GDK Reference Manual | ||||
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#include <gdk/gdk.h> enum GdkEventType; enum GdkEventMask; #define GDK_CURRENT_TIME #define GDK_PRIORITY_EVENTS #define GDK_PRIORITY_REDRAW gboolean 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 (const gchar *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()
and passed on to the appropriate widgets, so these
functions are rarely needed. Though some of the fields in the
Event Structures are useful.
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, GDK_GRAB_BROKEN = 35 } 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.
GDK_NOTHING |
a special code to indicate a null event. |
GDK_DELETE |
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. |
GDK_DESTROY |
the window has been destroyed. |
GDK_EXPOSE |
all or part of the window has become visible and needs to be redrawn. |
GDK_MOTION_NOTIFY |
the pointer (usually a mouse) has moved. |
GDK_BUTTON_PRESS |
a mouse button has been pressed. |
GDK_2BUTTON_PRESS |
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.
|
GDK_3BUTTON_PRESS |
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.
|
GDK_BUTTON_RELEASE |
a mouse button has been released. |
GDK_KEY_PRESS |
a key has been pressed. |
GDK_KEY_RELEASE |
a key has been released. |
GDK_ENTER_NOTIFY |
the pointer has entered the window. |
GDK_LEAVE_NOTIFY |
the pointer has left the window. |
GDK_FOCUS_CHANGE |
the keyboard focus has entered or left the window. |
GDK_CONFIGURE |
the size, position or stacking order of the window has changed.
Note that GTK+ discards these events for GDK_WINDOW_CHILD windows.
|
GDK_MAP |
the window has been mapped. |
GDK_UNMAP |
the window has been unmapped. |
GDK_PROPERTY_NOTIFY |
a property on the window has been changed or deleted. |
GDK_SELECTION_CLEAR |
the application has lost ownership of a selection. |
GDK_SELECTION_REQUEST |
another application has requested a selection. |
GDK_SELECTION_NOTIFY |
a selection has been received. |
GDK_PROXIMITY_IN |
an input device has moved into contact with a sensing surface (e.g. a touchscreen or graphics tablet). |
GDK_PROXIMITY_OUT |
an input device has moved out of contact with a sensing surface. |
GDK_DRAG_ENTER |
the mouse has entered the window while a drag is in progress. |
GDK_DRAG_LEAVE |
the mouse has left the window while a drag is in progress. |
GDK_DRAG_MOTION |
the mouse has moved in the window while a drag is in progress. |
GDK_DRAG_STATUS |
the status of the drag operation initiated by the window has changed. |
GDK_DROP_START |
a drop operation onto the window has started. |
GDK_DROP_FINISHED |
the drop operation initiated by the window has completed. |
GDK_CLIENT_EVENT |
a message has been received from another application. |
GDK_VISIBILITY_NOTIFY |
the window visibility status has changed. |
GDK_NO_EXPOSE |
indicates that the source region was completely available when parts of a drawable were copied. This is not very useful. |
GDK_SCROLL |
the scroll wheel was turned |
GDK_WINDOW_STATE |
the state of a window has changed. See GdkWindowState for the possible window states |
GDK_SETTING |
a setting has been modified. |
GDK_OWNER_CHANGE |
the owner of a selection has changed. This event type was added in 2.6 |
GDK_GRAB_BROKEN |
a pointer or keyboard grab was broken. This event type was added in 2.8. |
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()
.
#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 GLib Main Loop.
#define GDK_PRIORITY_REDRAW (G_PRIORITY_HIGH_IDLE + 20)
This is the priority that the idle handler processing window updates is given in the GLib Main Loop.
gboolean gdk_events_pending (void);
Checks if any events are ready to be processed for any display.
Returns : | TRUE if any events are pending.
|
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() .
|
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() .
|
GdkEvent* gdk_event_get_graphics_expose (GdkWindow *window);
Waits for a GraphicsExpose or NoExpose event from the X server. This is used in the GtkText and GtkCList widgets in GTK+ to make sure any GraphicsExpose events are handled before the widget is scrolled.
window : |
the GdkWindow to wait for the events for. |
Returns : | a GdkEventExpose if a GraphicsExpose was received, or NULL if a
NoExpose event was received.
|
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()
.
event : |
a GdkEvent. |
GdkEvent* gdk_event_new (GdkEventType type);
Creates a new event of the given type. All fields are set to 0.
type : |
a GdkEventType |
Returns : | a newly-allocated GdkEvent. The returned GdkEvent
should be freed with gdk_event_free() .
|
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).
event : |
a GdkEvent |
Returns : | a copy of event . The returned GdkEvent should be freed with
gdk_event_free() .
|
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()
.
event : |
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.
event : |
a GdkEvent |
Returns : | time stamp field from event
|
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.
event : |
a GdkEvent or NULL |
state : |
return location for state |
Returns : | TRUE if there was a state field in the event
|
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.
event : |
a GdkEvent |
axis_use : |
the axis use to look for |
value : |
location to store the value found |
Returns : | TRUE if the specified axis was found, otherwise FALSE
|
gboolean gdk_event_get_coords (GdkEvent *event, gdouble *x_win, gdouble *y_win);
Extract the event window relative x/y coordinates from an event.
event : |
a GdkEvent |
x_win : |
location to put event window x coordinate |
y_win : |
location to put event window y coordinate |
Returns : | TRUE if the event delivered event window coordinates
|
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.
event : |
a GdkEvent |
x_root : |
location to put root window x coordinate |
y_root : |
location to put root window y coordinate |
Returns : | TRUE if the event delivered root window coordinates
|
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()
to pass
events to GTK+.)
func : |
the function to call to handle events from GDK. |
data : |
user data to pass to the function. |
notify : |
the function to call when the handler function is removed, i.e. when
gdk_event_handler_set() is called with another event handler.
|
void (*GdkEventFunc) (GdkEvent *event, gpointer data);
Specifies the type of function passed to gdk_event_handler_set()
to handle
all GDK events.
event : |
the GdkEvent to process. |
data : |
user data set when the event handler was installed with
gdk_event_handler_set() .
|
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.
event : |
the GdkEvent to send, which should be a GdkEventClient. |
winid : |
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.
display : |
the GdkDisplay for the window where the message is to be sent. |
event : |
the GdkEvent to send, which should be a GdkEventClient. |
winid : |
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.
event : |
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()
.
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 .
|
gboolean gdk_get_show_events (void);
Gets whether event debugging output is enabled.
Returns : | TRUE if event debugging output is enabled.
|
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.
show_events : |
TRUE to output event debugging information.
|
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.
event : |
a GdkEvent |
Returns : | the screen for the event |
Since 2.2
gboolean gdk_setting_get (const gchar *name, GValue *value);
Obtains a desktop-wide setting, such as the double-click time,
for the default screen. See gdk_screen_get_setting()
.
name : |
the name of the setting. |
value : |
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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