GdkDisplayManager: GDK 4 Reference Manual

GdkDisplayManager

GdkDisplayManager — Maintains a list of all open GdkDisplays

Functions

GdkDisplayManager *	gdk_display_manager_get ()
GdkDisplay *	gdk_display_manager_get_default_display ()
void	gdk_display_manager_set_default_display ()
GSList *	gdk_display_manager_list_displays ()
GdkDisplay *	gdk_display_manager_open_display ()
void	gdk_set_allowed_backends ()

Properties

GdkDisplay *

default-display

Read / Write

Signals

void

display-opened

Run Last

Types and Values

GdkDisplayManager

Object Hierarchy

    GObject
    ╰── GdkDisplayManager

Includes

#include <gdk/gdk.h>

Description

The purpose of the GdkDisplayManager singleton object is to offer notification when displays appear or disappear or the default display changes.

You can use gdk_display_manager_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.

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:

Backend-specific code

#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");

Functions

gdk_display_manager_get ()

GdkDisplayManager *
gdk_display_manager_get (void);

Gets the singleton GdkDisplayManager object.

When called for the first time, this function consults the GDK_BACKEND environment variable to find out which of the supported GDK backends to use (in case GDK has been compiled with multiple backends). Applications can use gdk_set_allowed_backends() to limit what backends can be used.

Returns

The global GdkDisplayManager singleton.

[transfer none]

gdk_display_manager_get_default_display ()

GdkDisplay *
gdk_display_manager_get_default_display
                               (GdkDisplayManager *manager);

Gets the default GdkDisplay.

Parameters

manager

a GdkDisplayManager

Returns

a GdkDisplay, or NULL if there is no default display.

[nullable][transfer none]

gdk_display_manager_set_default_display ()

void
gdk_display_manager_set_default_display
                               (GdkDisplayManager *manager,
                                GdkDisplay *display);

Sets display as the default display.

Parameters

manager	a GdkDisplayManager
display	a GdkDisplay

gdk_display_manager_list_displays ()

GSList *
gdk_display_manager_list_displays (GdkDisplayManager *manager);

List all currently open displays.

Parameters

manager

a GdkDisplayManager

Returns

a newly allocated GSList of GdkDisplay objects. Free with g_slist_free() when you are done with it.

[transfer container][element-type GdkDisplay]

gdk_display_manager_open_display ()

GdkDisplay *
gdk_display_manager_open_display (GdkDisplayManager *manager,
                                  const char *name);

Opens a display.

Parameters

manager	a GdkDisplayManager
name	the name of the display to open

Returns

a GdkDisplay, or NULL if the display could not be opened.

[nullable][transfer none]

gdk_set_allowed_backends ()

void
gdk_set_allowed_backends (const char *backends);

Sets a list of backends that GDK should try to use.

This can be useful if your application does not work with certain GDK backends.

By default, GDK tries all included backends.

For example,

1	gdk_set_allowed_backends ("wayland,quartz,*");

instructs GDK to try the Wayland backend first, followed by the Quartz backend, and then all others.

If the GDK_BACKEND environment variable is set, it determines what backends are tried in what order, while still respecting the set of allowed backends that are specified by this function.

The possible backend names are x11, win32, quartz, broadway, wayland. You can also include a * in the list to try all remaining backends.

This call must happen prior to gdk_display_open(), gtk_init(), or gtk_init_check() in order to take effect.

Parameters

backends

a comma-separated list of backends

Types and Values