/mi/mispans.c

/***********************************************************

Copyright 1989, 1998  The Open Group

Permission to use, copy, modify, distribute, and sell this software and its
documentation for any purpose is hereby granted without fee, provided that
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in this Software without prior written authorization from The Open Group.


Copyright 1989 by Digital Equipment Corporation, Maynard, Massachusetts.

                        All Rights Reserved

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 Digital not be
used in advertising or publicity pertaining to distribution of the
software without specific, written prior permission.  

DIGITAL DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING
ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL
DIGITAL BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR
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******************************************************************/


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

#include "misc.h"
#include "pixmapstr.h"
#include "gcstruct.h"
#include "mispans.h"

/*

These routines maintain lists of Spans, in order to implement the
``touch-each-pixel-once'' rules of wide lines and arcs.

Written by Joel McCormack, Summer 1989.

*/


void miInitSpanGroup(SpanGroup *spanGroup)
{
    spanGroup->size = 0;
    spanGroup->count = 0;
    spanGroup->group = NULL;
    spanGroup->ymin = MAXSHORT;
    spanGroup->ymax = MINSHORT;
} /* InitSpanGroup */

#define YMIN(spans) (spans->points[0].y)
#define YMAX(spans)  (spans->points[spans->count-1].y)

static void miSubtractSpans (SpanGroup *spanGroup, Spans *sub)
{
    int		i, subCount, spansCount;
    int		ymin, ymax, xmin, xmax;
    Spans	*spans;
    DDXPointPtr	subPt, spansPt;
    int		*subWid, *spansWid;
    int		extra;

    ymin = YMIN(sub);
    ymax = YMAX(sub);
    spans = spanGroup->group;
    for (i = spanGroup->count; i; i--, spans++) {
	if (YMIN(spans) <= ymax && ymin <= YMAX(spans)) {
	    subCount = sub->count;
	    subPt = sub->points;
	    subWid = sub->widths;
	    spansCount = spans->count;
	    spansPt = spans->points;
	    spansWid = spans->widths;
	    extra = 0;
	    for (;;)
 	    {
		while (spansCount && spansPt->y < subPt->y)
		{
		    spansPt++;  spansWid++; spansCount--;
		}
		if (!spansCount)
		    break;
		while (subCount && subPt->y < spansPt->y)
		{
		    subPt++;	subWid++;   subCount--;
		}
		if (!subCount)
		    break;
		if (subPt->y == spansPt->y)
		{
		    xmin = subPt->x;
		    xmax = xmin + *subWid;
		    if (xmin >= spansPt->x + *spansWid || spansPt->x >= xmax)
		    {
			;
		    }
		    else if (xmin <= spansPt->x)
		    {
			if (xmax >= spansPt->x + *spansWid) 
			{
			    memmove (spansPt, spansPt + 1, sizeof *spansPt * (spansCount - 1));
			    memmove (spansWid, spansWid + 1, sizeof *spansWid * (spansCount - 1));
			    spansPt--;
			    spansWid--;
			    spans->count--;
			    extra++;
			}
			else 
			{
			    *spansWid = *spansWid - (xmax - spansPt->x);
			    spansPt->x = xmax;
			}
		    }
		    else
		    {
			if (xmax >= spansPt->x + *spansWid)
			{
			    *spansWid = xmin - spansPt->x;
			}
			else
			{
			    if (!extra) {
				DDXPointPtr newPt;
				int	    *newwid;

#define EXTRA 8
				newPt = (DDXPointPtr) realloc(spans->points, (spans->count + EXTRA) * sizeof (DDXPointRec));
				if (!newPt)
				    break;
				spansPt = newPt + (spansPt - spans->points);
				spans->points = newPt;
				newwid = (int *) realloc(spans->widths, (spans->count + EXTRA) * sizeof (int));
				if (!newwid)
				    break;
				spansWid = newwid + (spansWid - spans->widths);
				spans->widths = newwid;
				extra = EXTRA;
			    }
			    memmove (spansPt + 1, spansPt, sizeof *spansPt * (spansCount));
			    memmove (spansWid + 1, spansWid, sizeof *spansWid * (spansCount));
			    spans->count++;
			    extra--;
			    *spansWid = xmin - spansPt->x;
			    spansWid++;
			    spansPt++;
			    *spansWid = *spansWid - (xmax - spansPt->x);
			    spansPt->x = xmax;
			}
		    }
		}
		spansPt++;  spansWid++; spansCount--;
	    }
	}
    }
}

void miAppendSpans(SpanGroup *spanGroup, SpanGroup *otherGroup, Spans *spans)
{
    int ymin, ymax;
    int spansCount;

    spansCount = spans->count;
    if (spansCount > 0) {
	if (spanGroup->size == spanGroup->count) {
	    spanGroup->size = (spanGroup->size + 8) * 2;
	    spanGroup->group = (Spans *)
		realloc(spanGroup->group, sizeof(Spans) * spanGroup->size);
	 }

	spanGroup->group[spanGroup->count] = *spans;
	(spanGroup->count)++;
	ymin = spans->points[0].y;
	if (ymin < spanGroup->ymin) spanGroup->ymin = ymin;
	ymax = spans->points[spansCount - 1].y;
	if (ymax > spanGroup->ymax) spanGroup->ymax = ymax;
	if (otherGroup &&
	    otherGroup->ymin < ymax &&
	    ymin < otherGroup->ymax)
	{
	    miSubtractSpans (otherGroup, spans);
	}
    }
    else
    {
	free(spans->points);
	free(spans->widths);
    }
} /* AppendSpans */

void miFreeSpanGroup(SpanGroup *spanGroup)
{
    free(spanGroup->group);
}

static void QuickSortSpansX(
    DDXPointRec points[],
    int		widths[],
    int		numSpans )
{
    int	    		x;
    int	    		i, j, m;
    DDXPointPtr 	r;

/* Always called with numSpans > 1 */
/* Sorts only by x, as all y should be the same */

#define ExchangeSpans(a, b)				    \
{							    \
    DDXPointRec 	tpt;				    \
    int    		tw;				    \
							    \
    tpt = points[a]; points[a] = points[b]; points[b] = tpt;    \
    tw = widths[a]; widths[a] = widths[b]; widths[b] = tw;  \
}

    do {
	if (numSpans < 9) {
	    /* Do insertion sort */
	    int xprev;

	    xprev = points[0].x;
	    i = 1;
	    do { /* while i != numSpans */
		x = points[i].x;
		if (xprev > x) {
		    /* points[i] is out of order.  Move into proper location. */
		    DDXPointRec tpt;
		    int	    tw, k;

		    for (j = 0; x >= points[j].x; j++) {}
		    tpt = points[i];
		    tw  = widths[i];
		    for (k = i; k != j; k--) {
			points[k] = points[k-1];
			widths[k] = widths[k-1];
		    }
		    points[j] = tpt;
		    widths[j] = tw;
		    x = points[i].x;
		} /* if out of order */
		xprev = x;
		i++;
	    } while (i != numSpans);
	    return;
	}

	/* Choose partition element, stick in location 0 */
	m = numSpans / 2;
	if (points[m].x > points[0].x)		ExchangeSpans(m, 0);
	if (points[m].x > points[numSpans-1].x) ExchangeSpans(m, numSpans-1);
	if (points[m].x > points[0].x)		ExchangeSpans(m, 0);
	x = points[0].x;

        /* Partition array */
        i = 0;
        j = numSpans;
        do {
	    r = &(points[i]);
	    do {
		r++;
		i++;
            } while (i != numSpans && r->x < x);
	    r = &(points[j]);
	    do {
		r--;
		j--;
            } while (x < r->x);
            if (i < j) ExchangeSpans(i, j);
        } while (i < j);

        /* Move partition element back to middle */
        ExchangeSpans(0, j);

	/* Recurse */
        if (numSpans-j-1 > 1)
	    QuickSortSpansX(&points[j+1], &widths[j+1], numSpans-j-1);
        numSpans = j;
    } while (numSpans > 1);
} /* QuickSortSpans */


static int UniquifySpansX(
    Spans	    	*spans,
    DDXPointRec    	*newPoints,
    int	    		*newWidths )
{
    int 		newx1, newx2, oldpt, i, y;
    DDXPointRec		*oldPoints;
    int	    		*oldWidths;
    int			*startNewWidths;

/* Always called with numSpans > 1 */
/* Uniquify the spans, and stash them into newPoints and newWidths.  Return the
   number of unique spans. */


    startNewWidths = newWidths;

    oldPoints = spans->points;
    oldWidths = spans->widths;

    y = oldPoints->y;
    newx1 = oldPoints->x;
    newx2 = newx1 + *oldWidths;

    for (i = spans->count-1; i != 0; i--) {
	oldPoints++;
	oldWidths++;
	oldpt = oldPoints->x;
	if (oldpt > newx2) {
	    /* Write current span, start a new one */
	    newPoints->x = newx1;
	    newPoints->y = y;
	    *newWidths = newx2 - newx1;
	    newPoints++;
	    newWidths++;
	    newx1 = oldpt;
	    newx2 = oldpt + *oldWidths;
	} else {
	    /* extend current span, if old extends beyond new */
	    oldpt = oldpt + *oldWidths;
	    if (oldpt > newx2) newx2 = oldpt;
	}
    } /* for */

    /* Write final span */
    newPoints->x = newx1;
    *newWidths = newx2 - newx1;
    newPoints->y = y;

    return (newWidths - startNewWidths) + 1;
} /* UniquifySpansX */

static void
miDisposeSpanGroup (SpanGroup *spanGroup)
{
    int	    i;
    Spans   *spans;

    for (i = 0; i < spanGroup->count; i++)
    {
	spans = spanGroup->group + i;
	free(spans->points);
	free(spans->widths);
    }
}

void miFillUniqueSpanGroup(DrawablePtr pDraw, GCPtr pGC, SpanGroup *spanGroup)
{
    int    		i;
    Spans  		*spans;
    Spans  		*yspans;
    int    		*ysizes;
    int    		ymin, ylength;

    /* Outgoing spans for one big call to FillSpans */
    DDXPointPtr    	points;
    int	    		*widths;
    int	    		count;

    if (spanGroup->count == 0) return;

    if (spanGroup->count == 1) {
	/* Already should be sorted, unique */
	spans = spanGroup->group;
	(*pGC->ops->FillSpans)
	    (pDraw, pGC, spans->count, spans->points, spans->widths, TRUE);
	free(spans->points);
	free(spans->widths);
    }
    else
    {
	/* Yuck.  Gross.  Radix sort into y buckets, then sort x and uniquify */
	/* This seems to be the fastest thing to do.  I've tried sorting on
	   both x and y at the same time rather than creating into all those
	   y buckets, but it was somewhat slower. */

	ymin    = spanGroup->ymin;
	ylength = spanGroup->ymax - ymin + 1;

	/* Allocate Spans for y buckets */
	yspans = malloc(ylength * sizeof(Spans));
	ysizes = malloc(ylength * sizeof (int));

	if (!yspans || !ysizes)
	{
	    free(yspans);
	    free(ysizes);
	    miDisposeSpanGroup (spanGroup);
	    return;
	}
	
	for (i = 0; i != ylength; i++) {
	    ysizes[i]        = 0;
	    yspans[i].count  = 0;
	    yspans[i].points = NULL;
	    yspans[i].widths = NULL;
	}

	/* Go through every single span and put it into the correct bucket */
	count = 0;
	for (i = 0, spans = spanGroup->group;
		i != spanGroup->count;
		i++, spans++) {
	    int		index;
	    int		j;

	    for (j = 0, points = spans->points, widths = spans->widths;
		    j != spans->count;
		    j++, points++, widths++) {
		index = points->y - ymin;
		if (index >= 0 && index < ylength) {
		    Spans *newspans = &(yspans[index]);
		    if (newspans->count == ysizes[index]) {
			DDXPointPtr newpoints;
			int	    *newwidths;
			ysizes[index] = (ysizes[index] + 8) * 2;
			newpoints = (DDXPointPtr) realloc(
			    newspans->points,
			    ysizes[index] * sizeof(DDXPointRec));
			newwidths = (int *) realloc(
			    newspans->widths,
			    ysizes[index] * sizeof(int));
			if (!newpoints || !newwidths)
			{
			    int	i;

			    for (i = 0; i < ylength; i++)
			    {
				free(yspans[i].points);
				free(yspans[i].widths);
			    }
			    free(yspans);
			    free(ysizes);
			    free(newpoints);
			    free(newwidths);
			    miDisposeSpanGroup (spanGroup);
			    return;
			}
			newspans->points = newpoints;
			newspans->widths = newwidths;
		    }
		    newspans->points[newspans->count] = *points;
		    newspans->widths[newspans->count] = *widths;
		    (newspans->count)++;
		} /* if y value of span in range */
	    } /* for j through spans */
	    count += spans->count;
	    free(spans->points);
	    spans->points = NULL;
	    free(spans->widths);
	    spans->widths = NULL;
	} /* for i thorough Spans */

	/* Now sort by x and uniquify each bucket into the final array */
	points = malloc(count * sizeof(DDXPointRec));
	widths = malloc(count * sizeof(int));
	if (!points || !widths)
	{
	    int	i;

	    for (i = 0; i < ylength; i++)
	    {
		free(yspans[i].points);
		free(yspans[i].widths);
	    }
	    free(yspans);
	    free(ysizes);
	    free(points);
	    free(widths);
	    return;
	}
	count = 0;
	for (i = 0; i != ylength; i++) {
	    int ycount = yspans[i].count;
	    if (ycount > 0) {
		if (ycount > 1) {
		    QuickSortSpansX(yspans[i].points, yspans[i].widths, ycount);
		    count += UniquifySpansX
			(&(yspans[i]), &(points[count]), &(widths[count]));
		} else {
		    points[count] = yspans[i].points[0];
		    widths[count] = yspans[i].widths[0];
		    count++;
		}
		free(yspans[i].points);
		free(yspans[i].widths);
	    }
	}

	(*pGC->ops->FillSpans) (pDraw, pGC, count, points, widths, TRUE);
	free(points);
	free(widths);
	free(yspans);
	free(ysizes);		/* use (DE)xalloc for these? */
    }

    spanGroup->count = 0;
    spanGroup->ymin = MAXSHORT;
    spanGroup->ymax = MINSHORT;
}