erc@pai.UUCP (Eric F. Johnson) (06/22/91)
Here's the simple Xlib program from the July, 1991 C Users Journal,
in the article on "X Window Programming, Part 3: More Xlib
Programming", beginning on page 93.
I'll try to post the code from the rest of the articles (this is
part 3 of a six-part series) as they appear.
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/*
* xlib2.c
* A more advanced X Window
* (Xlib)-based program using text,
* written for the C Users Journal.
*
* Link with the X library, e.g.,
*
* cc -o xlib2 xlib2.c -lX11
*
* Define SYSV if you have malloc()
* declared in stdlib.h.
*
* E F Johnson
*
* Copyright 1991 Eric F. Johnson and
* Kevin Reichard, all rights reserved.
*/
#include <stdio.h>
#ifdef SYSV
#include <stdlib.h>
#endif
#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include <X11/keysymdef.h>
#include <X11/keysym.h>
/*
* We have a hard-coded size and location
*/
#define X_LOCATION 10
#define Y_LOCATION 20
#define WIDTH 400
#define HEIGHT 50
#define MAX_STRING_LENGTH 400
/*
* Use xlsfonts to find a font name
* that is available on your system.
*/
/* #define FONT_NAME "fixed" */
#define FONT_NAME "variable"
main( argc, argv )
int argc;
char *argv[];
{ /* main */
Display *display;
int screen;
Window rootwindow;
Window window;
XSizeHints *sizehints;
XWMHints *wmhints;
GC gc;
XEvent event;
int done;
char string[ MAX_STRING_LENGTH + 4 ];
XFontStruct *font;
/*
* Connect to an X server.
*/
display = XOpenDisplay( (char *) NULL );
if ( display == (Display *) NULL )
{
fprintf( stderr, "Error opening display\n" );
exit( 1 );
}
screen = DefaultScreen( display );
rootwindow = RootWindow( display, screen );
/*
* Create a window
*/
window = XCreateSimpleWindow( display,
rootwindow, /* parent */
X_LOCATION, Y_LOCATION,
WIDTH, HEIGHT,
1, /* border width */
BlackPixel( display, screen ),
WhitePixel( display, screen ) );
/*
* Set up Window Manager Hints for keyboard input
*/
wmhints = (XWMHints *) malloc( sizeof(XWMHints) );
wmhints->flags = InputHint;
wmhints->input = True;
XSetWMHints(display, window, wmhints );
free( wmhints );
/*
* Set up hints about the window
*/
sizehints = (XSizeHints *) malloc( sizeof(XSizeHints) );
sizehints->x = X_LOCATION;
sizehints->y = Y_LOCATION;
sizehints->width = WIDTH;
sizehints->height = HEIGHT;
sizehints->flags = PPosition | PSize;
/*
* Use XSetWMProperties() in R4
*
*/
XSetStandardProperties( display, window,
"Xlib2", /* window name */
"Xlib2", /* icon name */
(Pixmap) None, /* Icon pixmap */
argv, argc,
sizehints );
free( sizehints );
/*
* Ask for Expose, mouse (Button) and keyboard input
*/
XSelectInput( display, window,
ButtonPressMask | ExposureMask | KeyPressMask );
/*
* Load up a font.
*/
font = XLoadQueryFont( display, FONT_NAME );
if ( font == (XFontStruct *) NULL )
{
fprintf( stderr, "Error in loading %s font.\n",
FONT_NAME );
XCloseDisplay( display );
exit( 1 );
}
/*
* Create a Graphics Context (GC) for drawing text
*/
gc = XCreateGC( display, window,
0L, (XGCValues *) NULL );
XSetForeground( display, gc,
BlackPixel( display, screen ) );
/*
* Set the background color, too
*/
XSetBackground( display, gc,
WhitePixel( display, screen ) );
/*
* Set the GC to draw in the given font.
*/
XSetFont( display, gc, font->fid );
/*
* Make Window appear on the screen
*/
XMapWindow( display, window );
XFlush( display );
string[0] = '\0'; /* null out string */
done = False;
while( !done )
{
XNextEvent( display, &event );
switch( event.type )
{
case ButtonPress:
XCloseDisplay( display );
exit( 0 );
break;
case Expose:
/*
* Only redraw when all
* Expose events are in
*/
if ( event.xexpose.count == 0 )
{
RedrawText( display, window,
gc, string );
}
break;
case KeyPress:
EditString( display, window,
&event, string,
MAX_STRING_LENGTH );
RedrawText( display, window,
gc, string );
break;
}
}
} /* main */
RedrawText( display, window, gc, string )
Display *display;
Window window;
GC gc;
char string[];
{ /* RedrawText */
XDrawImageString( display, window, gc,
5, 20, /* location */
string,
strlen( string ) );
#define MESSAGE "Click a Mouse Button to Exit"
XDrawImageString( display, window, gc,
5, 40, /* location */
MESSAGE,
strlen( MESSAGE ) );
XFlush( display );
} /* RedrawText */
EditString( display, window, event, string, max_length )
Display *display;
Window window;
XKeyEvent *event;
char string[];
int max_length;
{ /* EditString */
int length;
char new_string[ 12 ];
KeySym keysym;
XComposeStatus composestatus;
length = XLookupString( event,
new_string,
1, /* max length of new_string */
&keysym,
&composestatus );
new_string[1] = '\0'; /* some systems add garbage to new_string */
if ( ( event->state & Mod1Mask ) || ( event->state & Mod2Mask ) )
{
/*
* ALT key
*/
}
if ( event->state & ShiftMask )
{
/*
* Shift key down
*/
}
/*
* This is a US ASCII test, so you may need to change this.
*/
if ( ( length > 0 ) && ( keysym > 31 ) && ( keysym < 127 ) )
{
if ( ( length + strlen( string ) ) < max_length )
{
strcat( string, new_string );
}
}
else
{
/*
* Could be a function or special key.
* We'll only check for a few here.
*/
switch( keysym )
{
case XK_Return: /* Return key */
break;
case XK_Escape:
string[0] = '\0';
XClearWindow( display, window );
break;
case XK_BackSpace: /* NOBREAK */
case XK_Delete:
/*
* We'll treat both back space and
* delete the same.
*/
length = strlen( string );
if ( length > 0 )
{
string[ length - 1 ] = '\0';
}
/*
* You should have a much better
* algorithm to refresh after a
* delete character, than this,
* but we'll just clear the window
* and start over.
*/
XClearWindow( display, window );
break;
case XK_Right: /* right arrow */
break;
case XK_Prior: /* PageUp to DOS folks */
break;
case XK_Next: /* PageDn to DOS folks */
break;
case XK_F1: /* functionkey 1 */
break;
}
}
} /* EditString */
/* end of file */
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Hope this helps,
-Eric
--
Eric F. Johnson BTI: Industrial
Boulware Technologies, Inc. fax: +1 612 894 0316 automation systems
415 W. Travelers Trail email: erc@pai.mn.org and services
Burnsville, MN 55337 USA