| GDK Reference Manual |
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EventsEvents — Functions for handling events from the window system |
#include <gdk/gdk.h> enum GdkEventType; enum GdkEventMask; #define GDK_CURRENT_TIME #define GDK_PRIORITY_EVENTS #define GDK_PRIORITY_REDRAWgboolean gdk_events_pending (void); GdkEvent* gdk_event_peek (void); GdkEvent* gdk_event_get (void); GdkEvent* gdk_event_get_graphics_expose (GdkWindow *window);void gdk_event_put (GdkEvent *event); GdkEvent* gdk_event_new (GdkEventType type); GdkEvent* gdk_event_copy (GdkEvent *event);void gdk_event_free (GdkEvent *event);guint32 gdk_event_get_time (GdkEvent *event);gboolean gdk_event_get_state (GdkEvent *event, GdkModifierType *state);gboolean gdk_event_get_axis (GdkEvent *event, GdkAxisUse axis_use,gdouble *value);gboolean gdk_event_get_coords (GdkEvent *event,gdouble *x_win,gdouble *y_win);gboolean gdk_event_get_root_coords (GdkEvent *event,gdouble *x_root,gdouble *y_root);void gdk_event_handler_set (GdkEventFunc func,gpointer data,GDestroyNotify notify);void (*GdkEventFunc) (GdkEvent *event,gpointer data);gboolean gdk_event_send_client_message (GdkEvent *event, GdkNativeWindow winid);gboolean gdk_event_send_client_message_for_display (GdkDisplay *display, GdkEvent *event, GdkNativeWindow winid);void gdk_event_send_clientmessage_toall (GdkEvent *event);void gdk_add_client_message_filter (GdkAtom message_type, GdkFilterFunc func,gpointer data);gboolean gdk_get_show_events (void);void gdk_set_show_events (gboolean show_events);void gdk_event_set_screen (GdkEvent *event, GdkScreen *screen); GdkScreen* gdk_event_get_screen (GdkEvent *event);gboolean gdk_setting_get (constgchar *name,GValue *value);
This section describes functions dealing with events from the window system.
In GTK+ applications the events are handled automatically in
gtk_main_do_event()
typedef enum
{
GDK_NOTHING = -1,
GDK_DELETE = 0,
GDK_DESTROY = 1,
GDK_EXPOSE = 2,
GDK_MOTION_NOTIFY = 3,
GDK_BUTTON_PRESS = 4,
GDK_2BUTTON_PRESS = 5,
GDK_3BUTTON_PRESS = 6,
GDK_BUTTON_RELEASE = 7,
GDK_KEY_PRESS = 8,
GDK_KEY_RELEASE = 9,
GDK_ENTER_NOTIFY = 10,
GDK_LEAVE_NOTIFY = 11,
GDK_FOCUS_CHANGE = 12,
GDK_CONFIGURE = 13,
GDK_MAP = 14,
GDK_UNMAP = 15,
GDK_PROPERTY_NOTIFY = 16,
GDK_SELECTION_CLEAR = 17,
GDK_SELECTION_REQUEST = 18,
GDK_SELECTION_NOTIFY = 19,
GDK_PROXIMITY_IN = 20,
GDK_PROXIMITY_OUT = 21,
GDK_DRAG_ENTER = 22,
GDK_DRAG_LEAVE = 23,
GDK_DRAG_MOTION = 24,
GDK_DRAG_STATUS = 25,
GDK_DROP_START = 26,
GDK_DROP_FINISHED = 27,
GDK_CLIENT_EVENT = 28,
GDK_VISIBILITY_NOTIFY = 29,
GDK_NO_EXPOSE = 30,
GDK_SCROLL = 31,
GDK_WINDOW_STATE = 32,
GDK_SETTING = 33,
GDK_OWNER_CHANGE = 34
} GdkEventType;
Specifies the type of the event.
Do not confuse these events with the signals that GTK+ widgets emit. Although many of these events result in corresponding signals being emitted, the events are often transformed or filtered along the way.
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a special code to indicate a null event. |
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the window manager has requested that the toplevel window be hidden or destroyed, usually when the user clicks on a special icon in the title bar. |
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the window has been destroyed. |
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all or part of the window has become visible and needs to be redrawn. |
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the pointer (usually a mouse) has moved. |
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a mouse button has been pressed. |
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a mouse button has been double-clicked (clicked twice
within a short period of time). Note that each click also generates a
GDK_BUTTON_PRESS event.
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a mouse button has been clicked 3 times in a short period
of time. Note that each click also generates a GDK_BUTTON_PRESS event.
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a mouse button has been released. |
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a key has been pressed. |
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a key has been released. |
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the pointer has entered the window. |
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the pointer has left the window. |
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the keyboard focus has entered or left the window. |
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the size, position or stacking order of the window has changed.
Note that GTK+ discards these events for GDK_WINDOW_CHILD windows.
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the window has been mapped. |
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the window has been unmapped. |
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a property on the window has been changed or deleted. |
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the application has lost ownership of a selection. |
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another application has requested a selection. |
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a selection has been received. |
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an input device has moved into contact with a sensing surface (e.g. a touchscreen or graphics tablet). |
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an input device has moved out of contact with a sensing surface. |
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the mouse has entered the window while a drag is in progress. |
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the mouse has left the window while a drag is in progress. |
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the mouse has moved in the window while a drag is in progress. |
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the status of the drag operation initiated by the window has changed. |
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a drop operation onto the window has started. |
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the drop operation initiated by the window has completed. |
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a message has been received from another application. |
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the window visibility status has changed. |
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indicates that the source region was completely available when parts of a drawable were copied. This is not very useful. |
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the owner of a selection has changed. This event type was added in 2.6 |
typedef enum
{
GDK_EXPOSURE_MASK = 1 << 1,
GDK_POINTER_MOTION_MASK = 1 << 2,
GDK_POINTER_MOTION_HINT_MASK = 1 << 3,
GDK_BUTTON_MOTION_MASK = 1 << 4,
GDK_BUTTON1_MOTION_MASK = 1 << 5,
GDK_BUTTON2_MOTION_MASK = 1 << 6,
GDK_BUTTON3_MOTION_MASK = 1 << 7,
GDK_BUTTON_PRESS_MASK = 1 << 8,
GDK_BUTTON_RELEASE_MASK = 1 << 9,
GDK_KEY_PRESS_MASK = 1 << 10,
GDK_KEY_RELEASE_MASK = 1 << 11,
GDK_ENTER_NOTIFY_MASK = 1 << 12,
GDK_LEAVE_NOTIFY_MASK = 1 << 13,
GDK_FOCUS_CHANGE_MASK = 1 << 14,
GDK_STRUCTURE_MASK = 1 << 15,
GDK_PROPERTY_CHANGE_MASK = 1 << 16,
GDK_VISIBILITY_NOTIFY_MASK = 1 << 17,
GDK_PROXIMITY_IN_MASK = 1 << 18,
GDK_PROXIMITY_OUT_MASK = 1 << 19,
GDK_SUBSTRUCTURE_MASK = 1 << 20,
GDK_SCROLL_MASK = 1 << 21,
GDK_ALL_EVENTS_MASK = 0x3FFFFE
} GdkEventMask;
A set of bit-flags to indicate which events a window is to receive. Most of these masks map onto one or more of the GdkEventType event types above.
GDK_POINTER_MOTION_HINT_MASK is a special mask which is used to reduce the
number of GDK_MOTION_NOTIFY events received. Normally a GDK_MOTION_NOTIFY
event is received each time the mouse moves. However, if the application
spends a lot of time processing the event (updating the display, for example),
it can easily lag behind the position of the mouse. When using the
GDK_POINTER_MOTION_HINT_MASK the server will only send a single GDK_MOTION_NOTIFY
event (which is marked as a hint) until the application asks for more, by calling
gdk_window_get_pointer().
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the combination of all the above event masks. |
#define GDK_CURRENT_TIME 0L
Represents the current time, and can be used anywhere a time is expected.
#define GDK_PRIORITY_EVENTS
This is the priority that events from the X server are given in the
#define GDK_PRIORITY_REDRAW (G_PRIORITY_HIGH_IDLE + 20)
This is the priority that the idle handler processing window updates
is given in the
gboolean gdk_events_pending (void);
Checks if any events are ready to be processed for any display.
Returns : |
TRUE if any events are pending.
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GdkEvent* gdk_event_peek (void);
If there is an event waiting in the event queue of some open
display, returns a copy of it. See gdk_display_peek_event().
Returns : |
a copy of the first GdkEvent on some event queue, or NULL if no
events are in any queues. The returned GdkEvent should be freed with
gdk_event_free().
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GdkEvent* gdk_event_get (void);
Checks all open displays for a GdkEvent to process,to be processed
on, fetching events from the windowing system if necessary.
See gdk_display_get_event().
Returns : |
the next GdkEvent to be processed, or NULL if no events
are pending. The returned GdkEvent should be freed with gdk_event_free().
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GdkEvent* gdk_event_get_graphics_expose (GdkWindow *window);
Waits for a GraphicsExpose or NoExpose event from the X server.
This is used in the
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the GdkWindow to wait for the events for. |
Returns : |
a GdkEventExpose if a GraphicsExpose was received, or NULL if a
NoExpose event was received.
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void gdk_event_put (GdkEvent *event);
Appends a copy of the given event onto the front of the event
queue for event->any.window's display, or the default event
queue if event->any.window is NULL. See gdk_display_put_event().
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a GdkEvent. |
GdkEvent* gdk_event_new (GdkEventType type);
Creates a new event of the given type. All fields are set to 0.
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a GdkEventType |
Returns : |
a newly-allocated GdkEvent. The returned GdkEvent
should be freed with gdk_event_free().
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Since 2.2
GdkEvent* gdk_event_copy (GdkEvent *event);
Copies a GdkEvent, copying or incrementing the reference count of the resources associated with it (e.g. GdkWindow's and strings).
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a GdkEvent |
Returns : |
a copy of event. The returned GdkEvent should be freed with
gdk_event_free().
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void gdk_event_free (GdkEvent *event);
Frees a GdkEvent, freeing or decrementing any resources associated with it.
Note that this function should only be called with events returned from
functions such as gdk_event_peek(), gdk_event_get(),
gdk_event_get_graphics_expose() and gdk_event_copy().
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a GdkEvent. |
guint32 gdk_event_get_time (GdkEvent *event);
Returns the time stamp from event, if there is one; otherwise
returns GDK_CURRENT_TIME. If event is NULL, returns GDK_CURRENT_TIME.
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a GdkEvent |
Returns : |
time stamp field from event
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gboolean gdk_event_get_state (GdkEvent *event, GdkModifierType *state);
If the event contains a "state" field, puts that field in state. Otherwise
stores an empty state (0). Returns TRUE if there was a state field
in the event. event may be NULL, in which case it's treated
as if the event had no state field.
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a GdkEvent or NULL |
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return location for state |
Returns : |
TRUE if there was a state field in the event
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gboolean gdk_event_get_axis (GdkEvent *event, GdkAxisUse axis_use,gdouble *value);
Extract the axis value for a particular axis use from an event structure.
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a GdkEvent |
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the axis use to look for |
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location to store the value found |
Returns : |
TRUE if the specified axis was found, otherwise FALSE
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gboolean gdk_event_get_coords (GdkEvent *event,gdouble *x_win,gdouble *y_win);
Extract the event window relative x/y coordinates from an event.
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a GdkEvent |
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location to put event window x coordinate |
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location to put event window y coordinate |
Returns : |
TRUE if the event delivered event window coordinates
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gboolean gdk_event_get_root_coords (GdkEvent *event,gdouble *x_root,gdouble *y_root);
Extract the root window relative x/y coordinates from an event.
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a GdkEvent |
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location to put root window x coordinate |
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location to put root window y coordinate |
Returns : |
TRUE if the event delivered root window coordinates
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void gdk_event_handler_set (GdkEventFunc func,gpointer data,GDestroyNotify notify);
Sets the function to call to handle all events from GDK.
Note that GTK+ uses this to install its own event handler, so it is
usually not useful for GTK+ applications. (Although an application
can call this function then call gtk_main_do_event()
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the function to call to handle events from GDK. |
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user data to pass to the function. |
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the function to call when the handler function is removed, i.e. when
gdk_event_handler_set() is called with another event handler.
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void (*GdkEventFunc) (GdkEvent *event,gpointer data);
Specifies the type of function passed to gdk_event_handler_set() to handle
all GDK events.
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the GdkEvent to process. |
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user data set when the event handler was installed with
gdk_event_handler_set().
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gboolean gdk_event_send_client_message (GdkEvent *event, GdkNativeWindow winid);
Sends an X ClientMessage event to a given window (which must be on the default GdkDisplay.) This could be used for communicating between different applications, though the amount of data is limited to 20 bytes.
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the GdkEvent to send, which should be a GdkEventClient. |
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the window to send the X ClientMessage event to. |
Returns : |
non-zero on success. |
gboolean gdk_event_send_client_message_for_display (GdkDisplay *display, GdkEvent *event, GdkNativeWindow winid);
On X11, sends an X ClientMessage event to a given window. On Windows, sends a message registered with the name GDK_WIN32_CLIENT_MESSAGE.
This could be used for communicating between different applications, though the amount of data is limited to 20 bytes on X11, and to just four bytes on Windows.
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the GdkDisplay for the window where the message is to be sent. |
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the GdkEvent to send, which should be a GdkEventClient. |
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the window to send the client message to. |
Returns : |
non-zero on success. |
Since 2.2
void gdk_event_send_clientmessage_toall (GdkEvent *event);
Sends an X ClientMessage event to all toplevel windows on the default GdkScreen.
Toplevel windows are determined by checking for the WM_STATE property, as described in the Inter-Client Communication Conventions Manual (ICCCM). If no windows are found with the WM_STATE property set, the message is sent to all children of the root window.
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the GdkEvent to send, which should be a GdkEventClient. |
void gdk_add_client_message_filter (GdkAtom message_type, GdkFilterFunc func,gpointer data);
Adds a filter to the default display to be called when X ClientMessage events
are received. See gdk_display_add_client_message_filter().
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the type of ClientMessage events to receive. This will be
checked against the message_type field of the
XClientMessage event struct.
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the function to call to process the event. |
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user data to pass to func.
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gboolean gdk_get_show_events (void);
Gets whether event debugging output is enabled.
Returns : |
TRUE if event debugging output is enabled.
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void gdk_set_show_events (gboolean show_events);
Sets whether a trace of received events is output.
Note that GTK+ must be compiled with debugging (that is,
configured using the --enable-debug option)
to use this option.
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TRUE to output event debugging information.
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void gdk_event_set_screen (GdkEvent *event, GdkScreen *screen);
Sets the screen for event to screen. The event must
have been allocated by GTK+, for instance, by
gdk_event_copy().
Since 2.2
GdkScreen* gdk_event_get_screen (GdkEvent *event);
Returns the screen for the event. The screen is
typically the screen for event->any.window, but
for events such as mouse events, it is the screen
where the pointer was when the event occurs -
that is, the screen which has the root window
to which event->motion.x_root and
event->motion.y_root are relative.
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a GdkEvent |
Returns : |
the screen for the event |
Since 2.2
gboolean gdk_setting_get (constgchar *name,GValue *value);
Obtains a desktop-wide setting, such as the double-click time,
for the default screen. See gdk_screen_get_setting().
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the name of the setting. |
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location to store the value of the setting. |
Returns : |
: TRUE if the setting existed and a value was stored
in value, FALSE otherwise.
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