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Add union and merge functions and tests.

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This commit is contained in:
Bill Currie 2012-01-06 12:57:25 +09:00
parent 73f2c12815
commit c25327f4ed
3 changed files with 138 additions and 1 deletions
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82
libs/util/vrect.c
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@ -38,14 +38,18 @@ static __attribute__ ((used)) const char rcsid[] = "$Id$";
#include "QF/mathlib.h"
#include "QF/vrect.h"
//#define TEST_MEMORY
#define RECT_BLOCK 128
#ifndef TEST_MEMORY
static vrect_t *free_rects;
#endif
VISIBLE vrect_t *
VRect_New (int x, int y, int width, int height)
{
vrect_t *r;
#ifndef TEST_MEMORY
if (!free_rects) {
int i;
@ -56,6 +60,9 @@ VRect_New (int x, int y, int width, int height)
}
r = free_rects;
free_rects = free_rects->next;
#else
r = malloc (sizeof (vrect_t));
#endif
r->next = 0;
r->x = x;
r->y = y;
@ -67,8 +74,12 @@ VRect_New (int x, int y, int width, int height)
VISIBLE void
VRect_Delete (vrect_t *rect)
{
#ifndef TEST_MEMORY
rect->next = free_rects;
free_rects = rect;
#else
free (rect);
#endif
}
VISIBLE vrect_t *
@ -178,3 +189,72 @@ VRect_Difference (const vrect_t *r, const vrect_t *s)
return rects;
}
VISIBLE vrect_t *
VRect_Union (const vrect_t *r1, const vrect_t *r2)
{
int minx, miny;
int maxx, maxy;
if (VRect_IsEmpty (r1))
return VRect_New (r2->x, r2->y, r2->width, r2->height);
if (VRect_IsEmpty (r2))
return VRect_New (r1->x, r1->y, r1->width, r1->height);
minx = min (VRect_MinX (r1), VRect_MinX (r2));
miny = min (VRect_MinY (r1), VRect_MinY (r2));
maxx = max (VRect_MaxX (r1), VRect_MaxX (r2));
maxy = max (VRect_MaxY (r1), VRect_MaxY (r2));
return VRect_New (minx, miny, maxx - minx, maxy - miny);
}
VISIBLE vrect_t *
VRect_Merge (const vrect_t *r1, const vrect_t *r2)
{
vrect_t *t, *u = 0;
vrect_t *merge;
// cannot merge intersecting rectangles
t = VRect_Intersect (r1, r2);
if (!VRect_IsEmpty (t)) {
VRect_Delete (t);
return 0;
}
VRect_Delete (t);
merge = VRect_Union (r1, r2);
if (VRect_IsEmpty (merge)) {
VRect_Delete (merge);
return 0;
}
// If the subtracting r1 from the union results in more than one rectangle
// then r1 and r2 cannot be merged.
t = VRect_Difference (merge, r1);
if (t && t->next)
goto cleanup;
// If subtracting r2 from the result of the previous difference results in
// any rectangles, then r1 and r2 cannot be merged.
if (t)
u = VRect_Difference (t, r2);
if (!u) {
VRect_Delete (t);
return merge;
}
cleanup:
VRect_Delete (merge);
// merge is used as a temp while freeing t and u
while (u) {
merge = u->next;
VRect_Delete (u);
u = merge;
}
while (t) {
merge = t->next;
VRect_Delete (t);
t = merge;
}
return 0;
}