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Drag and Drop

Drag and Drop — Functions for controlling drag and drop handling

Synopsis


#include <gtk/gtk.h>


enum        GtkDestDefaults;
enum        GtkTargetFlags;

void        gtk_drag_dest_set               (GtkWidget *widget,
                                             GtkDestDefaults flags,
                                             const GtkTargetEntry *targets,
                                             gint n_targets,
                                             GdkDragAction actions);
void        gtk_drag_dest_set_proxy         (GtkWidget *widget,
                                             GdkWindow *proxy_window,
                                             GdkDragProtocol protocol,
                                             gboolean use_coordinates);
void        gtk_drag_dest_unset             (GtkWidget *widget);
GdkAtom     gtk_drag_dest_find_target       (GtkWidget *widget,
                                             GdkDragContext *context,
                                             GtkTargetList *target_list);
GtkTargetList* gtk_drag_dest_get_target_list
                                            (GtkWidget *widget);
void        gtk_drag_dest_set_target_list   (GtkWidget *widget,
                                             GtkTargetList *target_list);
void        gtk_drag_dest_add_text_targets  (GtkWidget *widget);
void        gtk_drag_dest_add_image_targets (GtkWidget *widget);
void        gtk_drag_dest_add_uri_targets   (GtkWidget *widget);
void        gtk_drag_finish                 (GdkDragContext *context,
                                             gboolean success,
                                             gboolean del,
                                             guint32 time_);
void        gtk_drag_get_data               (GtkWidget *widget,
                                             GdkDragContext *context,
                                             GdkAtom target,
                                             guint32 time_);
GtkWidget*  gtk_drag_get_source_widget      (GdkDragContext *context);
void        gtk_drag_highlight              (GtkWidget *widget);
void        gtk_drag_unhighlight            (GtkWidget *widget);

GdkDragContext* gtk_drag_begin              (GtkWidget *widget,
                                             GtkTargetList *targets,
                                             GdkDragAction actions,
                                             gint button,
                                             GdkEvent *event);
void        gtk_drag_set_icon_widget        (GdkDragContext *context,
                                             GtkWidget *widget,
                                             gint hot_x,
                                             gint hot_y);
void        gtk_drag_set_icon_pixmap        (GdkDragContext *context,
                                             GdkColormap *colormap,
                                             GdkPixmap *pixmap,
                                             GdkBitmap *mask,
                                             gint hot_x,
                                             gint hot_y);
void        gtk_drag_set_icon_pixbuf        (GdkDragContext *context,
                                             GdkPixbuf *pixbuf,
                                             gint hot_x,
                                             gint hot_y);
void        gtk_drag_set_icon_stock         (GdkDragContext *context,
                                             const gchar *stock_id,
                                             gint hot_x,
                                             gint hot_y);
void        gtk_drag_set_icon_default       (GdkDragContext *context);
void        gtk_drag_set_default_icon       (GdkColormap *colormap,
                                             GdkPixmap *pixmap,
                                             GdkBitmap *mask,
                                             gint hot_x,
                                             gint hot_y);
gboolean    gtk_drag_check_threshold        (GtkWidget *widget,
                                             gint start_x,
                                             gint start_y,
                                             gint current_x,
                                             gint current_y);
void        gtk_drag_source_set             (GtkWidget *widget,
                                             GdkModifierType start_button_mask,
                                             const GtkTargetEntry *targets,
                                             gint n_targets,
                                             GdkDragAction actions);
void        gtk_drag_source_set_icon        (GtkWidget *widget,
                                             GdkColormap *colormap,
                                             GdkPixmap *pixmap,
                                             GdkBitmap *mask);
void        gtk_drag_source_set_icon_pixbuf (GtkWidget *widget,
                                             GdkPixbuf *pixbuf);
void        gtk_drag_source_set_icon_stock  (GtkWidget *widget,
                                             const gchar *stock_id);
void        gtk_drag_source_unset           (GtkWidget *widget);
void        gtk_drag_source_set_target_list (GtkWidget *widget,
                                             GtkTargetList *target_list);
GtkTargetList* gtk_drag_source_get_target_list
                                            (GtkWidget *widget);
void        gtk_drag_source_add_text_targets
                                            (GtkWidget *widget);
void        gtk_drag_source_add_image_targets
                                            (GtkWidget *widget);
void        gtk_drag_source_add_uri_targets (GtkWidget *widget);

Description

GTK+ has a rich set of functions for doing inter-process communication via the drag-and-drop metaphor. GTK+ can do drag-and-drop (DND) via multiple protocols. The currently supported protocols are the Xdnd and Motif protocols. 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.

Details

enum GtkDestDefaults

typedef enum {
  GTK_DEST_DEFAULT_MOTION     = 1 << 0, /* respond to "drag_motion" */
  GTK_DEST_DEFAULT_HIGHLIGHT  = 1 << 1, /* auto-highlight */
  GTK_DEST_DEFAULT_DROP       = 1 << 2, /* respond to "drag_drop" */
  GTK_DEST_DEFAULT_ALL        = 0x07
} GtkDestDefaults;

The GtkDestDefaults enumeration specifies the various types of action that will be taken on behalf of the user for a drag destination site.

GTK_DEST_DEFAULT_MOTION 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 gdk_drag_status() as appropriate.
GTK_DEST_DEFAULT_HIGHLIGHT 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.
GTK_DEST_DEFAULT_DROP 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 gtk_drag_get_data() on behalf of the widget. Whether or not the drop is successful, GTK+ will call gtk_drag_finish(). If the action was a move, then if the drag was successful, then TRUE will be passed for the delete parameter to gtk_drag_finish().
GTK_DEST_DEFAULT_ALL If set, specifies that all default actions should be taken.

enum GtkTargetFlags

typedef enum {
  GTK_TARGET_SAME_APP = 1 << 0,    /*< nick=same-app >*/
  GTK_TARGET_SAME_WIDGET = 1 << 1  /*< nick=same-widget >*/
} GtkTargetFlags;

The GtkTargetFlags enumeration is used to specify constraints on an entry in a GtkTargetTable.

GTK_TARGET_SAME_APP If this is set, the target will only be selected for drags within a single application.
GTK_TARGET_SAME_WIDGET If this is set, the target will only be selected for drags within a single widget.

gtk_drag_dest_set ()

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.

widget :a GtkWidget
flags :the flags that specify what actions GTK+ should take on behalf of a widget for drops onto that widget. The targets and actions fields only are used if GTK_DEST_DEFAULT_MOTION or GTK_DEST_DEFAULT_DROP are given.
targets :a pointer to an array of GtkTargetEntrys indicating the drop types that this widget will accept.
n_targets :the number of entries in targets.
actions :a bitmask of possible actions for a drop onto this widget.

gtk_drag_dest_set_proxy ()

void        gtk_drag_dest_set_proxy         (GtkWidget *widget,
                                             GdkWindow *proxy_window,
                                             GdkDragProtocol protocol,
                                             gboolean use_coordinates);

Sets this widget as a proxy for drops to another window.

widget :a GtkWidget
proxy_window :the window to which to forward drag events
protocol :the drag protocol which the proxy_window accepts (You can use gdk_drag_get_protocol() to determine this)
use_coordinates :If TRUE, send the same coordinates to the destination, because it is an embedded subwindow.

gtk_drag_dest_unset ()

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.

widget :a GtkWidget

gtk_drag_dest_find_target ()

GdkAtom     gtk_drag_dest_find_target       (GtkWidget *widget,
                                             GdkDragContext *context,
                                             GtkTargetList *target_list);

Looks for a match between context->targets 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.

widget : drag destination widget
context : drag context
target_list : list of droppable targets, or NULL to use gtk_drag_dest_get_target_list (widget).
Returns : first target that the source offers and the dest can accept, or GDK_NONE

gtk_drag_dest_get_target_list ()

GtkTargetList* gtk_drag_dest_get_target_list
                                            (GtkWidget *widget);

Returns the list of targets this widget can accept from drag-and-drop.

widget : a GtkWidget
Returns : the GtkTargetList, or NULL if none

gtk_drag_dest_set_target_list ()

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().

widget : a GtkWidget that's a drag destination
target_list : list of droppable targets, or NULL for none

gtk_drag_dest_add_text_targets ()

void        gtk_drag_dest_add_text_targets  (GtkWidget *widget);

Add the text targets supported by GtkSelection 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().

widget : a GtkWidget that's a drag destination

Since 2.6


gtk_drag_dest_add_image_targets ()

void        gtk_drag_dest_add_image_targets (GtkWidget *widget);

Add the image targets supported by GtkSelection 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().

widget : a GtkWidget that's a drag destination

Since 2.6


gtk_drag_dest_add_uri_targets ()

void        gtk_drag_dest_add_uri_targets   (GtkWidget *widget);

Add the URI targets supported by GtkSelection 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().

widget : a GtkWidget that's a drag destination

Since 2.6


gtk_drag_finish ()

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.

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 TRUE for a move)
time_ :the timestamp from the "drag_data_drop" signal.

gtk_drag_get_data ()

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.

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_data_motion" or "drag_data_drop" signal.

gtk_drag_get_source_widget ()

GtkWidget*  gtk_drag_get_source_widget      (GdkDragContext *context);

Determines the source widget for a drag.

context :a (destination side) drag context.
Returns :if the drag is occurring within a single application, a pointer to the source widget. Otherwise, NULL.

gtk_drag_highlight ()

void        gtk_drag_highlight              (GtkWidget *widget);

Draws a highlight around a widget. This will attach handlers to "expose_event" and "draw", so the highlight will continue to be displayed until gtk_drag_unhighlight() is called.

widget :a widget to highlight

gtk_drag_unhighlight ()

void        gtk_drag_unhighlight            (GtkWidget *widget);

Removes a highlight set by gtk_drag_highlight() from a widget.

widget :a widget to remove the highlight from.

gtk_drag_begin ()

GdkDragContext* gtk_drag_begin              (GtkWidget *widget,
                                             GtkTargetList *targets,
                                             GdkDragAction actions,
                                             gint button,
                                             GdkEvent *event);

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.

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.
Returns : the context for this drag.

gtk_drag_set_icon_widget ()

void        gtk_drag_set_icon_widget        (GdkDragContext *context,
                                             GtkWidget *widget,
                                             gint hot_x,
                                             gint hot_y);

Changes the icon for a widget to a given widget. GTK+ will not destroy the icon, so if you don't want it to persist, you should connect to the "drag_end" signal and destroy it yourself.

context : the context for a drag. (This must be called with a context for the source side of a drag)
widget : a toplevel window to use as an icon.
hot_x : the X offset within widget of the hotspot.
hot_y : the Y offset within widget of the hotspot.

gtk_drag_set_icon_pixmap ()

void        gtk_drag_set_icon_pixmap        (GdkDragContext *context,
                                             GdkColormap *colormap,
                                             GdkPixmap *pixmap,
                                             GdkBitmap *mask,
                                             gint hot_x,
                                             gint hot_y);

Sets pixmap as the icon for a given drag. GTK+ retains references for the arguments, and will release them when they are no longer needed. In general, gtk_drag_set_icon_pixbuf() will be more convenient to use.

context : the context for a drag. (This must be called with a context for the source side of a drag)
colormap : the colormap of the icon
pixmap : the image data for the icon
mask : the transparency mask for the icon
hot_x : the X offset within pixmap of the hotspot.
hot_y : the Y offset within pixmap of the hotspot.

gtk_drag_set_icon_pixbuf ()

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.

context : the context for a drag. (This must be called with a context for the source side of a drag)
pixbuf : the GdkPixbuf to use as the drag icon.
hot_x : the X offset within widget of the hotspot.
hot_y : the Y offset within widget of the hotspot.

gtk_drag_set_icon_stock ()

void        gtk_drag_set_icon_stock         (GdkDragContext *context,
                                             const gchar *stock_id,
                                             gint hot_x,
                                             gint hot_y);

Sets the icon for a given drag from a stock ID.

context : the context for a drag. (This must be called with a context for the source side of a drag)
stock_id : the ID of the stock icon to use for the drag.
hot_x : the X offset within the icon of the hotspot.
hot_y : the Y offset within the icon of the hotspot.

gtk_drag_set_icon_default ()

void        gtk_drag_set_icon_default       (GdkDragContext *context);

Sets the icon for a particular drag to the default icon.

context : the context for a drag. (This must be called with a context for the source side of a drag)

gtk_drag_set_default_icon ()

void        gtk_drag_set_default_icon       (GdkColormap *colormap,
                                             GdkPixmap *pixmap,
                                             GdkBitmap *mask,
                                             gint hot_x,
                                             gint hot_y);

Warning

gtk_drag_set_default_icon is deprecated and should not be used in newly-written code.

Changes the default drag icon. GTK+ retains references for the arguments, and will release them when they are no longer needed. This function is obsolete. The default icon should now be changed via the stock system by changing the stock pixbuf for GTK_STOCK_DND.

colormap : the colormap of the icon
pixmap : the image data for the icon
mask : the transparency mask for an image.
hot_x : The X offset within widget of the hotspot.
hot_y : The Y offset within widget of the hotspot.

gtk_drag_check_threshold ()

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.

widget : a GtkWidget
start_x : X coordinate of start of drag
start_y : Y coordinate of start of drag
current_x : current X coordinate
current_y : current Y coordinate
Returns : TRUE if the drag threshold has been passed.

gtk_drag_source_set ()

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.

widget :a GtkWidget
start_button_mask :the bitmask of buttons that can start the drag
targets :the table of targets that the drag will support
n_targets :the number of items in targets
actions :the bitmask of possible actions for a drag from this widget.

gtk_drag_source_set_icon ()

void        gtk_drag_source_set_icon        (GtkWidget *widget,
                                             GdkColormap *colormap,
                                             GdkPixmap *pixmap,
                                             GdkBitmap *mask);

Sets the icon that will be used for drags from a particular widget from a pixmap/mask. GTK+ retains references for the arguments, and will release them when they are no longer needed. Use gtk_drag_source_set_icon_pixbuf() instead.

widget : a GtkWidget
colormap : the colormap of the icon
pixmap : the image data for the icon
mask : the transparency mask for an image.

gtk_drag_source_set_icon_pixbuf ()

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.

widget : a GtkWidget
pixbuf : the GdkPixbuf for the drag icon

gtk_drag_source_set_icon_stock ()

void        gtk_drag_source_set_icon_stock  (GtkWidget *widget,
                                             const gchar *stock_id);

Sets the icon that will be used for drags from a particular source to a stock icon.

widget : a GtkWidget
stock_id : the ID of the stock icon to use

gtk_drag_source_unset ()

void        gtk_drag_source_unset           (GtkWidget *widget);

Undoes the effects of gtk_drag_source_set().

widget :a GtkWidget

gtk_drag_source_set_target_list ()

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().

widget : a GtkWidget that's a drag source
target_list : list of draggable targets, or NULL for none

Since 2.4


gtk_drag_source_get_target_list ()

GtkTargetList* gtk_drag_source_get_target_list
                                            (GtkWidget *widget);

Gets the list of targets this widget can provide for drag-and-drop.

widget : a GtkWidget
Returns : the GtkTargetList, or NULL if none

Since 2.4


gtk_drag_source_add_text_targets ()

void        gtk_drag_source_add_text_targets
                                            (GtkWidget *widget);

Add the text targets supported by GtkSelection 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().

widget : a GtkWidget that's is a drag source

Since 2.6


gtk_drag_source_add_image_targets ()

void        gtk_drag_source_add_image_targets
                                            (GtkWidget *widget);

Add the writable image targets supported by GtkSelection 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().

widget : a GtkWidget that's is a drag source

Since 2.6


gtk_drag_source_add_uri_targets ()

void        gtk_drag_source_add_uri_targets (GtkWidget *widget);

Add the URI targets supported by GtkSelection 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().

widget : a GtkWidget that's is a drag source

Since 2.6