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curve: Add a get_crossing vfunc

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This commit is contained in:
Matthias Clasen 2023-08-20 21:10:12 -07:00
parent cd7726bb31
commit fb0f5b5c14
1 changed files with 72 additions and 42 deletions
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114
gsk/gskcurve.c
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@ -78,6 +78,8 @@ struct _GskCurveClass
GskBoundingBox *bounds);
void (* get_derivative) (const GskCurve *curve,
GskCurve *derivative);
int (* get_crossing) (const GskCurve *curve,
const graphene_point_t *point);
};
/* {{{ Utilities */
@ -91,6 +93,51 @@ get_tangent (const graphene_point_t *p0,
graphene_vec2_normalize (t, t);
}
static int
line_get_crossing (const graphene_point_t *p,
const graphene_point_t *p1,
const graphene_point_t *p2)
{
if (p1->y <= p->y)
{
if (p2->y > p->y)
{
if ((p2->x - p1->x) * (p->y - p1->y) - (p->x - p1->x) * (p2->y - p1->y) > 0)
return 1;
}
}
else if (p2->y <= p->y)
{
if ((p2->x - p1->x) * (p->y - p1->y) - (p->x - p1->x) * (p2->y - p1->y) < 0)
return -1;
}
return 0;
}
static int
get_crossing_by_bisection (const GskCurve *curve,
const graphene_point_t *point)
{
GskBoundingBox bounds;
GskCurve c1, c2;
gsk_curve_get_bounds (curve, &bounds);
if (bounds.max.y < point->y || bounds.min.y > point->y || bounds.max.x < point->x)
return 0;
if (bounds.min.x > point->x)
return line_get_crossing (point, gsk_curve_get_start_point (curve), gsk_curve_get_end_point (curve));
if (graphene_point_distance (&bounds.min, &bounds.max, NULL, NULL) < 0.001)
return line_get_crossing (point, gsk_curve_get_start_point (curve), gsk_curve_get_end_point (curve));
gsk_curve_split (curve, 0.5, &c1, &c2);
return gsk_curve_get_crossing (&c1, point) + gsk_curve_get_crossing (&c2, point);
}
/* Replace a line by an equivalent quad,
* and a quad by an equivalent cubic.
*/
@ -326,6 +373,13 @@ gsk_line_curve_get_derivative (const GskCurve *curve,
gsk_line_curve_init_from_points (&deriv->line, GSK_PATH_LINE, &p, &p);
}
static int
gsk_line_curve_get_crossing (const GskCurve *curve,
const graphene_point_t *point)
{
return line_get_crossing (point, gsk_curve_get_start_point (curve), gsk_curve_get_end_point (curve));
}
static const GskCurveClass GSK_LINE_CURVE_CLASS = {
gsk_line_curve_init,
gsk_line_curve_init_foreach,
@ -346,6 +400,7 @@ static const GskCurveClass GSK_LINE_CURVE_CLASS = {
gsk_line_curve_get_bounds,
gsk_line_curve_get_bounds,
gsk_line_curve_get_derivative,
gsk_line_curve_get_crossing,
};
/* }}} */
@ -701,6 +756,13 @@ gsk_quad_curve_get_derivative (const GskCurve *curve,
gsk_line_curve_init_from_points (&deriv->line, GSK_PATH_LINE, &p[0], &p[1]);
}
static int
gsk_quad_curve_get_crossing (const GskCurve *curve,
const graphene_point_t *point)
{
return get_crossing_by_bisection (curve, point);
}
static const GskCurveClass GSK_QUAD_CURVE_CLASS = {
gsk_quad_curve_init,
gsk_quad_curve_init_foreach,
@ -721,6 +783,7 @@ static const GskCurveClass GSK_QUAD_CURVE_CLASS = {
gsk_quad_curve_get_bounds,
gsk_quad_curve_get_tight_bounds,
gsk_quad_curve_get_derivative,
gsk_quad_curve_get_crossing,
};
/* }}} */
@ -1147,6 +1210,13 @@ gsk_cubic_curve_get_derivative (const GskCurve *curve,
gsk_quad_curve_init_from_points (&deriv->quad, p);
}
static int
gsk_cubic_curve_get_crossing (const GskCurve *curve,
const graphene_point_t *point)
{
return get_crossing_by_bisection (curve, point);
}
static const GskCurveClass GSK_CUBIC_CURVE_CLASS = {
gsk_cubic_curve_init,
gsk_cubic_curve_init_foreach,
@ -1167,6 +1237,7 @@ static const GskCurveClass GSK_CUBIC_CURVE_CLASS = {
gsk_cubic_curve_get_bounds,
gsk_cubic_curve_get_tight_bounds,
gsk_cubic_curve_get_derivative,
gsk_cubic_curve_get_crossing,
};
/* }}} */
@ -1364,52 +1435,11 @@ gsk_curve_get_derivative (const GskCurve *curve,
get_class (curve->op)->get_derivative (curve, deriv);
}
static inline int
line_get_crossing (const graphene_point_t *p,
const graphene_point_t *p1,
const graphene_point_t *p2)
{
if (p1->y <= p->y)
{
if (p2->y > p->y)
{
if ((p2->x - p1->x) * (p->y - p1->y) - (p->x - p1->x) * (p2->y - p1->y) > 0)
return 1;
}
}
else if (p2->y <= p->y)
{
if ((p2->x - p1->x) * (p->y - p1->y) - (p->x - p1->x) * (p2->y - p1->y) < 0)
return -1;
}
return 0;
}
int
gsk_curve_get_crossing (const GskCurve *curve,
const graphene_point_t *point)
{
GskBoundingBox bounds;
GskCurve c1, c2;
if (curve->op == GSK_PATH_LINE || curve->op == GSK_PATH_CLOSE)
return line_get_crossing (point, gsk_curve_get_start_point (curve), gsk_curve_get_end_point (curve));
gsk_curve_get_bounds (curve, &bounds);
if (bounds.max.y < point->y || bounds.min.y > point->y || bounds.max.x < point->x)
return 0;
if (bounds.min.x > point->x)
return line_get_crossing (point, gsk_curve_get_start_point (curve), gsk_curve_get_end_point (curve));
if (graphene_point_distance (&bounds.min, &bounds.max, NULL, NULL) < 0.001)
return line_get_crossing (point, gsk_curve_get_start_point (curve), gsk_curve_get_end_point (curve));
gsk_curve_split (curve, 0.5, &c1, &c2);
return gsk_curve_get_crossing (&c1, point) + gsk_curve_get_crossing (&c2, point);
return get_class (curve->op)->get_crossing (curve, point);
}
static gboolean