common: add helper for subtracting rectangles

Not sure if generally useful; the following commit uses it.
This commit is contained in:
wm4 2020-05-22 14:17:46 +02:00
parent 320fa3bbe7
commit 1be32529b1
2 changed files with 24 additions and 0 deletions

View File

@ -126,6 +126,28 @@ bool mp_rect_equals(struct mp_rect *rc1, struct mp_rect *rc2)
rc1->x1 == rc2->x1 && rc1->y1 == rc2->y1;
}
// Compute rc1-rc2, put result in res_array, return number of rectangles in
// res_array. In the worst case, there are 4 rectangles, so res_array must
// provide that much storage space.
int mp_rect_subtract(const struct mp_rect *rc1, const struct mp_rect *rc2,
struct mp_rect res[4])
{
struct mp_rect rc = *rc1;
if (!mp_rect_intersection(&rc, rc2))
return 0;
int cnt = 0;
if (rc1->y0 < rc.y0)
res[cnt++] = (struct mp_rect){rc1->x0, rc1->y0, rc1->x1, rc.y0};
if (rc1->x0 < rc.x0)
res[cnt++] = (struct mp_rect){rc1->x0, rc.y0, rc.x0, rc.y1};
if (rc1->x1 > rc.x1)
res[cnt++] = (struct mp_rect){rc.x1, rc.y0, rc1->x1, rc.y1};
if (rc1->y1 > rc.y1)
res[cnt++] = (struct mp_rect){rc1->x0, rc.y1, rc1->x1, rc1->y1};
return cnt;
}
// This works like snprintf(), except that it starts writing the first output
// character to str[strlen(str)]. This returns the number of characters the
// string would have *appended* assuming a large enough buffer, will make sure

View File

@ -87,6 +87,8 @@ void mp_rect_union(struct mp_rect *rc, const struct mp_rect *src);
bool mp_rect_intersection(struct mp_rect *rc, const struct mp_rect *rc2);
bool mp_rect_contains(struct mp_rect *rc, int x, int y);
bool mp_rect_equals(struct mp_rect *rc1, struct mp_rect *rc2);
int mp_rect_subtract(const struct mp_rect *rc1, const struct mp_rect *rc2,
struct mp_rect res_array[4]);
unsigned int mp_log2(uint32_t v);
uint32_t mp_round_next_power_of_2(uint32_t v);