GTK+ Reference Manual
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Selections

Selections — Functions for handling inter-process communication via selections.

Synopsis


#include <gtk/gtk.h>


struct      GtkTargetEntry;
struct      GtkTargetList;
struct      GtkTargetPair;
GtkTargetList* gtk_target_list_new          (const GtkTargetEntry *targets,
                                             guint ntargets);
void        gtk_target_list_ref             (GtkTargetList *list);
void        gtk_target_list_unref           (GtkTargetList *list);
void        gtk_target_list_add             (GtkTargetList *list,
                                             GdkAtom target,
                                             guint flags,
                                             guint info);
void        gtk_target_list_add_table       (GtkTargetList *list,
                                             const GtkTargetEntry *targets,
                                             guint ntargets);
void        gtk_target_list_remove          (GtkTargetList *list,
                                             GdkAtom target);
gboolean    gtk_target_list_find            (GtkTargetList *list,
                                             GdkAtom target,
                                             guint *info);
gboolean    gtk_selection_owner_set         (GtkWidget *widget,
                                             GdkAtom selection,
                                             guint32 time);
gboolean    gtk_selection_owner_set_for_display
                                            (GdkDisplay *display,
                                             GtkWidget *widget,
                                             GdkAtom selection,
                                             guint32 time);
void        gtk_selection_add_target        (GtkWidget *widget,
                                             GdkAtom selection,
                                             GdkAtom target,
                                             guint info);
void        gtk_selection_add_targets       (GtkWidget *widget,
                                             GdkAtom selection,
                                             const GtkTargetEntry *targets,
                                             guint ntargets);
void        gtk_selection_clear_targets     (GtkWidget *widget,
                                             GdkAtom selection);
gboolean    gtk_selection_convert           (GtkWidget *widget,
                                             GdkAtom selection,
                                             GdkAtom target,
                                             guint32 time);
void        gtk_selection_data_set          (GtkSelectionData *selection_data,
                                             GdkAtom type,
                                             gint format,
                                             const guchar *data,
                                             gint length);
gboolean    gtk_selection_data_set_text     (GtkSelectionData *selection_data,
                                             const gchar *str,
                                             gint len);
guchar*     gtk_selection_data_get_text     (GtkSelectionData *selection_data);
gboolean    gtk_selection_data_get_targets  (GtkSelectionData *selection_data,
                                             GdkAtom **targets,
                                             gint *n_atoms);
gboolean    gtk_selection_data_targets_include_text
                                            (GtkSelectionData *selection_data);
void        gtk_selection_remove_all        (GtkWidget *widget);
gboolean    gtk_selection_clear             (GtkWidget *widget,
                                             GdkEventSelection *event);
GtkSelectionData* gtk_selection_data_copy   (GtkSelectionData *data);
void        gtk_selection_data_free         (GtkSelectionData *data);


Description

The selection mechanism provides the basis for different types of communication between processes. In particular, drag and drop and GtkClipboard work via selections. You will very seldom or never need to use most of the functions in this section directly; GtkClipboard provides a nicer interface to the same functionality.

Some of the datatypes defined this section are used in the GtkClipboard and drag-and-drop API's as well. The GtkTargetEntry structure and GtkTargetList objects represent lists of data types that are supported when sending or receiving data. The GtkSelectionData object is used to store a chunk of data along with the data type and other associated information.

Details

struct GtkTargetEntry

struct GtkTargetEntry {
  gchar *target;
  guint  flags;
  guint  info;
};

A GtkTargetEntry structure represents a single type of data than can be supplied for by a widget for a selection or for supplied or received during drag-and-drop. It contains a string representing the drag type, a flags field (used only for drag and drop - see GtkTargetFlags), and an application assigned integer ID. The integer ID will later be passed as a signal parameter for signals like "selection_get". It allows the application to identify the target type without extensive string compares.


struct GtkTargetList

struct GtkTargetList {
  GList *list;
  guint ref_count;
};

A GtkTargetList structure is a reference counted list of GtkTargetPair. It is used to represent the same information as a table of GtkTargetEntry, but in an efficient form. This structure should be treated as opaque.


struct GtkTargetPair

struct GtkTargetPair {
  GdkAtom   target;
  guint     flags;
  guint     info;
};

Internally used structure in the drag-and-drop and selection handling code.


gtk_target_list_new ()

GtkTargetList* gtk_target_list_new          (const GtkTargetEntry *targets,
                                             guint ntargets);

Creates a new GtkTargetList from an array of GtkTargetEntry.

targets :

Pointer to an array of GtkTargetEntry

ntargets :

number of entries in targets.

Returns :

the new GtkTargetList.


gtk_target_list_ref ()

void        gtk_target_list_ref             (GtkTargetList *list);

Increases the reference count of a GtkTargetList by one.

list :

a GtkTargetList


gtk_target_list_unref ()

void        gtk_target_list_unref           (GtkTargetList *list);

Decreases the reference count of a GtkTargetList by one. If the resulting reference count is zero, frees the list.

list :

a GtkTargetList


gtk_target_list_add ()

void        gtk_target_list_add             (GtkTargetList *list,
                                             GdkAtom target,
                                             guint flags,
                                             guint info);

Adds another target to a GtkTargetList.

list :

a GtkTargetList

target :

the interned atom representing the target

flags :

the flags for this target

info :

an ID that will be passed back to the application


gtk_target_list_add_table ()

void        gtk_target_list_add_table       (GtkTargetList *list,
                                             const GtkTargetEntry *targets,
                                             guint ntargets);

Adds a table of GtkTargetEntry into a target list.

list :

a GtkTargetList

targets :

the table of GtkTargetEntry

ntargets :

number of targets in the table


gtk_target_list_remove ()

void        gtk_target_list_remove          (GtkTargetList *list,
                                             GdkAtom target);

Removes a target from a target list.

list :

a GtkTargetList

target :

the interned atom representing the target


gtk_target_list_find ()

gboolean    gtk_target_list_find            (GtkTargetList *list,
                                             GdkAtom target,
                                             guint *info);

Looks up a given target in a GtkTargetList.

list :

a GtkTargetList

target :

an interned atom representing the target to search for

info :

a pointer to the location to store application info for target

Returns :

TRUE if the target was found, otherwise FALSE


gtk_selection_owner_set ()

gboolean    gtk_selection_owner_set         (GtkWidget *widget,
                                             GdkAtom selection,
                                             guint32 time);

Claims ownership of a given selection for a particular widget, or, if widget is NULL, release ownership of the selection.

widget :

a GtkWidget, or NULL.

selection :

an interned atom representing the selection to claim

time :

timestamp with which to claim the selection

Returns :

TRUE if the operation succeeded


gtk_selection_owner_set_for_display ()

gboolean    gtk_selection_owner_set_for_display
                                            (GdkDisplay *display,
                                             GtkWidget *widget,
                                             GdkAtom selection,
                                             guint32 time);

Claim ownership of a given selection for a particular widget, or, if widget is NULL, release ownership of the selection.

display :

the Gdkdisplay where the selection is set

widget :

new selection owner (a GdkWidget), or NULL.

selection :

an interned atom representing the selection to claim.

time :

timestamp with which to claim the selection

Returns :

TRUE if the operation succeeded


gtk_selection_add_target ()

void        gtk_selection_add_target        (GtkWidget *widget,
                                             GdkAtom selection,
                                             GdkAtom target,
                                             guint info);

Adds specified target to the list of supported targets for a given widget and selection.

widget :

a GtkTarget

selection :

the selection

target :

target to add.

info :

A unsigned integer which will be passed back to the application.


gtk_selection_add_targets ()

void        gtk_selection_add_targets       (GtkWidget *widget,
                                             GdkAtom selection,
                                             const GtkTargetEntry *targets,
                                             guint ntargets);

Adds a table of targets to the list of supported targets for a given widget and selection.

widget :

a GtkWidget

selection :

the selection

targets :

a table of targets to add

ntargets :

number of entries in targets


gtk_selection_clear_targets ()

void        gtk_selection_clear_targets     (GtkWidget *widget,
                                             GdkAtom selection);

Remove all targets registered for the given selection for the widget.

widget :

a GtkWidget

selection :

an atom representing a selection


gtk_selection_convert ()

gboolean    gtk_selection_convert           (GtkWidget *widget,
                                             GdkAtom selection,
                                             GdkAtom target,
                                             guint32 time);

Requests the contents of a selection. When received, a "selection_received" signal will be generated.

widget :

The widget which acts as requestor

selection :

Which selection to get

target :

Form of information desired (e.g., STRING)

time :

Time of request (usually of triggering event) In emergency, you could use GDK_CURRENT_TIME

Returns :

TRUE if requested succeeded. FALSE if we could not process request. (e.g., there was already a request in process for this widget).


gtk_selection_data_set ()

void        gtk_selection_data_set          (GtkSelectionData *selection_data,
                                             GdkAtom type,
                                             gint format,
                                             const guchar *data,
                                             gint length);

Stores new data into a GtkSelectionData object. Should only be called from a selection handler callback. Zero-terminates the stored data.

selection_data :

type :

the type of selection data

format :

format (number of bits in a unit)

data :

pointer to the data (will be copied)

length :

length of the data


gtk_selection_data_set_text ()

gboolean    gtk_selection_data_set_text     (GtkSelectionData *selection_data,
                                             const gchar *str,
                                             gint len);

Sets the contents of the selection from a UTF-8 encoded string. The string is converted to the form determined by selection_data->target.

selection_data :

a GtkSelectionData

str :

a UTF-8 string

len :

the length of str, or -1 if str is nul-terminated.

Returns :

TRUE if the selection was successfully set, otherwise FALSE.


gtk_selection_data_get_text ()

guchar*     gtk_selection_data_get_text     (GtkSelectionData *selection_data);

Gets the contents of the selection data as a UTF-8 string.

selection_data :

a GtkSelectionData

Returns :

if the selection data contained a recognized text type and it could be converted to UTF-8, a newly allocated string containing the converted text, otherwise NULL. If the result is non-NULL it must be freed with g_free().


gtk_selection_data_get_targets ()

gboolean    gtk_selection_data_get_targets  (GtkSelectionData *selection_data,
                                             GdkAtom **targets,
                                             gint *n_atoms);

Gets the contents of selection_data as an array of targets. This can be used to interpret the results of getting the standard TARGETS target that is always supplied for any selection.

selection_data :

a GtkSelectionData object

targets :

location to store an array of targets. The result stored here must be freed with g_free().

n_atoms :

location to store number of items in targets.

Returns :

TRUE if selection_data contains a valid array of targets, otherwise FALSE.


gtk_selection_data_targets_include_text ()

gboolean    gtk_selection_data_targets_include_text
                                            (GtkSelectionData *selection_data);

Given a GtkSelectionData object holding a list of targets, determines if any of the targets in targets can be used to provide text.

selection_data :

a GtkSelectionData object

Returns :

TRUE if selection_data holds a list of targets, and a suitable target for text is included, otherwise FALSE.


gtk_selection_remove_all ()

void        gtk_selection_remove_all        (GtkWidget *widget);

Removes all handlers and unsets ownership of all selections for a widget. Called when widget is being destroyed. This function will not generally be called by applications.

widget :

a GtkWidget


gtk_selection_clear ()

gboolean    gtk_selection_clear             (GtkWidget *widget,
                                             GdkEventSelection *event);

The default handler for the GtkWidget::selection_clear_event signal. Instead of calling this function, chain up from your selection_clear_event handler. Calling this function from any other context is illegal. This function will be deprecated in future versions of GTK+.

Internal function.

widget :

a GtkWidget

event :

the event

Returns :

TRUE if the event was handled, otherwise false


gtk_selection_data_copy ()

GtkSelectionData* gtk_selection_data_copy   (GtkSelectionData *data);

Makes a copy of a GtkSelectionData structure and its data.

data :

a pointer to a GtkSelectionData structure.

Returns :

a pointer to a copy of data.


gtk_selection_data_free ()

void        gtk_selection_data_free         (GtkSelectionData *data);

Frees a GtkSelectionData structure returned from gtk_selection_data_copy().

data :

a pointer to a GtkSelectionData structure.

See Also

GtkWidget

Much of the operation of selections happens via signals for GtkWidget. In particular, if you are using the functions in this section, you may need to pay attention to ::selection_get, ::selection_received, and :selection_clear_event signals.

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