class Gdk::DisplayManager


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

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

The GDK library can be built with support for multiple backends. The Gdk::DisplayManager 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 Gdk#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:

WARNING ⚠️ The following code is in c ⚠️

  if (GDK_IS_X11_DISPLAY (display))
      // make X11-specific calls here
  if (GDK_IS_MACOS_DISPLAY (display))
      // make Quartz-specific calls here
  g_error ("Unsupported GDK backend");

Defined in:



Class Method Summary

Instance Method Summary

Instance methods inherited from class GObject::Object

bind_property(source_property : String, target : GObject::Object, target_property : String, flags : GObject::BindingFlags) : GObject::Binding bind_property, bind_property_full(source_property : String, target : GObject::Object, target_property : String, flags : GObject::BindingFlags, transform_to : GObject::Closure, transform_from : GObject::Closure) : GObject::Binding bind_property_full, data(key : String) : Pointer(Void)? data, finalize finalize, freeze_notify : Nil freeze_notify, getv(names : Enumerable(String), values : Enumerable(_)) : Nil getv, notify(property_name : String) : Nil notify, notify_by_pspec(pspec : GObject::ParamSpec) : Nil notify_by_pspec, notify_signal notify_signal, property(property_name : String, value : _) : Nil property, qdata(quark : UInt32) : Pointer(Void)? qdata, ref_count : UInt32 ref_count, run_dispose : Nil run_dispose, set_data(key : String, data : Pointer(Void)?) : Nil set_data, set_property(property_name : String, value : _) : Nil set_property, steal_data(key : String) : Pointer(Void)? steal_data, steal_qdata(quark : UInt32) : Pointer(Void)? steal_qdata, thaw_notify : Nil thaw_notify, to_unsafe : Pointer(Void) to_unsafe, watch_closure(closure : GObject::Closure) : Nil watch_closure

Constructor methods inherited from class GObject::Object

cast(obj : GObject::Object) : self cast, cast?(obj : GObject::Object) : self? cast?, new(pointer : Pointer(Void), transfer : GICrystal::Transfer)
, newv(object_type : UInt64, parameters : Enumerable(GObject::Parameter)) : self newv

Class methods inherited from class GObject::Object

compat_control(what : UInt64, data : Pointer(Void)?) : UInt64 compat_control, g_type : UInt64 g_type, interface_find_property(g_iface : GObject::TypeInterface, property_name : String) : GObject::ParamSpec interface_find_property, interface_list_properties(g_iface : GObject::TypeInterface) : Enumerable(GObject::ParamSpec) interface_list_properties

Constructor Detail

def #

Initialize a new DisplayManager.

def*, default_display : Gdk::Display? = nil) #

Class Method Detail

def self.g_type : UInt64 #

Returns the type id (GType) registered in GLib type system.

def self.get : Gdk::DisplayManager #

Gets the singleton Gdk::DisplayManager 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 #allowed_backends= to limit what backends wil be used.

Instance Method Detail

def default_display : Gdk::Display? #

Gets the default Gdk::Display.

def default_display=(display : Gdk::Display) : Nil #

Sets @display as the default display.

def default_display=(value : Gdk::Display?) : Gdk::Display? #

def display_opened_signal #

def list_displays : GLib::SList #

List all currently open displays.

def open_display(name : String) : Gdk::Display? #

Opens a display.