<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/loose.dtd"> <HTML ><HEAD ><TITLE >Getting Started</TITLE ><META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.79"><LINK REL="HOME" TITLE="GTK+ 2.0 Tutorial" HREF="book1.html"><LINK REL="PREVIOUS" TITLE="Introduction" HREF="c24.html"><LINK REL="NEXT" TITLE="Compiling Hello World" HREF="x111.html"></HEAD ><BODY CLASS="CHAPTER" 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+ 2.0 Tutorial</TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="bottom" ><A HREF="c24.html" ACCESSKEY="P" ><<< Previous</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" ></TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="x111.html" ACCESSKEY="N" >Next >>></A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><DIV CLASS="CHAPTER" ><H1 ><A NAME="CH-GETTINGSTARTED" ></A >Getting Started</H1 ><P >The first thing to do, of course, is download the GTK source and install it. You can always get the latest version from <A HREF="ftp://ftp.gtk.org/pub/gtk" TARGET="_top" >ftp.gtk.org</A >. You can also view other sources of GTK information on <A HREF="http://www.gtk.org/" TARGET="_top" >http://www.gtk.org/</A >. GTK uses GNU autoconf for configuration. Once untar'd, type <TT CLASS="LITERAL" >./configure --help</TT > to see a list of options.</P ><P >The GTK source distribution also contains the complete source to all of the examples used in this tutorial, along with Makefiles to aid compilation.</P ><P >To begin our introduction to GTK, we'll start with the simplest program possible. This program will create a 200x200 pixel window and has no way of exiting except to be killed by using the shell.</P ><P ><SPAN CLASS="INLINEMEDIAOBJECT" ><IMG SRC="images/base.png"></SPAN ></P ><TABLE BORDER="0" BGCOLOR="#E0E0E0" WIDTH="100%" ><TR ><TD ><PRE CLASS="PROGRAMLISTING" > #include <gtk/gtk.h> int main( int argc, char *argv[] ) { GtkWidget *window; gtk_init (&argc, &argv); window = gtk_window_new (GTK_WINDOW_TOPLEVEL); gtk_widget_show (window); gtk_main (); return 0; }</PRE ></TD ></TR ></TABLE ><P >You can compile the above program with gcc using:</P ><P ><P CLASS="LITERALLAYOUT" ><TT CLASS="LITERAL" >gcc base.c -o base `pkg-config --cflags --libs gtk+-2.0`</TT ></P ></P ><P >The meaning of the unusual compilation options is explained below in <A HREF="x111.html" >Compiling Hello World</A >.</P ><P >All programs will of course include <TT CLASS="FILENAME" >gtk/gtk.h</TT > which declares the variables, functions, structures, etc. that will be used in your GTK application.</P ><P >The next line:</P ><TABLE BORDER="0" BGCOLOR="#E0E0E0" WIDTH="100%" ><TR ><TD ><PRE CLASS="PROGRAMLISTING" >gtk_init (&argc, &argv);</PRE ></TD ></TR ></TABLE ><P >calls the function gtk_init(gint *argc, gchar ***argv) which will be called in all GTK applications. This sets up a few things for us such as the default visual and color map and then proceeds to call gdk_init(gint *argc, gchar ***argv). This function initializes the library for use, sets up default signal handlers, and checks the arguments passed to your application on the command line, looking for one of the following:</P ><P ></P ><UL COMPACT="COMPACT" ><LI ><SPAN > <TT CLASS="LITERAL" >--gtk-module</TT ></SPAN ></LI ><LI ><SPAN > <TT CLASS="LITERAL" >--g-fatal-warnings</TT ></SPAN ></LI ><LI ><SPAN > <TT CLASS="LITERAL" >--gtk-debug</TT ></SPAN ></LI ><LI ><SPAN > <TT CLASS="LITERAL" >--gtk-no-debug</TT ></SPAN ></LI ><LI ><SPAN > <TT CLASS="LITERAL" >--gdk-debug</TT ></SPAN ></LI ><LI ><SPAN > <TT CLASS="LITERAL" >--gdk-no-debug</TT ></SPAN ></LI ><LI ><SPAN > <TT CLASS="LITERAL" >--display</TT ></SPAN ></LI ><LI ><SPAN > <TT CLASS="LITERAL" >--sync</TT ></SPAN ></LI ><LI ><SPAN > <TT CLASS="LITERAL" >--name</TT ></SPAN ></LI ><LI ><SPAN > <TT CLASS="LITERAL" >--class</TT ></SPAN ></LI ></UL ><P >It removes these from the argument list, leaving anything it does not recognize for your application to parse or ignore. This creates a set of standard arguments accepted by all GTK applications.</P ><P >The next two lines of code create and display a window.</P ><TABLE BORDER="0" BGCOLOR="#E0E0E0" WIDTH="100%" ><TR ><TD ><PRE CLASS="PROGRAMLISTING" > window = gtk_window_new (GTK_WINDOW_TOPLEVEL); gtk_widget_show (window);</PRE ></TD ></TR ></TABLE ><P >The <TT CLASS="LITERAL" >GTK_WINDOW_TOPLEVEL</TT > argument specifies that we want the window to undergo window manager decoration and placement. Rather than create a window of 0x0 size, a window without children is set to 200x200 by default so you can still manipulate it.</P ><P >The gtk_widget_show() function lets GTK know that we are done setting the attributes of this widget, and that it can display it.</P ><P >The last line enters the GTK main processing loop.</P ><TABLE BORDER="0" BGCOLOR="#E0E0E0" WIDTH="100%" ><TR ><TD ><PRE CLASS="PROGRAMLISTING" > gtk_main ();</PRE ></TD ></TR ></TABLE ><P >gtk_main() is another call you will see in every GTK application. When control reaches this point, GTK will sleep waiting for X events (such as button or key presses), timeouts, or file IO notifications to occur. In our simple example, however, events are ignored.</P ><DIV CLASS="SECT1" ><H1 CLASS="SECT1" ><A NAME="SEC-HELLOWORLD" >Hello World in GTK</A ></H1 ><P >Now for a program with a widget (a button). It's the classic hello world a la GTK.</P ><P ><SPAN CLASS="INLINEMEDIAOBJECT" ><IMG SRC="images/helloworld.png"></SPAN ></P ><TABLE BORDER="0" BGCOLOR="#E0E0E0" WIDTH="100%" ><TR ><TD ><PRE CLASS="PROGRAMLISTING" > #include <gtk/gtk.h> /* This is a callback function. The data arguments are ignored * in this example. More on callbacks below. */ static void hello( GtkWidget *widget, gpointer data ) { g_print ("Hello World\n"); } static gboolean delete_event( GtkWidget *widget, GdkEvent *event, gpointer data ) { /* If you return FALSE in the "delete-event" signal handler, * GTK will emit the "destroy" signal. Returning TRUE means * you don't want the window to be destroyed. * This is useful for popping up 'are you sure you want to quit?' * type dialogs. */ g_print ("delete event occurred\n"); /* Change TRUE to FALSE and the main window will be destroyed with * a "delete-event". */ return TRUE; } /* Another callback */ static void destroy( GtkWidget *widget, gpointer data ) { gtk_main_quit (); } int main( int argc, char *argv[] ) { /* GtkWidget is the storage type for widgets */ GtkWidget *window; GtkWidget *button; /* This is called in all GTK applications. Arguments are parsed * from the command line and are returned to the application. */ gtk_init (&argc, &argv); /* create a new window */ window = gtk_window_new (GTK_WINDOW_TOPLEVEL); /* When the window is given the "delete-event" signal (this is given * by the window manager, usually by the "close" option, or on the * titlebar), we ask it to call the delete_event () function * as defined above. The data passed to the callback * function is NULL and is ignored in the callback function. */ g_signal_connect (window, "delete-event", G_CALLBACK (delete_event), NULL); /* Here we connect the "destroy" event to a signal handler. * This event occurs when we call gtk_widget_destroy() on the window, * or if we return FALSE in the "delete-event" callback. */ g_signal_connect (window, "destroy", G_CALLBACK (destroy), NULL); /* Sets the border width of the window. */ gtk_container_set_border_width (GTK_CONTAINER (window), 10); /* Creates a new button with the label "Hello World". */ button = gtk_button_new_with_label ("Hello World"); /* When the button receives the "clicked" signal, it will call the * function hello() passing it NULL as its argument. The hello() * function is defined above. */ g_signal_connect (button, "clicked", G_CALLBACK (hello), NULL); /* This will cause the window to be destroyed by calling * gtk_widget_destroy(window) when "clicked". Again, the destroy * signal could come from here, or the window manager. */ g_signal_connect_swapped (button, "clicked", G_CALLBACK (gtk_widget_destroy), window); /* This packs the button into the window (a gtk container). */ gtk_container_add (GTK_CONTAINER (window), button); /* The final step is to display this newly created widget. */ gtk_widget_show (button); /* and the window */ gtk_widget_show (window); /* All GTK applications must have a gtk_main(). Control ends here * and waits for an event to occur (like a key press or * mouse event). */ gtk_main (); return 0; }</PRE ></TD ></TR ></TABLE ></DIV ></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="c24.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="x111.html" ACCESSKEY="N" >Next >>></A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >Introduction</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" > </TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >Compiling Hello World</TD ></TR ></TABLE ></DIV ></BODY ></HTML >