When possible use native os functions to make a blocking call waiting for
an incoming event. Previous behavior was to continuously poll the event
queue with a small delay between each poll.
The blocking call uses a new optional video driver event,
WaitEventTimeout, if available. It is called only if an window
already shown is available. If present the window is designated
using the variable wakeup_window to receive a wakeup event if
needed.
The WaitEventTimeout function accept a timeout parameter. If
positive the call will wait for an event or return if the timeout
expired without any event. If the timeout is zero it will
implement a polling behavior. If the timeout is negative the
function will block indefinetely waiting for an event.
To let the main thread sees events sent form a different thread
a "wake-up" signal is sent to the main thread if the main thread
is in a blocking state. The wake-up event is sent to the designated
wakeup_window if present.
The wake-up event is sent only if the PushEvent call is coming
from a different thread. Before sending the wake-up event
the ID of the thread making the blocking call is saved using the
variable blocking_thread_id and it is compared to the current
thread's id to decide if the wake-up event should be sent.
Two new optional video device methods are introduced:
WaitEventTimeout
SendWakeupEvent
in addition the mutex
wakeup_lock
which is defined and initialized but only for the drivers supporting the
methods above.
If the methods are not present the system behaves as previously
performing a periodic polling of the events queue.
The blocking call is disabled if a joystick or sensor is detected
and falls back to previous behavior.
This gives us flexibility to add others hints to control keyboard grab behavior
without having to touch all of the backends. It also allows us to possibly
expose keyboard grab separately from mouse grab for applications that want to
manage those independently.
Instead of creating an X11 connection to test that X11 is available,
closing the connection, and then reconnecting for real, use the same
connection to handle both cases.
The X11 connection retry delay mechanism in the case where X11 is
dynamically loaded has been removed. It was only necessary to avoid
authetnication token reuse from the XOpenDisplay call that used to
exist in X11_Available. Now that this call is only made once, it
is no longer needed.
Also drop unused and inapplicable code from a comment.
***
The two are only ever called together, and combining them makes it possible
to eliminate redundant symbol loading and redundant attempts to connect
to a display server.
Martin Fiedler
To be precise, this is about *desktop OpenGL* on X11. For OpenGL ES, EGL is already used (as it's the only way to get an OpenGL ES context), as Sylvain noted above.
To shine some light on why this is needed:
In 99% of all cases, using GLX on X11 is fine, even though it's effectively deprecated in favor of EGL [1]. However, there's at least one use case that *requires* the OpenGL context being created with EGL instead of GLX, and that's DRM_PRIME interoperability: The function glEGLImageTargetTexture2DOES simply doesn't work with GLX. (Currently, Mesa actually crashes when trying that.)
Some example code:
https://gist.github.com/kajott/d1b29c613be30893c855621edd1f212e
Runs on Intel and open-source AMD drivers just fine (others unconfirmed), but with #define USE_EGL 0 (i.e. forcing it to GLX), it crashes. The same happens when using SDL for window and context creation.
The good news is that most of the pieces for EGL support on X11 are already in place: SDL_egl.c is pretty complete (and used for desktop OpenGL on Wayland, for example), and SDL_x11opengl.c has the aforementioned OpenGL-ES-on-EGL support. However, when it comes to desktop OpenGL, it's hardcoded to fall back to GLX.
I'm not advocating to make EGL the default for desktop OpenGL on X11; don't fix what ain't broken. But something like an SDL_HINT_VIDEO_X11_FORCE_EGL would be very appreciated to make use cases like the above work with SDL.
[1] source: Eric Anholt, major Linux graphics stack developer, 7 years ago already - see last paragraph of https://www.phoronix.com/scan.php?page=news_item&px=MTE3MTI
First: disable d'n'd events by default; most apps don't need these at all, and
if an app doesn't explicitly handle these, each drop on the window will cause
a memory leak if the events are enabled. This follows the guidelines we have
for SDL_TEXTINPUT events already.
Second: when events are enabled or disabled, signal the video layer, as it
might be able to inform the OS, causing UI changes or optimizations (for
example, dropping a file icon on a Cocoa app that isn't accepting drops will
cause macOS to show a rejection animation instead of the drop operation just
vanishing into the ether, X11 might show a different cursor when dragging
onto an accepting window, etc).
Third: fill in the drop event details in the test library and enable the
events in testwm.c for making sure this all works as expected.
malferit
Hello, I began a little program with SDL2 on Linux in C, and when I call SDL_Init(SDL_INIT_VIDEO) I get an error and this is printed in the console:
XDM authorization key matches an existing client!
I searched through Internet, and found that some people suggest to run 'xhost +' or to specify this in /etc/X11/xdm/xdm-config:
DisplayManager*authName: MIT-MAGIC-COOKIE-1
I don't think an end user needs to know that...
But what bothered me is that first I started this little program in Pascal using the Freepascal compiler and it works. In freepascal you only use some thin header bindings in Pascal and then it links with the dynamic SDL library, so I don't understood why it worked with Freepascal and not in C.
I run ldd to the two generated applications:
Application in C:
linux-gate.so.1 (0xffffe000)
libSDL2-2.0.so.0 => /usr/lib/libSDL2-2.0.so.0 (0xb76ac000)
libpthread.so.0 => /lib/libpthread.so.0 (0xb766e000)
libc.so.6 => /lib/libc.so.6 (0xb74e2000)
libm.so.6 => /lib/libm.so.6 (0xb74a0000)
libdl.so.2 => /lib/libdl.so.2 (0xb749a000)
librt.so.1 => /lib/librt.so.1 (0xb7491000)
/lib/ld-linux.so.2 (0xb77b3000)
Application compiled with Freepascal:
linux-gate.so.1 (0xffffe000)
libSDL2-2.0.so.0 => /usr/lib/libSDL2-2.0.so.0 (0xb762a000)
libX11.so.6 => /usr/lib/libX11.so.6 (0xb74f3000)
libc.so.6 => /lib/libc.so.6 (0xb7367000)
libm.so.6 => /lib/libm.so.6 (0xb7325000)
libdl.so.2 => /lib/libdl.so.2 (0xb731f000)
libpthread.so.0 => /lib/libpthread.so.0 (0xb7305000)
librt.so.1 => /lib/librt.so.1 (0xb72fc000)
libxcb.so.1 => /usr/lib/libxcb.so.1 (0xb72dc000)
libXau.so.6 => /usr/lib/libXau.so.6 (0xb72d9000)
libXdmcp.so.6 => /usr/lib/libXdmcp.so.6 (0xb72d3000)
/lib/ld-linux.so.2 (0xb7755000)
It seems that Freepascal is linking with libX11, libxcb, libXau and libXdmcp .
Linking my C application with libxcb solved the problem (linking with libXau and/or libXdmcp without libxcb didn't work). Linking with X11 links all the other libraries and works as well.
So I fill this bug report mainly to let you know about this. I don't know if it is a problem that can be solved on the libSDL side or not, but at least I hope it will help.
Hi, some tests:
1. Disabled XDM. Login in console and running 'startx'. The program works without having to link with X11.
2. Enabled XDM. Added 'DisplayManager*authName: MIT-MAGIC-COOKIE-1' to /etc/X11/xdm/xdm-config.The program works without having to link with X11.
3. Enabled XDM without 'DisplayManager*authName: MIT-MAGIC-COOKIE-1' in /etc/X11/xdm/xdm-config . I get the authentication error unless I link with X11.
Now the clipboard isn't lost if you destroy a specific SDL_Window, as it
works on other platforms. You will still lose the clipboard data on
SDL_Quit() or process termination, but that's X11 for you; run a
Clipboard Manager daemon.
Fixes Bugzilla #3222.
Fixes Bugzilla #3718.
Volumetric
In X11 the SDL error "Unknown touch device" can occur after which the application stops recognizing touch events. For a kiosk-type application this results in a hang as far as the user is concerned. This is reproducible on HP Z220/Z230/Z240 workstations by swapping USB cables for a while and it also occurs with no physical changes, probably due to USB device power management. A workaround is to make SDL re-enumerate the touch devices like it does at startup. A patch is attached.
- Cache the _NET_FRAME_EXTENTS data locally, so we don't have to query
the X server for them (instead, we update our cached data when PropertyNotify
events alert us to a change).
- Use our cached extents for X11_GetWindowBordersSize(), so it's a fast call.
- Window position was meant to refer to the client area, not the window
decorations, so adjust appropriately when getting/setting the position.
This is for corner cases where a multi-window app is activated and wants to
make a decision about where focus should go.
This patch came from Unreal Engine 4's fork of SDL, compliments of Epic Games.
This is currently implemented for X11, Cocoa, Windows, and DirectFB.
This patch is based on work in Unreal Engine 4's fork of SDL,
compliments of Epic Games.
Specifically: always on top, skip taskbar, tooltip, utility, and popup menu.
This is currently only implemented for X11.
This patch is based on work in Unreal Engine 4's fork of SDL,
compliments of Epic Games.
The internal function SDL_EGL_LoadLibrary() did not delete and remove a mostly
uninitialized data structure if loading the library first failed. A later try to
use EGL then skipped initialization and assumed it was previously successful
because the data structure now already existed. This led to at least one crash
in the internal function SDL_EGL_ChooseConfig() because a NULL pointer was
dereferenced to make a call to eglBindAPI().
