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stroke: Precompute the line half-width

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Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
This commit is contained in:
Chris Wilson 2012-08-25 23:54:36 +01:00
parent 3cf6551ac7
commit fa93fc63b6
1 changed files with 38 additions and 44 deletions
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82
src/cairo-path-stroke-polygon.c
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@ -68,6 +68,7 @@ struct stroker {
const cairo_matrix_t *ctm_inverse;
double tolerance;
double spline_cusp_tolerance;
double half_line_width;
cairo_bool_t ctm_det_positive;
cairo_pen_t pen;
@ -378,6 +379,7 @@ outer_close (struct stroker *stroker,
{
return;
}
clockwise = join_is_clockwise (in, out);
if (clockwise) {
inpt = &in->cw;
@ -410,8 +412,8 @@ outer_close (struct stroker *stroker,
case CAIRO_LINE_JOIN_MITER:
default: {
/* dot product of incoming slope vector with outgoing slope vector */
double in_dot_out = -in->usr_vector.x * out->usr_vector.x +
-in->usr_vector.y * out->usr_vector.y;
double in_dot_out = in->dev_slope.x * out->dev_slope.x +
in->dev_slope.y * out->dev_slope.y;
double ml = stroker->style.miter_limit;
/* Check the miter limit -- lines meeting at an acute angle
@ -471,7 +473,7 @@ outer_close (struct stroker *stroker,
* 2 <= ml² (1 - in · out)
*
*/
if (2 <= ml * ml * (1 - in_dot_out)) {
if (2 <= ml * ml * (1 + in_dot_out)) {
double x1, y1, x2, y2;
double mx, my;
double dx1, dx2, dy1, dy2;
@ -488,16 +490,14 @@ outer_close (struct stroker *stroker,
/* outer point of incoming line face */
x1 = _cairo_fixed_to_double (inpt->x);
y1 = _cairo_fixed_to_double (inpt->y);
dx1 = in->usr_vector.x;
dy1 = in->usr_vector.y;
cairo_matrix_transform_distance (stroker->ctm, &dx1, &dy1);
dx1 = in->dev_slope.x;
dy1 = in->dev_slope.y;
/* outer point of outgoing line face */
x2 = _cairo_fixed_to_double (outpt->x);
y2 = _cairo_fixed_to_double (outpt->y);
dx2 = out->usr_vector.x;
dy2 = out->usr_vector.y;
cairo_matrix_transform_distance (stroker->ctm, &dx2, &dy2);
dx2 = out->dev_slope.x;
dy2 = out->dev_slope.y;
/*
* Compute the location of the outer corner of the miter.
@ -596,8 +596,8 @@ outer_join (struct stroker *stroker,
case CAIRO_LINE_JOIN_MITER:
default: {
/* dot product of incoming slope vector with outgoing slope vector */
double in_dot_out = -in->usr_vector.x * out->usr_vector.x +
-in->usr_vector.y * out->usr_vector.y;
double in_dot_out = in->dev_slope.x * out->dev_slope.x +
in->dev_slope.y * out->dev_slope.y;
double ml = stroker->style.miter_limit;
/* Check the miter limit -- lines meeting at an acute angle
@ -657,7 +657,7 @@ outer_join (struct stroker *stroker,
* 2 <= ml² (1 - in · out)
*
*/
if (2 <= ml * ml * (1 - in_dot_out)) {
if (2 <= ml * ml * (1 + in_dot_out)) {
double x1, y1, x2, y2;
double mx, my;
double dx1, dx2, dy1, dy2;
@ -674,16 +674,14 @@ outer_join (struct stroker *stroker,
/* outer point of incoming line face */
x1 = _cairo_fixed_to_double (inpt->x);
y1 = _cairo_fixed_to_double (inpt->y);
dx1 = in->usr_vector.x;
dy1 = in->usr_vector.y;
cairo_matrix_transform_distance (stroker->ctm, &dx1, &dy1);
dx1 = in->dev_slope.x;
dy1 = in->dev_slope.y;
/* outer point of outgoing line face */
x2 = _cairo_fixed_to_double (outpt->x);
y2 = _cairo_fixed_to_double (outpt->y);
dx2 = out->usr_vector.x;
dy2 = out->usr_vector.y;
cairo_matrix_transform_distance (stroker->ctm, &dx2, &dy2);
dx2 = out->dev_slope.x;
dy2 = out->dev_slope.y;
/*
* Compute the location of the outer corner of the miter.
@ -763,27 +761,25 @@ add_cap (struct stroker *stroker,
}
case CAIRO_LINE_CAP_SQUARE: {
cairo_slope_t fvector;
cairo_point_t p;
double dx, dy;
cairo_slope_t fvector;
cairo_point_t quad[4];
dx = f->usr_vector.x;
dy = f->usr_vector.y;
dx *= stroker->style.line_width / 2.0;
dy *= stroker->style.line_width / 2.0;
dx *= stroker->half_line_width;
dy *= stroker->half_line_width;
cairo_matrix_transform_distance (stroker->ctm, &dx, &dy);
fvector.dx = _cairo_fixed_from_double (dx);
fvector.dy = _cairo_fixed_from_double (dy);
quad[0] = f->ccw;
quad[1].x = f->ccw.x + fvector.dx;
quad[1].y = f->ccw.y + fvector.dy;
quad[2].x = f->cw.x + fvector.dx;
quad[2].y = f->cw.y + fvector.dy;
quad[3] = f->cw;
p.x = f->ccw.x + fvector.dx;
p.y = f->ccw.y + fvector.dy;
contour_add_point (stroker, c, &p);
contour_add_point (stroker, c, &quad[1]);
contour_add_point (stroker, c, &quad[2]);
p.x = f->cw.x + fvector.dx;
p.y = f->cw.y + fvector.dy;
contour_add_point (stroker, c, &p);
}
case CAIRO_LINE_CAP_BUTT:
@ -888,22 +884,19 @@ compute_face (const cairo_point_t *point,
&slope_dx, &slope_dy);
normalize_slope (&slope_dx, &slope_dy);
if (stroker->ctm_det_positive)
{
face_dx = - slope_dy * (stroker->style.line_width / 2.0);
face_dy = slope_dx * (stroker->style.line_width / 2.0);
}
else
{
face_dx = slope_dy * (stroker->style.line_width / 2.0);
face_dy = - slope_dx * (stroker->style.line_width / 2.0);
if (stroker->ctm_det_positive) {
face_dx = - slope_dy * stroker->half_line_width;
face_dy = slope_dx * stroker->half_line_width;
} else {
face_dx = slope_dy * stroker->half_line_width;
face_dy = - slope_dx * stroker->half_line_width;
}
/* back to device space */
cairo_matrix_transform_distance (stroker->ctm, &face_dx, &face_dy);
} else {
face_dx = - slope_dy * (stroker->style.line_width / 2.0);
face_dy = slope_dx * (stroker->style.line_width / 2.0);
face_dx = - slope_dy * stroker->half_line_width;
face_dy = slope_dx * stroker->half_line_width;
}
offset_ccw.x = _cairo_fixed_from_double (face_dx);
@ -1089,7 +1082,7 @@ spline_to (void *closure,
#if DEBUG
_cairo_contour_add_point (&stroker->path, point);
#endif
if (tangent->dx == 0 && tangent->dy == 0) {
if ((tangent->dx | tangent->dy) == 0) {
const cairo_point_t *inpt, *outpt;
struct stroke_contour *outer;
cairo_point_t t;
@ -1307,6 +1300,7 @@ _cairo_path_fixed_stroke_to_polygon (const cairo_path_fixed_t *path,
stroker.ctm = ctm;
stroker.ctm_inverse = ctm_inverse;
stroker.tolerance = tolerance;
stroker.half_line_width = style->line_width / 2.;
/* To test whether we need to join two segments of a spline using
* a round-join or a bevel-join, we can inspect the angle between the
* two segments. If the difference between the chord distance
@ -1314,7 +1308,7 @@ _cairo_path_fixed_stroke_to_polygon (const cairo_path_fixed_t *path,
* half-line-width itself is greater than tolerance then we need to
* inject a point.
*/
stroker.spline_cusp_tolerance = 1 - 2 * tolerance / style->line_width;
stroker.spline_cusp_tolerance = 1 - tolerance / stroker.half_line_width;
stroker.spline_cusp_tolerance *= stroker.spline_cusp_tolerance;
stroker.spline_cusp_tolerance *= 2;
stroker.spline_cusp_tolerance -= 1;
@ -1326,7 +1320,7 @@ _cairo_path_fixed_stroke_to_polygon (const cairo_path_fixed_t *path,
style->line_join == CAIRO_LINE_JOIN_ROUND ||
style->line_cap == CAIRO_LINE_CAP_ROUND) {
status = _cairo_pen_init (&stroker.pen,
style->line_width / 2.0,
stroker.half_line_width,
tolerance, ctm);
if (unlikely (status))
return status;