1 <!-- ##### SECTION Title ##### -->
4 <!-- ##### SECTION Short_Description ##### -->
5 functions for handling events from the window system.
7 <!-- ##### SECTION Long_Description ##### -->
9 This section describes functions dealing with events from the window system.
12 In GTK+ applications the events are handled automatically in
13 gtk_main_do_event() and passed on to the appropriate widgets, so these
14 functions are rarely needed. Though some of the fields in the
15 <link linkend="gdk-Event-Structures">Event Structures</link> are useful.
18 <!-- ##### SECTION See_Also ##### -->
22 <term><link linkend="gdk-Event-Structures">Event Structures</link></term>
24 The structs used for each type of event.
30 <!-- ##### ENUM GdkEventType ##### -->
32 Specifies the type of the event.
35 Do not confuse these events with the signals that GTK+ widgets emit.
36 Although many of these events result in corresponding signals being emitted,
37 the events are often transformed or filtered along the way.
40 @GDK_NOTHING: a special code to indicate a null event.
41 @GDK_DELETE: the window manager has requested that the toplevel window be
42 hidden or destroyed, usually when the user clicks on a special icon in the
44 @GDK_DESTROY: the window has been destroyed.
45 @GDK_EXPOSE: all or part of the window has become visible and needs to be
47 @GDK_MOTION_NOTIFY: the pointer (usually a mouse) has moved.
48 @GDK_BUTTON_PRESS: a mouse button has been pressed.
49 @GDK_2BUTTON_PRESS: a mouse button has been double-clicked (clicked twice
50 within a short period of time). Note that each click also generates a
51 %GDK_BUTTON_PRESS event.
52 @GDK_3BUTTON_PRESS: a mouse button has been clicked 3 times in a short period
53 of time. Note that each click also generates a %GDK_BUTTON_PRESS event.
54 @GDK_BUTTON_RELEASE: a mouse button has been released.
55 @GDK_KEY_PRESS: a key has been pressed.
56 @GDK_KEY_RELEASE: a key has been released.
57 @GDK_ENTER_NOTIFY: the pointer has entered the window.
58 @GDK_LEAVE_NOTIFY: the pointer has left the window.
59 @GDK_FOCUS_CHANGE: the keyboard focus has entered or left the window.
60 @GDK_CONFIGURE: the size, position or stacking order of the window has changed.
61 Note that GTK+ discards these events for %GDK_WINDOW_CHILD windows.
62 @GDK_MAP: the window has been mapped.
63 @GDK_UNMAP: the window has been unmapped.
64 @GDK_PROPERTY_NOTIFY: a property on the window has been changed or deleted.
65 @GDK_SELECTION_CLEAR: the application has lost ownership of a selection.
66 @GDK_SELECTION_REQUEST: another application has requested a selection.
67 @GDK_SELECTION_NOTIFY: a selection has been received.
68 @GDK_PROXIMITY_IN: an input device has moved into contact with a sensing
69 surface (e.g. a touchscreen or graphics tablet).
70 @GDK_PROXIMITY_OUT: an input device has moved out of contact with a sensing
72 @GDK_DRAG_ENTER: the mouse has entered the window while a drag is in progress.
73 @GDK_DRAG_LEAVE: the mouse has left the window while a drag is in progress.
74 @GDK_DRAG_MOTION: the mouse has moved in the window while a drag is in
76 @GDK_DRAG_STATUS: the status of the drag operation initiated by the window
78 @GDK_DROP_START: a drop operation onto the window has started.
79 @GDK_DROP_FINISHED: the drop operation initiated by the window has completed.
80 @GDK_CLIENT_EVENT: a message has been received from another application.
81 @GDK_VISIBILITY_NOTIFY: the window visibility status has changed.
82 @GDK_NO_EXPOSE: indicates that the source region was completely available
83 when parts of a drawable were copied. This is not very useful.
85 <!-- ##### ENUM GdkEventMask ##### -->
87 A set of bit-flags to indicate which events a window is to receive.
88 Most of these masks map onto one or more of the #GdkEventType event types
92 %GDK_POINTER_MOTION_HINT_MASK is a special mask which is used to reduce the
93 number of %GDK_MOTION_NOTIFY events received. Normally a %GDK_MOTION_NOTIFY
94 event is received each time the mouse moves. However, if the application
95 spends a lot of time processing the event (updating the display, for example),
96 it can easily lag behind the position of the mouse. When using the
97 %GDK_POINTER_MOTION_HINT_MASK the server will only send %GDK_MOTION_NOTIFY
98 events when the application asks for them, by calling gdk_window_get_pointer().
102 @GDK_POINTER_MOTION_MASK:
103 @GDK_POINTER_MOTION_HINT_MASK:
104 @GDK_BUTTON_MOTION_MASK:
105 @GDK_BUTTON1_MOTION_MASK:
106 @GDK_BUTTON2_MOTION_MASK:
107 @GDK_BUTTON3_MOTION_MASK:
108 @GDK_BUTTON_PRESS_MASK:
109 @GDK_BUTTON_RELEASE_MASK:
111 @GDK_KEY_RELEASE_MASK:
112 @GDK_ENTER_NOTIFY_MASK:
113 @GDK_LEAVE_NOTIFY_MASK:
114 @GDK_FOCUS_CHANGE_MASK:
116 @GDK_PROPERTY_CHANGE_MASK:
117 @GDK_VISIBILITY_NOTIFY_MASK:
118 @GDK_PROXIMITY_IN_MASK:
119 @GDK_PROXIMITY_OUT_MASK:
120 @GDK_SUBSTRUCTURE_MASK:
121 @GDK_ALL_EVENTS_MASK: the combination of all the above event masks.
123 <!-- ##### MACRO GDK_CURRENT_TIME ##### -->
125 Represents the current time, and can be used anywhere a time is expected.
130 <!-- ##### MACRO GDK_PRIORITY_EVENTS ##### -->
132 This is the priority that events from the X server are given in the
133 <link linkend="glib-The-Main-Event-Loop">GLib Main Loop</link>.
138 <!-- ##### FUNCTION gdk_events_pending ##### -->
140 Checks if any events are waiting to be processed.
143 @Returns: TRUE if any events are pending.
146 <!-- ##### FUNCTION gdk_event_peek ##### -->
148 Gets a copy of the first #GdkEvent in the event queue.
149 (Note that this function will not get more events from the X server.
150 It only checks the events that have already been moved to the GDK event queue.)
153 @Returns: a copy of the first #GdkEvent on the event queue, or NULL if no
154 events are in the queue. The returned #GdkEvent should be freed with
158 <!-- ##### FUNCTION gdk_event_get ##### -->
160 Gets the next #GdkEvent to be processed, fetching events from the X server if
164 @Returns: the next #GdkEvent to be processed, or NULL if no events are pending.
165 The returned #GdkEvent should be freed with gdk_event_free().
168 <!-- ##### FUNCTION gdk_event_get_graphics_expose ##### -->
170 Waits for a GraphicsExpose or NoExpose event from the X server.
171 This is used in the #GtkText and #GtkCList widgets in GTK+ to make sure any
172 GraphicsExpose events are handled before the widget is scrolled.
175 @window: the #GdkWindow to wait for the events for.
176 @Returns: a #GdkEventExpose if a GraphicsExpose was received, or NULL if a
177 NoExpose event was received.
180 <!-- ##### FUNCTION gdk_event_put ##### -->
182 Appends a copy of the given event onto the front of the event queue.
188 <!-- ##### FUNCTION gdk_event_copy ##### -->
190 Copies a #GdkEvent, copying or incrementing the reference count of the
191 resources associated with it (e.g. #GdkWindow's and strings).
195 @Returns: a copy of @event. The returned #GdkEvent should be freed with
199 <!-- ##### FUNCTION gdk_event_free ##### -->
201 Frees a #GdkEvent, freeing or decrementing any resources associated with it.
202 Note that this function should only be called with events returned from
203 gdk_event_peek(), gdk_event_get(), gdk_event_get_graphics_expose() and
210 <!-- ##### FUNCTION gdk_event_get_time ##### -->
212 Gets the timestamp from a #GdkEvent.
216 @Returns: the timestamp from @event, or #GDK_CURRENT_TIME if the event has
220 <!-- ##### FUNCTION gdk_event_handler_set ##### -->
222 Sets the function to call to handle all events from GDK.
225 Note that GTK+ uses this to install its own event handler, so it is probably
226 not useful for GTK+ applications.
229 @func: the function to call to handle events from GDK.
230 @data: user data to pass to the function.
231 @notify: the function to call when the handler function is removed, i.e. when
232 gdk_event_handler_set() is called with another event handler.
235 <!-- ##### USER_FUNCTION GdkEventFunc ##### -->
237 Specifies the type of function passed to gdk_event_handler_set() to handle
241 @event: the #GdkEvent to process.
242 @data: user data set when the event handler was installed with
243 gdk_event_handler_set().
246 <!-- ##### FUNCTION gdk_event_send_client_message ##### -->
248 Sends an X ClientMessage event to a given window.
251 This could be used for communicating between different applications,
252 though the amount of data is limited to 20 bytes.
255 @event: the #GdkEvent to send, which should be a #GdkEventClient.
256 @xid: the window to send the X ClientMessage event to.
257 @Returns: non-zero on success.
260 <!-- ##### FUNCTION gdk_event_send_clientmessage_toall ##### -->
262 Sends an X ClientMessage event to all toplevel windows.
265 Toplevel windows are determined by checking for the WM_STATE property, as
266 described in the Inter-Client Communication Conventions Manual (ICCCM).
267 If no windows are found with the WM_STATE property set, the message is sent
268 to all children of the root window.
271 @event: the #GdkEvent to send, which should be a #GdkEventClient.
274 <!-- ##### FUNCTION gdk_add_client_message_filter ##### -->
276 Adds a filter to be called when X ClientMessage events are received.
279 @message_type: the type of ClientMessage events to receive. This will be
280 checked against the <structfield>message_type</structfield> field of the
281 XClientMessage event struct.
282 @func: the function to call to process the event.
283 @data: user data to pass to @func.
286 <!-- ##### FUNCTION gdk_get_show_events ##### -->
288 Returns non-zero if event debugging output is enabled.
291 @Returns: non-zero if event debugging output is enabled.
294 <!-- ##### FUNCTION gdk_set_show_events ##### -->
296 Sets whether event debugging information is output.
297 Note that GTK+ must be compiled with debugging enabled, i.e. using the
298 '--enable-debug' configure option.
301 @show_events: TRUE to output event debugging information.