Learning_GTK4_tree/docs/reference/gdk/wayland.md

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Title: Wayland Interaction
## Wayland backend-specific functions
The functions in this section are specific to the GDK Wayland backend.
To use them, you need to include the `<gdk/wayland/gdkwayland.h>` header and
use the Wayland-specific pkg-config `gtk4-wayland` file to build your
application.
## Checking for the Wayland backend
GDK can be built with support for multiple backends, which means you will
need to perform both compile time *and* run time checks if you wish to call
backend-specific API; for instance, the code sample below will guard the
calls to different backends, and error out on unsupported windowing systems:
```c
#ifdef GDK_WINDOWING_WAYLAND
#include <gdk/wayland/gdkwayland.h>
#endif
#ifdef GDK_WINDOWING_X11
#include <gdk/x11/gdkx.h>
#endif
#ifdef GDK_WINDOWING_WAYLAND
if (GDK_IS_WAYLAND_DISPLAY (display))
{
// make Wayland-specific calls here
}
else
#endif
#ifdef GDK_WINDOWING_X11
if (GDK_IS_X11_DISPLAY (display))
{
// make X11-specific calls here
}
else
#endif
g_error ("Unsupported GDK backend");
```
The compile time check is performed by using the `GDK_WINDOWING_*`
pre-processor symbols; there is one defined for each windowing system
backend built into GDK. For Wayland, the symbol is `GDK_WINDOWING_WAYLAND`.
The run time check is performed by looking at the type of the
[class@Gdk.Display] object. For Wayland, the display objects will be of type
`GdkWaylandDisplay`.