/* -*- Mode: c; tab-width: 8; c-basic-offset: 4; indent-tabs-mode: t; -*- */
/* cairo - a vector graphics library with display and print output
*
* Copyright © 2002 University of Southern California
* Copyright © 2011 Intel Corporation
*
* This library is free software; you can redistribute it and/or
* modify it either under the terms of the GNU Lesser General Public
* License version 2.1 as published by the Free Software Foundation
* (the "LGPL") or, at your option, under the terms of the Mozilla
* Public License Version 1.1 (the "MPL"). If you do not alter this
* notice, a recipient may use your version of this file under either
* the MPL or the LGPL.
*
* You should have received a copy of the LGPL along with this library
* in the file COPYING-LGPL-2.1; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Suite 500, Boston, MA 02110-1335, USA
* You should have received a copy of the MPL along with this library
* in the file COPYING-MPL-1.1
*
* The contents of this file are subject to the Mozilla Public License
* Version 1.1 (the "License"); you may not use this file except in
* compliance with the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
* OF ANY KIND, either express or implied. See the LGPL or the MPL for
* the specific language governing rights and limitations.
*
* The Original Code is the cairo graphics library.
*
* The Initial Developer of the Original Code is University of Southern
* California.
*
* Contributor(s):
* Carl D. Worth <cworth@cworth.org>
* Chris Wilson <chris@chris-wilson.co.uk>
*/
#define _BSD_SOURCE /* for hypot() */
#include "cairoint.h"
#include "cairo-box-inline.h"
#include "cairo-boxes-private.h"
#include "cairo-contour-inline.h"
#include "cairo-contour-private.h"
#include "cairo-error-private.h"
#include "cairo-path-fixed-private.h"
#include "cairo-slope-private.h"
#define DEBUG 0
struct stroker {
cairo_stroke_style_t style;
#if DEBUG
cairo_contour_t path;
#endif
struct stroke_contour {
/* Note that these are not strictly contours as they may intersect */
cairo_contour_t contour;
} cw, ccw;
cairo_uint64_t contour_tolerance;
cairo_polygon_t *polygon;
const cairo_matrix_t *ctm;
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;
cairo_point_t first_point;
cairo_bool_t has_initial_sub_path;
cairo_bool_t has_current_face;
cairo_stroke_face_t current_face;
cairo_bool_t has_first_face;
cairo_stroke_face_t first_face;
cairo_bool_t has_bounds;
cairo_box_t bounds;
};
static inline double
normalize_slope (double *dx, double *dy);
static void
compute_face (const cairo_point_t *point,
const cairo_slope_t *dev_slope,
struct stroker *stroker,
cairo_stroke_face_t *face);
static cairo_uint64_t
point_distance_sq (const cairo_point_t *p1,
const cairo_point_t *p2)
{
int32_t dx = p1->x - p2->x;
int32_t dy = p1->y - p2->y;
return _cairo_int32x32_64_mul (dx, dx) + _cairo_int32x32_64_mul (dy, dy);
}
static cairo_bool_t
within_tolerance (const cairo_point_t *p1,
const cairo_point_t *p2,
cairo_uint64_t tolerance)
{
return FALSE;
return _cairo_int64_lt (point_distance_sq (p1, p2), tolerance);
}
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
translate_point (cairo_point_t *point, const cairo_point_t *offset)
{
point->x += offset->x;
point->y += offset->y;
}
static int
slope_compare_sgn (double dx1, double dy1, double dx2, double dy2)
{
double c = (dx1 * dy2 - dx2 * dy1);
if (c > 0) return 1;
if (c < 0) return -1;
return 0;
}
static inline int
range_step (int i, int step, int max)
{
i += step;
if (i < 0)
i = max - 1;
if (i >= max)
i = 0;
return i;
}
/*
* Construct a fan around the midpoint using the vertices from pen between
* inpt and outpt.
*/
static void
add_fan (struct stroker *stroker,
const cairo_slope_t *in_vector,
const cairo_slope_t *out_vector,
const cairo_point_t *midpt,
cairo_bool_t clockwise,
struct stroke_contour *c)
{
cairo_pen_t *pen = &stroker->pen;
int start, stop;
if (stroker->has_bounds &&
! _cairo_box_contains_point (&stroker->bounds, midpt))
return;
assert (stroker
->pen.
num_vertices);
if (clockwise) {
_cairo_pen_find_active_cw_vertices (pen,
in_vector, out_vector,
&start, &stop);
while (start != stop) {
cairo_point_t p = *midpt;
translate_point (&p, &pen->vertices[start].point);
contour_add_point (stroker, c, &p);
if (++start == pen->num_vertices)
start = 0;
}
} else {
_cairo_pen_find_active_ccw_vertices (pen,
in_vector, out_vector,
&start, &stop);
while (start != stop) {
cairo_point_t p = *midpt;
translate_point (&p, &pen->vertices[start].point);
contour_add_point (stroker, c, &p);
if (start-- == 0)
start += pen->num_vertices;
}
}
}
static int
join_is_clockwise (const cairo_stroke_face_t *in,
const cairo_stroke_face_t *out)
{
return _cairo_slope_compare (&in->dev_vector, &out->dev_vector) < 0;
}
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 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
outer_close (struct stroker *stroker,
const cairo_stroke_face_t *in,
const cairo_stroke_face_t *out)
{
const cairo_point_t *inpt, *outpt;
struct stroke_contour *outer;
int clockwise;
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;
}
clockwise = join_is_clockwise (in, out);
if (clockwise) {
inpt = &in->cw;
outpt = &out->cw;
outer = &stroker->cw;
} else {
inpt = &in->ccw;
outpt = &out->ccw;
outer = &stroker->ccw;
}
if (within_tolerance (inpt, outpt, stroker->contour_tolerance)) {
*_cairo_contour_first_point (&outer->contour) =
*_cairo_contour_last_point (&outer->contour);
return;
}
switch (stroker->style.line_join) {
case CAIRO_LINE_JOIN_ROUND:
/* construct a fan around the common midpoint */
if ((in->dev_slope.x * out->dev_slope.x +
in->dev_slope.y * out->dev_slope.y) < stroker->spline_cusp_tolerance)
{
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));
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;
*_cairo_contour_first_point (&outer->contour) = p;
return;
}
}
break;
}
case CAIRO_LINE_JOIN_BEVEL:
break;
}
contour_add_point (stroker, outer, outpt);
}
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));
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
add_cap (struct stroker *stroker,
const cairo_stroke_face_t *f,
struct stroke_contour *c)
{
switch (stroker->style.line_cap) {
case CAIRO_LINE_CAP_ROUND: {
cairo_slope_t slope;
slope.dx = -f->dev_vector.dx;
slope.dy = -f->dev_vector.dy;
add_fan (stroker, &f->dev_vector, &slope, &f->point, FALSE, c);
break;
}
case CAIRO_LINE_CAP_SQUARE: {
cairo_slope_t fvector;
cairo_point_t p;
double dx, dy;
dx = f->usr_vector.x;
dy = f->usr_vector.y;
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);
p.x = f->ccw.x + fvector.dx;
p.y = f->ccw.y + fvector.dy;
contour_add_point (stroker, c, &p);
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:
default:
break;
}
contour_add_point (stroker, c, &f->cw);
}
static void
add_leading_cap (struct stroker *stroker,
const cairo_stroke_face_t *face,
struct stroke_contour *c)
{
cairo_stroke_face_t reversed;
cairo_point_t t;
reversed = *face;
/* The initial cap needs an outward facing vector. Reverse everything */
reversed.usr_vector.x = -reversed.usr_vector.x;
reversed.usr_vector.y = -reversed.usr_vector.y;
reversed.dev_vector.dx = -reversed.dev_vector.dx;
reversed.dev_vector.dy = -reversed.dev_vector.dy;
t = reversed.cw;
reversed.cw = reversed.ccw;
reversed.ccw = t;
add_cap (stroker, &reversed, c);
}
static void
add_trailing_cap (struct stroker *stroker,
const cairo_stroke_face_t *face,
struct stroke_contour *c)
{
add_cap (stroker, face, c);
}
static inline double
normalize_slope (double *dx, double *dy)
{
double dx0 = *dx, dy0 = *dy;
double mag;
assert (dx0
!= 0.0 || dy0
!= 0.0);
if (dx0 == 0.0) {
*dx = 0.0;
if (dy0 > 0.0) {
mag = dy0;
*dy = 1.0;
} else {
mag = -dy0;
*dy = -1.0;
}
} else if (dy0 == 0.0) {
*dy = 0.0;
if (dx0 > 0.0) {
mag = dx0;
*dx = 1.0;
} else {
mag = -dx0;
*dx = -1.0;
}
} else {
mag = hypot (dx0, dy0);
*dx = dx0 / mag;
*dy = dy0 / mag;
}
return mag;
}
static void
compute_face (const cairo_point_t *point,
const cairo_slope_t *dev_slope,
struct stroker *stroker,
cairo_stroke_face_t *face)
{
double face_dx, face_dy;
cairo_point_t offset_ccw, offset_cw;
double slope_dx, slope_dy;
slope_dx = _cairo_fixed_to_double (dev_slope->dx);
slope_dy = _cairo_fixed_to_double (dev_slope->dy);
face->length = normalize_slope (&slope_dx, &slope_dy);
face->dev_slope.x = slope_dx;
face->dev_slope.y = slope_dy;
/*
* rotate to get a line_width/2 vector along the face, note that
* the vector must be rotated the right direction in device space,
* but by 90° in user space. So, the rotation depends on
* whether the ctm reflects or not, and that can be determined
* by looking at the determinant of the matrix.
*/
if (! _cairo_matrix_is_identity (stroker->ctm_inverse)) {
/* Normalize the matrix! */
cairo_matrix_transform_distance (stroker->ctm_inverse,
&slope_dx, &slope_dy);
normalize_slope (&slope_dx, &slope_dy);
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->half_line_width;
face_dy = slope_dx * stroker->half_line_width;
}
offset_ccw.x = _cairo_fixed_from_double (face_dx);
offset_ccw.y = _cairo_fixed_from_double (face_dy);
offset_cw.x = -offset_ccw.x;
offset_cw.y = -offset_ccw.y;
face->ccw = *point;
translate_point (&face->ccw, &offset_ccw);
face->point = *point;
face->cw = *point;
translate_point (&face->cw, &offset_cw);
face->usr_vector.x = slope_dx;
face->usr_vector.y = slope_dy;
face->dev_vector = *dev_slope;
}
static void
add_caps (struct stroker *stroker)
{
/* check for a degenerative sub_path */
if (stroker->has_initial_sub_path &&
! stroker->has_first_face &&
! stroker->has_current_face &&
stroker->style.line_cap == CAIRO_LINE_CAP_ROUND)
{
/* pick an arbitrary slope to use */
cairo_slope_t slope = { CAIRO_FIXED_ONE, 0 };
cairo_stroke_face_t face;
/* arbitrarily choose first_point */
compute_face (&stroker->first_point, &slope, stroker, &face);
add_leading_cap (stroker, &face, &stroker->ccw);
add_trailing_cap (stroker, &face, &stroker->ccw);
/* ensure the circle is complete */
_cairo_contour_add_point (&stroker->ccw.contour,
_cairo_contour_first_point (&stroker->ccw.contour));
_cairo_polygon_add_contour (stroker->polygon, &stroker->ccw.contour);
_cairo_contour_reset (&stroker->ccw.contour);
} else {
if (stroker->has_current_face)
add_trailing_cap (stroker, &stroker->current_face, &stroker->ccw);
#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);
_cairo_contour_reset (&stroker->path);
}
#endif
_cairo_polygon_add_contour (stroker->polygon, &stroker->ccw.contour);
_cairo_contour_reset (&stroker->ccw.contour);
if (stroker->has_first_face) {
_cairo_contour_add_point (&stroker->ccw.contour,
&stroker->first_face.cw);
add_leading_cap (stroker, &stroker->first_face, &stroker->ccw);
#if DEBUG
{
FILE
*file
= fopen ("contours.txt", "a"); _cairo_debug_print_contour (file, &stroker->ccw.contour);
}
#endif
_cairo_polygon_add_contour (stroker->polygon,
&stroker->ccw.contour);
_cairo_contour_reset (&stroker->ccw.contour);
}
_cairo_polygon_add_contour (stroker->polygon, &stroker->cw.contour);
_cairo_contour_reset (&stroker->cw.contour);
}
}
static cairo_status_t
close_path (void *closure);
static cairo_status_t
move_to (void *closure,
const cairo_point_t *point)
{
struct stroker *stroker = closure;
/* Cap the start and end of the previous sub path as needed */
add_caps (stroker);
stroker->has_first_face = FALSE;
stroker->has_current_face = FALSE;
stroker->has_initial_sub_path = FALSE;
stroker->first_point = *point;
#if DEBUG
_cairo_contour_add_point (&stroker->path, point);
#endif
stroker->current_face.point = *point;
return CAIRO_STATUS_SUCCESS;
}
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;
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) {
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;
contour_add_point (stroker, &stroker->cw, &stroker->current_face.cw);
contour_add_point (stroker, &stroker->ccw, &stroker->current_face.ccw);
return CAIRO_STATUS_SUCCESS;
}
static cairo_status_t
spline_to (void *closure,
const cairo_point_t *point,
const cairo_slope_t *tangent)
{
struct stroker *stroker = closure;
cairo_stroke_face_t face;
#if DEBUG
_cairo_contour_add_point (&stroker->path, point);
#endif
if ((tangent->dx | tangent->dy) == 0) {
const cairo_point_t *inpt, *outpt;
struct stroke_contour *outer;
cairo_point_t t;
int clockwise;
face = stroker->current_face;
face.usr_vector.x = -face.usr_vector.x;
face.usr_vector.y = -face.usr_vector.y;
face.dev_vector.dx = -face.dev_vector.dx;
face.dev_vector.dy = -face.dev_vector.dy;
t = face.cw;
face.cw = face.ccw;
face.ccw = t;
clockwise = join_is_clockwise (&stroker->current_face, &face);
if (clockwise) {
inpt = &stroker->current_face.cw;
outpt = &face.cw;
outer = &stroker->cw;
} else {
inpt = &stroker->current_face.ccw;
outpt = &face.ccw;
outer = &stroker->ccw;
}
add_fan (stroker,
&stroker->current_face.dev_vector,
&face.dev_vector,
&stroker->current_face.point,
clockwise, outer);
} else {
compute_face (point, tangent, stroker, &face);
if ((face.dev_slope.x * stroker->current_face.dev_slope.x +
face.dev_slope.y * stroker->current_face.dev_slope.y) < stroker->spline_cusp_tolerance)
{
const cairo_point_t *inpt, *outpt;
struct stroke_contour *outer;
int clockwise = join_is_clockwise (&stroker->current_face, &face);
stroker->current_face.cw.x += face.point.x - stroker->current_face.point.x;
stroker->current_face.cw.y += face.point.y - stroker->current_face.point.y;
contour_add_point (stroker, &stroker->cw, &stroker->current_face.cw);
stroker->current_face.ccw.x += face.point.x - stroker->current_face.point.x;
stroker->current_face.ccw.y += face.point.y - stroker->current_face.point.y;
contour_add_point (stroker, &stroker->ccw, &stroker->current_face.ccw);
if (clockwise) {
inpt = &stroker->current_face.cw;
outpt = &face.cw;
outer = &stroker->cw;
} else {
inpt = &stroker->current_face.ccw;
outpt = &face.ccw;
outer = &stroker->ccw;
}
add_fan (stroker,
&stroker->current_face.dev_vector,
&face.dev_vector,
&stroker->current_face.point,
clockwise, outer);
}
contour_add_point (stroker, &stroker->cw, &face.cw);
contour_add_point (stroker, &stroker->ccw, &face.ccw);
}
stroker->current_face = face;
return CAIRO_STATUS_SUCCESS;
}
static cairo_status_t
curve_to (void *closure,
const cairo_point_t *b,
const cairo_point_t *c,
const cairo_point_t *d)
{
struct stroker *stroker = closure;
cairo_spline_t spline;
cairo_stroke_face_t face;
if (stroker->has_bounds &&
! _cairo_spline_intersects (&stroker->current_face.point, b, c, d,
&stroker->bounds))
return line_to (closure, d);
if (! _cairo_spline_init (&spline, spline_to, stroker,
&stroker->current_face.point, b, c, d))
return line_to (closure, d);
compute_face (&stroker->current_face.point, &spline.initial_slope,
stroker, &face);
if (stroker->has_current_face) {
int clockwise = join_is_clockwise (&stroker->current_face, &face);
/* Join with final face from previous segment */
outer_join (stroker, &stroker->current_face, &face, clockwise);
inner_join (stroker, &stroker->current_face, &face, clockwise);
} else {
if (! stroker->has_first_face) {
/* Save sub path's first face in case needed for closing join */
stroker->first_face = face;
stroker->has_first_face = TRUE;
}
stroker->has_current_face = TRUE;
contour_add_point (stroker, &stroker->cw, &face.cw);
contour_add_point (stroker, &stroker->ccw, &face.ccw);
}
stroker->current_face = face;
return _cairo_spline_decompose (&spline, stroker->tolerance);
}
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);
_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;
}
cairo_status_t
_cairo_path_fixed_stroke_to_polygon (const cairo_path_fixed_t *path,
const cairo_stroke_style_t *style,
const cairo_matrix_t *ctm,
const cairo_matrix_t *ctm_inverse,
double tolerance,
cairo_polygon_t *polygon)
{
struct stroker stroker;
cairo_status_t status;
if (style->num_dashes) {
return _cairo_path_fixed_stroke_dashed_to_polygon (path,
style,
ctm,
ctm_inverse,
tolerance,
polygon);
}
stroker.has_bounds = polygon->num_limits;
if (stroker.has_bounds) {
/* Extend the bounds in each direction to account for the maximum area
* we might generate trapezoids, to capture line segments that are
* outside of the bounds but which might generate rendering that's
* within bounds.
*/
double dx, dy;
cairo_fixed_t fdx, fdy;
int i;
stroker.bounds = polygon->limits[0];
for (i = 1; i < polygon->num_limits; i++)
_cairo_box_add_box (&stroker.bounds, &polygon->limits[i]);
_cairo_stroke_style_max_distance_from_path (style, path, ctm, &dx, &dy);
fdx = _cairo_fixed_from_double (dx);
fdy = _cairo_fixed_from_double (dy);
stroker.bounds.p1.x -= fdx;
stroker.bounds.p2.x += fdx;
stroker.bounds.p1.y -= fdy;
stroker.bounds.p2.y += fdy;
}
stroker.style = *style;
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
* (half-line-width times the cosine of the bisection angle) and the
* half-line-width itself is greater than tolerance then we need to
* inject a point.
*/
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;
stroker.ctm_det_positive =
_cairo_matrix_compute_determinant (ctm) >= 0.0;
stroker.pen.num_vertices = 0;
if (path->has_curve_to ||
style->line_join == CAIRO_LINE_JOIN_ROUND ||
style->line_cap == CAIRO_LINE_CAP_ROUND) {
status = _cairo_pen_init (&stroker.pen,
stroker.half_line_width,
tolerance, ctm);
if (unlikely (status))
return status;
/* If the line width is so small that the pen is reduced to a
single point, then we have nothing to do. */
if (stroker.pen.num_vertices <= 1)
return CAIRO_STATUS_SUCCESS;
}
stroker.has_current_face = FALSE;
stroker.has_first_face = FALSE;
stroker.has_initial_sub_path = FALSE;
#if DEBUG
_cairo_contour_init (&stroker.path, 0);
#endif
_cairo_contour_init (&stroker.cw.contour, 1);
_cairo_contour_init (&stroker.ccw.contour, -1);
tolerance *= CAIRO_FIXED_ONE;
tolerance *= tolerance;
stroker.contour_tolerance = tolerance;
stroker.polygon = polygon;
status = _cairo_path_fixed_interpret (path,
move_to,
line_to,
curve_to,
close_path,
&stroker);
/* Cap the start and end of the final sub path as needed */
if (likely (status == CAIRO_STATUS_SUCCESS))
add_caps (&stroker);
_cairo_contour_fini (&stroker.cw.contour);
_cairo_contour_fini (&stroker.ccw.contour);
if (stroker.pen.num_vertices)
_cairo_pen_fini (&stroker.pen);
#if DEBUG
{
FILE
*file
= fopen ("polygons.txt", "a"); _cairo_debug_print_polygon (file, polygon);
}
#endif
return status;
}