## GdkDisplay

GdkDisplay — Controls the keyboard/mouse pointer grabs and a set of GdkScreens

## Synopsis

    #include <gdk/gdk.h>

    struct      GdkDisplay;
    GdkDisplay* gdk_display_open                (const gchar *display_name);
    GdkDisplay* gdk_display_get_default         (void);
    G_CONST_RETURN gchar* gdk_display_get_name  (GdkDisplay *display);
    gint        gdk_display_get_n_screens       (GdkDisplay *display);
    GdkScreen*  gdk_display_get_screen          (GdkDisplay *display,
                                                 gint screen_num);
    GdkScreen*  gdk_display_get_default_screen  (GdkDisplay *display);
    void        gdk_display_pointer_ungrab      (GdkDisplay *display,
                                                 guint32 time_);
    void        gdk_display_keyboard_ungrab     (GdkDisplay *display,
                                                 guint32 time_);
    gboolean    gdk_display_pointer_is_grabbed  (GdkDisplay *display);
    void        gdk_display_beep                (GdkDisplay *display);
    void        gdk_display_sync                (GdkDisplay *display);
    void        gdk_display_flush               (GdkDisplay *display);
    void        gdk_display_close               (GdkDisplay *display);
    GList*      gdk_display_list_devices        (GdkDisplay *display);
    GdkEvent*   gdk_display_get_event           (GdkDisplay *display);
    GdkEvent*   gdk_display_peek_event          (GdkDisplay *display);
    void        gdk_display_put_event           (GdkDisplay *display,
                                                 GdkEvent *event);
    void        gdk_display_add_client_message_filter
                                                (GdkDisplay *display,
                                                 GdkAtom message_type,
                                                 GdkFilterFunc func,
                                                 gpointer data);
    void        gdk_display_set_double_click_time
                                                (GdkDisplay *display,
                                                 guint msec);
    void        gdk_display_set_double_click_distance
                                                (GdkDisplay *display,
                                                 guint distance);
    void        gdk_display_get_pointer         (GdkDisplay *display,
                                                 GdkScreen **screen,
                                                 gint *x,
                                                 gint *y,
                                                 GdkModifierType *mask);
    GdkWindow*  gdk_display_get_window_at_pointer
                                                (GdkDisplay *display,
                                                 gint *win_x,
                                                 gint *win_y);
    struct      GdkDisplayPointerHooks;
    GdkDisplayPointerHooks* gdk_display_set_pointer_hooks
                                                (GdkDisplay *display,
                                                 const GdkDisplayPointerHooks *new_hooks);
    gboolean    gdk_display_supports_cursor_color
                                                (GdkDisplay *display);
    gboolean    gdk_display_supports_cursor_alpha
                                                (GdkDisplay *display);
    guint       gdk_display_get_default_cursor_size
                                                (GdkDisplay *display);
    void        gdk_display_get_maximal_cursor_size
                                                (GdkDisplay *display,
                                                 guint *width,
                                                 guint *height);
    GdkWindow*  gdk_display_get_default_group   (GdkDisplay *display);

## Object Hierarchy

      GObject
       +----GdkDisplay

## Signal Prototypes

    "closed"    void        user_function      (GdkDisplay *display,
                                                gboolean is_error,
                                                gpointer user_data);

## Description

GdkDisplay objects purpose are two fold:

- To grab/ungrab keyboard focus and mouse pointer

- To manage and provide information about the GdkScreen(s) available for this GdkDisplay

GdkDisplay objects are the GDK representation of the X Display which can be described as a workstation consisting of a keyboard a pointing device (such as a mouse) and one or more screens. It is used to open and keep track of various GdkScreen objects currently instanciated by the application. It is also used to grab and release the keyboard and the mouse pointer.

## Details

### struct GdkDisplay

    struct GdkDisplay;

The GdkDisplay struct is the GDK representation of an X display. All its fields are private and should not be accessed directly.

Since 2.2

### gdk_display_open ()

    GdkDisplay* gdk_display_open                (const gchar *display_name);

Opens a display.

`display_name` : | the name of the display to open
Returns : | a GdkDisplay, or `NULL` if the display could not be opened.

Since 2.2

### gdk_display_get_default ()

    GdkDisplay* gdk_display_get_default         (void);

Gets the default GdkDisplay. This is a convenience function for:

      gdk_display_manager_get_default_display (gdk_display_manager_get())

Returns : | a GdkDisplay, or `NULL` if there is no default display.

Since 2.2

### gdk_display_get_name ()

    G_CONST_RETURN gchar* gdk_display_get_name  (GdkDisplay *display);

Gets the name of the display.

`display` : | a GdkDisplay
Returns : | a string representing the display name. This string is owned by GDK and should not be modified or freed.

Since 2.2

### gdk_display_get_n_screens ()

    gint        gdk_display_get_n_screens       (GdkDisplay *display);

Gets the number of screen managed by the `display`.

`display` : | a GdkDisplay
Returns : | number of screens.

Since 2.2

### gdk_display_get_screen ()

    GdkScreen*  gdk_display_get_screen          (GdkDisplay *display,
                                                 gint screen_num);

Returns a screen object for one of the screens of the display.

`display` : | a GdkDisplay
`screen_num` : | the screen number
Returns : | the GdkScreen object

Since 2.2

### gdk_display_get_default_screen ()

    GdkScreen*  gdk_display_get_default_screen  (GdkDisplay *display);

Get the default GdkScreen for `display`.

`display` : | a GdkDisplay
Returns : | the default GdkScreen object for `display`

Since 2.2

### gdk_display_pointer_ungrab ()

    void        gdk_display_pointer_ungrab      (GdkDisplay *display,
                                                 guint32 time_);

Release any pointer grab.

`display` : | a GdkDisplay.
`time_` : | a timestap (e.g. GDK_CURRENT_TIME).

Since 2.2

### gdk_display_keyboard_ungrab ()

    void        gdk_display_keyboard_ungrab     (GdkDisplay *display,
                                                 guint32 time_);

Release any keyboard grab

`display` : | a GdkDisplay.
`time_` : | a timestap (e.g GDK_CURRENT_TIME).

Since 2.2

### gdk_display_pointer_is_grabbed ()

    gboolean    gdk_display_pointer_is_grabbed  (GdkDisplay *display);

Test if the pointer is grabbed.

`display` : | a GdkDisplay
Returns : | `TRUE` if an active X pointer grab is in effect

Since 2.2

### gdk_display_beep ()

    void        gdk_display_beep                (GdkDisplay *display);

Emits a short beep on `display`

`display` : | a GdkDisplay

Since 2.2

### gdk_display_sync ()

    void        gdk_display_sync                (GdkDisplay *display);

Flushes any requests queued for the windowing system and waits until all requests have been handled. This is often used for making sure that the display is synchronized with the current state of the program. Calling `gdk_display_sync()` before `gdk_error_trap_pop()` makes sure that any errors generated from earlier requests are handled before the error trap is removed.

This is most useful for X11. On windowing systems where requests are handled synchronously, this function will do nothing.

`display` : | a GdkDisplay

Since 2.2

### gdk_display_flush ()

    void        gdk_display_flush               (GdkDisplay *display);

Flushes any requests queued for the windowing system; this happens automatically when the main loop blocks waiting for new events, but if your application is drawing without returning control to the main loop, you may need to call this function explicitely. A common case where this function needs to be called is when an application is executing drawing commands from a thread other than the thread where the main loop is running.

This is most useful for X11. On windowing systems where requests are handled synchronously, this function will do nothing.

`display` : | a GdkDisplay

Since 2.4

### gdk_display_close ()

    void        gdk_display_close               (GdkDisplay *display);

Closes the connection to the windowing system for the given display, and cleans up associated resources.

`display` : | a GdkDisplay

Since 2.2

### gdk_display_list_devices ()

    GList*      gdk_display_list_devices        (GdkDisplay *display);

Returns the list of available input devices attached to `display`. The list is statically allocated and should not be freed.

`display` : | a GdkDisplay
Returns : | a list of GdkDevice

Since 2.2

### gdk_display_get_event ()

    GdkEvent*   gdk_display_get_event           (GdkDisplay *display);

Gets the next GdkEvent to be processed for `display`, fetching events from the windowing system if necessary.

`display` : | a GdkDisplay
Returns : | the next GdkEvent to be processed, or `NULL` if no events are pending. The returned GdkEvent should be freed with `gdk_event_free()`.

Since 2.2

### gdk_display_peek_event ()

    GdkEvent*   gdk_display_peek_event          (GdkDisplay *display);

Gets a copy of the first GdkEvent in the `display`'s event queue, without removing the event from the queue. (Note that this function will not get more events from the windowing system. It only checks the events that have already been moved to the GDK event queue.)

`display` : | a GdkDisplay
Returns : | a copy of the first GdkEvent on the event queue, or `NULL` if no events are in the queue. The returned GdkEvent should be freed with `gdk_event_free()`.

Since 2.2

### gdk_display_put_event ()

    void        gdk_display_put_event           (GdkDisplay *display,
                                                 GdkEvent *event);

Appends a copy of the given event onto the front of the event queue for `display`.

`display` : | a GdkDisplay
`event` : | a GdkEvent.

Since 2.2

### gdk_display_add_client_message_filter ()

    void        gdk_display_add_client_message_filter
                                                (GdkDisplay *display,
                                                 GdkAtom message_type,
                                                 GdkFilterFunc func,
                                                 gpointer data);

Adds a filter to be called when X ClientMessage events are received.

`display` : | a GdkDisplay for which this message filter applies
`message_type` : | the type of ClientMessage events to receive. This will be checked against the `message_type` field of the XClientMessage event struct.
`func` : | the function to call to process the event.
`data` : | user data to pass to `func`.

Since 2.2

### gdk_display_set_double_click_time ()

    void        gdk_display_set_double_click_time
                                                (GdkDisplay *display,
                                                 guint msec);

Sets the double click time (two clicks within this time interval count as a double click and result in a GDK_2BUTTON_PRESS event). Applications should not set this, it is a global user-configured setting.

`display` : | a GdkDisplay
`msec` : | double click time in milliseconds (thousandths of a second)

Since 2.2

### gdk_display_set_double_click_distance ()

    void        gdk_display_set_double_click_distance
                                                (GdkDisplay *display,
                                                 guint distance);

Sets the double click distance (two clicks within this distance count as a double click and result in a GDK_2BUTTON_PRESS event). See also `gdk_display_set_double_click_time()`. Applications should not set this, it is a global user-configured setting.

`display` : | a GdkDisplay
`distance` : | distance in pixels

Since 2.4

### gdk_display_get_pointer ()

    void        gdk_display_get_pointer         (GdkDisplay *display,
                                                 GdkScreen **screen,
                                                 gint *x,
                                                 gint *y,
                                                 GdkModifierType *mask);

Gets the current location of the pointer and the current modifier mask for a given display.

`display` : | a GdkDisplay
`screen` : | location to store the screen that the cursor is on, or `NULL`.
`x` : | location to store root window X coordinate of pointer, or `NULL`.
`y` : | location to store root window Y coordinate of pointer, or `NULL`.
`mask` : | location to store current modifier mask, or `NULL`

Since 2.2

### gdk_display_get_window_at_pointer ()

    GdkWindow*  gdk_display_get_window_at_pointer
                                                (GdkDisplay *display,
                                                 gint *win_x,
                                                 gint *win_y);

Obtains the window underneath the mouse pointer, returning the location of that window in `win_x`, `win_y` for `screen`. Returns `NULL` if the window under the mouse pointer is not known to GDK (for example, belongs to another application).

`display` : | a GdkDisplay
`win_x` : | return location for origin of the window under the pointer
`win_y` : | return location for origin of the window under the pointer
Returns : | the window under the mouse pointer, or `NULL`

Since 2.2

### struct GdkDisplayPointerHooks

    struct GdkDisplayPointerHooks {

      void (*get_pointer)              (GdkDisplay      *display,
    				    GdkScreen      **screen,
    				    gint            *x,
    				    gint            *y,
    				    GdkModifierType *mask);
      GdkWindow* (*window_get_pointer) (GdkDisplay      *display,
    				    GdkWindow       *window,
    				    gint            *x,
    				    gint            *y,
    				    GdkModifierType *mask);
      GdkWindow* (*window_at_pointer)  (GdkDisplay      *display,
    				    gint            *win_x,
    				    gint            *win_y);
    };

A table of pointers to functions for getting quantities related to the current pointer position. Each GdkDisplay has a table of this type, which can be set using `gdk_display_set_pointer_hooks()`.

This is only useful for such low-level tools as an event recorder. Applications should never have any reason to use this facility

void (*`get_pointer`) (GdkDisplay *display, GdkScreen **screen, gint *x, gint *y, GdkModifierType *mask) | Obtains the current pointer position and modifier state. The position is given in coordinates relative to the window containing the pointer, which is returned in `window`.
GdkWindow* (*`window_get_pointer`) (GdkDisplay *display, GdkWindow *window, gint *x, gint *y, GdkModifierType *mask) | Obtains the window underneath the mouse pointer. Current pointer position and modifier state are returned in `x`, `y` and `mask`. The position is given in coordinates relative to `window`.
GdkWindow* (*`window_at_pointer`) (GdkDisplay *display, gint *win_x, gint *win_y) | Obtains the window underneath the mouse pointer, returning the location of that window in `win_x`, `win_y`. Returns `NULL` if the window under the mouse pointer is not known to GDK (for example, belongs to another application).

Since 2.2

### gdk_display_set_pointer_hooks ()

    GdkDisplayPointerHooks* gdk_display_set_pointer_hooks
                                                (GdkDisplay *display,
                                                 const GdkDisplayPointerHooks *new_hooks);

This function allows for hooking into the operation of getting the current location of the pointer on a particular display. This is only useful for such low-level tools as an event recorder. Applications should never have any reason to use this facility.

`display` : | a GdkDisplay
`new_hooks` : | a table of pointers to functions for getting quantities related to the current pointer position, or `NULL` to restore the default table.
Returns : | the previous pointer hook table

Since 2.2

### gdk_display_supports_cursor_color ()

    gboolean    gdk_display_supports_cursor_color
                                                (GdkDisplay *display);

Returns `TRUE` if multicolored cursors are supported on `display`. Otherwise, cursors have only a forground and a background color.

`display` : | a GdkDisplay
Returns : | whether cursors can have multiple colors.

Since 2.4

### gdk_display_supports_cursor_alpha ()

    gboolean    gdk_display_supports_cursor_alpha
                                                (GdkDisplay *display);

Returns `TRUE` if cursors can use an 8bit alpha channel on `display`. Otherwise, cursors are restricted to bilevel alpha (i.e. a mask).

`display` : | a GdkDisplay
Returns : | whether cursors can have alpha channels.

Since 2.4

### gdk_display_get_default_cursor_size ()

    guint       gdk_display_get_default_cursor_size
                                                (GdkDisplay *display);

Returns the default size to use for cursors on `display`.

`display` : | a GdkDisplay
Returns : | the default cursor size.

Since 2.4

### gdk_display_get_maximal_cursor_size ()

    void        gdk_display_get_maximal_cursor_size
                                                (GdkDisplay *display,
                                                 guint *width,
                                                 guint *height);

Gets the maximal size to use for cursors on `display`.

`display` : | a GdkDisplay
`width` : | the return location for the maximal cursor width
`height` : | the return location for the maximal cursor height

Since 2.4

### gdk_display_get_default_group ()

    GdkWindow*  gdk_display_get_default_group   (GdkDisplay *display);

Returns the default group leader window for all toplevel windows on `display`. This window is implicitly created by GDK. See `gdk_window_set_group()`.

`display` : | a GdkDisplay
Returns : | The default group leader window for `display`

Since 2.4

## Signals

### The "closed" signal

    void        user_function                  (GdkDisplay *display,
                                                gboolean is_error,
                                                gpointer user_data);

The ::closed signal is emitted when the connection to the windowing system for `display` is closed.

`display` : | the object on which the signal is emitted
`is_error` : | `TRUE` if the display was closed due to an error
`user_data` : | user data set when the signal handler was connected.

Since 2.2