static cairo_status_t
close_path (void *closure)
{
struct stroker *stroker = closure;
cairo_status_t status;
status = line_to (stroker, &stroker->first_point);
if (unlikely (status))
return status;
if (stroker->has_first_face && stroker->has_current_face) {
/* Join first and final faces of sub path */
outer_close (stroker, &stroker->current_face, &stroker->first_face);
inner_close (stroker, &stroker->current_face, &stroker->first_face);
#if 0
*_cairo_contour_first_point (&stroker->ccw.contour) =
*_cairo_contour_last_point (&stroker->ccw.contour);
*_cairo_contour_first_point (&stroker->cw.contour) =
*_cairo_contour_last_point (&stroker->cw.contour);
#endif
_cairo_polygon_add_contour (stroker->polygon, &stroker->cw.contour);
_cairo_polygon_add_contour (stroker->polygon, &stroker->ccw.contour);
#if DEBUG
{
FILE *file = fopen ("contours.txt", "a");
_cairo_debug_print_contour (file, &stroker->path);
_cairo_debug_print_contour (file, &stroker->cw.contour);
_cairo_debug_print_contour (file, &stroker->ccw.contour);
fclose (file);
_cairo_contour_reset (&stroker->path);
}
#endif
_cairo_contour_reset (&stroker->cw.contour);
_cairo_contour_reset (&stroker->ccw.contour);
} else {
/* Cap the start and end of the sub path as needed */
add_caps (stroker);
}
stroker->has_initial_sub_path = FALSE;
stroker->has_first_face = FALSE;
stroker->has_current_face = FALSE;
return CAIRO_STATUS_SUCCESS;
}
static void
contour_add_point (struct stroker *stroker,
struct stroke_contour *c,
const cairo_point_t *point)
{
if (! within_tolerance (point, _cairo_contour_last_point (&c->contour),
stroker->contour_tolerance))
_cairo_contour_add_point (&c->contour, point);
//*_cairo_contour_last_point (&c->contour) = *point;
}
static void
outer_join (struct stroker *stroker,
const cairo_stroke_face_t *in,
const cairo_stroke_face_t *out,
int clockwise)
{
const cairo_point_t *inpt, *outpt;
struct stroke_contour *outer;
if (in->cw.x == out->cw.x && in->cw.y == out->cw.y &&
in->ccw.x == out->ccw.x && in->ccw.y == out->ccw.y)
{
return;
}
if (clockwise) {
inpt = &in->cw;
outpt = &out->cw;
outer = &stroker->cw;
} else {
inpt = &in->ccw;
outpt = &out->ccw;
outer = &stroker->ccw;
}
switch (stroker->style.line_join) {
case CAIRO_LINE_JOIN_ROUND:
/* construct a fan around the common midpoint */
add_fan (stroker,
&in->dev_vector, &out->dev_vector, &in->point,
clockwise, outer);
break;
case CAIRO_LINE_JOIN_MITER:
default: {
/* dot product of incoming slope vector with outgoing slope vector */
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
* can generate long miters, the limit converts them to bevel
*
* Consider the miter join formed when two line segments
* meet at an angle psi:
*
* /.\
* /. .\
* /./ \.\
* /./psi\.\
*
* We can zoom in on the right half of that to see:
*
* |\
* | \ psi/2
* | \
* | \
* | \
* | \
* miter \
* length \
* | \
* | .\
* | . \
* |. line \
* \ width \
* \ \
*
*
* The right triangle in that figure, (the line-width side is
* shown faintly with three '.' characters), gives us the
* following expression relating miter length, angle and line
* width:
*
* 1 /sin (psi/2) = miter_length / line_width
*
* The right-hand side of this relationship is the same ratio
* in which the miter limit (ml) is expressed. We want to know
* when the miter length is within the miter limit. That is
* when the following condition holds:
*
* 1/sin(psi/2) <= ml
* 1 <= ml sin(psi/2)
* 1 <= ml² sin²(psi/2)
* 2 <= ml² 2 sin²(psi/2)
* 2·sin²(psi/2) = 1-cos(psi)
* 2 <= ml² (1-cos(psi))
*
* in · out = |in| |out| cos (psi)
*
* in and out are both unit vectors, so:
*
* in · out = cos (psi)
*
* 2 <= ml² (1 - in · out)
*
*/
if (2 <= ml * ml * (1 + in_dot_out)) {
double x1, y1, x2, y2;
double mx, my;
double dx1, dx2, dy1, dy2;
double ix, iy;
double fdx1, fdy1, fdx2, fdy2;
double mdx, mdy;
/*
* we've got the points already transformed to device
* space, but need to do some computation with them and
* also need to transform the slope from user space to
* device space
*/
/* outer point of incoming line face */
x1 = _cairo_fixed_to_double (inpt->x);
y1 = _cairo_fixed_to_double (inpt->y);
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->dev_slope.x;
dy2 = out->dev_slope.y;
/*
* Compute the location of the outer corner of the miter.
* That's pretty easy -- just the intersection of the two
* outer edges. We've got slopes and points on each
* of those edges. Compute my directly, then compute
* mx by using the edge with the larger dy; that avoids
* dividing by values close to zero.
*/
my = (((x2 - x1) * dy1 * dy2 - y2 * dx2 * dy1 + y1 * dx1 * dy2) /
(dx1 * dy2 - dx2 * dy1));
if (fabs (dy1) >= fabs (dy2))
mx = (my - y1) * dx1 / dy1 + x1;
else
mx = (my - y2) * dx2 / dy2 + x2;
/*
* When the two outer edges are nearly parallel, slight
* perturbations in the position of the outer points of the lines
* caused by representing them in fixed point form can cause the
* intersection point of the miter to move a large amount. If
* that moves the miter intersection from between the two faces,
* then draw a bevel instead.
*/
ix = _cairo_fixed_to_double (in->point.x);
iy = _cairo_fixed_to_double (in->point.y);
/* slope of one face */
fdx1 = x1 - ix; fdy1 = y1 - iy;
/* slope of the other face */
fdx2 = x2 - ix; fdy2 = y2 - iy;
/* slope from the intersection to the miter point */
mdx = mx - ix; mdy = my - iy;
/*
* Make sure the miter point line lies between the two
* faces by comparing the slopes
*/
if (slope_compare_sgn (fdx1, fdy1, mdx, mdy) !=
slope_compare_sgn (fdx2, fdy2, mdx, mdy))
{
cairo_point_t p;
p.x = _cairo_fixed_from_double (mx);
p.y = _cairo_fixed_from_double (my);
*_cairo_contour_last_point (&outer->contour) = p;
return;
}
}
break;
}
case CAIRO_LINE_JOIN_BEVEL:
break;
}
contour_add_point (stroker,outer, outpt);
}
static void
inner_close (struct stroker *stroker,
const cairo_stroke_face_t *in,
cairo_stroke_face_t *out)
{
#if 0
cairo_point_t last;
const cairo_point_t *p, *outpt, *inpt;
struct stroke_contour *inner;
struct _cairo_contour_chain *chain;
/* XXX line segments shorter than line-width */
if (join_is_clockwise (in, out)) {
inner = &stroker->ccw;
outpt = &in->ccw;
inpt = &out->ccw;
} else {
inner = &stroker->cw;
outpt = &in->cw;
inpt = &out->cw;
}
if (inner->contour.chain.num_points == 0) {
contour_add_point (stroker, inner, &in->point);
contour_add_point (stroker, inner, inpt);
*_cairo_contour_first_point (&inner->contour) =
*_cairo_contour_last_point (&inner->contour);
return;
}
line_width = stroker->style.line_width/2;
line_width *= CAIRO_FIXED_ONE;
d_last = sign * distance_from_face (out, outpt);
last = *outpt;
for (chain = &inner->contour.chain; chain; chain = chain->next) {
for (i = 0; i < chain->num_points; i++) {
p = &chain->points[i];
if ((d_p = sign * distance_from_face (in, p)) >= line_width &&
distance_from_edge (stroker, inpt, &last, p) < line_width)
{
goto out;
}
if (p->x != last.x || p->y != last.y) {
last = *p;
d_last = d_p;
}
}
}
out:
if (d_p != d_last) {
double dot = (line_width - d_last) / (d_p - d_last);
last.x += dot * (p->x - last.x);
last.y += dot * (p->y - last.y);
}
*_cairo_contour_last_point (&inner->contour) = last;
for (chain = &inner->contour.chain; chain; chain = chain->next) {
for (i = 0; i < chain->num_points; i++) {
cairo_point_t *pp = &chain->points[i];
if (pp == p)
return;
*pp = last;
}
}
#else
const cairo_point_t *inpt;
struct stroke_contour *inner;
if (join_is_clockwise (in, out)) {
inner = &stroker->ccw;
inpt = &out->ccw;
} else {
inner = &stroker->cw;
inpt = &out->cw;
}
contour_add_point (stroker, inner, &in->point);
contour_add_point (stroker, inner, inpt);
*_cairo_contour_first_point (&inner->contour) =
*_cairo_contour_last_point (&inner->contour);
#endif
}
static void
inner_join (struct stroker *stroker,
const cairo_stroke_face_t *in,
const cairo_stroke_face_t *out,
int clockwise)
{
#if 0
cairo_point_t last;
const cairo_point_t *p, *outpt;
struct stroke_contour *inner;
cairo_int64_t d_p, d_last;
cairo_int64_t half_line_width;
cairo_bool_t negate;
/* XXX line segments shorter than line-width */
if (clockwise) {
inner = &stroker->ccw;
outpt = &out->ccw;
negate = 1;
} else {
inner = &stroker->cw;
outpt = &out->cw;
negate = 0;
}
half_line_width = CAIRO_FIXED_ONE*CAIRO_FIXED_ONE/2 * stroker->style.line_width * out->length + .5;
/* On the inside, the previous end-point is always
* closer to the new face by definition.
*/
last = *_cairo_contour_last_point (&inner->contour);
d_last = distance_from_face (out, &last, negate);
_cairo_contour_remove_last_point (&inner->contour);
prev:
if (inner->contour.chain.num_points == 0) {
contour_add_point (stroker, inner, outpt);
return;
}
p = _cairo_contour_last_point (&inner->contour);
d_p = distance_from_face (out, p, negate);
if (_cairo_int64_lt (d_p, half_line_width) &&
!_cairo_int64_negative (distance_along_face (out, p)))
{
last = *p;
d_last = d_p;
_cairo_contour_remove_last_point (&inner->contour);
goto prev;
}
compute_inner_joint (&last, d_last, p, d_p, half_line_width);
contour_add_point (stroker, inner, &last);
#else
const cairo_point_t *outpt;
struct stroke_contour *inner;
if (clockwise) {
inner = &stroker->ccw;
outpt = &out->ccw;
} else {
inner = &stroker->cw;
outpt = &out->cw;
}
contour_add_point (stroker, inner, &in->point);
contour_add_point (stroker, inner, outpt);
#endif
}
static cairo_status_t
line_to (void *closure,
const cairo_point_t *point)
{
struct stroker *stroker = closure;
cairo_stroke_face_t start;
cairo_point_t *p1 = &stroker->current_face.point;
cairo_slope_t dev_slope;
int move_last = 0;
stroker->has_initial_sub_path = TRUE;
if (p1->x == point->x && p1->y == point->y)
return CAIRO_STATUS_SUCCESS;
#if DEBUG
_cairo_contour_add_point (&stroker->path, point);
#endif
_cairo_slope_init (&dev_slope, p1, point);
compute_face (p1, &dev_slope, stroker, &start);
if (stroker->has_current_face) {
int clockwise = _cairo_slope_compare (&stroker->current_face.dev_vector,
&start.dev_vector);
if (clockwise == 0) {
move_last = 1;
} else {
clockwise = clockwise < 0;
/* Join with final face from previous segment */
if (! within_tolerance (&stroker->current_face.ccw, &start.ccw,
stroker->contour_tolerance) ||
! within_tolerance (&stroker->current_face.cw, &start.cw,
stroker->contour_tolerance))
{
outer_join (stroker, &stroker->current_face, &start, clockwise);
inner_join (stroker, &stroker->current_face, &start, clockwise);
}
}
} else {
if (! stroker->has_first_face) {
/* Save sub path's first face in case needed for closing join */
stroker->first_face = start;
stroker->has_first_face = TRUE;
}
stroker->has_current_face = TRUE;
contour_add_point (stroker, &stroker->cw, &start.cw);
contour_add_point (stroker, &stroker->ccw, &start.ccw);
}
stroker->current_face = start;
stroker->current_face.point = *point;
stroker->current_face.ccw.x += dev_slope.dx;
stroker->current_face.ccw.y += dev_slope.dy;
stroker->current_face.cw.x += dev_slope.dx;
stroker->current_face.cw.y += dev_slope.dy;
if (move_last) {
*_cairo_contour_last_point (&stroker->cw.contour) = stroker->current_face.cw;
*_cairo_contour_last_point (&stroker->ccw.contour) = stroker->current_face.ccw;
} else {
contour_add_point (stroker, &stroker->cw, &stroker->current_face.cw);
contour_add_point (stroker, &stroker->ccw, &stroker->current_face.ccw);
}
return CAIRO_STATUS_SUCCESS;
}