Closes#4924.
Based on patches of the past, such as this work by James Cloos in July
2010:
d7d98751b7,
as well as code comments in the Perl module X11::Protocol::WM
(https://metacpan.org/pod/X11::Protocol::WM) and even the code to Xlib
itself, which taught me that we should never have been using
`XStoreName`, all it does is call `XChangeProperty`, hardcoded to
`XA_STRING`!
What can I say, when the task is old school, the sources are too 😂
This API and implementation comes from the Unreal Engine branch of SDL, which
originally called this "SDL_ConfineCursor".
Some minor cleanup and changes for consistency with the rest of SDL_video, but
there are two major changes:
1. The coordinate system has been changed so that `rect` is _window_ relative
and not _screen_ relative, making it easier to implement without having
global access to the display.
2. The UE version unset all rects when passing `NULL` as a parameter for
`window`, this has been removed as it was an unused feature anyhow.
Currently this is only implemented for X, but can be supported on Wayland and
Windows at minimum too.
This can give some performance boost, and save some resources, as there's no
reason to keep a copy of an SDL window's contents on the server: most SDL
apps are redrawing completely every frame, and the API allows for expose
events to tell an app a redraw is needed anyhow.
(And compositors are free to ignore this setting if it makes sense to do so,
according to the Xlib docs.)
Reference Issue #3776.
This adds SDL_SetWindowKeyboardGrab(), SDL_GetWindowKeyboardGrab(),
SDL_SetWindowMouseGrab(), SDL_GetWindowMouseGrab(), and new
SDL_WINDOW_KEYBOARD_GRABBED flag. It also updates the test harness to exercise
this functionality and makes a minor fix to X11 that I missed in
https://hg.libsdl.org/SDL/rev/02a2d609369b
To fit in with this new support, SDL_WINDOW_INPUT_CAPTURE has been renamed to
SDL_WINDOW_MOUSE_CAPTURE with the old name remaining as an alias for backwards
compatibility with older code.
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.
Wait up to 100 milliseconds, since the window manager might alter or
outright veto the window change...or not respond at all.
In a well-functioning system, though, this should help make sure
that SDL_SetWindowPosition's results match reality.
Fixes Bugzilla #4646.
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
Solra Bizna
I have written a program that, in the event that the user requests more MSAA samples than their hardware supports, attempts to gracefully fall back to the best MSAA available. This code works with my conventional OpenGL renderer, but if I change nothing about the code except to make it request an OpenGL ES profile instead, Xlib kills the program with an error that looks like:
X Error of failed request: BadWindow (invalid Window parameter)
Major opcode of failed request: 4 (X_DestroyWindow)
Resource id in failed request: 0x5c00008
Serial number of failed request: 188
Current serial number in output stream: 193
To trigger the bug, attempt to create a window with the SDL_WINDOW_OPENGL flag, with SDL_GL_CONTEXT_PROFILE_MASK set to SDL_GL_CONTEXT_PROFILE_ES, and with SDL_GL_MULTISAMPLESAMPLES set to any unsupported value. SDL_CreateWindow properly returns NULL, but at this point the program is already doomed. Xlib will shortly terminate the program with an error. Calling SDL_CreateWindow again will immediately trigger this termination.
I have attached a skeletal program that reproduces this bug for me. Replacing SDL_GL_CONTEXT_PROFILE_ES with SDL_GL_CONTEXT_PROFILE_COMPATIBILITY avoids the bug (but, obviously, doesn't create an OpenGL ES context).
As I suspected, the problem was with XDestroyWindow being called twice on the same window. The X11_CreateWindow function in src/video/x11/SDL_x11window.c calls SetupWindowData. If initialization fails after that point, XDestroyWindow gets called on the window by a subsequent call to X11_DestroyWindow. But, later in the same function, iff a GLES context is requested and initializing it fails, X11_XDestroyWindow (which wraps XDestroyWindow) is manually called. Shortly after, the intended call to X11_DestroyWindow occurs, which attempts to destroy the same window again. Boom.
(The above confusing summary involves three separate, similarly-named functions: XDestroyWindow, X11_DestroyWindow, X11_XDestroyWindow)
I have attached a simple patch that removes the redundant X11_XDestroyWindow calls. I've tested that XDestroyWindow still gets called for the windows in question, and that it only gets called once.
This can happen if a window is still grabbed when we try to move it, or if
the X11 ecosystem is just in a bad mood, I guess.
This makes sure that SDL will report the correct position for a window;
otherwise, SDL_GetWindowPosition will just report whatever the last
SDL_SetWindowPosition call requested, even if the window didn't actually move.
Fixes Bugzilla #4646.
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.
Callum McGing
This patch allows the user to disable the behaviour that blocks the compositor through a new hint: SDL_VIDEO_X11_NET_WM_BYPASS_COMPOSITOR. This allows tools or other windowed applications to behave properly under KWin.
This fixes a strange corner case (notes appended below), and should be
safe to do anyhow.
Fixes Bugzilla #3674.
"I did more tests.
It appears the bug only happens if there is
another window on the screen that has "always
on top" property. For me it is xawtv - it is
always opened in a screen corner. Closing
xawtv or removing "always on top" property
from it makes the problem to go away.
Plus, it doesn't appear like the buttons are
not delivered at all. It appears that instead
the button presses are delivered on some mouse
positions, but not delivered when you move the
mouse to other part of the window... So this is
really weird and is likely somewhere deep in the
Xorg.
Maybe somehow it happens that the cursor is
actually above the xawtv window, but, because
my app uses grab, it is not visible there, and
in that case the events are not delivered to
my app?
But with my patch the button events are
always delivered flawlessly, it seems.
Hmm, and that indeed seems to explain my problem:
if the mask is set properly and my app uses
grab, then, even if the mouse is above some
other window, the events would still be delivered
to the grabbing app, which is what actually wanted
because my app uses relative mouse mode, so it
doesn't know the pointer can cross some other window
(my app draws the pointer itself).
So my current theory is that my patch only enforces
the mouse grab, which otherwise can be tricked by
some other window preventing the button events
delivery (but motion events are still delivered
via xinput2, which makes it all look very obscure)."
Alvin
I'm interested in this bug as well. I have experienced it when trying to embed an SDL_Window into a FLTK application. To do this, I create a FLTK window (window inside a window - think video player) and then use SDL_CreateWindowFrom() on the inner most window's Xlib Window*. After which, I create a renderer.
In my situation I am using the FLTK GUI toolkit.
What I have experienced is that the SDL_CreateRender() will recreate the window in order to properly setup OpenGL capability. As part of this process, the window is hidden and a call is executed that waits indefinitely for an acknowledgement that the window was indeed unmapped. This is where my program hangs.
Please correct me if I am wrong, but should SDL2 not make Xlib calls that effect the Xlib Window in this situation (e.g. When SDL_CreateWindowFrom() is used)? The toolkit being used typically assumes responsibility and, I presume, tracks all Xlib Windows it creates.
On line src/video/SDL_video.c:1372 the comment associated with setting SDL_WINDOW_FOREIGN reads:
/* Can't destroy and re-create foreign windows, hrm */
Since I do not know the reason for hiding the window in the first place, the attached patch simply does not wait for a response when X11_XWithdrawWindow() and X11_XMapRaised() are issued by X11_HideWindow() and X11_ShowWindow(), respectively. I presume that the GUI toolkit (GTK, FLTK, etc.) has or will consume the acknowledging event as it is managing the Xlib Window (or it thinks it is).
I have tested the patch against hg 5c645d037de2 and I have successfully tested:
* Embedding the SDL_Window inside a FLTK application.
* Calling SDL_SetWindowSize() when FLTK resizes the window (e.g. dragging cursor on the edge of the window).
* Filling the renderer's default target blue and drawing a red fill square at the centre (exciting, I know!)
* Calling SDL_Quit() when the application terminates
I do not receive any Xlib erorr messages (BadWindow, etc.) in any of those situations.
Jason Wyatt
After hiding the window, SDL_WINDOW_HIDDEN/SDL_WINDOW_SHOWN flags on a window are correctly updated. However on the next SDL_PumpEvents, they are set incorrectly.
This appears to be because X11_GetNetWMState does not check whether the _NET_WM_STATE property exists (it shouldn't on unmapped windows, see https://specifications.freedesktop.org/wm-spec/wm-spec-1.3.html#idm140130317598336). This results in an empty list of atoms for the state, which would imply that the window is not hidden.
(Seen on Fedora 24, Gnome)
--
Dan Ginsburg
More details on my proposed patch: I am on Kubuntu 16.04.2. I ran into this same bug, but with Jason's patch I found that actualType != None was true so the SDL_WINDOW_HIDDEN would still not be set. My fix instead is to explicitly check for whether the window is unmapped rather than relying on the returned values in XGetWindowProperty.
The Xlib documentation demands that 32-bit values here be passed in a long,
even when long itself isn't a 32-bit value. Otherwise libx11 might read
memory incorrectly.
Fixes Bugzilla #3692.
