+/************************************************************
+Copyright 1989 by The Massachusetts Institute of Technology
+
+Permission to use, copy, modify, and distribute this
+software and its documentation for any purpose and without
+fee is hereby granted, provided that the above copyright
+notice appear in all copies and that both that copyright
+notice and this permission notice appear in supporting
+documentation, and that the name of MIT not be used in
+advertising or publicity pertaining to distribution of the
+software without specific prior written permission.
+M.I.T. makes no representation about the suitability of
+this software for any purpose. It is provided "as is"
+without any express or implied warranty.
+
+********************************************************/
+
+/* $XConsortium: mfbzerarc.c,v 5.10 89/09/20 18:55:33 rws Exp $ */
+
+/* Derived from:
+ * "Algorithm for drawing ellipses or hyperbolae with a digital plotter"
+ * by M. L. V. Pitteway
+ * The Computer Journal, November 1967, Volume 10, Number 3, pp. 282-289
+ */
+
+#include "X.h"
+#include "Xprotostr.h"
+#include "miscstruct.h"
+#include "gcstruct.h"
+#include "pixmapstr.h"
+#include "scrnintstr.h"
+#include "mfb.h"
+#include "maskbits.h"
+#include "mizerarc.h"
+
+extern void miPolyArc(), miZeroPolyArc();
+
+#if (BITMAP_BIT_ORDER == MSBFirst)
+#define LEFTMOST ((unsigned int) 0x80000000)
+#else
+#define LEFTMOST ((unsigned int) 1)
+#endif
+
+#define PixelateWhite(addr,off) \
+ (addr)[(off)>>5] |= SCRRIGHT (LEFTMOST, ((off) & 0x1f))
+#define PixelateBlack(addr,off) \
+ (addr)[(off)>>5] &= ~(SCRRIGHT (LEFTMOST, ((off) & 0x1f)))
+
+#define Pixelate(base,off) \
+{ \
+ paddr = base + ((off)>>5); \
+ pmask = SCRRIGHT(LEFTMOST, (off) & 0x1f); \
+ *paddr = (*paddr & ~pmask) | (pixel & pmask); \
+}
+
+#define DoPix(bit,base,off) if (mask & bit) Pixelate(base,off);
+
+static void
+mfbZeroArcSS(pDraw, pGC, arc)
+ DrawablePtr pDraw;
+ GCPtr pGC;
+ xArc *arc;
+{
+ miZeroArcRec info;
+ Bool do360;
+ register int x, y, a, b, d, mask;
+ register int k1, k3, dx, dy;
+ int *addrl;
+ int *yorgl, *yorgol;
+ unsigned long pixel;
+ int nlwidth, yoffset, dyoffset;
+ int pmask;
+ register int *paddr;
+
+ if (((mfbPrivGC *)(pGC->devPrivates[mfbGCPrivateIndex].ptr))->rop ==
+ RROP_BLACK)
+ pixel = 0;
+ else
+ pixel = ~0L;
+
+ if (pDraw->type == DRAWABLE_WINDOW)
+ {
+ addrl = (int *) getPrivScreenPtr(pDraw->pScreen)->bits;
+ nlwidth = (int) getPrivScreenPtr(pDraw->pScreen)->stride >> 2;
+ }
+ else
+ {
+ addrl = (int *) getPrivPixmapPtr(pDraw)->bits;
+ nlwidth = (int) getPrivPixmapPtr(pDraw)->stride >> 2;
+ }
+ do360 = miZeroArcSetup(arc, &info, TRUE);
+ yorgl = addrl + ((info.yorg + pDraw->y) * nlwidth);
+ yorgol = addrl + ((info.yorgo + pDraw->y) * nlwidth);
+ info.xorg += pDraw->x;
+ info.xorgo += pDraw->x;
+ MIARCSETUP();
+ yoffset = y ? nlwidth : 0;
+ dyoffset = 0;
+ mask = info.initialMask;
+ if (!(arc->width & 1))
+ {
+ DoPix(2, yorgl, info.xorgo);
+ DoPix(8, yorgol, info.xorgo);
+ }
+ if (!info.end.x || !info.end.y)
+ {
+ mask = info.end.mask;
+ info.end = info.altend;
+ }
+ if (do360 && (arc->width == arc->height) && !(arc->width & 1))
+ {
+ int xoffset = nlwidth;
+ int *yorghl = yorgl + (info.h * nlwidth);
+ int xorghp = info.xorg + info.h;
+ int xorghn = info.xorg - info.h;
+
+ if (pixel)
+ {
+ while (1)
+ {
+ PixelateWhite(yorgl + yoffset, info.xorg + x);
+ PixelateWhite(yorgl + yoffset, info.xorg - x);
+ PixelateWhite(yorgol- yoffset, info.xorg - x);
+ PixelateWhite(yorgol - yoffset, info.xorg + x);
+ if (a < 0)
+ break;
+ PixelateWhite(yorghl - xoffset, xorghp - y);
+ PixelateWhite(yorghl - xoffset, xorghn + y);
+ PixelateWhite(yorghl + xoffset, xorghn + y);
+ PixelateWhite(yorghl + xoffset, xorghp - y);
+ xoffset += nlwidth;
+ MIARCCIRCLESTEP(yoffset += nlwidth;);
+ }
+ }
+ else
+ {
+ while (1)
+ {
+ PixelateBlack(yorgl + yoffset, info.xorg + x);
+ PixelateBlack(yorgl + yoffset, info.xorg - x);
+ PixelateBlack(yorgol- yoffset, info.xorg - x);
+ PixelateBlack(yorgol - yoffset, info.xorg + x);
+ if (a < 0)
+ break;
+ PixelateBlack(yorghl - xoffset, xorghp - y);
+ PixelateBlack(yorghl - xoffset, xorghn + y);
+ PixelateBlack(yorghl + xoffset, xorghn + y);
+ PixelateBlack(yorghl + xoffset, xorghp - y);
+ xoffset += nlwidth;
+ MIARCCIRCLESTEP(yoffset += nlwidth;);
+ }
+ }
+ x = info.w;
+ yoffset = info.h * nlwidth;
+ }
+ else if (do360)
+ {
+ while (y < info.h || x < info.w)
+ {
+ MIARCOCTANTSHIFT(dyoffset = nlwidth;);
+ Pixelate(yorgl + yoffset, info.xorg + x);
+ Pixelate(yorgl + yoffset, info.xorgo - x);
+ Pixelate(yorgol - yoffset, info.xorgo - x);
+ Pixelate(yorgol - yoffset, info.xorg + x);
+ MIARCSTEP(yoffset += dyoffset;, yoffset += nlwidth;);
+ }
+ }
+ else
+ {
+ while (y < info.h || x < info.w)
+ {
+ MIARCOCTANTSHIFT(dyoffset = nlwidth;);
+ if ((x == info.start.x) || (y == info.start.y))
+ {
+ mask = info.start.mask;
+ info.start = info.altstart;
+ }
+ DoPix(1, yorgl + yoffset, info.xorg + x);
+ DoPix(2, yorgl + yoffset, info.xorgo - x);
+ DoPix(4, yorgol - yoffset, info.xorgo - x);
+ DoPix(8, yorgol - yoffset, info.xorg + x);
+ if ((x == info.end.x) || (y == info.end.y))
+ {
+ mask = info.end.mask;
+ info.end = info.altend;
+ }
+ MIARCSTEP(yoffset += dyoffset;, yoffset += nlwidth;);
+ }
+ }
+ if ((x == info.start.x) || (y == info.start.y))
+ mask = info.start.mask;
+ DoPix(1, yorgl + yoffset, info.xorg + x);
+ DoPix(4, yorgol - yoffset, info.xorgo - x);
+ if (arc->height & 1)
+ {
+ DoPix(2, yorgl + yoffset, info.xorgo - x);
+ DoPix(8, yorgol - yoffset, info.xorg + x);
+ }
+}
+
+void
+mfbZeroPolyArcSS(pDraw, pGC, narcs, parcs)
+ DrawablePtr pDraw;
+ GCPtr pGC;
+ int narcs;
+ xArc *parcs;
+{
+ register xArc *arc;
+ register int i;
+ BoxRec box;
+ RegionPtr cclip;
+
+ if (!pGC->planemask & 1)
+ return;
+ cclip = ((mfbPrivGC *)(pGC->devPrivates[mfbGCPrivateIndex].ptr))->pCompositeClip;
+ for (arc = parcs, i = narcs; --i >= 0; arc++)
+ {
+ if (miCanZeroArc(arc))
+ {
+ box.x1 = arc->x + pDraw->x;
+ box.y1 = arc->y + pDraw->y;
+ box.x2 = box.x1 + (int)arc->width + 1;
+ box.y2 = box.y1 + (int)arc->height + 1;
+ if ((*pDraw->pScreen->RectIn)(cclip, &box) == rgnIN)
+ mfbZeroArcSS(pDraw, pGC, arc);
+ else
+ miZeroPolyArc(pDraw, pGC, 1, arc);
+ }
+ else
+ miPolyArc(pDraw, pGC, 1, arc);
+ }
+}
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