DisplayManagerRef

public struct DisplayManagerRef : DisplayManagerProtocol, GWeakCapturing

The DisplayManagerRef type acts as a lightweight Swift reference to an underlying GdkDisplayManager instance. It exposes methods that can operate on this data type through DisplayManagerProtocol conformance. Use DisplayManagerRef only as an unowned reference to an existing GdkDisplayManager instance.

A singleton object that offers notification when displays appear or disappear.

You can use [funcGdk.DisplayManager.get] to obtain the GdkDisplayManager singleton, but that should be rarely necessary. Typically, initializing GTK opens a display that you can work with without ever accessing the GdkDisplayManager.

The GDK library can be built with support for multiple backends. The GdkDisplayManager object determines which backend is used at runtime.

In the rare case that you need to influence which of the backends is being used, you can use [funcGdk.set_allowed_backends]. Note that you need to call this function before initializing GTK.

Backend-specific code

When writing backend-specific code that is supposed to work with multiple GDK backends, you have to consider both compile time and runtime. At compile time, use the GDK_WINDOWING_X11, GDK_WINDOWING_WIN32 macros, etc. to find out which backends are present in the GDK library you are building your application against. At runtime, use type-check macros like GDK_IS_X11_DISPLAY() to find out which backend is in use:

`ifdef` GDK_WINDOWING_X11
  if (GDK_IS_X11_DISPLAY (display))
    {
      // make X11-specific calls here
    }
  else
`endif`
`ifdef` GDK_WINDOWING_MACOS
  if (GDK_IS_MACOS_DISPLAY (display))
    {
      // make Quartz-specific calls here
    }
  else
`endif`
  g_error ("Unsupported GDK backend");