Path: utzoo!attcan!uunet!mcsun!inria!bull!echbull!cahors.Berkeley.EDU!francois
From: Francois.Laagel@ec.bull.fr
Newsgroups: comp.windows.x
Subject: XDrawRectangle and stipples in GC.
Keywords: X11R3, GC
Message-ID: <351@echbull.bull.fr>
Date: 29 May 90 08:17:50 GMT
Sender: news@bull.bull.fr
Organization: Bull SA, Echirolles France
Lines: 71

I am writing a small widget set which is intended to be used to represent
figures like histograms, pies charts and so on.

One of my widgets needs a GC to redraw itself. The fill style must be
FillStippled. XFillRectangle works with no trouble and uses the pixmap
specified by the stipple member of the GC.
 
But although O'Reilly Xlib programming manual states that XDrawRectangle
doesn't care about stipples or tiles members of the GC, the fact is that
my server (X11R3) uses the stipple even if the line_style member is set to
LineSolid.

So, what are the members of the GC which are meaningfull to XDrawRectangle
as far as the line style is concerned ?
Another question by the way, was is the diffrence between a thin line
(gc.line_width == 0) and a wide line (gc.line_width == 1) ?

Thanks in advance to anyone who could answer these few questions.


                                Francois LAAGEL


Here follows, two pieces of code concerning GC creation, and the Redisplay
method of my widget.

static void RecomputeGC(w)
  XmValueWidget w;
{ long      valueMask;
  XGCValues gcValues;

  if(w->value.gc!=NULL)
  { XtReleaseGC(w,w->value.gc);
    w->value.gc=NULL;
  }
  valueMask=GCForeground | GCBackground | GCFillStyle | GCStipple |
            GCLineStyle | GCLineWidth;
  gcValues.foreground = w->value.foreground;
  gcValues.background = XtBackground(w);
  gcValues.fill_style = FillStippled;
  gcValues.stipple= stippleTable[w->value.stippleType].pixmap;
  gcValues.line_style=LineSolid;
  gcValues.line_width=0;
  w->value.gc=XtGetGC(w, valueMask, &gcValues);
}

static void Redisplay (w, event, region)
     XmValueWidget  w;
     XEvent         *event;
     Region         region;
{ Display    *display=XtDisplay(w);
  Window     win=XtWindow(w);
  int        width=XtWidth(w),
             height=XtHeight(w);
  XRectangle xr;

#ifdef DEBUG
  fprintf(stderr,"Redisplay(%s)\n",XtName(w));
#endif

  if(w->core.visible)
  { XSetRegion(display, w->value.gc, region);

    xr.x=xr.y=(short)0;
    xr.width=(unsigned short)(width-1);
    xr.height=(unsigned short)(height-1);
    XDrawRectangles(display, win, w->value.gc,&xr,1);
    XFillRectangle(display, win, w->value.gc,1,1,width-2,height-2);
    XSync(XtDisplay(w), False);
  }
}