blob: 4d4ede8136190c0dd06cad89afe6cefa7abcddf6 [file] [log] [blame]
/* -*- 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
*
* 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-error-private.h"
#include "cairo-path-fixed-private.h"
#include "cairo-slope-private.h"
#include "cairo-stroke-dash-private.h"
#include "cairo-traps-private.h"
typedef struct cairo_stroker {
cairo_stroke_style_t style;
const cairo_matrix_t *ctm;
const cairo_matrix_t *ctm_inverse;
double half_line_width;
double tolerance;
double spline_cusp_tolerance;
double ctm_determinant;
cairo_bool_t ctm_det_positive;
void *closure;
cairo_status_t (*add_external_edge) (void *closure,
const cairo_point_t *p1,
const cairo_point_t *p2);
cairo_status_t (*add_triangle) (void *closure,
const cairo_point_t triangle[3]);
cairo_status_t (*add_triangle_fan) (void *closure,
const cairo_point_t *midpt,
const cairo_point_t *points,
int npoints);
cairo_status_t (*add_convex_quad) (void *closure,
const cairo_point_t quad[4]);
cairo_pen_t pen;
cairo_point_t current_point;
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_stroker_dash_t dash;
cairo_bool_t has_bounds;
cairo_box_t bounds;
} cairo_stroker_t;
static void
_cairo_stroker_limit (cairo_stroker_t *stroker,
const cairo_path_fixed_t *path,
const cairo_box_t *boxes,
int num_boxes)
{
double dx, dy;
cairo_fixed_t fdx, fdy;
stroker->has_bounds = TRUE;
_cairo_boxes_get_extents (boxes, num_boxes, &stroker->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.
*/
_cairo_stroke_style_max_distance_from_path (&stroker->style, path,
stroker->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;
}
static cairo_status_t
_cairo_stroker_init (cairo_stroker_t *stroker,
const cairo_path_fixed_t *path,
const cairo_stroke_style_t *stroke_style,
const cairo_matrix_t *ctm,
const cairo_matrix_t *ctm_inverse,
double tolerance,
const cairo_box_t *limits,
int num_limits)
{
cairo_status_t status;
stroker->style = *stroke_style;
stroker->ctm = ctm;
stroker->ctm_inverse = ctm_inverse;
stroker->tolerance = tolerance;
stroker->half_line_width = stroke_style->line_width / 2.0;
/* 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_determinant = _cairo_matrix_compute_determinant (stroker->ctm);
stroker->ctm_det_positive = stroker->ctm_determinant >= 0.0;
status = _cairo_pen_init (&stroker->pen,
stroker->half_line_width, tolerance, ctm);
if (unlikely (status))
return status;
stroker->has_current_face = FALSE;
stroker->has_first_face = FALSE;
stroker->has_initial_sub_path = FALSE;
_cairo_stroker_dash_init (&stroker->dash, stroke_style);
stroker->add_external_edge = NULL;
stroker->has_bounds = FALSE;
if (num_limits)
_cairo_stroker_limit (stroker, path, limits, num_limits);
return CAIRO_STATUS_SUCCESS;
}
static void
_cairo_stroker_fini (cairo_stroker_t *stroker)
{
_cairo_pen_fini (&stroker->pen);
}
static void
_translate_point (cairo_point_t *point, const cairo_point_t *offset)
{
point->x += offset->x;
point->y += offset->y;
}
static int
_cairo_stroker_join_is_clockwise (const cairo_stroke_face_t *in,
const cairo_stroke_face_t *out)
{
cairo_slope_t in_slope, out_slope;
_cairo_slope_init (&in_slope, &in->point, &in->cw);
_cairo_slope_init (&out_slope, &out->point, &out->cw);
return _cairo_slope_compare (&in_slope, &out_slope) < 0;
}
/**
* _cairo_slope_compare_sgn:
*
* Return -1, 0 or 1 depending on the relative slopes of
* two lines.
**/
static int
_cairo_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 cairo_status_t
_tessellate_fan (cairo_stroker_t *stroker,
const cairo_slope_t *in_vector,
const cairo_slope_t *out_vector,
const cairo_point_t *midpt,
const cairo_point_t *inpt,
const cairo_point_t *outpt,
cairo_bool_t clockwise)
{
cairo_point_t stack_points[64], *points = stack_points;
cairo_pen_t *pen = &stroker->pen;
int start, stop, num_points = 0;
cairo_status_t status;
if (stroker->has_bounds &&
! _cairo_box_contains_point (&stroker->bounds, midpt))
goto BEVEL;
assert (stroker->pen.num_vertices);
if (clockwise) {
_cairo_pen_find_active_ccw_vertices (pen,
in_vector, out_vector,
&start, &stop);
if (stroker->add_external_edge) {
cairo_point_t last;
last = *inpt;
while (start != stop) {
cairo_point_t p = *midpt;
_translate_point (&p, &pen->vertices[start].point);
status = stroker->add_external_edge (stroker->closure,
&last, &p);
if (unlikely (status))
return status;
last = p;
if (start-- == 0)
start += pen->num_vertices;
}
status = stroker->add_external_edge (stroker->closure,
&last, outpt);
} else {
if (start == stop)
goto BEVEL;
num_points = stop - start;
if (num_points < 0)
num_points += pen->num_vertices;
num_points += 2;
if (num_points > ARRAY_LENGTH(stack_points)) {
points = _cairo_malloc_ab (num_points, sizeof (cairo_point_t));
if (unlikely (points == NULL))
return _cairo_error (CAIRO_STATUS_NO_MEMORY);
}
points[0] = *inpt;
num_points = 1;
while (start != stop) {
points[num_points] = *midpt;
_translate_point (&points[num_points], &pen->vertices[start].point);
num_points++;
if (start-- == 0)
start += pen->num_vertices;
}
points[num_points++] = *outpt;
}
} else {
_cairo_pen_find_active_cw_vertices (pen,
in_vector, out_vector,
&start, &stop);
if (stroker->add_external_edge) {
cairo_point_t last;
last = *inpt;
while (start != stop) {
cairo_point_t p = *midpt;
_translate_point (&p, &pen->vertices[start].point);
status = stroker->add_external_edge (stroker->closure,
&p, &last);
if (unlikely (status))
return status;
last = p;
if (++start == pen->num_vertices)
start = 0;
}
status = stroker->add_external_edge (stroker->closure,
outpt, &last);
} else {
if (start == stop)
goto BEVEL;
num_points = stop - start;
if (num_points < 0)
num_points += pen->num_vertices;
num_points += 2;
if (num_points > ARRAY_LENGTH(stack_points)) {
points = _cairo_malloc_ab (num_points, sizeof (cairo_point_t));
if (unlikely (points == NULL))
return _cairo_error (CAIRO_STATUS_NO_MEMORY);
}
points[0] = *inpt;
num_points = 1;
while (start != stop) {
points[num_points] = *midpt;
_translate_point (&points[num_points], &pen->vertices[start].point);
num_points++;
if (++start == pen->num_vertices)
start = 0;
}
points[num_points++] = *outpt;
}
}
if (num_points) {
status = stroker->add_triangle_fan (stroker->closure,
midpt, points, num_points);
}
if (points != stack_points)
free (points);
return status;
BEVEL:
/* Ensure a leak free connection... */
if (stroker->add_external_edge != NULL) {
if (clockwise)
return stroker->add_external_edge (stroker->closure, inpt, outpt);
else
return stroker->add_external_edge (stroker->closure, outpt, inpt);
} else {
stack_points[0] = *midpt;
stack_points[1] = *inpt;
stack_points[2] = *outpt;
return stroker->add_triangle (stroker->closure, stack_points);
}
}
static cairo_status_t
_cairo_stroker_join (cairo_stroker_t *stroker,
const cairo_stroke_face_t *in,
const cairo_stroke_face_t *out)
{
int clockwise = _cairo_stroker_join_is_clockwise (out, in);
const cairo_point_t *inpt, *outpt;
cairo_point_t points[4];
cairo_status_t status;
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 CAIRO_STATUS_SUCCESS;
}
if (clockwise) {
if (stroker->add_external_edge != NULL) {
status = stroker->add_external_edge (stroker->closure,
&out->cw, &in->point);
if (unlikely (status))
return status;
status = stroker->add_external_edge (stroker->closure,
&in->point, &in->cw);
if (unlikely (status))
return status;
}
inpt = &in->ccw;
outpt = &out->ccw;
} else {
if (stroker->add_external_edge != NULL) {
status = stroker->add_external_edge (stroker->closure,
&in->ccw, &in->point);
if (unlikely (status))
return status;
status = stroker->add_external_edge (stroker->closure,
&in->point, &out->ccw);
if (unlikely (status))
return status;
}
inpt = &in->cw;
outpt = &out->cw;
}
switch (stroker->style.line_join) {
case CAIRO_LINE_JOIN_ROUND:
/* construct a fan around the common midpoint */
return _tessellate_fan (stroker,
&in->dev_vector,
&out->dev_vector,
&in->point, inpt, outpt,
clockwise);
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 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->usr_vector.x;
dy1 = in->usr_vector.y;
cairo_matrix_transform_distance (stroker->ctm, &dx1, &dy1);
/* 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);
/*
* 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 (_cairo_slope_compare_sgn (fdx1, fdy1, mdx, mdy) !=
_cairo_slope_compare_sgn (fdx2, fdy2, mdx, mdy))
{
if (stroker->add_external_edge != NULL) {
points[0].x = _cairo_fixed_from_double (mx);
points[0].y = _cairo_fixed_from_double (my);
if (clockwise) {
status = stroker->add_external_edge (stroker->closure,
inpt, &points[0]);
if (unlikely (status))
return status;
status = stroker->add_external_edge (stroker->closure,
&points[0], outpt);
if (unlikely (status))
return status;
} else {
status = stroker->add_external_edge (stroker->closure,
outpt, &points[0]);
if (unlikely (status))
return status;
status = stroker->add_external_edge (stroker->closure,
&points[0], inpt);
if (unlikely (status))
return status;
}
return CAIRO_STATUS_SUCCESS;
} else {
points[0] = in->point;
points[1] = *inpt;
points[2].x = _cairo_fixed_from_double (mx);
points[2].y = _cairo_fixed_from_double (my);
points[3] = *outpt;
return stroker->add_convex_quad (stroker->closure, points);
}
}
}
}
/* fall through ... */
case CAIRO_LINE_JOIN_BEVEL:
if (stroker->add_external_edge != NULL) {
if (clockwise) {
return stroker->add_external_edge (stroker->closure,
inpt, outpt);
} else {
return stroker->add_external_edge (stroker->closure,
outpt, inpt);
}
} else {
points[0] = in->point;
points[1] = *inpt;
points[2] = *outpt;
return stroker->add_triangle (stroker->closure, points);
}
}
}
static cairo_status_t
_cairo_stroker_add_cap (cairo_stroker_t *stroker,
const cairo_stroke_face_t *f)
{
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;
return _tessellate_fan (stroker,
&f->dev_vector,
&slope,
&f->point, &f->cw, &f->ccw,
FALSE);
}
case CAIRO_LINE_CAP_SQUARE: {
double dx, dy;
cairo_slope_t fvector;
cairo_point_t quad[4];
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);
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;
if (stroker->add_external_edge != NULL) {
cairo_status_t status;
status = stroker->add_external_edge (stroker->closure,
&quad[0], &quad[1]);
if (unlikely (status))
return status;
status = stroker->add_external_edge (stroker->closure,
&quad[1], &quad[2]);
if (unlikely (status))
return status;
status = stroker->add_external_edge (stroker->closure,
&quad[2], &quad[3]);
if (unlikely (status))
return status;
return CAIRO_STATUS_SUCCESS;
} else {
return stroker->add_convex_quad (stroker->closure, quad);
}
}
case CAIRO_LINE_CAP_BUTT:
default:
if (stroker->add_external_edge != NULL) {
return stroker->add_external_edge (stroker->closure,
&f->ccw, &f->cw);
} else {
return CAIRO_STATUS_SUCCESS;
}
}
}
static cairo_status_t
_cairo_stroker_add_leading_cap (cairo_stroker_t *stroker,
const cairo_stroke_face_t *face)
{
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;
return _cairo_stroker_add_cap (stroker, &reversed);
}
static cairo_status_t
_cairo_stroker_add_trailing_cap (cairo_stroker_t *stroker,
const cairo_stroke_face_t *face)
{
return _cairo_stroker_add_cap (stroker, face);
}
static inline cairo_bool_t
_compute_normalized_device_slope (double *dx, double *dy,
const cairo_matrix_t *ctm_inverse,
double *mag_out)
{
double dx0 = *dx, dy0 = *dy;
double mag;
cairo_matrix_transform_distance (ctm_inverse, &dx0, &dy0);
if (dx0 == 0.0 && dy0 == 0.0) {
if (mag_out)
*mag_out = 0.0;
return FALSE;
}
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;
}
if (mag_out)
*mag_out = mag;
return TRUE;
}
static void
_compute_face (const cairo_point_t *point,
const cairo_slope_t *dev_slope,
double slope_dx,
double slope_dy,
cairo_stroker_t *stroker,
cairo_stroke_face_t *face)
{
double face_dx, face_dy;
cairo_point_t offset_ccw, offset_cw;
/*
* 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 (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);
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 cairo_status_t
_cairo_stroker_add_caps (cairo_stroker_t *stroker)
{
cairo_status_t status;
/* 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 */
double dx = 1.0, dy = 0.0;
cairo_slope_t slope = { CAIRO_FIXED_ONE, 0 };
cairo_stroke_face_t face;
_compute_normalized_device_slope (&dx, &dy,
stroker->ctm_inverse, NULL);
/* arbitrarily choose first_point
* first_point and current_point should be the same */
_compute_face (&stroker->first_point, &slope, dx, dy, stroker, &face);
status = _cairo_stroker_add_leading_cap (stroker, &face);
if (unlikely (status))
return status;
status = _cairo_stroker_add_trailing_cap (stroker, &face);
if (unlikely (status))
return status;
}
if (stroker->has_first_face) {
status = _cairo_stroker_add_leading_cap (stroker,
&stroker->first_face);
if (unlikely (status))
return status;
}
if (stroker->has_current_face) {
status = _cairo_stroker_add_trailing_cap (stroker,
&stroker->current_face);
if (unlikely (status))
return status;
}
return CAIRO_STATUS_SUCCESS;
}
static cairo_status_t
_cairo_stroker_add_sub_edge (cairo_stroker_t *stroker,
const cairo_point_t *p1,
const cairo_point_t *p2,
cairo_slope_t *dev_slope,
double slope_dx, double slope_dy,
cairo_stroke_face_t *start,
cairo_stroke_face_t *end)
{
_compute_face (p1, dev_slope, slope_dx, slope_dy, stroker, start);
*end = *start;
if (p1->x == p2->x && p1->y == p2->y)
return CAIRO_STATUS_SUCCESS;
end->point = *p2;
end->ccw.x += p2->x - p1->x;
end->ccw.y += p2->y - p1->y;
end->cw.x += p2->x - p1->x;
end->cw.y += p2->y - p1->y;
if (stroker->add_external_edge != NULL) {
cairo_status_t status;
status = stroker->add_external_edge (stroker->closure,
&end->cw, &start->cw);
if (unlikely (status))
return status;
status = stroker->add_external_edge (stroker->closure,
&start->ccw, &end->ccw);
if (unlikely (status))
return status;
return CAIRO_STATUS_SUCCESS;
} else {
cairo_point_t quad[4];
quad[0] = start->cw;
quad[1] = end->cw;
quad[2] = end->ccw;
quad[3] = start->ccw;
return stroker->add_convex_quad (stroker->closure, quad);
}
}
static cairo_status_t
_cairo_stroker_move_to (void *closure,
const cairo_point_t *point)
{
cairo_stroker_t *stroker = closure;
cairo_status_t status;
/* reset the dash pattern for new sub paths */
_cairo_stroker_dash_start (&stroker->dash);
/* Cap the start and end of the previous sub path as needed */
status = _cairo_stroker_add_caps (stroker);
if (unlikely (status))
return status;
stroker->first_point = *point;
stroker->current_point = *point;
stroker->has_first_face = FALSE;
stroker->has_current_face = FALSE;
stroker->has_initial_sub_path = FALSE;
return CAIRO_STATUS_SUCCESS;
}
static cairo_status_t
_cairo_stroker_line_to (void *closure,
const cairo_point_t *point)
{
cairo_stroker_t *stroker = closure;
cairo_stroke_face_t start, end;
cairo_point_t *p1 = &stroker->current_point;
cairo_slope_t dev_slope;
double slope_dx, slope_dy;
cairo_status_t status;
stroker->has_initial_sub_path = TRUE;
if (p1->x == point->x && p1->y == point->y)
return CAIRO_STATUS_SUCCESS;
_cairo_slope_init (&dev_slope, p1, point);
slope_dx = _cairo_fixed_to_double (point->x - p1->x);
slope_dy = _cairo_fixed_to_double (point->y - p1->y);
_compute_normalized_device_slope (&slope_dx, &slope_dy,
stroker->ctm_inverse, NULL);
status = _cairo_stroker_add_sub_edge (stroker,
p1, point,
&dev_slope,
slope_dx, slope_dy,
&start, &end);
if (unlikely (status))
return status;
if (stroker->has_current_face) {
/* Join with final face from previous segment */
status = _cairo_stroker_join (stroker,
&stroker->current_face,
&start);
if (unlikely (status))
return status;
} 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->current_face = end;
stroker->has_current_face = TRUE;
stroker->current_point = *point;
return CAIRO_STATUS_SUCCESS;
}
static cairo_status_t
_cairo_stroker_spline_to (void *closure,
const cairo_point_t *point,
const cairo_slope_t *tangent)
{
cairo_stroker_t *stroker = closure;
cairo_stroke_face_t new_face;
double slope_dx, slope_dy;
cairo_point_t points[3];
cairo_point_t intersect_point;
stroker->has_initial_sub_path = TRUE;
if (stroker->current_point.x == point->x &&
stroker->current_point.y == point->y)
return CAIRO_STATUS_SUCCESS;
slope_dx = _cairo_fixed_to_double (tangent->dx);
slope_dy = _cairo_fixed_to_double (tangent->dy);
if (! _compute_normalized_device_slope (&slope_dx, &slope_dy,
stroker->ctm_inverse, NULL))
return CAIRO_STATUS_SUCCESS;
_compute_face (point, tangent,
slope_dx, slope_dy,
stroker, &new_face);
assert (stroker->has_current_face);
if ((new_face.dev_slope.x * stroker->current_face.dev_slope.x +
new_face.dev_slope.y * stroker->current_face.dev_slope.y) < stroker->spline_cusp_tolerance) {
const cairo_point_t *inpt, *outpt;
int clockwise = _cairo_stroker_join_is_clockwise (&new_face,
&stroker->current_face);
if (clockwise) {
inpt = &stroker->current_face.cw;
outpt = &new_face.cw;
} else {
inpt = &stroker->current_face.ccw;
outpt = &new_face.ccw;
}
_tessellate_fan (stroker,
&stroker->current_face.dev_vector,
&new_face.dev_vector,
&stroker->current_face.point,
inpt, outpt,
clockwise);
}
if (_slow_segment_intersection (&stroker->current_face.cw,
&stroker->current_face.ccw,
&new_face.cw,
&new_face.ccw,
&intersect_point)) {
points[0] = stroker->current_face.ccw;
points[1] = new_face.ccw;
points[2] = intersect_point;
stroker->add_triangle (stroker->closure, points);
points[0] = stroker->current_face.cw;
points[1] = new_face.cw;
stroker->add_triangle (stroker->closure, points);
} else {
points[0] = stroker->current_face.ccw;
points[1] = stroker->current_face.cw;
points[2] = new_face.cw;
stroker->add_triangle (stroker->closure, points);
points[0] = stroker->current_face.ccw;
points[1] = new_face.cw;
points[2] = new_face.ccw;
stroker->add_triangle (stroker->closure, points);
}
stroker->current_face = new_face;
stroker->has_current_face = TRUE;
stroker->current_point = *point;
return CAIRO_STATUS_SUCCESS;
}
/*
* Dashed lines. Cap each dash end, join around turns when on
*/
static cairo_status_t
_cairo_stroker_line_to_dashed (void *closure,
const cairo_point_t *p2)
{
cairo_stroker_t *stroker = closure;
double mag, remain, step_length = 0;
double slope_dx, slope_dy;
double dx2, dy2;
cairo_stroke_face_t sub_start, sub_end;
cairo_point_t *p1 = &stroker->current_point;
cairo_slope_t dev_slope;
cairo_line_t segment;
cairo_bool_t fully_in_bounds;
cairo_status_t status;
stroker->has_initial_sub_path = stroker->dash.dash_starts_on;
if (p1->x == p2->x && p1->y == p2->y)
return CAIRO_STATUS_SUCCESS;
fully_in_bounds = TRUE;
if (stroker->has_bounds &&
(! _cairo_box_contains_point (&stroker->bounds, p1) ||
! _cairo_box_contains_point (&stroker->bounds, p2)))
{
fully_in_bounds = FALSE;
}
_cairo_slope_init (&dev_slope, p1, p2);
slope_dx = _cairo_fixed_to_double (p2->x - p1->x);
slope_dy = _cairo_fixed_to_double (p2->y - p1->y);
if (! _compute_normalized_device_slope (&slope_dx, &slope_dy,
stroker->ctm_inverse, &mag))
{
return CAIRO_STATUS_SUCCESS;
}
remain = mag;
segment.p1 = *p1;
while (remain) {
step_length = MIN (stroker->dash.dash_remain, remain);
remain -= step_length;
dx2 = slope_dx * (mag - remain);
dy2 = slope_dy * (mag - remain);
cairo_matrix_transform_distance (stroker->ctm, &dx2, &dy2);
segment.p2.x = _cairo_fixed_from_double (dx2) + p1->x;
segment.p2.y = _cairo_fixed_from_double (dy2) + p1->y;
if (stroker->dash.dash_on &&
(fully_in_bounds ||
(! stroker->has_first_face && stroker->dash.dash_starts_on) ||
_cairo_box_intersects_line_segment (&stroker->bounds, &segment)))
{
status = _cairo_stroker_add_sub_edge (stroker,
&segment.p1, &segment.p2,
&dev_slope,
slope_dx, slope_dy,
&sub_start, &sub_end);
if (unlikely (status))
return status;
if (stroker->has_current_face)
{
/* Join with final face from previous segment */
status = _cairo_stroker_join (stroker,
&stroker->current_face,
&sub_start);
if (unlikely (status))
return status;
stroker->has_current_face = FALSE;
}
else if (! stroker->has_first_face &&
stroker->dash.dash_starts_on)
{
/* Save sub path's first face in case needed for closing join */
stroker->first_face = sub_start;
stroker->has_first_face = TRUE;
}
else
{
/* Cap dash start if not connecting to a previous segment */
status = _cairo_stroker_add_leading_cap (stroker, &sub_start);
if (unlikely (status))
return status;
}
if (remain) {
/* Cap dash end if not at end of segment */
status = _cairo_stroker_add_trailing_cap (stroker, &sub_end);
if (unlikely (status))
return status;
} else {
stroker->current_face = sub_end;
stroker->has_current_face = TRUE;
}
} else {
if (stroker->has_current_face) {
/* Cap final face from previous segment */
status = _cairo_stroker_add_trailing_cap (stroker,
&stroker->current_face);
if (unlikely (status))
return status;
stroker->has_current_face = FALSE;
}
}
_cairo_stroker_dash_step (&stroker->dash, step_length);
segment.p1 = segment.p2;
}
if (stroker->dash.dash_on && ! stroker->has_current_face) {
/* This segment ends on a transition to dash_on, compute a new face
* and add cap for the beginning of the next dash_on step.
*
* Note: this will create a degenerate cap if this is not the last line
* in the path. Whether this behaviour is desirable or not is debatable.
* On one side these degenerate caps can not be reproduced with regular
* path stroking.
* On the other hand, Acroread 7 also produces the degenerate caps.
*/
_compute_face (p2, &dev_slope,
slope_dx, slope_dy,
stroker,
&stroker->current_face);
status = _cairo_stroker_add_leading_cap (stroker,
&stroker->current_face);
if (unlikely (status))
return status;
stroker->has_current_face = TRUE;
}
stroker->current_point = *p2;
return CAIRO_STATUS_SUCCESS;
}
static cairo_status_t
_cairo_stroker_curve_to (void *closure,
const cairo_point_t *b,
const cairo_point_t *c,
const cairo_point_t *d)
{
cairo_stroker_t *stroker = closure;
cairo_spline_t spline;
cairo_line_join_t line_join_save;
cairo_stroke_face_t face;
double slope_dx, slope_dy;
cairo_spline_add_point_func_t line_to;
cairo_spline_add_point_func_t spline_to;
cairo_status_t status = CAIRO_STATUS_SUCCESS;
line_to = stroker->dash.dashed ?
(cairo_spline_add_point_func_t) _cairo_stroker_line_to_dashed :
(cairo_spline_add_point_func_t) _cairo_stroker_line_to;
/* spline_to is only capable of rendering non-degenerate splines. */
spline_to = stroker->dash.dashed ?
(cairo_spline_add_point_func_t) _cairo_stroker_line_to_dashed :
(cairo_spline_add_point_func_t) _cairo_stroker_spline_to;
if (! _cairo_spline_init (&spline,
spline_to,
stroker,
&stroker->current_point, b, c, d))
{
cairo_slope_t fallback_slope;
_cairo_slope_init (&fallback_slope, &stroker->current_point, d);
return line_to (closure, d, &fallback_slope);
}
/* 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;
/* Compute the initial face */
if (! stroker->dash.dashed || stroker->dash.dash_on) {
slope_dx = _cairo_fixed_to_double (spline.initial_slope.dx);
slope_dy = _cairo_fixed_to_double (spline.initial_slope.dy);
if (_compute_normalized_device_slope (&slope_dx, &slope_dy,
stroker->ctm_inverse, NULL))
{
_compute_face (&stroker->current_point,
&spline.initial_slope,
slope_dx, slope_dy,
stroker, &face);
}
if (stroker->has_current_face) {
status = _cairo_stroker_join (stroker,
&stroker->current_face, &face);
if (unlikely (status))
return status;
} else if (! stroker->has_first_face) {
stroker->first_face = face;
stroker->has_first_face = TRUE;
}
stroker->current_face = face;
stroker->has_current_face = TRUE;
}
/* Temporarily modify the stroker to use round joins to guarantee
* smooth stroked curves. */
line_join_save = stroker->style.line_join;
stroker->style.line_join = CAIRO_LINE_JOIN_ROUND;
status = _cairo_spline_decompose (&spline, stroker->tolerance);
if (unlikely (status))
return status;
/* And join the final face */
if (! stroker->dash.dashed || stroker->dash.dash_on) {
slope_dx = _cairo_fixed_to_double (spline.final_slope.dx);
slope_dy = _cairo_fixed_to_double (spline.final_slope.dy);
if (_compute_normalized_device_slope (&slope_dx, &slope_dy,
stroker->ctm_inverse, NULL))
{
_compute_face (&stroker->current_point,
&spline.final_slope,
slope_dx, slope_dy,
stroker, &face);
}
status = _cairo_stroker_join (stroker, &stroker->current_face, &face);
if (unlikely (status))
return status;
stroker->current_face = face;
}
stroker->style.line_join = line_join_save;
return CAIRO_STATUS_SUCCESS;
}
static cairo_status_t
_cairo_stroker_close_path (void *closure)
{
cairo_stroker_t *stroker = closure;
cairo_status_t status;
if (stroker->dash.dashed)
status = _cairo_stroker_line_to_dashed (stroker, &stroker->first_point);
else
status = _cairo_stroker_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 */
status = _cairo_stroker_join (stroker,
&stroker->current_face,
&stroker->first_face);
if (unlikely (status))
return status;
} else {
/* Cap the start and end of the sub path as needed */
status = _cairo_stroker_add_caps (stroker);
if (unlikely (status))
return status;
}
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_shaper (cairo_path_fixed_t *path,
const cairo_stroke_style_t *stroke_style,
const cairo_matrix_t *ctm,
const cairo_matrix_t *ctm_inverse,
double tolerance,
cairo_status_t (*add_triangle) (void *closure,
const cairo_point_t triangle[3]),
cairo_status_t (*add_triangle_fan) (void *closure,
const cairo_point_t *midpt,
const cairo_point_t *points,
int npoints),
cairo_status_t (*add_convex_quad) (void *closure,
const cairo_point_t quad[4]),
void *closure)
{
cairo_stroker_t stroker;
cairo_status_t status;
status = _cairo_stroker_init (&stroker, path, stroke_style,
ctm, ctm_inverse, tolerance,
NULL, 0);
if (unlikely (status))
return status;
stroker.add_triangle = add_triangle;
stroker.add_triangle_fan = add_triangle_fan;
stroker.add_convex_quad = add_convex_quad;
stroker.closure = closure;
status = _cairo_path_fixed_interpret (path,
_cairo_stroker_move_to,
stroker.dash.dashed ?
_cairo_stroker_line_to_dashed :
_cairo_stroker_line_to,
_cairo_stroker_curve_to,
_cairo_stroker_close_path,
&stroker);
if (unlikely (status))
goto BAIL;
/* Cap the start and end of the final sub path as needed */
status = _cairo_stroker_add_caps (&stroker);
BAIL:
_cairo_stroker_fini (&stroker);
return status;
}
cairo_status_t
_cairo_path_fixed_stroke_dashed_to_polygon (const cairo_path_fixed_t *path,
const cairo_stroke_style_t *stroke_style,
const cairo_matrix_t *ctm,
const cairo_matrix_t *ctm_inverse,
double tolerance,
cairo_polygon_t *polygon)
{
cairo_stroker_t stroker;
cairo_status_t status;
status = _cairo_stroker_init (&stroker, path, stroke_style,
ctm, ctm_inverse, tolerance,
polygon->limits, polygon->num_limits);
if (unlikely (status))
return status;
stroker.add_external_edge = _cairo_polygon_add_external_edge,
stroker.closure = polygon;
status = _cairo_path_fixed_interpret (path,
_cairo_stroker_move_to,
stroker.dash.dashed ?
_cairo_stroker_line_to_dashed :
_cairo_stroker_line_to,
_cairo_stroker_curve_to,
_cairo_stroker_close_path,
&stroker);
if (unlikely (status))
goto BAIL;
/* Cap the start and end of the final sub path as needed */
status = _cairo_stroker_add_caps (&stroker);
BAIL:
_cairo_stroker_fini (&stroker);
return status;
}
cairo_int_status_t
_cairo_path_fixed_stroke_polygon_to_traps (const cairo_path_fixed_t *path,
const cairo_stroke_style_t *stroke_style,
const cairo_matrix_t *ctm,
const cairo_matrix_t *ctm_inverse,
double tolerance,
cairo_traps_t *traps)
{
cairo_int_status_t status;
cairo_polygon_t polygon;
_cairo_polygon_init (&polygon, traps->limits, traps->num_limits);
status = _cairo_path_fixed_stroke_to_polygon (path,
stroke_style,
ctm,
ctm_inverse,
tolerance,
&polygon);
if (unlikely (status))
goto BAIL;
status = _cairo_polygon_status (&polygon);
if (unlikely (status))
goto BAIL;
status = _cairo_bentley_ottmann_tessellate_polygon (traps, &polygon,
CAIRO_FILL_RULE_WINDING);
BAIL:
_cairo_polygon_fini (&polygon);
return status;
}