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GTK+ has a rich set of functions for doing inter-process communication via the drag-and-drop metaphor.
As well as the functions listed here, applications may need to use some facilities provided for Selections. Also, the Drag and Drop API makes use of signals in the GtkWidget class.
void gtk_drag_dest_set (GtkWidget *widget
,GtkDestDefaults flags
,const GtkTargetEntry *targets
,gint n_targets
,GdkDragAction actions
);
Sets a widget as a potential drop destination, and adds default behaviors.
The default behaviors listed in flags
have an effect similar
to installing default handlers for the widget’s drag-and-drop signals
(“drag-motion”, “drag-drop”, ...). They all exist
for convenience. When passing GTK_DEST_DEFAULT_ALL for instance it is
sufficient to connect to the widget’s “drag-data-received”
signal to get primitive, but consistent drag-and-drop support.
Things become more complicated when you try to preview the dragged data,
as described in the documentation for “drag-motion”. The default
behaviors described by flags
make some assumptions, that can conflict
with your own signal handlers. For instance GTK_DEST_DEFAULT_DROP causes
invokations of gdk_drag_status()
in the context of “drag-motion”,
and invokations of gtk_drag_finish()
in “drag-data-received”.
Especially the later is dramatic, when your own “drag-motion”
handler calls gtk_drag_get_data()
to inspect the dragged data.
There’s no way to set a default action here, you can use the “drag-motion” callback for that. Here’s an example which selects the action to use depending on whether the control key is pressed or not:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 |
static void drag_motion (GtkWidget *widget, GdkDragContext *context, gint x, gint y, guint time) { GdkModifierType mask; gdk_window_get_pointer (gtk_widget_get_window (widget), NULL, NULL, &mask); if (mask & GDK_CONTROL_MASK) gdk_drag_status (context, GDK_ACTION_COPY, time); else gdk_drag_status (context, GDK_ACTION_MOVE, time); } |
[method]
widget |
||
flags |
which types of default drag behavior to use |
|
targets |
a pointer to an array of
GtkTargetEntrys indicating the drop types that this |
[allow-none][array length=n_targets] |
n_targets |
the number of entries in |
|
actions |
a bitmask of possible actions for a drop onto this |
void gtk_drag_dest_set_proxy (GtkWidget *widget
,GdkWindow *proxy_window
,GdkDragProtocol protocol
,gboolean use_coordinates
);
gtk_drag_dest_set_proxy
has been deprecated since version 3.22 and should not be used in newly-written code.
Sets this widget as a proxy for drops to another window.
[method]
void
gtk_drag_dest_unset (GtkWidget *widget
);
Clears information about a drop destination set with
gtk_drag_dest_set()
. The widget will no longer receive
notification of drags.
[method]
GdkAtom gtk_drag_dest_find_target (GtkWidget *widget
,GdkDragContext *context
,GtkTargetList *target_list
);
Looks for a match between the supported targets of context
and the
dest_target_list
, returning the first matching target, otherwise
returning GDK_NONE
. dest_target_list
should usually be the return
value from gtk_drag_dest_get_target_list()
, but some widgets may
have different valid targets for different parts of the widget; in
that case, they will have to implement a drag_motion handler that
passes the correct target list to this function.
[method]
widget |
drag destination widget |
|
context |
drag context |
|
target_list |
list of droppable targets, or |
[allow-none] |
GtkTargetList *
gtk_drag_dest_get_target_list (GtkWidget *widget
);
Returns the list of targets this widget can accept from drag-and-drop.
[method]
void gtk_drag_dest_set_target_list (GtkWidget *widget
,GtkTargetList *target_list
);
Sets the target types that this widget can accept from drag-and-drop.
The widget must first be made into a drag destination with
gtk_drag_dest_set()
.
[method]
void
gtk_drag_dest_add_text_targets (GtkWidget *widget
);
Add the text targets supported by GtkSelectionData to
the target list of the drag destination. The targets
are added with info
= 0. If you need another value,
use gtk_target_list_add_text_targets()
and
gtk_drag_dest_set_target_list()
.
[method]
Since: 2.6
void
gtk_drag_dest_add_image_targets (GtkWidget *widget
);
Add the image targets supported by GtkSelectionData to
the target list of the drag destination. The targets
are added with info
= 0. If you need another value,
use gtk_target_list_add_image_targets()
and
gtk_drag_dest_set_target_list()
.
[method]
Since: 2.6
void
gtk_drag_dest_add_uri_targets (GtkWidget *widget
);
Add the URI targets supported by GtkSelectionData to
the target list of the drag destination. The targets
are added with info
= 0. If you need another value,
use gtk_target_list_add_uri_targets()
and
gtk_drag_dest_set_target_list()
.
[method]
Since: 2.6
void gtk_drag_dest_set_track_motion (GtkWidget *widget
,gboolean track_motion
);
Tells the widget to emit “drag-motion” and
“drag-leave” events regardless of the targets and the
GTK_DEST_DEFAULT_MOTION
flag.
This may be used when a widget wants to do generic actions regardless of the targets that the source offers.
[method]
Since: 2.10
gboolean
gtk_drag_dest_get_track_motion (GtkWidget *widget
);
Returns whether the widget has been configured to always emit “drag-motion” signals.
[method]
Since: 2.10
void gtk_drag_finish (GdkDragContext *context
,gboolean success
,gboolean del
,guint32 time_
);
Informs the drag source that the drop is finished, and that the data of the drag will no longer be required.
[method]
context |
the drag context |
|
success |
a flag indicating whether the drop was successful |
|
del |
a flag indicating whether the source should delete the
original data. (This should be |
|
time_ |
the timestamp from the “drag-drop” signal |
void gtk_drag_get_data (GtkWidget *widget
,GdkDragContext *context
,GdkAtom target
,guint32 time_
);
Gets the data associated with a drag. When the data
is received or the retrieval fails, GTK+ will emit a
“drag-data-received” signal. Failure of the retrieval
is indicated by the length field of the selection_data
signal parameter being negative. However, when gtk_drag_get_data()
is called implicitely because the GTK_DEST_DEFAULT_DROP
was set,
then the widget will not receive notification of failed
drops.
[method]
widget |
the widget that will receive the “drag-data-received” signal |
|
context |
the drag context |
|
target |
the target (form of the data) to retrieve |
|
time_ |
a timestamp for retrieving the data. This will generally be the time received in a “drag-motion” or “drag-drop” signal |
GtkWidget *
gtk_drag_get_source_widget (GdkDragContext *context
);
Determines the source widget for a drag.
[method]
if the drag is occurring
within a single application, a pointer to the source widget.
Otherwise, NULL
.
[nullable][transfer none]
void
gtk_drag_highlight (GtkWidget *widget
);
Highlights a widget as a currently hovered drop target.
To end the highlight, call gtk_drag_unhighlight()
.
GTK+ calls this automatically if GTK_DEST_DEFAULT_HIGHLIGHT
is set.
[method]
void
gtk_drag_unhighlight (GtkWidget *widget
);
Removes a highlight set by gtk_drag_highlight()
from
a widget.
[method]
GdkDragContext * gtk_drag_begin (GtkWidget *widget
,GtkTargetList *targets
,GdkDragAction actions
,gint button
,GdkEvent *event
);
gtk_drag_begin
has been deprecated since version 3.10 and should not be used in newly-written code.
Use gtk_drag_begin_with_coordinates()
instead
This function is equivalent to gtk_drag_begin_with_coordinates()
,
passing -1, -1 as coordinates.
[method]
widget |
the source widget |
|
targets |
The targets (data formats) in which the source can provide the data |
|
actions |
A bitmask of the allowed drag actions for this drag |
|
button |
The button the user clicked to start the drag |
|
event |
The event that triggered the start of the drag,
or |
[nullable] |
GdkDragContext * gtk_drag_begin_with_coordinates (GtkWidget *widget
,GtkTargetList *targets
,GdkDragAction actions
,gint button
,GdkEvent *event
,gint x
,gint y
);
Initiates a drag on the source side. The function only needs to be used
when the application is starting drags itself, and is not needed when
gtk_drag_source_set()
is used.
The event
is used to retrieve the timestamp that will be used internally to
grab the pointer. If event
is NULL
, then GDK_CURRENT_TIME
will be used.
However, you should try to pass a real event in all cases, since that can be
used to get information about the drag.
Generally there are three cases when you want to start a drag by hand by calling this function:
During a “button-press-event” handler, if you want to start a drag
immediately when the user presses the mouse button. Pass the event
that you have in your “button-press-event” handler.
During a “motion-notify-event” handler, if you want to start a drag
when the mouse moves past a certain threshold distance after a button-press.
Pass the event
that you have in your “motion-notify-event” handler.
During a timeout handler, if you want to start a drag after the mouse
button is held down for some time. Try to save the last event that you got
from the mouse, using gdk_event_copy()
, and pass it to this function
(remember to free the event with gdk_event_free()
when you are done).
If you really cannot pass a real event, pass NULL
instead.
[method]
widget |
the source widget |
|
targets |
The targets (data formats) in which the source can provide the data |
|
actions |
A bitmask of the allowed drag actions for this drag |
|
button |
The button the user clicked to start the drag |
|
event |
The event that triggered the start of the drag,
or |
[nullable] |
x |
The initial x coordinate to start dragging from, in the coordinate space
of |
|
y |
The initial y coordinate to start dragging from, in the coordinate space
of |
Since: 3.10
void
gtk_drag_cancel (GdkDragContext *context
);
Cancels an ongoing drag operation on the source side.
If you want to be able to cancel a drag operation in this way,
you need to keep a pointer to the drag context, either from an
explicit call to gtk_drag_begin_with_coordinates()
, or by
connecting to “drag-begin”.
If context
does not refer to an ongoing drag operation, this
function does nothing.
If a drag is cancelled in this way, the result
argument of
“drag-failed” is set to GTK_DRAG_RESULT_ERROR
.
[method]
Since: 3.16
void gtk_drag_set_icon_widget (GdkDragContext *context
,GtkWidget *widget
,gint hot_x
,gint hot_y
);
Changes the icon for drag operation to a given widget. GTK+ will not destroy the widget, so if you don’t want it to persist, you should connect to the “drag-end” signal and destroy it yourself.
[method]
void gtk_drag_set_icon_pixbuf (GdkDragContext *context
,GdkPixbuf *pixbuf
,gint hot_x
,gint hot_y
);
Sets pixbuf
as the icon for a given drag.
void gtk_drag_set_icon_stock (GdkDragContext *context
,const gchar *stock_id
,gint hot_x
,gint hot_y
);
gtk_drag_set_icon_stock
has been deprecated since version 3.10 and should not be used in newly-written code.
Use gtk_drag_set_icon_name()
instead.
Sets the icon for a given drag from a stock ID.
void gtk_drag_set_icon_surface (GdkDragContext *context
,cairo_surface_t *surface
);
Sets surface
as the icon for a given drag. GTK+ retains
references for the arguments, and will release them when
they are no longer needed.
To position the surface relative to the mouse, use
cairo_surface_set_device_offset()
on surface
. The mouse
cursor will be positioned at the (0,0) coordinate of the
surface.
void gtk_drag_set_icon_name (GdkDragContext *context
,const gchar *icon_name
,gint hot_x
,gint hot_y
);
Sets the icon for a given drag from a named themed icon. See
the docs for GtkIconTheme for more details. Note that the
size of the icon depends on the icon theme (the icon is
loaded at the symbolic size GTK_ICON_SIZE_DND), thus
hot_x
and hot_y
have to be used with care.
context |
the context for a drag (This must be called with a context for the source side of a drag) |
|
icon_name |
name of icon to use |
|
hot_x |
the X offset of the hotspot within the icon |
|
hot_y |
the Y offset of the hotspot within the icon |
Since: 2.8
void gtk_drag_set_icon_gicon (GdkDragContext *context
,GIcon *icon
,gint hot_x
,gint hot_y
);
Sets the icon for a given drag from the given icon
.
See the documentation for gtk_drag_set_icon_name()
for more details about using icons in drag and drop.
context |
the context for a drag (This must be called with a context for the source side of a drag) |
|
icon |
a GIcon |
|
hot_x |
the X offset of the hotspot within the icon |
|
hot_y |
the Y offset of the hotspot within the icon |
Since: 3.2
void
gtk_drag_set_icon_default (GdkDragContext *context
);
Sets the icon for a particular drag to the default icon.
[method]
gboolean gtk_drag_check_threshold (GtkWidget *widget
,gint start_x
,gint start_y
,gint current_x
,gint current_y
);
Checks to see if a mouse drag starting at (start_x
, start_y
) and ending
at (current_x
, current_y
) has passed the GTK+ drag threshold, and thus
should trigger the beginning of a drag-and-drop operation.
[method]
void gtk_drag_source_set (GtkWidget *widget
,GdkModifierType start_button_mask
,const GtkTargetEntry *targets
,gint n_targets
,GdkDragAction actions
);
Sets up a widget so that GTK+ will start a drag operation when the user clicks and drags on the widget. The widget must have a window.
[method]
void gtk_drag_source_set_icon_pixbuf (GtkWidget *widget
,GdkPixbuf *pixbuf
);
Sets the icon that will be used for drags from a particular widget
from a GdkPixbuf. GTK+ retains a reference for pixbuf
and will
release it when it is no longer needed.
[method]
void gtk_drag_source_set_icon_stock (GtkWidget *widget
,const gchar *stock_id
);
gtk_drag_source_set_icon_stock
has been deprecated since version 3.10 and should not be used in newly-written code.
Use gtk_drag_source_set_icon_name()
instead.
Sets the icon that will be used for drags from a particular source to a stock icon.
[method]
void gtk_drag_source_set_icon_name (GtkWidget *widget
,const gchar *icon_name
);
Sets the icon that will be used for drags from a particular source to a themed icon. See the docs for GtkIconTheme for more details.
[method]
Since: 2.8
void gtk_drag_source_set_icon_gicon (GtkWidget *widget
,GIcon *icon
);
Sets the icon that will be used for drags from a particular source
to icon
. See the docs for GtkIconTheme for more details.
[method]
Since: 3.2
void
gtk_drag_source_unset (GtkWidget *widget
);
Undoes the effects of gtk_drag_source_set()
.
[method]
void gtk_drag_source_set_target_list (GtkWidget *widget
,GtkTargetList *target_list
);
Changes the target types that this widget offers for drag-and-drop.
The widget must first be made into a drag source with
gtk_drag_source_set()
.
[method]
Since: 2.4
GtkTargetList *
gtk_drag_source_get_target_list (GtkWidget *widget
);
Gets the list of targets this widget can provide for drag-and-drop.
[method]
Since: 2.4
void
gtk_drag_source_add_text_targets (GtkWidget *widget
);
Add the text targets supported by GtkSelectionData to
the target list of the drag source. The targets
are added with info
= 0. If you need another value,
use gtk_target_list_add_text_targets()
and
gtk_drag_source_set_target_list()
.
[method]
Since: 2.6
void
gtk_drag_source_add_image_targets (GtkWidget *widget
);
Add the writable image targets supported by GtkSelectionData to
the target list of the drag source. The targets
are added with info
= 0. If you need another value,
use gtk_target_list_add_image_targets()
and
gtk_drag_source_set_target_list()
.
[method]
Since: 2.6
void
gtk_drag_source_add_uri_targets (GtkWidget *widget
);
Add the URI targets supported by GtkSelectionData to
the target list of the drag source. The targets
are added with info
= 0. If you need another value,
use gtk_target_list_add_uri_targets()
and
gtk_drag_source_set_target_list()
.
[method]
Since: 2.6
The GtkDestDefaults enumeration specifies the various types of action that will be taken on behalf of the user for a drag destination site.
If set for a widget, GTK+, during a drag over this
widget will check if the drag matches this widget’s list of possible targets
and actions.
GTK+ will then call |
||
If set for a widget, GTK+ will draw a highlight on this widget as long as a drag is over this widget and the widget drag format and action are acceptable. |
||
If set for a widget, when a drop occurs, GTK+ will
will check if the drag matches this widget’s list of possible targets and
actions. If so, GTK+ will call |
||
If set, specifies that all default actions should be taken. |
The GtkTargetFlags enumeration is used to specify constraints on a GtkTargetEntry.
If this is set, the target will only be selected for drags within a single application. |
||
If this is set, the target will only be selected for drags within a single widget. |
||
If this is set, the target will not be selected for drags within a single application. |
||
If this is set, the target will not be selected for drags withing a single widget. |
Gives an indication why a drag operation failed. The value can by obtained by connecting to the “drag-failed” signal.