static inline cairo_bool_t
edges_colinear (const cairo_bo_edge_t *a, const cairo_bo_edge_t *b)
{
if (_line_equal (&a->edge.line, &b->edge.line))
return TRUE;
if (_slope_compare (a, b))
return FALSE;
/* The choice of y is not truly arbitrary since we must guarantee that it
* is greater than the start of either line.
*/
if (a->edge.line.p1.y == b->edge.line.p1.y) {
return a->edge.line.p1.x == b->edge.line.p1.x;
} else if (a->edge.line.p2.y == b->edge.line.p2.y) {
return a->edge.line.p2.x == b->edge.line.p2.x;
} else if (a->edge.line.p1.y < b->edge.line.p1.y) {
return edge_compare_for_y_against_x (b,
a->edge.line.p1.y,
a->edge.line.p1.x) == 0;
} else {
return edge_compare_for_y_against_x (a,
b->edge.line.p1.y,
b->edge.line.p1.x) == 0;
}
}
static void
_cairo_in_fill_add_edge (cairo_in_fill_t *in_fill,
const cairo_point_t *p1,
const cairo_point_t *p2)
{
int dir;
if (in_fill->on_edge)
return;
/* count the number of edge crossing to -∞ */
dir = 1;
if (p2->y < p1->y) {
const cairo_point_t *tmp;
tmp = p1;
p1 = p2;
p2 = tmp;
dir = -1;
}
/* First check whether the query is on an edge */
if ((p1->x == in_fill->x && p1->y == in_fill->y) ||
(p2->x == in_fill->x && p2->y == in_fill->y) ||
(! (p2->y < in_fill->y || p1->y > in_fill->y ||
(p1->x > in_fill->x && p2->x > in_fill->x) ||
(p1->x < in_fill->x && p2->x < in_fill->x)) &&
edge_compare_for_y_against_x (p1, p2, in_fill->y, in_fill->x) == 0))
{
in_fill->on_edge = TRUE;
return;
}
/* edge is entirely above or below, note the shortening rule */
if (p2->y <= in_fill->y || p1->y > in_fill->y)
return;
/* edge lies wholly to the right */
if (p1->x >= in_fill->x && p2->x >= in_fill->x)
return;
if ((p1->x <= in_fill->x && p2->x <= in_fill->x) ||
edge_compare_for_y_against_x (p1, p2, in_fill->y, in_fill->x) < 0)
{
in_fill->winding += dir;
}
}
static int
edges_compare_x_for_y (const cairo_bo_edge_t *a,
const cairo_bo_edge_t *b,
int32_t y)
{
/* If the sweep-line is currently on an end-point of a line,
* then we know its precise x value (and considering that we often need to
* compare events at end-points, this happens frequently enough to warrant
* special casing).
*/
enum {
HAVE_NEITHER = 0x0,
HAVE_AX = 0x1,
HAVE_BX = 0x2,
HAVE_BOTH = HAVE_AX | HAVE_BX
} have_ax_bx = HAVE_BOTH;
int32_t ax = 0, bx = 0;
if (y == a->edge.line.p1.y)
ax = a->edge.line.p1.x;
else if (y == a->edge.line.p2.y)
ax = a->edge.line.p2.x;
else
have_ax_bx &= ~HAVE_AX;
if (y == b->edge.line.p1.y)
bx = b->edge.line.p1.x;
else if (y == b->edge.line.p2.y)
bx = b->edge.line.p2.x;
else
have_ax_bx &= ~HAVE_BX;
switch (have_ax_bx) {
default:
case HAVE_NEITHER:
return edges_compare_x_for_y_general (a, b, y);
case HAVE_AX:
return -edge_compare_for_y_against_x (b, y, ax);
case HAVE_BX:
return edge_compare_for_y_against_x (a, y, bx);
case HAVE_BOTH:
return ax - bx;
}
}
