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path: Add gsk_curve_segment()

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Using split() twice with scaled t values does not work with conics.
This commit is contained in:
Benjamin Otte
2020-12-09 03:40:58 +01:00
parent 7a6b008479
commit 92b472fec1
3 changed files with 107 additions and 8 deletions
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16
gsk/gskcontour.c
View File

@@ -1334,19 +1334,19 @@ gsk_standard_contour_add_segment (const GskContour *contour,
gsk_curve_init (&curve, self->ops[start_measure->op]);
gsk_curve_split (&curve, start_progress, NULL, &cut);
start_point = gsk_curve_get_start_point (&cut);
gsk_path_builder_move_to (builder, start_point->x, start_point->y);
if (end_measure && end_measure->op == start_measure->op)
{
GskCurve cut2;
gsk_curve_split (&cut, (end_progress - start_progress) / (1 - start_progress), &cut2, NULL);
gsk_curve_builder_to (&cut2, builder);
gsk_curve_segment (&curve, start_progress, end_progress, &cut);
start_point = gsk_curve_get_start_point (&cut);
gsk_path_builder_move_to (builder, start_point->x, start_point->y);
gsk_curve_builder_to (&cut, builder);
return;
}
gsk_curve_split (&curve, start_progress, NULL, &cut);
start_point = gsk_curve_get_start_point (&cut);
gsk_path_builder_move_to (builder, start_point->x, start_point->y);
gsk_curve_builder_to (&cut, builder);
i = start_measure->op + 1;
}

95
gsk/gskcurve.c
View File

@@ -39,6 +39,10 @@ struct _GskCurveClass
float progress,
GskCurve *result1,
GskCurve *result2);
void (* segment) (const GskCurve *curve,
float start,
float end,
GskCurve *segment);
gboolean (* decompose) (const GskCurve *curve,
float tolerance,
GskCurveAddLineFunc add_line_func,
@@ -121,6 +125,21 @@ gsk_line_curve_split (const GskCurve *curve,
gsk_line_curve_init_from_points (&end->line, GSK_PATH_LINE, &point, &self->points[1]);
}
static void
gsk_line_curve_segment (const GskCurve *curve,
float start,
float end,
GskCurve *segment)
{
const GskLineCurve *self = &curve->line;
graphene_point_t start_point, end_point;
graphene_point_interpolate (&self->points[0], &self->points[1], start, &start_point);
graphene_point_interpolate (&self->points[0], &self->points[1], end, &end_point);
gsk_line_curve_init_from_points (&segment->line, GSK_PATH_LINE, &start_point, &end_point);
}
static gboolean
gsk_line_curve_decompose (const GskCurve *curve,
float tolerance,
@@ -170,6 +189,7 @@ static const GskCurveClass GSK_LINE_CURVE_CLASS = {
gsk_line_curve_get_point,
gsk_line_curve_get_tangent,
gsk_line_curve_split,
gsk_line_curve_segment,
gsk_line_curve_decompose,
gsk_line_curve_pathop,
gsk_line_curve_get_start_point,
@@ -273,6 +293,18 @@ gsk_curve_curve_split (const GskCurve *curve,
gsk_curve_curve_init_from_points (&end->curve, (graphene_point_t[4]) { final, bccd, cd, pts[3] });
}
static void
gsk_curve_curve_segment (const GskCurve *curve,
float start,
float end,
GskCurve *segment)
{
GskCurve tmp;
gsk_curve_curve_split (curve, start, NULL, &tmp);
gsk_curve_curve_split (&tmp, (end - start) / (1.0f - start), segment, NULL);
}
/* taken from Skia, including the very descriptive name */
static gboolean
gsk_curve_curve_too_curvy (const GskCurveCurve *self,
@@ -370,6 +402,7 @@ static const GskCurveClass GSK_CURVE_CURVE_CLASS = {
gsk_curve_curve_get_point,
gsk_curve_curve_get_tangent,
gsk_curve_curve_split,
gsk_curve_curve_segment,
gsk_curve_curve_decompose,
gsk_curve_curve_pathop,
gsk_curve_curve_get_start_point,
@@ -598,6 +631,52 @@ gsk_conic_curve_split (const GskCurve *curve,
gsk_curve_init (end, gsk_pathop_encode (GSK_PATH_CONIC, right));
}
static void
gsk_conic_curve_segment (const GskCurve *curve,
float start,
float end,
GskCurve *segment)
{
const GskConicCurve *self = &curve->conic;
graphene_point_t start_num, start_denom;
graphene_point_t mid_num, mid_denom;
graphene_point_t end_num, end_denom;
graphene_point_t ctrl_num, ctrl_denom;
float mid;
if (start <= 0.0f)
return gsk_conic_curve_split (curve, end, segment, NULL);
else if (end >= 1.0f)
return gsk_conic_curve_split (curve, start, NULL, segment);
gsk_conic_curve_ensure_coefficents (self);
gsk_curve_eval_quad (self->num, start, &start_num);
gsk_curve_eval_quad (self->denom, start, &start_denom);
mid = (start + end) / 2;
gsk_curve_eval_quad (self->num, mid, &mid_num);
gsk_curve_eval_quad (self->denom, mid, &mid_denom);
gsk_curve_eval_quad (self->num, end, &end_num);
gsk_curve_eval_quad (self->denom, end, &end_denom);
ctrl_num = GRAPHENE_POINT_INIT (2 * mid_num.x - (start_num.x + end_num.x) / 2,
2 * mid_num.y - (start_num.y + end_num.y) / 2);
ctrl_denom = GRAPHENE_POINT_INIT (2 * mid_denom.x - (start_denom.x + end_denom.x) / 2,
2 * mid_denom.y - (start_denom.y + end_denom.y) / 2);
gsk_conic_curve_init_from_points (&segment->conic,
(graphene_point_t[4]) {
GRAPHENE_POINT_INIT (start_num.x / start_denom.x,
start_num.y / start_denom.y),
GRAPHENE_POINT_INIT (ctrl_num.x / ctrl_denom.x,
ctrl_num.y / ctrl_denom.y),
GRAPHENE_POINT_INIT (ctrl_denom.x / sqrtf (start_denom.x * end_denom.x),
0),
GRAPHENE_POINT_INIT (end_num.x / end_denom.x,
end_num.y / end_denom.y)
});
}
/* taken from Skia, including the very descriptive name */
static gboolean
gsk_conic_curve_too_curvy (const graphene_point_t *start,
@@ -706,6 +785,7 @@ static const GskCurveClass GSK_CONIC_CURVE_CLASS = {
gsk_conic_curve_get_point,
gsk_conic_curve_get_tangent,
gsk_conic_curve_split,
gsk_conic_curve_segment,
gsk_conic_curve_decompose,
gsk_conic_curve_pathop,
gsk_conic_curve_get_start_point,
@@ -763,6 +843,21 @@ gsk_curve_split (const GskCurve *curve,
get_class (curve->op)->split (curve, progress, start, end);
}
void
gsk_curve_segment (const GskCurve *curve,
float start,
float end,
GskCurve *segment)
{
if (start <= 0 && end >= 1)
{
*segment = *curve;
return;
}
get_class (curve->op)->segment (curve, start, end, segment);
}
gboolean
gsk_curve_decompose (const GskCurve *curve,
float tolerance,

4
gsk/gskcurveprivate.h
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@@ -92,6 +92,10 @@ void gsk_curve_split (const GskCurve
float progress,
GskCurve *start,
GskCurve *end);
void gsk_curve_segment (const GskCurve *curve,
float start,
float end,
GskCurve *segment);
gboolean gsk_curve_decompose (const GskCurve *curve,
float tolerance,
GskCurveAddLineFunc add_line_func,