list_16_17.c

This source code has been tested under OpenWindows 2.0, Sun s X11/NeWS server. For Xlib programs th

/***********************************************************************
**                                                                    **
**  listing_16_17.c                                                   **
**                                                                    **
**  String-to-UnitType converter. This program shows an example of    **
**  quarks in use.                                                    **
**                                                                    **
***********************************************************************/


#include <Xm/Label.h>


void    CvtStringToUnitType();		/* FORWARD Definition	      */


Widget	appshell,			/* Application Shell	      */
	a_label,			/* Dummy label		      */
	the_label;			/* The only true label        */


void main( argc, argv )
    int     argc;
    char    *argv[];
{
    appshell = XtInitialize( argv[0], "Listing_16_17", NULL, 0, &argc, argv );

    a_label = XmCreateLabel( appshell, "ALabel", NULL, 0 );
    XtDestroyWidget( a_label );

    XtAddConverter( XmRString, XmRUnitType, CvtStringToUnitType, NULL, 0 );

    the_label = XmCreateLabel( appshell, "TheLabel", NULL, 0 );
    XtManageChild( the_label );

    XtRealizeWidget( appshell );
    XtMainLoop();
}


/**
*** CvtStringToUnitType( args, num_args, from, to )
***
*** Converts "String" data (NUL-terminated ASCII strings) to 
*** UnitType data. Recognizes five unit-type specifications:
***   PIXELS, 100TH_MILLIMETERS, 1000TH_INCHES, 100TH_POINTS,
***   and 100TH_FONT_UNITS. 
*** Does not recognize any spellings other than those listed.
**/

void    CvtStringToUnitType( args, num_args, from, to )
    XrmValue	*args;
    Cardinal	*num_args;
    XrmValue	*from;
    XrmValue	*to;
{
    static unsigned char    val;
    static Boolean	    inited = FALSE;
    static XrmQuark	    q_pixel, q_mm, q_inch, q_pt, q_font;
    XrmQuark		    the_val;

    if (!inited)
        {
	inited = TRUE;
	q_pixel = XrmStringToQuark( "PIXELS" );
	q_mm    = XrmStringToQuark( "100TH_MILLIMETERS" );
	q_inch  = XrmStringToQuark( "1000TH_INCHES" );
	q_pt    = XrmStringToQuark( "100TH_POINTS" );
	q_font  = XrmStringToQuark( "100TH_FONT_UNITS" );
	}

   the_val = XrmStringToQuark( (char*)from->addr ); 
   if (the_val == q_pixel)
       val = XmPIXELS;
   else if (the_val == q_mm)
       val = Xm100TH_MILLIMETERS;
   else if (the_val == q_inch)
       val = Xm1000TH_INCHES;
   else if (the_val == q_pt)
       val = Xm100TH_POINTS;
   else if (the_val == q_font)
       val = Xm100TH_FONT_UNITS;
   else
       {
       val = XmPIXELS;
       XtStringConversionWarning( (char*)from->addr, "UnitType" );
       }

   to->addr = (caddr_t)&val;
   to->size = sizeof(unsigned char);
}