list_16_13.c

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

/***********************************************************************
**                                                                    **
**  listing_16_13.c                                                   **
**                                                                    **
**  String-to-XmString converter example. This converter allows a     **
**  program to specify multi-line XmStrings in a resource file. It    **
**  is in the context of "Hello, World".                              **
**                                                                    **
***********************************************************************/


#include <Xm/Label.h>


void    CvtStringToXmString();		/* 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_13", NULL, 0, &argc, argv );

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

    XtAddConverter( XmRString, XmRXmString, CvtStringToXmString, NULL, 0 );

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

    XtRealizeWidget( appshell );
    XtMainLoop();
}


/**
*** CvtStringToXmString( args, num_args, from, to )
***
*** Converts "String" data (NUL-terminated ASCII strings) to 
*** "XmString" data (compound strings). Recognizes the sequence
*** "\n" as an embedded newline, allowing the compound string
*** to have multiple lines.
***
*** Notes: 
***      - The parameters "args" and "num_args" are not used by this 
***        conversion.
***      - The maximum size of the compound string is 1024 bytes. This
***        limit is imposed by the fact that the string is copied into
***        a local buffer.
**/

void CvtStringToXmString( args, num_args, from, to )
    XrmValue	*args;
    Cardinal	*num_args;
    XrmValue	*from;
    XrmValue	*to;
{
    static char	    lcl_buf[1024];
    static XmString lcl_ptr = lcl_buf;
    XmString	    xms;
    String	    str;
    int  	    siz;

    str = (String)from->addr;
    xms = XmStringCreateLtoR( str, XmSTRING_DEFAULT_CHARSET );
    siz = XmStringLength(xms);
    if (siz < 1024)
        {
        memcpy( lcl_buf, xms, siz );
        to->addr = (caddr_t)&lcl_ptr;
        to->size = sizeof(XmString);
        }
    else
        {
        to->addr = NULL;
        to->size = 0;
        }
    XmStringFree( xms );
}