant to the upcoming API freeze. In particular, I wanted to:
decouple ncvisuals from ncplanes. It should be possible to render a ncvisual to multiple planes, with different scaling each time. It should be possible to create an ncvisual without a plane, etc.
normalize the various ways of constructing an ncvisual -- file, memory, plane, etc.
Support multiple blitters, from 7-bit ASCII to Sixel. This required writing the blitters in several cases, and they're not yet in their final implementations (but the API is fine)
I have not yet unified Plots and Visuals, and might not, given that the Plot code works fine. We could at this point implement Plots in terms of Visuals, though -- the blitter backend range has been unified. Sixel is not yet implemented, though it is listed.
There is a new POC tool, blitter. It renders its arguments using all possible blitter+scaling combinations. Another new POC, resize, displays its argument, then resizes it to the screen size and displays that, explicitly making use of ncvisual_resize() rather than a scaling parameter to ncvisual_render().
This also eliminates some memory leaks and bugs we were seeing in trunk, and brings in Sixel scaffolding.
The C++ wrapper will also need patching back up; I cut most of it down while wrestling with this crap, urk.
Closes#638, #562, and #622.
Replace the singly-linked z-axis with a doubly-linked list,
and reimplement all z-axis moves as O(1) functions.
Eliminate ncplane_move_{above/below}_unsafe(), as there are no
longer unsafe moves.
* normal/visual: need dup stdplane for rotate
* add ncplane_center(), unit tests
* ncplane_center_abs(): add, unit tests
* ncvisual_bounding_box() for #599
* ncvisual_rotate(): works via bounding box #599
* normal demo: comment out broken section
* rotate: resize underlying plane as needed #599
* ncvisual_rotate: support negative rads #599
Unify ffmpeg/oiio/null implementations, where possible. This effectively
required placing all three in the same file, which meant they're all now
C++. Update FFmpeg implemenation to be C++-usable. Implement
ncvisual_rotate_cw() and ncvisual_rotate_ccw() #515. Move most of tetris
over to Visual from Plane #558. Add bgra_to_rgba(), necessary for
creating ncvisual from BGRA memory. Implement ncvisual_from_rgba()
and ncvisual_from_bgra() #557. Add unit tests on ncvisual rotation.
We need support three distinct paths for destruction of
ncsubprocs: (1) external call to ncsubproc_destroy() while
the subprocess is running, (2) external call to
ncsubproc_destroy() after the subprocess has terminated, and
(3) internal call to ncsubproc_destroy() without any external
call. To do this properly, we always waitid() on the subprocess
in our ncsubproc thread, and do not cancel said thread. This
guarantees that the subprocess has been reaped if the thread
has exited. We throw a pidfd_send_signal() into the thread
prior to the waitid(), because this is safe with pidfds. The
thread reclaims no resources otherwise. ncsubproc_destroy(),
instead, reclaims them, after joining the ncsubproc thread.
It sends SIGKILL before the join, which is once again safe
thanks to pidfds. Resolves#552.
