All graphics drivers supporting cursor planes support ARGB8888,
the default cursor format, so this fallback is almost certainly
unused.
Essentially all cursor themes use alpha transparency to make it
clearer where relative to the screen content the cursor hotspot is.
It is better to fall back to a slightly slower software cursor than
it is to fall back to the opaque square that is a hardware cursor
without an alpha channel.
This change introduces new double buffered state to the wlr_output,
corresponding to the buffer format to render to.
The format being rendered to does not control the bit depth of colors
being sent to the display; it does generally determine the format with
which screenshot data is provided. The DRM backend _may_ sent higher
bit depths if the render format depth is increased, but hardware and
other limitations may apply.
Most (and possibly all) compositors using wlroots only ever render
fully opaque content. To provide better performance, this change
switches the default format used by wlr_output buffers from
ARGB8888 to the opaque XRGB8888.
Compositors like mutter, kwin, and weston already default to
XRGB8888, so this change is unlikely to expose any new bugs in
underlying drivers and hardware.
This does not affect the hardware cursor's buffer format, which is
still ARGB8888 by default.
As part of this change, the X11 backend (which does not support
changing format at runtime) now picks a true color, 24 bit depth
visual (i.e. XRGB8888) instead of a 32 bit depth (ARGB8888) one.
This makes it possible for the two functions using output_pick_format
(output_pick_cursor_format and output_create_swapchain) to select
different buffer formats.
The backend and renderer don't directly interact together, so there's
no point in checking that their buffer caps intersect. What we want to
check is that:
- The backend and allocator buffer caps are compatible, because the
backend consumes buffers to display them.
- The renderer and allocator buffer caps are compatible, because the
renderer imports buffers to sample them or render to them.
For instance, when running with the DRM backend and the Pixman renderer,
the (backend & renderer) check will fail because backend = DMABUF and
renderer = DATA_PTR.
Variables on the stack are released when the parent block is closed.
Here, `now` is used outside of the `if` block, causing the following
crash when starting Sway with the headless backend:
==49606==ERROR: AddressSanitizer: stack-use-after-scope on address 0x7fff94645f90 at pc 0x5558aeae9e29 bp 0x7fff94645df0 sp 0x7fff94645de0
READ of size 16 at 0x7fff94645f90 thread T0
#0 0x5558aeae9e28 in handle_present ../sway/desktop/output.c:834
#1 0x7fdc8d6792fb in wlr_signal_emit_safe ../subprojects/wlroots/util/signal.c:29
#2 0x7fdc8d54f77f in wlr_output_send_present ../subprojects/wlroots/types/output/output.c:766
#3 0x7fdc8d524a28 in output_commit ../subprojects/wlroots/backend/headless/output.c:71
#4 0x7fdc8d54d2db in wlr_output_commit ../subprojects/wlroots/types/output/output.c:629
#5 0x5558aeb013cb in output_render ../sway/desktop/render.c:1157
#6 0x5558aeae549e in output_repaint_timer_handler ../sway/desktop/output.c:544
#7 0x5558aeae5f8a in damage_handle_frame ../sway/desktop/output.c:606
#8 0x7fdc8d6792fb in wlr_signal_emit_safe ../subprojects/wlroots/util/signal.c:29
#9 0x7fdc8d6007d5 in output_handle_frame ../subprojects/wlroots/types/wlr_output_damage.c:44
#10 0x7fdc8d6792fb in wlr_signal_emit_safe ../subprojects/wlroots/util/signal.c:29
#11 0x7fdc8d54ee84 in wlr_output_send_frame ../subprojects/wlroots/types/output/output.c:720
#12 0x7fdc8d54efc3 in schedule_frame_handle_idle_timer ../subprojects/wlroots/types/output/output.c:728
#13 0x7fdc8c9dcf5a in wl_event_loop_dispatch_idle (/usr/lib/libwayland-server.so.0+0xaf5a)
#14 0x7fdc8c9dcfb4 in wl_event_loop_dispatch (/usr/lib/libwayland-server.so.0+0xafb4)
#15 0x7fdc8c9dabc6 in wl_display_run (/usr/lib/libwayland-server.so.0+0x8bc6)
#16 0x5558aeac8e30 in server_run ../sway/server.c:285
#17 0x5558aeac3c7d in main ../sway/main.c:396
#18 0x7fdc8be35b24 in __libc_start_main (/usr/lib/libc.so.6+0x27b24)
#19 0x5558aea8686d in _start (/home/simon/src/sway/build/sway/sway+0x33f86d)
This organizes the wlr_output implementation into separate files.
This avoids having a single mega-file with lots of unrelated parts
and makes it more obvious what the interactions between all the
parts are.
No functional changes, just moving code around.
Manuel Stoeckl
Simon Ser
Isaac Freund