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[in-fill] Treat on-edge queries as inside.

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Jeff Muizelaar noted that the treatment of edges differed with firefox's
canvas definition, which considers a point on any edge as inside. The
current implementation has a similar definition to that of flash, for
which the top and right edges are outside. Arguably, firefox has the more
intuitive definition here...
This commit is contained in:
Chris Wilson 2009-02-27 16:32:21 +00:00
parent efd0f0b292
commit b71b019fe5
1 changed files with 20 additions and 1 deletions
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21
src/cairo-path-in-fill.c
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@ -41,6 +41,7 @@ typedef struct cairo_in_fill {
int winding;
cairo_fixed_t x, y;
cairo_bool_t on_edge;
cairo_bool_t has_current_point;
cairo_point_t current_point;
@ -58,6 +59,7 @@ _cairo_in_fill_init (cairo_in_fill_t *in_fill,
in_fill->x = _cairo_fixed_from_double (x);
in_fill->y = _cairo_fixed_from_double (y);
in_fill->on_edge = FALSE;
in_fill->has_current_point = FALSE;
in_fill->current_point.x = 0;
@ -103,6 +105,9 @@ _cairo_in_fill_add_edge (cairo_in_fill_t *in_fill,
{
int dir;
if (in_fill->on_edge)
return;
/* count the number of edge crossing to -∞ */
dir = 1;
@ -116,6 +121,18 @@ _cairo_in_fill_add_edge (cairo_in_fill_t *in_fill,
dir = -1;
}
/* First check whether the query is on an edge */
if ((p1->x == in_fill->x && p1->x == in_fill->y) ||
(p2->x == in_fill->x && p2->x == 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;
@ -250,7 +267,9 @@ _cairo_path_fixed_in_fill (cairo_path_fixed_t *path,
_cairo_in_fill_close_path (&in_fill);
switch (fill_rule) {
if (in_fill.on_edge) {
*is_inside = TRUE;
} else switch (fill_rule) {
case CAIRO_FILL_RULE_EVEN_ODD:
*is_inside = in_fill.winding & 1;
break;