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[rectangle] Fix unsigned promotion whilst computing intersect.

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_cairo_rectangle_intersect() incorrectly allows unsigned promotion during
its arithmetic.
This commit is contained in:
Chris Wilson 2008-10-23 13:37:41 +01:00
parent 2464b8a0a9
commit 0e4156121f
2 changed files with 19 additions and 15 deletions
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31
src/cairo-rectangle.c
View file

@ -96,29 +96,32 @@ _cairo_box_round_to_rectangle (const cairo_box_t *box,
}
void
_cairo_rectangle_intersect (cairo_rectangle_int_t *dest, cairo_rectangle_int_t *src)
_cairo_rectangle_intersect (cairo_rectangle_int_t *dst,
const cairo_rectangle_int_t *src)
{
int x1, y1, x2, y2;
x1 = MAX (dest->x, src->x);
y1 = MAX (dest->y, src->y);
x2 = MIN (dest->x + dest->width, src->x + src->width);
y2 = MIN (dest->y + dest->height, src->y + src->height);
x1 = MAX (dst->x, src->x);
y1 = MAX (dst->y, src->y);
/* Beware the unsigned promotion, fortunately we have bits to spare
* as (CAIRO_RECT_INT_MAX - CAIRO_RECT_INT_MIN) < UINT_MAX
*/
x2 = MIN (dst->x + (int) dst->width, src->x + (int) src->width);
y2 = MIN (dst->y + (int) dst->height, src->y + (int) src->height);
if (x1 >= x2 || y1 >= y2) {
dest->x = 0;
dest->y = 0;
dest->width = 0;
dest->height = 0;
dst->x = 0;
dst->y = 0;
dst->width = 0;
dst->height = 0;
} else {
dest->x = x1;
dest->y = y1;
dest->width = x2 - x1;
dest->height = y2 - y1;
dst->x = x1;
dst->y = y1;
dst->width = x2 - x1;
dst->height = y2 - y1;
}
}
#define P1x (line->p1.x)
#define P1y (line->p1.y)
#define P2x (line->p2.x)

3
src/cairoint.h
View file

@ -254,7 +254,8 @@ _cairo_box_round_to_rectangle (const cairo_box_t *box,
cairo_rectangle_int_t *rectangle);
cairo_private void
_cairo_rectangle_intersect (cairo_rectangle_int_t *dest, cairo_rectangle_int_t *src);
_cairo_rectangle_intersect (cairo_rectangle_int_t *dst,
const cairo_rectangle_int_t *src);
cairo_private cairo_bool_t
_cairo_box_intersects_line_segment (cairo_box_t *box, cairo_line_t *line);