gtk2/docs/reference/gtk/tmpl/gtkclipboard.sgml

<!-- ##### SECTION Title ##### -->
Clipboards

<!-- ##### SECTION Short_Description ##### -->
Storing data on Clipboards.

<!-- ##### SECTION Long_Description ##### -->
  <para>
    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. 
  </para>
  <para>
    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.
  </para>
  <para>
    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.
  </para>
  <para>
    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.
  </para>
  <para>
    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+.)
  </para>

<!-- ##### SECTION See_Also ##### -->
<para>
<variablelist>

<varlistentry>
<term>#GtkSelection</term>
<listitem><para>@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.</para></listitem>
</varlistentry>

</variablelist>
</para>

<!-- ##### STRUCT GtkClipboard ##### -->
<para>

</para>


<!-- ##### USER_FUNCTION GtkClipboardReceivedFunc ##### -->
<para>
    A function to be called when the results of gtk_clipboard_request_text()
    are received, or when the request fails.
</para>

@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().


<!-- ##### USER_FUNCTION GtkClipboardTextReceivedFunc ##### -->
<para>
    A function to be called when the results of gtk_clipboard_request_text()
    are received, or when the request fails.
</para>

@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().


<!-- ##### USER_FUNCTION GtkClipboardGetFunc ##### -->
<para>
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.    
</para>

@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_owner()


<!-- ##### USER_FUNCTION GtkClipboardClearFunc ##### -->
<para>
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.
</para>

@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_owner()


<!-- ##### FUNCTION gtk_clipboard_get ##### -->
<para>

</para>

@selection: 
@Returns: 


<!-- ##### FUNCTION gtk_clipboard_set_with_data ##### -->
<para>

</para>

@clipboard: 
@targets: 
@n_targets: 
@get_func: 
@clear_func: 
@user_data: 
@Returns: 


<!-- ##### FUNCTION gtk_clipboard_set_with_owner ##### -->
<para>

</para>

@clipboard: 
@targets: 
@n_targets: 
@get_func: 
@clear_func: 
@owner: 
@Returns: 


<!-- ##### FUNCTION gtk_clipboard_get_owner ##### -->
<para>

</para>

@clipboard: 
@Returns: 


<!-- ##### FUNCTION gtk_clipboard_clear ##### -->
<para>

</para>

@clipboard: 


<!-- ##### FUNCTION gtk_clipboard_set_text ##### -->
<para>

</para>

@clipboard: 
@text: 
@len: 


<!-- ##### FUNCTION gtk_clipboard_request_contents ##### -->
<para>

</para>

@clipboard: 
@target: 
@callback: 
@user_data: 


<!-- ##### FUNCTION gtk_clipboard_request_text ##### -->
<para>

</para>

@clipboard: 
@callback: 
@user_data: 


<!-- ##### FUNCTION gtk_clipboard_wait_for_contents ##### -->
<para>

</para>

@clipboard: 
@target: 
@Returns: 


<!-- ##### FUNCTION gtk_clipboard_wait_for_text ##### -->
<para>

</para>

@clipboard: 
@Returns: 
<!--
Local variables:
mode: sgml
sgml-parent-document: ("../gtk-docs.sgml" "book" "refsect2" "")
End:
-->