We can have spurious wakeups in WaitEventTimeout() due to Wayland events
that don't end up causing us to generate an SDL event. Fortunately for us,
SDL_WaitEventTimeout_Device() handles this situation properly by calling
WaitEventTimeout() again with an adjusted timeout.
Wayland provides the prepare_read()/read_events() family of APIs for
reading from the display fd in a deadlock-free manner across multiple
threads in a multi-threaded application. Let's use those instead of
trying to roll our own solution using a mutex.
This fixes an issue where a call to SDL_GL_SwapWindow() doesn't swap
buffers if it happens to collide with SDL_PumpEvents() in the main
thread. It also allows coexistence with other code or toolkits in
our process that may want read and dispatch events themselves.
wl_display_dispatch() will block if there are no events available, and
while we try to avoid this by using SDL_IOReady() to verify there are
events before calling it, there is a race condition between
SDL_IOReady() and wl_display_dispatch() if multiple threads are
involved.
This is made more likely by the fact that SDL_GL_SwapWindow() calls
wl_display_dispatch() if vsync is enabled, in order to wait for frame
events. Therefore any program which pumps events on a different thread
from SDL_GL_SwapWindow() could end up blocking in one or other of them
until another event arrives.
This change fixes this by wrapping wl_display_dispatch() in a new mutex,
which ensures only one thread can compete for wayland events at a time,
and hence the SDL_IOReady() check should successfully prevent either
from blocking.
There were a few places throughout the SDL code where values were
clamped using SDL_min() and SDL_max(). Now that we have an SDL_clamp()
macro, use this instead.
This fixes a crash on pressing keyboard button when compositor sends
zero as repeat rate, indicating that key repeat should be disabled.
From Wayland protocol spec:
> Negative values for either rate or delay are illegal. A rate of zero
> will disable any repeating (regardless of the value of delay).
As of [1], SDL now compiles with a warning in SDL_waylandevents.c on
32-bit systems under gcc 10.3.0:
/tmp/SDL/src/video/wayland/SDL_waylandevents.c: In function 'seat_handle_capabilities':
/tmp/SDL/src/video/wayland/SDL_waylandevents.c:958:22: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
958 | SDL_AddTouch((SDL_TouchID)seat, SDL_TOUCH_DEVICE_DIRECT, "wayland_touch");
| ^
/tmp/SDL/src/video/wayland/SDL_waylandevents.c:964:22: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
964 | SDL_DelTouch((SDL_TouchID)seat);
| ^
This is due to SDL_TouchID always being 32-bit, but seat being a pointer
which is (obviously) only 32-bit on 32-bit systems. The conversion is
therefore harmless, so silence it with an extra cast via intptr_t.
This is what the cocoa backend does (and is similar to what the Win32
backend does, except with size_t).
Fixes: 03c19efbd1 ("Added support for multiple seats with touch input on Wayland")
[1]: 03c19efbd1
Wayland video subsystem uses a mix of libc and SDL function.
This patch switches libc functions to SDL ones and fixes a mismatch in memory
allocation/dealoccation of SDL_Cursor in SDL_waylandmouse.c (calloc on line 201
and SDL_free on line 313) which caused memory corruption if custom memory
allocator where provided to SDL.
There is no guarantee on what order the Wayland interfaces will come in, but the
callbacks were assuming that wl_data_device_manager would could before wl_seat.
This would cause certain desktops to not have any data_device to work with,
meaning certain features like the clipboard would silently no-op.
Note that this is purely to make it possible to enter text that requires
composition - for example, before this commit Kanji input didn't work at all.
The big problem this still has is that we need the window position, and this is
still not implemented. Once we have this information we can do the equivalent
of XTranslateCoordinates to put the rectangle where we want it.
Unlike Mutter and Sway, KWin actually checks the serial passed in
wl_pointer_set_cursor(). The serial provided is supposed to be the
serial of the pointer enter event, but We were always passing 0.
This caused KWin to drop our requests to hide the cursor.
Thanks to the KDE folks for spotting this in my debug logs.
Fixes#3576
SDL_SetKeyboardFocus(NULL) will lift any keys still pressed when keyboard focus
leaves the window, but then key repeat comes behind our backs and presses the
key down again. This results in an infinite stream of SDL_KEYDOWN events when
focus leaves the window with a key down (particularly noticeable with Alt+Tab).
Wayland compositors seem to have standardized on 10 units per "wheel tick" for
continuous scroll events, so we need to convert these axis values to ticks by
dividing by 10 before reporting them in SDL_MOUSEWHEEL events.
Hiding the cursor doesn't appear to work reliably on GNOME when another window
steals mouse focus right as we call SDL_ShowCursor(SDL_DISABLE). This can happen
when the keyboard shortcut inhibition permission prompt appears in response to a
call to SDL_SetRelativeMouseMode() with SDL_HINT_GRAB_KEYBOARD=1. The result is
that the default cursor is stuck locked in position and visible on screen
indefinitely.
By redrawing the cursor on pointer focus enter, the cursor now disappears upon
the first mouse motion event. It's not perfect but it's way better than the
current behavior.
Use zwp_keyboard_shortcuts_inhibit_manager_v1 to allow SDL applications
to capture system keyboard shortcuts like Alt+Tab when keyboard grab is
enabled via SDL_HINT_GRAB_KEYBOARD.
It is a protocol error to attempt to create a pointer confine (i.e.
`SDL_SetWindowGrab`) while a locked pointer is active, and vice-versa.
Instead of aborting due to a protocol error, this commit makes SDL
gracefully downgrade locked pointers to confines when appropriate.
Luis Caceres
The current handling of Wayland mouse pointer events only handles wl_pointer.axis events, which, according to the Wayland documentation, deal with mouse wheel scroll events on a continuous scale. While this is reasonable for some input sources (e.g. touchpad two-finger scrolling), it is not for mouse wheel clicks which generate wl_pointer.axis events with large deltas.
This patch adds handling for wl_pointer.axis_discrete and wl_pointer.frame events and prefers to report SDL_MouseWheelEvent in discrete units if they are available. This means that for mouse wheel scrolling we count in clicks, but for touchpad two-finger scrolling we still use whatever units Wayland uses. This behaviour is closer to that of the X11 backend.
Since these events are only available since version 5 of the wl_seat interface, this patch also checks for this and falls back to the previous behaviour if its not available. I also had to add definitions for some of the pointer and keyboard events specified in versions 2-5 but these are just stubs and do nothing.
M Stoeckl
To reproduce:
1. Run any SDL-based program with a Wayland compositor, orphaning it so that it doesn't have an immediate parent process. (For example, from a terminal, running `supertux2 & disown`.) The program should use the wayland backend, i.e. by setting environment variable SDL_VIDEODRIVER=wayland.
2. Kill the compositor process.
Results:
- The SDL program will keep running.
Expected results:
- The SDL program should close. (What close should mean here, I'm not sure - is injecting an SDL_Quit the appropriate action when a video driver disconnects?)
Build data:
2019-06-22, hg tip (12901:bf8d9d29cbf1), Linux, can reproduce with sway, weston, and other Wayland oompositors.
This happens if you try to lock the pointer and (caps & WL_SEAT_CAPABILITY_POINTER) is false
Leading to input->pointer being NULL which ends up bringing the wayland client down (at lease on weston)
Touch device types include SDL_TOUCH_DEVICE_DIRECT (a touch screen with window-relative coordinates for touches), SDL_TOUCH_DEVICE_INDIRECT_ABSOLUTE (a trackpad-style device with absolute device coordinates), and SDL_TOUCH_DEVICE_INDIRECT_RELATIVE (a trackpad-style device with screen cursor-relative coordinates).
Phone screens are an example of a direct device type. Mac trackpads are the indirect-absolute touch device type. The Apple TV remote is an indirect-relative touch device type.
Polling without wl_display_flush() never responds to ping requests.
In that case ping-pong works only on other events, such as user input
or on frame swapped.
From https://git.merproject.org/mer-core/libsdl/merge_requests/3
Original author: Alexander Akulich <a.akulich@omprussia.ru>
