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
GtkClipboardReceivedFunc ()
A function to be called when the results of gtk_clipboard_request_text()
are received, or when the request fails.
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.
GtkClipboardGetFunc ()
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 succesfully 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_seletion_data_get().) If no data is set, the requestor
will be informed that the attempt to get the data failed.
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.
gtk_clipboard_get ()
Returns the clipboard object for the given selection.
gtk_clipboard_set_with_data ()
Virtually set 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.
gtk_clipboard_set_with_owner ()
Virtually set 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. Because of this,
gtk_clipboard_get_owner ()
If the clipboard contents callbacks were set with gtk_clipboard_set_owner(),
and the gtk_clipboard_set_with_data() or gtk_clipboard_clear() has not
subsequently called, returns the owner set by gtk_clipboard_set_owner().
gtk_clipboard_clear ()
Clear the contents of the clipboard. Generally this should only
be called between the time you call gtk_clipboard_set_contents(),
and when the clear_func you supplied is called. Otherwise, the
clipboard may be owned by someone else.
gtk_clipboard_set_text ()
void gtk_clipboard_set_text (GtkClipboard *clipboard,
const gchar *text,
gint len); |
Set 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.
gtk_clipboard_request_contents ()
Requests the contents of clipboard as the given target.
When the results of the result are later received the supplied callback
will be called.
gtk_clipboard_request_text ()
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.
gtk_clipboard_wait_for_contents ()
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.
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.