<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/loose.dtd"> <HTML ><HEAD ><TITLE >How do I attach data to some GTK+ object/widget? [GTK 2.x]</TITLE ><META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.79"><LINK REL="HOME" TITLE="GTK+ FAQ" HREF="book1.html"><LINK REL="UP" TITLE="Development with GTK+: general questions" HREF="c466.html"><LINK REL="PREVIOUS" TITLE="Why doesn't my widget (e.g. progressbar) update? [GTK 2.x]" HREF="x592.html"><LINK REL="NEXT" TITLE="How do I remove the data I have attached to an object?" HREF="x614.html"></HEAD ><BODY CLASS="SECT1" BGCOLOR="#FFFFFF" TEXT="#000000" LINK="#0000FF" VLINK="#840084" ALINK="#0000FF" ><DIV CLASS="NAVHEADER" ><TABLE SUMMARY="Header navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TH COLSPAN="3" ALIGN="center" >GTK+ FAQ</TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="bottom" ><A HREF="x592.html" ACCESSKEY="P" ><<< Previous</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" >Development with GTK+: general questions</TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="x614.html" ACCESSKEY="N" >Next >>></A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><DIV CLASS="SECT1" ><H1 CLASS="SECT1" ><A NAME="AEN601" >How do I attach data to some GTK+ object/widget? <I CLASS="EMPHASIS" >[GTK 2.x]</I ></A ></H1 ><P >First of all, the attached data is stored in the object_data field of a GtkObject. The type of this field is GData, which is defined in glib.h. So you should read the gdataset.c file in your glib source directory very carefully.</P ><P >There are two (easy) ways to attach some data to a gtk object. Using <TT CLASS="LITERAL" >g_object_set_data()</TT > and <TT CLASS="LITERAL" >g_object_get_data()</TT > seems to be the most common way to do this, as it provides a powerful interface to connect objects and data.</P ><TABLE BORDER="0" BGCOLOR="#E0E0E0" WIDTH="100%" ><TR ><TD ><PRE CLASS="PROGRAMLISTING" >void g_object_set_data(GObject *object, const gchar *key, gpointer data); gpointer g_object_get_data(GObject *object, const gchar *key);</PRE ></TD ></TR ></TABLE ><P >Since a short example is better than any lengthy speech:</P ><TABLE BORDER="0" BGCOLOR="#E0E0E0" WIDTH="100%" ><TR ><TD ><PRE CLASS="PROGRAMLISTING" >struct my_struct p1,p2,*result; GtkWidget *w; g_object_set_data(G_OBJECT(w),"p1 data",(gpointer)&p1); g_object_set_data(G_OBJECT(w),"p2 data",(gpointer)&p2); result = g_object_get_data(G_OBJECT(w),"p1 data");</PRE ></TD ></TR ></TABLE ><P >The <TT CLASS="LITERAL" >gtk_object_set_user_data()</TT > and <TT CLASS="LITERAL" >gtk_object_get_user_data()</TT > functions does exactly the same thing as the functions above, but does not let you specify the "key" parameter.Instead, it uses a standard "user_data" key. Note that the use of these functions is deprecated in 1.2. They only provide a compatibility mode with some old gtk packages.</P ></DIV ><DIV CLASS="NAVFOOTER" ><HR ALIGN="LEFT" WIDTH="100%"><TABLE SUMMARY="Footer navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><A HREF="x592.html" ACCESSKEY="P" ><<< Previous</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="book1.html" ACCESSKEY="H" >Home</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="x614.html" ACCESSKEY="N" >Next >>></A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >Why doesn't my widget (e.g. progressbar) update? <I CLASS="EMPHASIS" >[GTK 2.x]</I ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="c466.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >How do I remove the data I have attached to an object?</TD ></TR ></TABLE ></DIV ></BODY ></HTML >