mfbzerarc.c   [plain text]

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/* 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
 */

#ifdef HAVE_DIX_CONFIG_H
#include <dix-config.h>
#endif

#include <limits.h>

#include <X11/X.h>
#include <X11/Xprotostr.h>
#include "regionstr.h"
#include "gcstruct.h"
#include "pixmapstr.h"
#include "scrnintstr.h"
#include "mfb.h"
#include "maskbits.h"
#include "mizerarc.h"
#include "mi.h"

/*
 * Note: LEFTMOST must be the bit leftmost in the actual screen
 * representation.  This depends also on the IMAGE_BYTE_ORDER.
 * LONG2CHARS() takes care of the re-ordering as required. (DHD)
 */
#if (BITMAP_BIT_ORDER == MSBFirst)
#define LEFTMOST	((PixelType) LONG2CHARS(((MfbBits)1 << PLST)))
#else
#define LEFTMOST	((PixelType) LONG2CHARS(1))
#endif

#define PixelateWhite(addr,yoff,xoff) \
    *mfbScanlineOffset(addr, (yoff)+((xoff)>>PWSH)) |= \
	SCRRIGHT (LEFTMOST, ((xoff) & PIM))
#define PixelateBlack(addr,yoff,xoff) \
    *mfbScanlineOffset(addr, (yoff)+((xoff)>>PWSH)) &= \
	~(SCRRIGHT (LEFTMOST, ((xoff) & PIM)))

#define Pixelate(base,yoff,xoff) \
{ \
    paddr = mfbScanlineOffset(base, (yoff) + ((xoff)>>PWSH)); \
    pmask = SCRRIGHT(LEFTMOST, (xoff) & PIM); \
    *paddr = (*paddr & ~pmask) | (pixel & pmask); \
}

#define DoPix(bit,base,yoff,xoff) if (mask & bit) Pixelate(base,yoff,xoff);

static void
mfbZeroArcSS(
    DrawablePtr pDraw,
    GCPtr pGC,
    xArc *arc)
{
    miZeroArcRec info;
    Bool do360;
    register int x, y, a, b, d, mask;
    register int k1, k3, dx, dy;
    PixelType *addrl;
    PixelType *yorgl, *yorgol;
    PixelType pixel;
    int nlwidth, yoffset, dyoffset;
    PixelType pmask;
    register PixelType *paddr;

    if (((mfbPrivGC *)(pGC->devPrivates[mfbGCPrivateIndex].ptr))->rop ==
	RROP_BLACK)
	pixel = 0;
    else
	pixel = ~0;

    mfbGetPixelWidthAndPointer(pDraw, nlwidth, addrl);
    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, 0, info.xorgo);
	DoPix(8, yorgol, 0, 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;
	PixelType *yorghl = mfbScanlineDeltaNoBankSwitch(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;
    int x2, y2;
    RegionPtr cclip;

    if (!(pGC->planemask & 1))
	return;
    cclip = pGC->pCompositeClip;
    for (arc = parcs, i = narcs; --i >= 0; arc++)
    {
	if (miCanZeroArc(arc))
	{
	    box.x1 = arc->x + pDraw->x;
	    box.y1 = arc->y + pDraw->y;
 	    /*
 	     * Because box.x2 and box.y2 get truncated to 16 bits, and the
 	     * RECT_IN_REGION test treats the resulting number as a signed
 	     * integer, the RECT_IN_REGION test alone can go the wrong way.
 	     * This can result in a server crash because the rendering
 	     * routines in this file deal directly with cpu addresses
 	     * of pixels to be stored, and do not clip or otherwise check
 	     * that all such addresses are within their respective pixmaps.
 	     * So we only allow the RECT_IN_REGION test to be used for
 	     * values that can be expressed correctly in a signed short.
 	     */
 	    x2 = box.x1 + (int)arc->width + 1;
 	    box.x2 = x2;
 	    y2 = box.y1 + (int)arc->height + 1;
 	    box.y2 = y2;
 	    if ( (x2 <= SHRT_MAX) && (y2 <= SHRT_MAX) &&
 		    (RECT_IN_REGION(pDraw->pScreen, cclip, &box) == rgnIN) )
		mfbZeroArcSS(pDraw, pGC, arc);
	    else
		miZeroPolyArc(pDraw, pGC, 1, arc);
	}
	else
	    miPolyArc(pDraw, pGC, 1, arc);
    }
}