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<HTML><HEAD><TITLE>Rulers</TITLE><METANAME="GENERATOR"CONTENT="Modular DocBook HTML Stylesheet Version 1.49"><LINKREL="HOME"TITLE="GTK+ 1.2 Tutorial"HREF="gtk-tut.html"><LINKREL="UP"TITLE="Miscellaneous Widgets"HREF="ch-miscwidgets.html"><LINKREL="PREVIOUS"TITLE="Pixmaps"HREF="sec-pixmaps.html"><LINKREL="NEXT"TITLE="Statusbars"HREF="sec-statusbars.html"></HEAD></head><body bgcolor="#FFFFFF" marginheight=0 marginwidth=0 width="100%"><table cellspacing=6 border=0 cellpadding=0 width="100%">  <tr>    <td bgcolor="#FFFFFF" valign=top nowrap>    <centeR><A HREF="/"><img src="/images/gtk-logo-rgb.gif" width=107 height=140 border=0></A>      <font face="helvetica,lucidia" color="#000000"><BR><BR><b>GTK+<BR>The GIMP Toolkit</b></center><BR><table width=100% cellspacing=0 cellpadding=2 border=0><tr><td bgcolor="#000000"><table width=100% cellspacing=0 cellpadding=4 border=0><tr><td bgcolor="#AAAAEE" nowrap><B>General</B></td></tr><tr><td bgcolor="#FFFFFF" nowrap><A HREF="/">Introduction</A><BR><A HREF="/screenshots/">Screenshots</A><br><A HREF="/download/">Download</A><br><A HREF="/mailinglists.html">Mailing Lists</A><BR><A HREF="/bindings.html">Language Bindings</A><BR><A HREF="http://gtk.themes.org/">Themes</A><BR><A HREF="/bugs.html">Bug Tracker</A><BR></td></tr></table></td></tr></table><BR>  <table width=100% cellspacing=0 cellpadding=2 border=0><tr><td bgcolor="#000000"><table width=100% cellspacing=0 cellpadding=4 border=0><tr><td bgcolor="#AAAAEE" nowrap><B>Documentation</B></td></tr><tr><td bgcolor="#FFFFFF" nowrap><A HREF="/faq/">FAQ</A><br><A HREF="/tutorial/">Tutorial</A><BR><A HREF="/api/">API Reference</A><br><A HREF="/books.html">Published Books</A><BR></td></tr></table></td></tr></table><BR>  <table width=100% cellspacing=0 cellpadding=2 border=0><tr><td bgcolor="#000000"><table width=100% cellspacing=0 cellpadding=4 border=0><tr><td bgcolor="#AAAAEE" nowrap><B>Projects</B></td></tr><tr><td bgcolor="#FFFFFF" nowrap><A HREF="http://www.pango.org/">Pango</A><BR><A HREF="http://sources.redhat.com/inti/">Inti</A><BR><A HREF="http://www.gnome.org/">GNOME</A><BR><A HREF="http://user.sgic.fi/~tml/gimp/win32/">GTK+ for Win32</A><br><A HREF="http://people.redhat.com/sopwith/gtkfb/">GtkFB (Framebuffer)</A><br><A HREF="http://www.directfb.org/gtk.xml">GTK+ on DirectFB</A><BR><A HREF="/beos/">GTK+ for BeOS</A></td></tr></table></td></tr></table><BR>  <table width=100% cellspacing=0 cellpadding=2 border=0><tr><td bgcolor="#000000"><table width=100% cellspacing=0 cellpadding=4 border=0><tr><td bgcolor="#AAAAEE" nowrap><B><B>Applications</B></B></td></tr><tr><td bgcolor="#FFFFFF" nowrap><A HREF="http://www.gimp.org/">GIMP</A><BR><A HREF="http://www.abiword.org/">Abiword</A><BR><A HREF="http://www.lysator.liu.se/~alla/dia/dia.html">Dia</A><BR><A HREF="http://glade.pn.org/">Glade</A><BR><A HREF="http://www.gnucash.org/">GnuCash</A><BR><A HREF="http://www.gnome.org/projects/gnumeric/">Gnumeric</A><BR><BR><A HREF="http://www.gnome.org/applist/">GNOME Software Map</A><br></td></tr></table></td></tr></table><BR>      </td>  <td bgcolor="#ffffff" valign=top width="99%"><font face="lucida,helvetica"><BODYCLASS="SECT1"BGCOLOR="#FFFFFF"TEXT="#000000"LINK="#0000FF"VLINK="#840084"ALINK="#0000FF"><DIVCLASS="NAVHEADER"><TABLEWIDTH="100%"BORDER="0"CELLPADDING="0"CELLSPACING="0"><TR><THCOLSPAN="3"ALIGN="center">GTK+ 1.2 Tutorial</TH></TR><TR><TDWIDTH="10%"ALIGN="left"VALIGN="bottom"><AHREF="sec-pixmaps.html">&#60;&#60;&#60; Previous</A></TD><TDWIDTH="80%"ALIGN="center"VALIGN="bottom">Chapter 9. Miscellaneous Widgets</TD><TDWIDTH="10%"ALIGN="right"VALIGN="bottom"><AHREF="sec-statusbars.html">Next &#62;&#62;&#62;</A></TD></TR></TABLE><HRALIGN="LEFT"WIDTH="100%"></DIV><DIVCLASS="SECT1"><H1CLASS="SECT1"><ANAME="SEC-RULERS">9.7. Rulers</A></H1><P>Ruler widgets are used to indicate the location of the mouse pointerin a given window. A window can have a vertical ruler spanning acrossthe width and a horizontal ruler spanning down the height. A smalltriangular indicator on the ruler shows the exact location of thepointer relative to the ruler.</P><P>A ruler must first be created. Horizontal and vertical rulers arecreated using</P><TABLEBORDER="0"BGCOLOR="#E0E0E0"WIDTH="100%"><TR><TD><PRECLASS="PROGRAMLISTING">GtkWidget *gtk_hruler_new( void );    /* horizontal ruler */GtkWidget *gtk_vruler_new( void );    /* vertical ruler   */</PRE></TD></TR></TABLE><P>Once a ruler is created, we can define the unit of measurement. Unitsof measure for rulers can be<TTCLASS="LITERAL">GTK_PIXELS</TT>, <TTCLASS="LITERAL">GTK_INCHES</TT> or<TTCLASS="LITERAL">GTK_CENTIMETERS</TT>. This is set using</P><TABLEBORDER="0"BGCOLOR="#E0E0E0"WIDTH="100%"><TR><TD><PRECLASS="PROGRAMLISTING">void gtk_ruler_set_metric( GtkRuler      *ruler,                           GtkMetricType  metric );</PRE></TD></TR></TABLE><P>The default measure is <TTCLASS="LITERAL">GTK_PIXELS</TT>.</P><TABLEBORDER="0"BGCOLOR="#E0E0E0"WIDTH="100%"><TR><TD><PRECLASS="PROGRAMLISTING">    gtk_ruler_set_metric( GTK_RULER(ruler), GTK_PIXELS );</PRE></TD></TR></TABLE><P>Other important characteristics of a ruler are how to mark the unitsof scale and where the position indicator is initially placed. Theseare set for a ruler using</P><TABLEBORDER="0"BGCOLOR="#E0E0E0"WIDTH="100%"><TR><TD><PRECLASS="PROGRAMLISTING">void gtk_ruler_set_range( GtkRuler *ruler,                          gfloat    lower,                          gfloat    upper,                          gfloat    position,                          gfloat    max_size );</PRE></TD></TR></TABLE><P>The lower and upper arguments define the extent of the ruler, andmax_size is the largest possible number that will be displayed.Position defines the initial position of the pointer indicator withinthe ruler.</P><P>A vertical ruler can span an 800 pixel wide window thus</P><TABLEBORDER="0"BGCOLOR="#E0E0E0"WIDTH="100%"><TR><TD><PRECLASS="PROGRAMLISTING">    gtk_ruler_set_range( GTK_RULER(vruler), 0, 800, 0, 800);</PRE></TD></TR></TABLE><P>The markings displayed on the ruler will be from 0 to 800, with anumber for every 100 pixels. If instead we wanted the ruler to rangefrom 7 to 16, we would code</P><TABLEBORDER="0"BGCOLOR="#E0E0E0"WIDTH="100%"><TR><TD><PRECLASS="PROGRAMLISTING">    gtk_ruler_set_range( GTK_RULER(vruler), 7, 16, 0, 20);</PRE></TD></TR></TABLE><P>The indicator on the ruler is a small triangular mark that indicatesthe position of the pointer relative to the ruler. If the ruler isused to follow the mouse pointer, the motion_notify_event signalshould be connected to the motion_notify_event method of the ruler.To follow all mouse movements within a window area, we would use</P><TABLEBORDER="0"BGCOLOR="#E0E0E0"WIDTH="100%"><TR><TD><PRECLASS="PROGRAMLISTING">#define EVENT_METHOD(i, x) GTK_WIDGET_CLASS(GTK_OBJECT(i)-&#62;klass)-&#62;x    gtk_signal_connect_object( GTK_OBJECT(area), "motion_notify_event",           (GtkSignalFunc)EVENT_METHOD(ruler, motion_notify_event),           GTK_OBJECT(ruler) );</PRE></TD></TR></TABLE><P>The following example creates a drawing area with a horizontal rulerabove it and a vertical ruler to the left of it. The size of thedrawing area is 600 pixels wide by 400 pixels high. The horizontalruler spans from 7 to 13 with a mark every 100 pixels, while thevertical ruler spans from 0 to 400 with a mark every 100 pixels.Placement of the drawing area and the rulers is done using a table.</P><TABLEBORDER="0"BGCOLOR="#E0E0E0"WIDTH="100%"><TR><TD><PRECLASS="PROGRAMLISTING">/* example-start rulers rulers.c */#include &#60;gtk/gtk.h&#62;#define EVENT_METHOD(i, x) GTK_WIDGET_CLASS(GTK_OBJECT(i)-&#62;klass)-&#62;x#define XSIZE  600#define YSIZE  400/* This routine gets control when the close button is clicked */gint close_application( GtkWidget *widget,                        GdkEvent  *event,                        gpointer   data ){    gtk_main_quit();    return(FALSE);}/* The main routine */int main( int   argc,          char *argv[] ) {    GtkWidget *window, *table, *area, *hrule, *vrule;    /* Initialize GTK and create the main window */    gtk_init( &#38;argc, &#38;argv );    window = gtk_window_new( GTK_WINDOW_TOPLEVEL );    gtk_signal_connect (GTK_OBJECT (window), "delete_event",            GTK_SIGNAL_FUNC( close_application ), NULL);    gtk_container_set_border_width (GTK_CONTAINER (window), 10);    /* Create a table for placing the ruler and the drawing area */    table = gtk_table_new( 3, 2, FALSE );    gtk_container_add( GTK_CONTAINER(window), table );    area = gtk_drawing_area_new();    gtk_drawing_area_size( (GtkDrawingArea *)area, XSIZE, YSIZE );    gtk_table_attach( GTK_TABLE(table), area, 1, 2, 1, 2,                      GTK_EXPAND|GTK_FILL, GTK_FILL, 0, 0 );    gtk_widget_set_events( area, GDK_POINTER_MOTION_MASK |                                 GDK_POINTER_MOTION_HINT_MASK );    /* The horizontal ruler goes on top. As the mouse moves across the     * drawing area, a motion_notify_event is passed to the     * appropriate event handler for the ruler. */    hrule = gtk_hruler_new();    gtk_ruler_set_metric( GTK_RULER(hrule), GTK_PIXELS );    gtk_ruler_set_range( GTK_RULER(hrule), 7, 13, 0, 20 );    gtk_signal_connect_object( GTK_OBJECT(area), "motion_notify_event",                               (GtkSignalFunc)EVENT_METHOD(hrule,                                                        motion_notify_event),                               GTK_OBJECT(hrule) );    /*  GTK_WIDGET_CLASS(GTK_OBJECT(hrule)-&#62;klass)-&#62;motion_notify_event, */    gtk_table_attach( GTK_TABLE(table), hrule, 1, 2, 0, 1,                      GTK_EXPAND|GTK_SHRINK|GTK_FILL, GTK_FILL, 0, 0 );        /* The vertical ruler goes on the left. As the mouse moves across     * the drawing area, a motion_notify_event is passed to the     * appropriate event handler for the ruler. */    vrule = gtk_vruler_new();    gtk_ruler_set_metric( GTK_RULER(vrule), GTK_PIXELS );    gtk_ruler_set_range( GTK_RULER(vrule), 0, YSIZE, 10, YSIZE );    gtk_signal_connect_object( GTK_OBJECT(area), "motion_notify_event",                               (GtkSignalFunc)                                  GTK_WIDGET_CLASS(GTK_OBJECT(vrule)-&#62;klass)-&#62;				                         motion_notify_event,                               GTK_OBJECT(vrule) );    gtk_table_attach( GTK_TABLE(table), vrule, 0, 1, 1, 2,                      GTK_FILL, GTK_EXPAND|GTK_SHRINK|GTK_FILL, 0, 0 );    /* Now show everything */    gtk_widget_show( area );    gtk_widget_show( hrule );    gtk_widget_show( vrule );    gtk_widget_show( table );    gtk_widget_show( window );    gtk_main();    return(0);}/* example-end */</PRE></TD></TR></TABLE></DIV><DIVCLASS="NAVFOOTER"><HRALIGN="LEFT"WIDTH="100%"><TABLEWIDTH="100%"BORDER="0"CELLPADDING="0"CELLSPACING="0"><TR><TDWIDTH="33%"ALIGN="left"VALIGN="top"><AHREF="sec-pixmaps.html">&#60;&#60;&#60; Previous</A></TD><TDWIDTH="34%"ALIGN="center"VALIGN="top"><AHREF="gtk-tut.html">Home</A></TD><TDWIDTH="33%"ALIGN="right"VALIGN="top"><AHREF="sec-statusbars.html">Next &#62;&#62;&#62;</A></TD></TR><TR><TDWIDTH="33%"ALIGN="left"VALIGN="top">Pixmaps</TD><TDWIDTH="34%"ALIGN="center"VALIGN="top"><AHREF="ch-miscwidgets.html">Up</A></TD><TDWIDTH="33%"ALIGN="right"VALIGN="top">Statusbars</TD></TR></TABLE></DIV>        </td>    </tr></table>  </td>  </tr></table></body></BODY></HTML>
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