## General

General — Library initialization and miscellaneous functions

## Synopsis

    #include <gdk/gdk.h>

    void                gdk_init                            (gint *argc,
                                                             gchar ***argv);
    gboolean            gdk_init_check                      (gint *argc,
                                                             gchar ***argv);
    void                gdk_parse_args                      (gint *argc,
                                                             gchar ***argv);
    const gchar *       gdk_get_display_arg_name            (void);
    void                gdk_notify_startup_complete         (void);
    void                gdk_notify_startup_complete_with_id (const gchar *startup_id);

    const gchar *       gdk_get_program_class               (void);
    void                gdk_set_program_class               (const gchar *program_class);

    gchar *             gdk_get_display                     (void);

    void                gdk_flush                           (void);

    gint                gdk_screen_width                    (void);
    gint                gdk_screen_height                   (void);
    gint                gdk_screen_width_mm                 (void);
    gint                gdk_screen_height_mm                (void);

    GdkGrabStatus       gdk_pointer_grab                    (GdkWindow *window,
                                                             gboolean owner_events,
                                                             GdkEventMask event_mask,
                                                             GdkWindow *confine_to,
                                                             GdkCursor *cursor,
                                                             guint32 time_);
    enum                GdkGrabStatus;
    void                gdk_pointer_ungrab                  (guint32 time_);
    gboolean            gdk_pointer_is_grabbed              (void);
    void                gdk_set_double_click_time           (guint msec);

    GdkGrabStatus       gdk_keyboard_grab                   (GdkWindow *window,
                                                             gboolean owner_events,
                                                             guint32 time_);
    void                gdk_keyboard_ungrab                 (guint32 time_);

    void                gdk_beep                            (void);

    void                gdk_error_trap_push                 (void);
    void                gdk_error_trap_pop_ignored          (void);

    #define             GDK_WINDOWING_X11
    #define             GDK_WINDOWING_WIN32

## Description

This section describes the GDK initialization functions and miscellaneous utility functions.

## Details

### gdk_init ()

    void                gdk_init                            (gint *argc,
                                                             gchar ***argv);

Initializes the GDK library and connects to the windowing system. If initialization fails, a warning message is output and the application terminates with a call to `exit(1)`.

Any arguments used by GDK are removed from the array and `argc` and `argv` are updated accordingly.

GTK+ initializes GDK in `gtk_init()` and so this function is not usually needed by GTK+ applications.

`argc` : | the number of command line arguments. [inout]
`argv` : | the array of command line arguments. [array length=argc][inout]

### gdk_init_check ()

    gboolean            gdk_init_check                      (gint *argc,
                                                             gchar ***argv);

Initializes the GDK library and connects to the windowing system, returning `TRUE` on success.

Any arguments used by GDK are removed from the array and `argc` and `argv` are updated accordingly.

GTK+ initializes GDK in `gtk_init()` and so this function is not usually needed by GTK+ applications.

`argc` : | the number of command line arguments. [inout]
`argv` : | the array of command line arguments. [array length=argc][inout]
Returns : | `TRUE` if initialization succeeded.

### gdk_parse_args ()

    void                gdk_parse_args                      (gint *argc,
                                                             gchar ***argv);

Parse command line arguments, and store for future use by calls to `gdk_display_open()`.

Any arguments used by GDK are removed from the array and `argc` and `argv` are updated accordingly.

You shouldn't call this function explicitely if you are using `gtk_init()`, `gtk_init_check()`, `gdk_init()`, or `gdk_init_check()`.

`argc` : | the number of command line arguments.
`argv` : | the array of command line arguments. [inout][array length=argc]

Since 2.2

### gdk_get_display_arg_name ()

    const gchar *       gdk_get_display_arg_name            (void);

Gets the display name specified in the command line arguments passed to `gdk_init()` or `gdk_parse_args()`, if any.

Returns : | the display name, if specified explicitely, otherwise `NULL` this string is owned by GTK+ and must not be modified or freed.

Since 2.2

### gdk_notify_startup_complete ()

    void                gdk_notify_startup_complete         (void);

Indicates to the GUI environment that the application has finished loading. If the applications opens windows, this function is normally called after opening the application's initial set of windows.

GTK+ will call this function automatically after opening the first GtkWindow unless `gtk_window_set_auto_startup_notification()` is called to disable that feature.

Since 2.2

### gdk_notify_startup_complete_with_id ()

    void                gdk_notify_startup_complete_with_id (const gchar *startup_id);

Indicates to the GUI environment that the application has finished loading, using a given identifier.

GTK+ will call this function automatically for GtkWindow with custom startup-notification identifier unless `gtk_window_set_auto_startup_notification()` is called to disable that feature.

`startup_id` : | a startup-notification identifier, for which notification process should be completed

Since 2.12

### gdk_get_program_class ()

    const gchar *       gdk_get_program_class               (void);

Gets the program class. Unless the program class has explicitly been set with `gdk_set_program_class()` or with the `--class` commandline option, the default value is the program name (determined with `g_get_prgname()`) with the first character converted to uppercase.

Returns : | the program class.

### gdk_set_program_class ()

    void                gdk_set_program_class               (const gchar *program_class);

Sets the program class. The X11 backend uses the program class to set the class name part of the `WM_CLASS` property on toplevel windows; see the ICCCM.

`program_class` : | a string.

### gdk_get_display ()

    gchar *             gdk_get_display                     (void);

Gets the name of the display, which usually comes from the `DISPLAY` environment variable or the `--display` command line option.

Returns : | the name of the display.

### gdk_flush ()

    void                gdk_flush                           (void);

Flushes the output buffers of all display connections and waits until all requests have been processed. This is rarely needed by applications.

### gdk_screen_width ()

    gint                gdk_screen_width                    (void);

Returns the width of the default screen in pixels.

Returns : | the width of the default screen in pixels.

### gdk_screen_height ()

    gint                gdk_screen_height                   (void);

Returns the height of the default screen in pixels.

Returns : | the height of the default screen in pixels.

### gdk_screen_width_mm ()

    gint                gdk_screen_width_mm                 (void);

Returns the width of the default screen in millimeters. Note that on many X servers this value will not be correct.

Returns : | the width of the default screen in millimeters, though it is not always correct.

### gdk_screen_height_mm ()

    gint                gdk_screen_height_mm                (void);

Returns the height of the default screen in millimeters. Note that on many X servers this value will not be correct.

Returns : | the height of the default screen in millimeters, though it is not always correct.

### gdk_pointer_grab ()

    GdkGrabStatus       gdk_pointer_grab                    (GdkWindow *window,
                                                             gboolean owner_events,
                                                             GdkEventMask event_mask,
                                                             GdkWindow *confine_to,
                                                             GdkCursor *cursor,
                                                             guint32 time_);

### Warning

`gdk_pointer_grab` has been deprecated since version 3.0 and should not be used in newly-written code. Use `gdk_device_grab()` instead.

Grabs the pointer (usually a mouse) so that all events are passed to this application until the pointer is ungrabbed with `gdk_pointer_ungrab()`, or the grab window becomes unviewable. This overrides any previous pointer grab by this client.

Pointer grabs are used for operations which need complete control over mouse events, even if the mouse leaves the application. For example in GTK+ it is used for Drag and Drop, for dragging the handle in the GtkHPaned and GtkVPaned widgets.

Note that if the event mask of an X window has selected both button press and button release events, then a button press event will cause an automatic pointer grab until the button is released. X does this automatically since most applications expect to receive button press and release events in pairs. It is equivalent to a pointer grab on the window with `owner_events` set to `TRUE`.

If you set up anything at the time you take the grab that needs to be cleaned up when the grab ends, you should handle the GdkEventGrabBroken events that are emitted when the grab ends unvoluntarily.

`window` : | the GdkWindow which will own the grab (the grab window).
`owner_events` : | if `FALSE` then all pointer events are reported with respect to `window` and are only reported if selected by `event_mask`. If `TRUE` then pointer events for this application are reported as normal, but pointer events outside this application are reported with respect to `window` and only if selected by `event_mask`. In either mode, unreported events are discarded.
`event_mask` : | specifies the event mask, which is used in accordance with `owner_events`. Note that only pointer events (i.e. button and motion events) may be selected.
`confine_to` : | If non-`NULL`, the pointer will be confined to this window during the grab. If the pointer is outside `confine_to`, it will automatically be moved to the closest edge of `confine_to` and enter and leave events will be generated as necessary. [allow-none]
`cursor` : | the cursor to display while the grab is active. If this is `NULL` then the normal cursors are used for `window` and its descendants, and the cursor for `window` is used for all other windows. [allow-none]
`time_` : | the timestamp of the event which led to this pointer grab. This usually comes from a GdkEventButton struct, though `GDK_CURRENT_TIME` can be used if the time isn't known.
Returns : | `GDK_GRAB_SUCCESS` if the grab was successful.

### enum GdkGrabStatus

    typedef enum
    {
      GDK_GRAB_SUCCESS         = 0,
      GDK_GRAB_ALREADY_GRABBED = 1,
      GDK_GRAB_INVALID_TIME    = 2,
      GDK_GRAB_NOT_VIEWABLE    = 3,
      GDK_GRAB_FROZEN          = 4
    } GdkGrabStatus;

Returned by `gdk_pointer_grab()` and `gdk_keyboard_grab()` to indicate success or the reason for the failure of the grab attempt.

`GDK_GRAB_SUCCESS` | the resource was successfully grabbed.
`GDK_GRAB_ALREADY_GRABBED` | the resource is actively grabbed by another client.
`GDK_GRAB_INVALID_TIME` | the resource was grabbed more recently than the specified time.
`GDK_GRAB_NOT_VIEWABLE` | the grab window or the `confine_to` window are not viewable.
`GDK_GRAB_FROZEN` | the resource is frozen by an active grab of another client.

### gdk_pointer_ungrab ()

    void                gdk_pointer_ungrab                  (guint32 time_);

### Warning

`gdk_pointer_ungrab` has been deprecated since version 3.0 and should not be used in newly-written code. Use `gdk_device_ungrab()`, together with `gdk_device_grab()` instead.

Ungrabs the pointer on the default display, if it is grabbed by this application.

`time_` : | a timestamp from a GdkEvent, or `GDK_CURRENT_TIME` if no timestamp is available.

### gdk_pointer_is_grabbed ()

    gboolean            gdk_pointer_is_grabbed              (void);

### Warning

`gdk_pointer_is_grabbed` has been deprecated since version 3.0 and should not be used in newly-written code. Use `gdk_display_device_is_grabbed()` instead.

Returns `TRUE` if the pointer on the default display is currently grabbed by this application.

Note that this does not take the inmplicit pointer grab on button presses into account.

Returns : | `TRUE` if the pointer is currently grabbed by this application.

### gdk_set_double_click_time ()

    void                gdk_set_double_click_time           (guint msec);

Set the double click time for the default display. See `gdk_display_set_double_click_time()`. See also `gdk_display_set_double_click_distance()`. Applications should not set this, it is a global user-configured setting.

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

### gdk_keyboard_grab ()

    GdkGrabStatus       gdk_keyboard_grab                   (GdkWindow *window,
                                                             gboolean owner_events,
                                                             guint32 time_);

### Warning

`gdk_keyboard_grab` has been deprecated since version 3.0 and should not be used in newly-written code. Use `gdk_device_grab()` instead.

Grabs the keyboard so that all events are passed to this application until the keyboard is ungrabbed with `gdk_keyboard_ungrab()`. This overrides any previous keyboard grab by this client.

If you set up anything at the time you take the grab that needs to be cleaned up when the grab ends, you should handle the GdkEventGrabBroken events that are emitted when the grab ends unvoluntarily.

`window` : | the GdkWindow which will own the grab (the grab window).
`owner_events` : | if `FALSE` then all keyboard events are reported with respect to `window`. If `TRUE` then keyboard events for this application are reported as normal, but keyboard events outside this application are reported with respect to `window`. Both key press and key release events are always reported, independant of the event mask set by the application.
`time_` : | a timestamp from a GdkEvent, or `GDK_CURRENT_TIME` if no timestamp is available.
Returns : | `GDK_GRAB_SUCCESS` if the grab was successful.

### gdk_keyboard_ungrab ()

    void                gdk_keyboard_ungrab                 (guint32 time_);

### Warning

`gdk_keyboard_ungrab` has been deprecated since version 3.0 and should not be used in newly-written code. Use `gdk_device_ungrab()`, together with `gdk_device_grab()` instead.

Ungrabs the keyboard on the default display, if it is grabbed by this application.

`time_` : | a timestamp from a GdkEvent, or `GDK_CURRENT_TIME` if no timestamp is available.

### gdk_beep ()

    void                gdk_beep                            (void);

Emits a short beep on the default display.

### gdk_error_trap_push ()

    void                gdk_error_trap_push                 (void);

This function allows X errors to be trapped instead of the normal behavior of exiting the application. It should only be used if it is not possible to avoid the X error in any other way. Errors are ignored on all GdkDisplay currently known to the GdkDisplayManager. If you don't care which error happens and just want to ignore everything, pop with `gdk_error_trap_pop_ignored()`. If you need the error code, use `gdk_error_trap_pop()` which may have to block and wait for the error to arrive from the X server.

This API exists on all platforms but only does anything on X.

You can use `gdk_x11_display_error_trap_push()` to ignore errors on only a single display.

Example 1. Trapping an X error

    1
    2
    3
    4
    5
    6
    7
    8
    9

    gdk_error_trap_push ();

     // ... Call the X function which may cause an error here ...

    if (gdk_error_trap_pop ())
     {
       // ... Handle the error here ...
     }

### gdk_error_trap_pop_ignored ()

    void                gdk_error_trap_pop_ignored          (void);

Removes an error trap pushed with `gdk_error_trap_push()`, but without bothering to wait and see whether an error occurred. If an error arrives later asynchronously that was triggered while the trap was pushed, that error will be ignored.

Since 3.0

### GDK_WINDOWING_X11

    #define GDK_WINDOWING_X11

The GDK_WINDOWING_X11 macro is defined if the X11 backend is supported.

Use this macro to guard code that is specific to the X11 backend.

### GDK_WINDOWING_WIN32

    #define GDK_WINDOWING_WIN32

The GDK_WINDOWING_WIN32 macro is defined if the Win32 backend is supported.

Use this macro to guard code that is specific to the Win32 backend.