I dug up the guts of Xlib source (X11R6.4). Here is what I found. There are
clear signs of 65535!!!, so it seems that it may also be the npoints that
is punished, if "dpy->bigreq_siz" is not set.
Cheers
Ali
---------------------------------------------------------
/* $TOG: Xlibint.h /main/116 1998/02/06 18:02:35 kaleb $ */
/* $TOG: XlibInt.c /main/116 1998/02/06 18:02:35 kaleb $ */
XDrawLines (dpy, d, gc, points, npoints, mode)
register Display *dpy;
Drawable d;
GC gc;
XPoint *points;
int npoints;
int mode;
{
register xPolyLineReq *req;
register long length;
LockDisplay(dpy);
FlushGC(dpy, gc);
GetReq (PolyLine, req);
req->drawable = d;
req->gc = gc->gid;
req->coordMode = mode;
SetReqLen(req, npoints, 65535 - req->length);
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
/* each point is 2 16-bit integers */
length = npoints << 2; /* watch out for macros... */
Data16 (dpy, (short *) points, length);
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
UnlockDisplay(dpy);
SyncHandle();
return 1;
}
---------------------------------------------------------
#define SetReqLen(req,n,badlen) \
if ((req->length + n) > (unsigned)65535) { \
if (dpy->bigreq_size) { \
MakeBigReq(req,n) \
} else { \
n = badlen; \
req->length += n; \
} \
} else \
req->length += n
---------------------------------------------------------
#ifdef WORD64
#define Data16(dpy, data, len) _XData16(dpy, (short *)data, len)
#else
#define Data16(dpy, data, len) Data((dpy), (char *)(data), (len))
---------------------------------------------------------
void Data (dpy, data, len)
Display *dpy;
char *data;
long len;
{
if (dpy->bufptr + (len) <= dpy->bufmax) {
memcpy(dpy->bufptr, data, (int)len);
dpy->bufptr += ((len) + 3) & ~3;
} else {
_XSend(dpy, data, len);
}
}
#define PACKBUFFERSIZE 4096
_XData16 (dpy, data, len)
Display *dpy;
short *data;
unsigned len;
{
char packbuffer[PACKBUFFERSIZE];
unsigned nunits = PACKBUFFERSIZE >> 1;
for (; len > PACKBUFFERSIZE; len -= PACKBUFFERSIZE, data += nunits) {
doData16 (dpy, data, PACKBUFFERSIZE, packbuffer);
}
if (len) doData16 (dpy, data, len, packbuffer);
}
---------------------------------------------------------
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