Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ncar!boulder!stan!garya
From: garya@Solbourne.COM (Gary Aitken)
Newsgroups: comp.windows.x
Subject: XDrawImageString bug
Keywords: XDrawImageString
Message-ID: <1850@garya.Solbourne.COM>
Date: 3 Aug 89 23:14:27 GMT
Organization: Solbourne Computer Inc., Longmont, Co.
Lines: 63


XDrawImageString has a bug in it for fonts like .../75dpi/courR14.snf which have
pixels at the top of the font for things like umlauts.  The font height,
as measured by maxbounds ascent+descent, is 16.  A font property, PIXEL_SIZE,
is 14.  XDrawImageString does not draw the top two pixels in some cases.
I'm guessing it's using the property somehow to determine a clip region?

Here's a demo:
Fails on X11R3 and the pre release R4 Xlib

==================================  cut here  ========================================
#include <X11/Xlib.h>
 main(argc,argv)
		int		argc ;
		char		**argv ;
 {
		Display		*dpy ;
		Window		rt,win1,win2 ;
		int		x,y ;
		char		*fnp ;		/* font name */
		XFontStruct	*fp ;		/* ptr to X font structure for new font */
		XGCValues	tempgc ;	/* temporary X graphics context for creating GC's */
		GC		gc1,gc2 ;
	unsigned long		mask ;
	static	char		string[] = "H\305" ;	/* H, A with a circle over it in courR14.snf */
		XEvent		event ;

	dpy = XOpenDisplay("unix:0.0") ;
	XSynchronize(dpy,1) ;
	rt = XDefaultRootWindow(dpy) ;
	fp = XLoadQueryFont(dpy,"-adobe-courier-medium-r-normal--14-140-75-75-m-90-iso8859-1") ;
	tempgc.graphics_exposures = False ;
	tempgc.foreground = XBlackPixel(dpy,0) ;
	tempgc.background = XWhitePixel(dpy,0) ;
	tempgc.font = fp->fid ;
	mask = GCForeground | GCBackground | GCGraphicsExposures | GCFont ;
	gc1 = XCreateGC(dpy,rt,mask,&tempgc) ;
	win1 = XCreateSimpleWindow(dpy,rt,100,100,300,200,4,tempgc.foreground,tempgc.background) ;
	win2 = XCreateSimpleWindow(dpy,rt,200,100,300,200,4,tempgc.foreground,tempgc.foreground) ;
	XSelectInput(dpy,win1,StructureNotifyMask) ;
	XSelectInput(dpy,win2,StructureNotifyMask) ;
	XMapWindow(dpy,win1) ;
	XMapWindow(dpy,win2) ;
	while (!XCheckTypedWindowEvent(dpy,win1,MapNotify,&event))
		 ;
	while (!XCheckTypedWindowEvent(dpy,win2,MapNotify,&event))
		 ;
	tempgc.foreground = XWhitePixel(dpy,0) ;
	tempgc.background = XBlackPixel(dpy,0) ;
	gc2 = XCreateGC(dpy,rt,mask,&tempgc) ;

	XDrawImageString(dpy,win1,gc1,50,50,string,2) ;
	XDrawImageString(dpy,win1,gc2,100,50,string,2) ;
	XDrawImageString(dpy,win2,gc1,50,50,string,2) ;
	XDrawImageString(dpy,win2,gc2,100,50,string,2) ;
	
	while (1) ;
 }
-- 
Gary Aitken

Solbourne Computer Inc.    ARPA: garya@Solbourne.COM
Longmont, CO               UUCP: !{boulder,nbires,sun}!stan!garya