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#include <Alib.h>
#include <stdio.h>
static ColorSegment *CSOverflow () {
fprintf (stderr, "Color Segment pool overflow\n");
return (ColorSegment *) NULL;
}
#define mallocCS(w) ( (w->curPool) ? \
((w->CSTop1 == w->CSSize1) ? \
CSOverflow() : &(w->csPool1[(w->CSTop1)++])) : \
((w->CSTop0 == w->CSSize0) ? \
CSOverflow() : &(w->csPool0[(w->CSTop0)++])) )
#define freeLastCS(w) ( (w->curPool) ? -- (w->CSTop1) : -- (w->CSTop0) )
/*
* DrawScanLine : draw a line segment. Successive calls on the same scan line
* must be ordered by x0 value.
*/
void DrawScanLine (w, y, x0, x1, color)
AWindow *w;
int y, x0, x1;
Color color; {
register ColorSegment *p;
register int lastx;
#ifdef DEBUG
printf ("DrawScanLine (w, %d, %d, %d, %d)\n", y, x0, x1, color);
#endif
if (w->scanLine[y].count == 0) {
/*
* This is the first segment on this scan line.
*/
if ((p = mallocCS(w)) != (ColorSegment *) NULL) {
p->x = x0;
p->length = x1 - x0 + 1;
p->color = color;
w->scanLine[y].head = w->scanLine[y].tail = p;
w->scanLine[y].count = 1;
}
}
/*
* The scan line wasn't empty. Check the previous scan line entry for
* any overlap with this one.
*/
else {
p = w->scanLine[y].tail;
lastx = p->x + p->length - 1;
if (lastx >= x0) {
/*
* The segments overlap.
*
* If the overlapping segments have the same color, then simply
* extend the previous segment's length.
*/
if (p->color == color)
p->length = x1 - p->x + 1;
/*
* The overlapping segment's colors are different. Shorten the previous
* segment and allocate an entry for the current one. If the shortened
* segment is eliminated, use it to store this segment's information.
*/
else {
if ((p->length = x0 - p->x) > 0) {
if ((p = mallocCS(w)) != (ColorSegment *) NULL) {
++ w->scanLine[y].count;
w->scanLine[y].tail = p;
}
}
/*
* If the shortened segment's length went to zero, we may need to merge
* this segment with the last one.
*/
if (((p-1)->color == color) &&
(w->scanLine[y].count > 1)) {
freeLastCS (w);
p = w->scanLine[y].tail = p-1;
-- w->scanLine[y].count;
p->length = x1 - p->x + 1;
}
else {
p->x = x0;
p->length = x1 - x0 + 1;
p->color = color;
}
}
}
/*
* The segments do not overlap.
*
* If the segments are adjacent and the colors are the same, extend the
* last segment.
*
* Otehrwise, create a new segment and append it to this line.
*/
else if ((lastx == x0 - 1) && (p->color == color))
p->length = x1 - p->x + 1;
else if ((p = mallocCS(w)) != (ColorSegment *) NULL) {
++ w->scanLine[y].count;
w->scanLine[y].tail = p;
p->x = x0;
p->length = x1 - x0 + 1;
p->color = color;
}
}
}
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