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curve: Add gsk_curve_get_{start,end}_tangent

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Add a way to get the tangents at the start and end of the curve.
This will be used in stroking.
This commit is contained in:
Matthias Clasen
2020-12-06 23:13:56 -05:00
parent 77d6bc9158
commit 0c2f43d1bd
2 changed files with 82 additions and 0 deletions
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78
gsk/gskcurve.c
View File

@@ -44,10 +44,23 @@ struct _GskCurveClass
gskpathop (* pathop) (const GskCurve *curve);
const graphene_point_t * (* get_start_point) (const GskCurve *curve);
const graphene_point_t * (* get_end_point) (const GskCurve *curve);
void (* get_start_tangent) (const GskCurve *curve,
graphene_vec2_t *tangent);
void (* get_end_tangent) (const GskCurve *curve,
graphene_vec2_t *tangent);
};
/* {{{ Line implementation */
static void
get_tangent (const graphene_point_t *p0,
const graphene_point_t *p1,
graphene_vec2_t *t)
{
graphene_vec2_init (t, p1->x - p0->x, p1->y - p0->y);
graphene_vec2_normalize (t, t);
}
static void
gsk_line_curve_init_from_points (GskLineCurve *self,
GskPathOperation op,
@@ -139,6 +152,15 @@ gsk_line_curve_get_end_point (const GskCurve *curve)
return &self->points[1];
}
static void
gsk_line_curve_get_tangent (const GskCurve *curve,
graphene_vec2_t *tangent)
{
const GskLineCurve *self = &curve->line;
get_tangent (&self->points[0], &self->points[1], tangent);
}
static const GskCurveClass GSK_LINE_CURVE_CLASS = {
gsk_line_curve_init,
gsk_line_curve_eval,
@@ -147,6 +169,8 @@ static const GskCurveClass GSK_LINE_CURVE_CLASS = {
gsk_line_curve_pathop,
gsk_line_curve_get_start_point,
gsk_line_curve_get_end_point,
gsk_line_curve_get_tangent,
gsk_line_curve_get_tangent
};
/* }}} */
@@ -312,6 +336,24 @@ gsk_curve_curve_get_end_point (const GskCurve *curve)
return &self->points[3];
}
static void
gsk_curve_curve_get_start_tangent (const GskCurve *curve,
graphene_vec2_t *tangent)
{
const GskCurveCurve *self = &curve->curve;
get_tangent (&self->points[0], &self->points[1], tangent);
}
static void
gsk_curve_curve_get_end_tangent (const GskCurve *curve,
graphene_vec2_t *tangent)
{
const GskCurveCurve *self = &curve->curve;
get_tangent (&self->points[2], &self->points[3], tangent);
}
static const GskCurveClass GSK_CURVE_CURVE_CLASS = {
gsk_curve_curve_init,
gsk_curve_curve_eval,
@@ -320,6 +362,8 @@ static const GskCurveClass GSK_CURVE_CURVE_CLASS = {
gsk_curve_curve_pathop,
gsk_curve_curve_get_start_point,
gsk_curve_curve_get_end_point,
gsk_curve_curve_get_start_tangent,
gsk_curve_curve_get_end_tangent
};
/* }}} */
@@ -626,6 +670,24 @@ gsk_conic_curve_get_end_point (const GskCurve *curve)
return &self->points[3];
}
static void
gsk_conic_curve_get_start_tangent (const GskCurve *curve,
graphene_vec2_t *tangent)
{
const GskConicCurve *self = &curve->conic;
get_tangent (&self->points[0], &self->points[1], tangent);
}
static void
gsk_conic_curve_get_end_tangent (const GskCurve *curve,
graphene_vec2_t *tangent)
{
const GskConicCurve *self = &curve->conic;
get_tangent (&self->points[1], &self->points[3], tangent);
}
static const GskCurveClass GSK_CONIC_CURVE_CLASS = {
gsk_conic_curve_init,
gsk_conic_curve_eval,
@@ -634,6 +696,8 @@ static const GskCurveClass GSK_CONIC_CURVE_CLASS = {
gsk_conic_curve_pathop,
gsk_conic_curve_get_start_point,
gsk_conic_curve_get_end_point,
gsk_conic_curve_get_start_tangent,
gsk_conic_curve_get_end_tangent
};
/* }}} */
@@ -706,6 +770,20 @@ gsk_curve_get_end_point (const GskCurve *curve)
return get_class (curve->op)->get_end_point (curve);
}
void
gsk_curve_get_start_tangent (const GskCurve *curve,
graphene_vec2_t *tangent)
{
get_class (curve->op)->get_start_tangent (curve, tangent);
}
void
gsk_curve_get_end_tangent (const GskCurve *curve,
graphene_vec2_t *tangent)
{
get_class (curve->op)->get_end_tangent (curve, tangent);
}
/* }}} */
/* vim:set foldmethod=marker expandtab: */

4
gsk/gskcurveprivate.h
View File

@@ -98,6 +98,10 @@ gskpathop gsk_curve_pathop (const GskCurve
#define gsk_curve_builder_to(curve, builder) gsk_path_builder_pathop_to ((builder), gsk_curve_pathop (curve))
const graphene_point_t *gsk_curve_get_start_point (const GskCurve *curve);
const graphene_point_t *gsk_curve_get_end_point (const GskCurve *curve);
void gsk_curve_get_start_tangent (const GskCurve *curve,
graphene_vec2_t *tangent);
void gsk_curve_get_end_tangent (const GskCurve *curve,
graphene_vec2_t *tangent);