list_17_04.c

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

/***********************************************************************
**                                                                    **
**  listing_17_04.c                                                   **
**                                                                    **
**  File Browser, Edition 2. The file browser of Chapter 9, with      **
**  the capability to read StdIn if no file is specified. It uses     **
**  an input callback to provide this capability.                     **
**                                                                    **
***********************************************************************/


#include <stdio.h>
#include <Xm/Text.h>


void	    LoadFile();			/* FORWARD Definitions	      */
void	    UseStdIn();
void	    InputCB();


Widget	    appshell,			/* Application Shell	      */
	    the_text;			/* The text widget            */
long	    text_cnt = 0;		/* Number of bytes in buffer  */


void main( argc, argv )
    int     argc;
    char    *argv[];
{
    appshell = XtInitialize( argv[0], "Listing_17_04", NULL, 0, &argc, argv );

    the_text = XmCreateScrolledText( appshell, "TheText", NULL, 0 );
    XtManageChild( the_text );

    if (argc > 2)
        {
	fprintf( stderr, "\nbrowser: Usage:\n" );
	fprintf( stderr, "         browser FILENAME\n" );
	fprintf( stderr, "         (or)\n" );
	fprintf( stderr, "         ??? | browser\n" );
	exit( 1 );
	}
    else if (argc == 2)
        LoadFile( argv[1] );
    else
	UseStdIn();

    XtRealizeWidget( appshell );
    XtMainLoop();
}



/**
*** LoadFile( fname )
***
*** Called when the text is to come from a file, this function
*** opens the file and loads it into the text widget.
**/

void LoadFile( fname )
    char    	*fname;
{
    FILE	*infile;
    long    	fsize;
    char    	*lclptr;

    infile = fopen( fname, "r" );
    if (infile == NULL)
        {
	perror( "browser: unable to open input file" );
	exit( 2 );
	}

    fseek( infile, 0, 2 );
    fsize = ftell( infile );
    rewind( infile );

    lclptr = (char *)XtMalloc( fsize + 1 );
    fread( lclptr, sizeof(char), fsize, infile );
    lclptr[fsize] = '\0';

    XmTextSetString( the_text, lclptr );

    XtFree( lclptr );
    fclose( infile );
}



/**
*** UseStdIn()
***
*** This function is called when input is to come from StdIn. It
*** simply attaches an input callback.
**/

void UseStdIn()
{
    XtAddInput( fileno(stdin), XtInputReadMask, InputCB, NULL );
}



/**
*** InputCB( client_data, source, id )
***
*** Called whenever data is present on StdIn. This function
*** reads a single character, and appends it to the text buffer.
**/

void InputCB( client_data, source, id )
    caddr_t	client_data;
    int		*source;
    XtInputId	*id;
{
    char	lcl_buf[2];
    int		in_char;

    if ((in_char = getchar()) != EOF)
        {
	lcl_buf[0] = in_char;
	lcl_buf[1] = '\0';;
	XmTextReplace( the_text, text_cnt, text_cnt, lcl_buf );
	text_cnt++;
	}
    else
        XtRemoveInput( *id );
}