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Clipboards

Clipboards — Storing data on clipboards

Synopsis


#include <gtk/gtk.h>


            GtkClipboard;
void        (*GtkClipboardReceivedFunc)     (GtkClipboard *clipboard,
                                             GtkSelectionData *selection_data,
                                             gpointer data);
void        (*GtkClipboardTextReceivedFunc) (GtkClipboard *clipboard,
                                             const gchar *text,
                                             gpointer data);
void        (*GtkClipboardTargetsReceivedFunc)
                                            (GtkClipboard *clipboard,
                                             GdkAtom *atoms,
                                             gint n_atoms,
                                             gpointer data);
void        (*GtkClipboardGetFunc)          (GtkClipboard *clipboard,
                                             GtkSelectionData *selection_data,
                                             guint info,
                                             gpointer user_data_or_owner);
void        (*GtkClipboardClearFunc)        (GtkClipboard *clipboard,
                                             gpointer user_data_or_owner);
GtkClipboard* gtk_clipboard_get             (GdkAtom selection);
GtkClipboard* gtk_clipboard_get_for_display (GdkDisplay *display,
                                             GdkAtom selection);
GdkDisplay* gtk_clipboard_get_display       (GtkClipboard *clipboard);
gboolean    gtk_clipboard_set_with_data     (GtkClipboard *clipboard,
                                             const GtkTargetEntry *targets,
                                             guint n_targets,
                                             GtkClipboardGetFunc get_func,
                                             GtkClipboardClearFunc clear_func,
                                             gpointer user_data);
gboolean    gtk_clipboard_set_with_owner    (GtkClipboard *clipboard,
                                             const GtkTargetEntry *targets,
                                             guint n_targets,
                                             GtkClipboardGetFunc get_func,
                                             GtkClipboardClearFunc clear_func,
                                             GObject *owner);
GObject*    gtk_clipboard_get_owner         (GtkClipboard *clipboard);
void        gtk_clipboard_clear             (GtkClipboard *clipboard);
void        gtk_clipboard_set_text          (GtkClipboard *clipboard,
                                             const gchar *text,
                                             gint len);
void        gtk_clipboard_set_image         (GtkClipboard *clipboard,
                                             GdkPixbuf *pixbuf);
void        gtk_clipboard_request_contents  (GtkClipboard *clipboard,
                                             GdkAtom target,
                                             GtkClipboardReceivedFunc callback,
                                             gpointer user_data);
void        gtk_clipboard_request_text      (GtkClipboard *clipboard,
                                             GtkClipboardTextReceivedFunc callback,
                                             gpointer user_data);
void        gtk_clipboard_request_image     (GtkClipboard *clipboard,
                                             GtkClipboardImageReceivedFunc callback,
                                             gpointer user_data);
void        gtk_clipboard_request_targets   (GtkClipboard *clipboard,
                                             GtkClipboardTargetsReceivedFunc callback,
                                             gpointer user_data);
GtkSelectionData* gtk_clipboard_wait_for_contents
                                            (GtkClipboard *clipboard,
                                             GdkAtom target);
gchar*      gtk_clipboard_wait_for_text     (GtkClipboard *clipboard);
GdkPixbuf*  gtk_clipboard_wait_for_image    (GtkClipboard *clipboard);
gboolean    gtk_clipboard_wait_is_text_available
                                            (GtkClipboard *clipboard);
gboolean    gtk_clipboard_wait_is_image_available
                                            (GtkClipboard *clipboard);
gboolean    gtk_clipboard_wait_for_targets  (GtkClipboard *clipboard,
                                             GdkAtom **targets,
                                             gint *n_targets);
gboolean    gtk_clipboard_wait_is_target_available
                                            (GtkClipboard *clipboard,
                                             GdkAtom target);
void        gtk_clipboard_set_can_store     (GtkClipboard *clipboard,
                                             const GtkTargetEntry *targets,
                                             gint n_targets);
void        gtk_clipboard_store             (GtkClipboard *clipboard);


Description

The GtkClipboard object represents a clipboard of data shared between different processes or between different widgets in the same process. Each clipboard is identified by a name encoded as a GdkAtom. (Conversion to and from strings can be done with gdk_atom_intern() and gdk_atom_name().) The default clipboard corresponds to the "CLIPBOARD" atom; another commonly used clipboard is the "PRIMARY" clipboard, which, in X, traditionally contains the currently selected text.

To support having a number of different formats on the clipboard at the same time, the clipboard mechanism allows providing callbacks instead of the actual data. When you set the contents of the clipboard, you can either supply the data directly (via functions like gtk_clipboard_set_text()), or you can supply a callback to be called at a later time when the data is needed (via gtk_clipboard_set_with_data() or gtk_clipboard_set_with_owner().) Providing a callback also avoids having to make copies of the data when it is not needed.

gtk_clipboard_set_with_data() and gtk_clipboard_set_with_owner() are quite similar; the choice between the two depends mostly on which is more convenient in a particular situation. The former is most useful when you want to have a blob of data with callbacks to convert it into the various data types that you advertise. When the clear_func you provided is called, you simply free the data blob. The latter is more useful when the contents of clipboard reflect the internal state of a GObject (As an example, for the PRIMARY clipboard, when an entry widget provides the clipboard's contents the contents are simply the text within the selected region.) If the contents change, the entry widget can call gtk_clipboard_set_with_owner() to update the timestamp for clipboard ownership, without having to worry about clear_func being called.

Requesting the data from the clipboard is essentially asynchronous. If the contents of the clipboard are provided within the same process, then a direct function call will be made to retrieve the data, but if they are provided by another process, then the data needs to be retrieved from the other process, which may take some time. To avoid blocking the user interface, the call to request the selection, gtk_clipboard_request_contents() takes a callback that will be called when the contents are received (or when the request fails.) If you don't want to deal with providing a separate callback, you can also use gtk_clipboard_wait_for_contents(). What this does is run the GLib main loop recursively waiting for the contents. This can simplify the code flow, but you still have to be aware that other callbacks in your program can be called while this recursive mainloop is running.

Along with the functions to get the clipboard contents as an arbitrary data chunk, there are also functions to retrieve it as text, gtk_clipboard_request_text() and gtk_clipboard_wait_for_text(). These functions take care of determining which formats are advertised by the clipboard provider, asking for the clipboard in the best available format and converting the results into the UTF-8 encoding. (The standard form for representing strings in GTK+.)

Details

GtkClipboard

typedef struct _GtkClipboard GtkClipboard;


GtkClipboardReceivedFunc ()

void        (*GtkClipboardReceivedFunc)     (GtkClipboard *clipboard,
                                             GtkSelectionData *selection_data,
                                             gpointer data);

A function to be called when the results of gtk_clipboard_request_contents() are received, or when the request fails.

clipboard :the GtkClipboard
selection_data :a GtkSelectionData containing the data was received. If retrieving the data failed, then then length field of selection_data will be negative.
data :the user_data supplied to gtk_clipboard_request_contents().

GtkClipboardTextReceivedFunc ()

void        (*GtkClipboardTextReceivedFunc) (GtkClipboard *clipboard,
                                             const gchar *text,
                                             gpointer data);

A function to be called when the results of gtk_clipboard_request_text() are received, or when the request fails.

clipboard :the GtkClipboard
text :the text received, as a UTF-8 encoded string, or NULL if retrieving the data failed.
data :the user_data supplied to gtk_clipboard_request_text().

GtkClipboardTargetsReceivedFunc ()

void        (*GtkClipboardTargetsReceivedFunc)
                                            (GtkClipboard *clipboard,
                                             GdkAtom *atoms,
                                             gint n_atoms,
                                             gpointer data);

A function to be called when the results of gtk_clipboard_request_targets() are received, or when the request fails.

clipboard :the GtkClipboard
atoms :the supported targets, as array of GdkAtom, or NULL if retrieving the data failed.
n_atoms :the length of the atoms array.
data :the user_data supplied to gtk_clipboard_request_targets().

Since 2.4


GtkClipboardGetFunc ()

void        (*GtkClipboardGetFunc)          (GtkClipboard *clipboard,
                                             GtkSelectionData *selection_data,
                                             guint info,
                                             gpointer user_data_or_owner);

A function that will be called to provide the contents of the selection. If multiple types of data were advertised, the requested type can be determined from the info parameter or by checking the target field of selection_data. If the data could successfully be converted into then it should be stored into the selection_data object by calling gtk_selection_data_set() (or related functions such as gtk_selection_data_set_text()). If no data is set, the requestor will be informed that the attempt to get the data failed.

clipboard :the GtkClipboard
selection_data :a GtkSelectionData argument in which the requested data should be stored.
info :the info field corresponding to the requested target from the GtkTargetEntry array passed to gtk_clipboard_set_with_data() or gtk_clipboard_set_with_owner().
user_data_or_owner :the user_data argument passed to gtk_clipboard_set_with_data(), or the owner argument passed to gtk_clipboard_set_with_owner()

GtkClipboardClearFunc ()

void        (*GtkClipboardClearFunc)        (GtkClipboard *clipboard,
                                             gpointer user_data_or_owner);

A function that will be called when the contents of the clipboard are changed or cleared. Once this has called, the user_data_or_owner argument will not be used again.

clipboard :the GtkClipboard
user_data_or_owner :the user_data argument passed to gtk_clipboard_set_with_data(), or the owner argument passed to gtk_clipboard_set_with_owner()

gtk_clipboard_get ()

GtkClipboard* gtk_clipboard_get             (GdkAtom selection);

Returns the clipboard object for the given selection. See gtk_clipboard_get_for_display() for complete details.

selection : a GdkAtom which identifies the clipboard to use.
Returns : the appropriate clipboard object. If no clipboard already exists, a new one will be created. Once a clipboard object has been created, it is persistent and, since it is owned by GTK+, must not be freed or unrefd.

gtk_clipboard_get_for_display ()

GtkClipboard* gtk_clipboard_get_for_display (GdkDisplay *display,
                                             GdkAtom selection);

Returns the clipboard object for the given selection. Cut/copy/paste menu items and keyboard shortcuts should use the default clipboard, returned by passing GDK_SELECTION_CLIPBOARD for selection. (GDK_NONE is supported as a synonym for GDK_SELECTION_CLIPBOARD for backwards compatibility reasons.) The currently-selected object or text should be provided on the clipboard identified by GDK_SELECTION_PRIMARY. Cut/copy/paste menu items conceptually copy the contents of the GDK_SELECTION_PRIMARY clipboard to the default clipboard, i.e. they copy the selection to what the user sees as the clipboard.

(Passing GDK_NONE is the same as using gdk_atom_intern ("CLIPBOARD", FALSE). See http://www.freedesktop.org/standards/clipboards-spec/clipboards.txt for a detailed discussion of the "CLIPBOARD" vs. "PRIMARY" selections under the X window system. On Win32 the GDK_SELECTION_PRIMARY clipboard is essentially ignored.)

It's possible to have arbitrary named clipboards; if you do invent new clipboards, you should prefix the selection name with an underscore (because the ICCCM requires that nonstandard atoms are underscore-prefixed), and namespace it as well. For example, if your application called "Foo" has a special-purpose clipboard, you might call it "_FOO_SPECIAL_CLIPBOARD".

display : the display for which the clipboard is to be retrieved or created
selection : a GdkAtom which identifies the clipboard to use.
Returns : the appropriate clipboard object. If no clipboard already exists, a new one will be created. Once a clipboard object has been created, it is persistent and, since it is owned by GTK+, must not be freed or unrefd.

Since 2.2


gtk_clipboard_get_display ()

GdkDisplay* gtk_clipboard_get_display       (GtkClipboard *clipboard);

Gets the GdkDisplay associated with clipboard

clipboard : a GtkClipboard
Returns : the GdkDisplay associated with clipboard

Since 2.2


gtk_clipboard_set_with_data ()

gboolean    gtk_clipboard_set_with_data     (GtkClipboard *clipboard,
                                             const GtkTargetEntry *targets,
                                             guint n_targets,
                                             GtkClipboardGetFunc get_func,
                                             GtkClipboardClearFunc clear_func,
                                             gpointer user_data);

Virtually sets the contents of the specified clipboard by providing a list of supported formats for the clipboard data and a function to call to get the actual data when it is requested.

clipboard : a GtkClipboard
targets : array containing information about the available forms for the clipboard data
n_targets : number of elements in targets
get_func : function to call to get the actual clipboard data
clear_func : when the clipboard contents are set again, this function will be called, and get_func will not be subsequently called.
user_data : user data to pass to get_func and clear_func.
Returns : TRUE if setting the clipboard data succeeded. If setting the clipboard data failed the provided callback functions will be ignored.

gtk_clipboard_set_with_owner ()

gboolean    gtk_clipboard_set_with_owner    (GtkClipboard *clipboard,
                                             const GtkTargetEntry *targets,
                                             guint n_targets,
                                             GtkClipboardGetFunc get_func,
                                             GtkClipboardClearFunc clear_func,
                                             GObject *owner);

Virtually sets the contents of the specified clipboard by providing a list of supported formats for the clipboard data and a function to call to get the actual data when it is requested.

The difference between this function and gtk_clipboard_set_with_data() is that instead of an generic user_data pointer, a GObject is passed in.

clipboard : a GtkClipboard
targets : array containing information about the available forms for the clipboard data
n_targets : number of elements in targets
get_func : function to call to get the actual clipboard data
clear_func : when the clipboard contents are set again, this function will be called, and get_func will not be subsequently called.
owner : an object that "owns" the data. This object will be passed to the callbacks when called.
Returns : TRUE if setting the clipboard data succeeded. If setting the clipboard data failed the provided callback functions will be ignored.

gtk_clipboard_get_owner ()

GObject*    gtk_clipboard_get_owner         (GtkClipboard *clipboard);

If the clipboard contents callbacks were set with gtk_clipboard_set_with_owner(), and the gtk_clipboard_set_with_data() or gtk_clipboard_clear() has not subsequently called, returns the owner set by gtk_clipboard_set_with_owner().

clipboard : a GtkClipboard
Returns : the owner of the clipboard, if any; otherwise NULL.

gtk_clipboard_clear ()

void        gtk_clipboard_clear             (GtkClipboard *clipboard);

Clears the contents of the clipboard. Generally this should only be called between the time you call gtk_clipboard_set_with_owner() or gtk_clipboard_set_with_data(), and when the clear_func you supplied is called. Otherwise, the clipboard may be owned by someone else.

clipboard : a GtkClipboard

gtk_clipboard_set_text ()

void        gtk_clipboard_set_text          (GtkClipboard *clipboard,
                                             const gchar *text,
                                             gint len);

Sets the contents of the clipboard to the given UTF-8 string. GTK+ will make a copy of the text and take responsibility for responding for requests for the text, and for converting the text into the requested format.

clipboard : a GtkClipboard object
text : a UTF-8 string.
len : length of text, in bytes, or -1, in which case the length will be determined with strlen().

gtk_clipboard_set_image ()

void        gtk_clipboard_set_image         (GtkClipboard *clipboard,
                                             GdkPixbuf *pixbuf);

Sets the contents of the clipboard to the given GdkPixbuf. GTK+ will take responsibility for responding for requests for the image, and for converting the image into the requested format.

clipboard : a GtkClipboard object
pixbuf : a GdkPixbuf

Since 2.6


gtk_clipboard_request_contents ()

void        gtk_clipboard_request_contents  (GtkClipboard *clipboard,
                                             GdkAtom target,
                                             GtkClipboardReceivedFunc callback,
                                             gpointer user_data);

Requests the contents of clipboard as the given target. When the results of the result are later received the supplied callback will be called.

clipboard : a GtkClipboard
target : an atom representing the form into which the clipboard owner should convert the selection.
callback : A function to call when the results are received (or the retrieval fails). If the retrieval fails the length field of selection_data will be negative.
user_data : user data to pass to callback

gtk_clipboard_request_text ()

void        gtk_clipboard_request_text      (GtkClipboard *clipboard,
                                             GtkClipboardTextReceivedFunc callback,
                                             gpointer user_data);

Requests the contents of the clipboard as text. When the text is later received, it will be converted to UTF-8 if necessary, and callback will be called.

The text parameter to callback will contain the resulting text if the request succeeded, or NULL if it failed. This could happen for various reasons, in particular if the clipboard was empty or if the contents of the clipboard could not be converted into text form.

clipboard : a GtkClipboard
callback : a function to call when the text is received, or the retrieval fails. (It will always be called one way or the other.)
user_data : user data to pass to callback.

gtk_clipboard_request_image ()

void        gtk_clipboard_request_image     (GtkClipboard *clipboard,
                                             GtkClipboardImageReceivedFunc callback,
                                             gpointer user_data);

Requests the contents of the clipboard as image. When the image is later received, it will be converted to a GdkPixbuf, and callback will be called.

The pixbuf parameter to callback will contain the resulting GdkPixbuf if the request succeeded, or NULL if it failed. This could happen for various reasons, in particular if the clipboard was empty or if the contents of the clipboard could not be converted into an image.

clipboard : a GtkClipboard
callback : a function to call when the image is received, or the retrieval fails. (It will always be called one way or the other.)
user_data : user data to pass to callback.

Since 2.6


gtk_clipboard_request_targets ()

void        gtk_clipboard_request_targets   (GtkClipboard *clipboard,
                                             GtkClipboardTargetsReceivedFunc callback,
                                             gpointer user_data);

Requests the contents of the clipboard as list of supported targets. When the list is later received, callback will be called.

The targets parameter to callback will contain the resulting targets if the request succeeded, or NULL if it failed.

clipboard : a GtkClipboard
callback : a function to call when the targets are received, or the retrieval fails. (It will always be called one way or the other.)
user_data : user data to pass to callback.

Since 2.4


gtk_clipboard_wait_for_contents ()

GtkSelectionData* gtk_clipboard_wait_for_contents
                                            (GtkClipboard *clipboard,
                                             GdkAtom target);

Requests the contents of the clipboard using the given target. This function waits for the data to be received using the main loop, so events, timeouts, etc, may be dispatched during the wait.

clipboard : a GtkClipboard
target : an atom representing the form into which the clipboard owner should convert the selection.
Returns : a newly-allocated GtkSelectionData object or NULL if retrieving the given target failed. If non-NULL, this value must be freed with gtk_selection_data_free() when you are finished with it.

gtk_clipboard_wait_for_text ()

gchar*      gtk_clipboard_wait_for_text     (GtkClipboard *clipboard);

Requests the contents of the clipboard as text and converts the result to UTF-8 if necessary. This function waits for the data to be received using the main loop, so events, timeouts, etc, may be dispatched during the wait.

clipboard : a GtkClipboard
Returns : a newly-allocated UTF-8 string which must be freed with g_free(), or NULL if retrieving the selection data failed. (This could happen for various reasons, in particular if the clipboard was empty or if the contents of the clipboard could not be converted into text form.)

gtk_clipboard_wait_for_image ()

GdkPixbuf*  gtk_clipboard_wait_for_image    (GtkClipboard *clipboard);

Requests the contents of the clipboard as image and converts the result to a GdkPixbuf. This function waits for the data to be received using the main loop, so events, timeouts, etc, may be dispatched during the wait.

clipboard : a GtkClipboard
Returns : a newly-allocated GdkPixbuf object which must be disposed with g_object_unref(), or NULL if retrieving the selection data failed. (This could happen for various reasons, in particular if the clipboard was empty or if the contents of the clipboard could not be converted into an image.)

Since 2.6


gtk_clipboard_wait_is_text_available ()

gboolean    gtk_clipboard_wait_is_text_available
                                            (GtkClipboard *clipboard);

Test to see if there is text available to be pasted This is done by requesting the TARGETS atom and checking if it contains any of the supported text targets. This function waits for the data to be received using the main loop, so events, timeouts, etc, may be dispatched during the wait.

This function is a little faster than calling gtk_clipboard_wait_for_text() since it doesn't need to retrieve the actual text.

clipboard : a GtkClipboard
Returns : TRUE is there is text available, FALSE otherwise.

gtk_clipboard_wait_is_image_available ()

gboolean    gtk_clipboard_wait_is_image_available
                                            (GtkClipboard *clipboard);

Test to see if there is an image available to be pasted This is done by requesting the TARGETS atom and checking if it contains any of the supported image targets. This function waits for the data to be received using the main loop, so events, timeouts, etc, may be dispatched during the wait.

This function is a little faster than calling gtk_clipboard_wait_for_image() since it doesn't need to retrieve the actual image data.

clipboard : a GtkClipboard
Returns : TRUE is there is an image available, FALSE otherwise.

Since 2.6


gtk_clipboard_wait_for_targets ()

gboolean    gtk_clipboard_wait_for_targets  (GtkClipboard *clipboard,
                                             GdkAtom **targets,
                                             gint *n_targets);

Returns a list of targets that are present on the clipboard, or NULL if there aren't any targets available. The returned list must be freed with g_free(). This function waits for the data to be received using the main loop, so events, timeouts, etc, may be dispatched during the wait.

clipboard : a GtkClipboard
targets : location to store an array of targets. The result stored here must be freed with g_free().
n_targets : location to store number of items in targets.
Returns : TRUE if any targets are present on the clipboard, otherwise FALSE.

Since 2.4


gtk_clipboard_wait_is_target_available ()

gboolean    gtk_clipboard_wait_is_target_available
                                            (GtkClipboard *clipboard,
                                             GdkAtom target);

Checks if a clipboard supports pasting data of a given type. This function can be used to determine if a "Paste" menu item should be insensitive or not.

If you want to see if there's text available on the clipboard, use gtk_clipboard_wait_is_text_available() instead.

clipboard : a GtkClipboard
target : A GdkAtom indicating which target to look for.
Returns : TRUE if the target is available, FALSE otherwise.

Since 2.6


gtk_clipboard_set_can_store ()

void        gtk_clipboard_set_can_store     (GtkClipboard *clipboard,
                                             const GtkTargetEntry *targets,
                                             gint n_targets);

Hints that the clipboard data should be stored somewhere when the application exits or when gtk_clipboard_store() is called.

This value is reset when the clipboard owner changes. Where the clipboard data is stored is platform dependent, see gdk_display_store_clipboard() for more information.

clipboard : a GtkClipboard
targets : array containing information about which forms should be stored or NULL to indicate that all forms should be stored.
n_targets : number of elements in targets

Since 2.6


gtk_clipboard_store ()

void        gtk_clipboard_store             (GtkClipboard *clipboard);

Stores the current clipboard data somewhere so that it will stay around after the application has quit.

clipboard : a GtkClipboard

Since 2.6

See Also

GtkSelection

GtkClipboard provides a high-level wrapper around the lower level routines that deal with X selections. It is also possibly to directly manipulate the X selections, though it is seldom necessary to do so.