GTK+ Reference Manual
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# Selections

## Name

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);
    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_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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