[Xpert]Clipped stippled polygon and pixmap cache bug on ATI Radeon VE w/4.2.0

[Andrew P. Lentvorski]

Okay, after tracking this, it turns out to be a pixmap cache bug.  At
least, I can stop the problem from occurring by adding the "Option
"XaaNoPixmapCache"" line to my XF86Config file.

Bug: A stippled polygon which intersects a clip region gets filled in all
black

How to reproduce: Compile and run the attached program.  It draws 8
polygons.  The left 4 should be draw correctly.  The right four *should*
be drawn at one-half the height of the left four (the right four are
clipped).  If you have the bug, the right four rectangles will be half
height, but filled with black (possibly something else, but it should not
be what filled the left 4 polygons)

Workaround:  Set the XaaNoPixmapCache flag in your XF86Config

Aside: Is this the right place to post this kind of stuff?  I'd rather not
waste everybody's time, if not.

If anyone needs more info or log files, just holler.

Thanks,
-a

#include <X11/Xlib.h>

#define stipple_bitmap_width 16
#define stipple_bitmap_height 16
static unsigned char stipple_bitmap_bits[] = {
   0x33, 0x33, 0x66, 0x66, 0xcc, 0xcc, 0x99, 0x99, 0x33, 0x33, 0x66, 0x66,
   0xcc, 0xcc, 0x99, 0x99, 0x33, 0x33, 0x66, 0x66, 0xcc, 0xcc, 0x99, 0x99,
   0x33, 0x33, 0x66, 0x66, 0xcc, 0xcc, 0x99, 0x99};

Display *display;
int screen_num;

static char *progname;

int main(int argc, char **argv)
{
  Window win;
  Pixmap stippleBitmap;
  char *display_name = NULL;
  GC gc0,gc1,gc2,gc3;
  unsigned long valuemask = 0;
  XGCValues values;
  XEvent event;
  Colormap defaultColormap;
  XColor red,green,blue,black,white,junk;

  XRectangle clipRects[1] = {{400,50,400,400}};
  XPoint rb[5] = {{0,0},{100,0},{100,100},{0,100},{0,0}};



  XPoint r[8][5];
  int i,j,k;

  for(i=0; i<8; i++)
    {
      for(j=0; j<5; j++)
        {
          r[i][j].x = rb[j].x + i*100 + i*2;
          r[i][j].y = rb[j].y;
        }
    }

  progname = argv[0];

  if ((display=XOpenDisplay(display_name)) == NULL)
    {
      printf("Failed to open display\n");
      exit(-1);
    }

  win = XCreateSimpleWindow(display, RootWindow(display, screen_num),
                            0, 0, 800, 150, 0, BlackPixel(display, screen_num),
                            WhitePixel(display, screen_num));
  screen_num = DefaultScreen(display);


  stippleBitmap = XCreateBitmapFromData(display, win, stipple_bitmap_bits,
                                        stipple_bitmap_width, stipple_bitmap_height);

  XSelectInput(display, win, ExposureMask | KeyPressMask);

  defaultColormap = DefaultColormap(display, screen_num);

  XAllocNamedColor(display, defaultColormap, "red", &red, &junk);
  XAllocNamedColor(display, defaultColormap, "green", &green, &junk);
  XAllocNamedColor(display, defaultColormap, "blue", &blue, &junk);
  XAllocNamedColor(display, defaultColormap, "black", &black, &junk);
  XAllocNamedColor(display, defaultColormap, "white", &white, &junk);
  
  values.foreground = red.pixel;
  values.background = green.pixel;
  values.fill_style = FillStippled;
  values.stipple = stippleBitmap;
  valuemask = GCForeground | GCBackground | GCFillStyle | GCStipple;
  gc0 = XCreateGC(display, win, valuemask, &values);
  
  XMapWindow(display, win);

  while(1)
    {
      XNextEvent(display, &event);

      switch (event.type)
        {
        case Expose:
          /* Draw something */
          XSetClipMask(display, gc0, None);
          for(i=0; i<4; i++)
            {
              XFillPolygon(display, win, gc0, r[i], 5, Convex, CoordModeOrigin);
            }
          XSetClipRectangles(display, gc0, 0, 0, clipRects, 1, Unsorted);
          for(i=4; i<8; i++)
            {
              XFillPolygon(display, win, gc0, r[i], 5, Convex, CoordModeOrigin);
            }
          break;
        case KeyPress:
          XFreeGC(display, gc0);
          XCloseDisplay(display);
          exit(-1);
          break;
        default:
          break;
        }
    }
}