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/* -*- 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 © 2013 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 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
*
* 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>
*/
#include "cairoint.h"
#include "cairo-box-inline.h"
#include "cairo-path-fixed-private.h"
#include "cairo-slope-private.h"
#include "cairo-stroke-dash-private.h"
#include "cairo-traps-private.h"
#include <float.h>
struct stroker {
const cairo_stroke_style_t *style;
const cairo_matrix_t *ctm;
const cairo_matrix_t *ctm_inverse;
double spline_cusp_tolerance;
double half_line_width;
double tolerance;
double ctm_determinant;
cairo_bool_t ctm_det_positive;
cairo_line_join_t line_join;
cairo_traps_t *traps;
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_stroker_dash_t dash;
cairo_bool_t has_bounds;
cairo_box_t tight_bounds;
cairo_box_t line_bounds;
cairo_box_t join_bounds;
};
static cairo_status_t
stroker_init (struct stroker *stroker,
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_traps_t *traps)
{
cairo_status_t status;
stroker->style = style;
stroker->ctm = ctm;
stroker->ctm_inverse = NULL;
if (! _cairo_matrix_is_identity (ctm_inverse))
stroker->ctm_inverse = ctm_inverse;
stroker->line_join = style->line_join;
stroker->half_line_width = style->line_width / 2.0;
stroker->tolerance = tolerance;
stroker->traps = traps;
/* 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, style);
stroker->has_bounds = traps->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;
stroker->tight_bounds = traps->bounds;
_cairo_stroke_style_max_distance_from_path (stroker->style, path,
stroker->ctm, &dx, &dy);
_cairo_stroke_style_max_line_distance_from_path (stroker->style, path,
stroker->ctm, &dx, &dy);
fdx = _cairo_fixed_from_double (dx);
fdy = _cairo_fixed_from_double (dy);
stroker->line_bounds = stroker->tight_bounds;
stroker->line_bounds.p1.x -= fdx;
stroker->line_bounds.p2.x += fdx;
stroker->line_bounds.p1.y -= fdy;
stroker->line_bounds.p2.y += fdy;
_cairo_stroke_style_max_join_distance_from_path (stroker->style, path,
stroker->ctm, &dx, &dy);
fdx = _cairo_fixed_from_double (dx);
fdy = _cairo_fixed_from_double (dy);
stroker->join_bounds = stroker->tight_bounds;
stroker->join_bounds.p1.x -= fdx;
stroker->join_bounds.p2.x += fdx;
stroker->join_bounds.p1.y -= fdy;
stroker->join_bounds.p2.y += fdy;
}
return CAIRO_STATUS_SUCCESS;
}
static void
stroker_fini (struct stroker *stroker)
{
_cairo_pen_fini (&stroker->pen);
}
static void
translate_point (cairo_point_t *point, cairo_point_t *offset)
{
point->x += offset->x;
point->y += offset->y;
}
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 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 cairo_bool_t
stroker_intersects_join (const struct stroker *stroker,
const cairo_point_t *in,
const cairo_point_t *out)
{
cairo_line_t segment;
if (! stroker->has_bounds)
return TRUE;
segment.p1 = *in;
segment.p2 = *out;
return _cairo_box_intersects_line_segment (&stroker->join_bounds, &segment);
}
static void
join (struct stroker *stroker,
cairo_stroke_face_t *in,
cairo_stroke_face_t *out)
{
int clockwise = join_is_clockwise (out, in);
cairo_point_t *inpt, *outpt;
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->ccw;
outpt = &out->ccw;
} else {
inpt = &in->cw;
outpt = &out->cw;
}
if (! stroker_intersects_join (stroker, inpt, outpt))
return;
switch (stroker->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)
{
int start, stop;
cairo_point_t tri[3], edges[4];
cairo_pen_t *pen = &stroker->pen;
edges[0] = in->cw;
edges[1] = in->ccw;
tri[0] = in->point;
tri[1] = *inpt;
if (clockwise) {
_cairo_pen_find_active_ccw_vertices (pen,
&in->dev_vector, &out->dev_vector,
&start, &stop);
while (start != stop) {
tri[2] = in->point;
translate_point (&tri[2], &pen->vertices[start].point);
edges[2] = in->point;
edges[3] = tri[2];
_cairo_traps_tessellate_triangle_with_edges (stroker->traps,
tri, edges);
tri[1] = tri[2];
edges[0] = edges[2];
edges[1] = edges[3];
if (start-- == 0)
start += pen->num_vertices;
}
} else {
_cairo_pen_find_active_cw_vertices (pen,
&in->dev_vector, &out->dev_vector,
&start, &stop);
while (start != stop) {
tri[2] = in->point;
translate_point (&tri[2], &pen->vertices[start].point);
edges[2] = in->point;
edges[3] = tri[2];
_cairo_traps_tessellate_triangle_with_edges (stroker->traps,
tri, edges);
tri[1] = tri[2];
edges[0] = edges[2];
edges[1] = edges[3];
if (++start == pen->num_vertices)
start = 0;
}
}
tri[2] = *outpt;
edges[2] = out->cw;
edges[3] = out->ccw;
_cairo_traps_tessellate_triangle_with_edges (stroker->traps,
tri, edges);
} else {
cairo_point_t t[] = { { in->point.x, in->point.y}, { inpt->x, inpt->y }, { outpt->x, outpt->y } };
cairo_point_t e[] = { { in->cw.x, in->cw.y}, { in->ccw.x, in->ccw.y },
{ out->cw.x, out->cw.y}, { out->ccw.x, out->ccw.y } };
_cairo_traps_tessellate_triangle_with_edges (stroker->traps, t, e);
}
break;
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;
cairo_point_t outer;
cairo_point_t quad[4];
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 (slope_compare_sgn (fdx1, fdy1, mdx, mdy) !=
slope_compare_sgn (fdx2, fdy2, mdx, mdy))
{
/*
* Draw the quadrilateral
*/
outer.x = _cairo_fixed_from_double (mx);
outer.y = _cairo_fixed_from_double (my);
quad[0] = in->point;
quad[1] = *inpt;
quad[2] = outer;
quad[3] = *outpt;
_cairo_traps_tessellate_convex_quad (stroker->traps, quad);
break;
}
}
}
/* fall through ... */
case CAIRO_LINE_JOIN_BEVEL: {
cairo_point_t t[] = { { in->point.x, in->point.y }, { inpt->x, inpt->y }, { outpt->x, outpt->y } };
cairo_point_t e[] = { { in->cw.x, in->cw.y }, { in->ccw.x, in->ccw.y },
{ out->cw.x, out->cw.y }, { out->ccw.x, out->ccw.y } };
_cairo_traps_tessellate_triangle_with_edges (stroker->traps, t, e);
break;
}
}
}
static void
add_cap (struct stroker *stroker, cairo_stroke_face_t *f)
{
switch (stroker->style->line_cap) {
case CAIRO_LINE_CAP_ROUND: {
int start, stop;
cairo_slope_t in_slope, out_slope;
cairo_point_t tri[3], edges[4];
cairo_pen_t *pen = &stroker->pen;
in_slope = f->dev_vector;
out_slope.dx = -in_slope.dx;
out_slope.dy = -in_slope.dy;
_cairo_pen_find_active_cw_vertices (pen, &in_slope, &out_slope,
&start, &stop);
edges[0] = f->cw;
edges[1] = f->ccw;
tri[0] = f->point;
tri[1] = f->cw;
while (start != stop) {
tri[2] = f->point;
translate_point (&tri[2], &pen->vertices[start].point);
edges[2] = f->point;
edges[3] = tri[2];
_cairo_traps_tessellate_triangle_with_edges (stroker->traps,
tri, edges);
tri[1] = tri[2];
edges[0] = edges[2];
edges[1] = edges[3];
if (++start == pen->num_vertices)
start = 0;
}
tri[2] = f->ccw;
edges[2] = f->cw;
edges[3] = f->ccw;
_cairo_traps_tessellate_triangle_with_edges (stroker->traps,
tri, edges);
break;
}
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->cw;
quad[1].x = f->cw.x + fvector.dx;
quad[1].y = f->cw.y + fvector.dy;
quad[2].x = f->ccw.x + fvector.dx;
quad[2].y = f->ccw.y + fvector.dy;
quad[3] = f->ccw;
_cairo_traps_tessellate_convex_quad (stroker->traps, quad);
break;
}
case CAIRO_LINE_CAP_BUTT:
default:
break;
}
}
static void
add_leading_cap (struct stroker *stroker,
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;
add_cap (stroker, &reversed);
}
static void
add_trailing_cap (struct stroker *stroker, cairo_stroke_face_t *face)
{
add_cap (stroker, face);
}
static inline double
normalize_slope (double *dx, double *dy)
{
double dx0 = *dx, dy0 = *dy;
if (dx0 == 0.0 && dy0 == 0.0)
return 0;
if (dx0 == 0.0) {
*dx = 0.0;
if (dy0 > 0.0) {
*dy = 1.0;
return dy0;
} else {
*dy = -1.0;
return -dy0;
}
} else if (dy0 == 0.0) {
*dy = 0.0;
if (dx0 > 0.0) {
*dx = 1.0;
return dx0;
} else {
*dx = -1.0;
return -dx0;
}
} else {
double 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 (stroker->ctm_inverse) {
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
* first_point and current_point should be the same */
compute_face (&stroker->first_point, &slope, stroker, &face);
add_leading_cap (stroker, &face);
add_trailing_cap (stroker, &face);
}
if (stroker->has_first_face)
add_leading_cap (stroker, &stroker->first_face);
if (stroker->has_current_face)
add_trailing_cap (stroker, &stroker->current_face);
}
static cairo_bool_t
stroker_intersects_edge (const struct stroker *stroker,
const cairo_stroke_face_t *start,
const cairo_stroke_face_t *end)
{
cairo_box_t box;
if (! stroker->has_bounds)
return TRUE;
if (_cairo_box_contains_point (&stroker->tight_bounds, &start->cw))
return TRUE;
box.p2 = box.p1 = start->cw;
if (_cairo_box_contains_point (&stroker->tight_bounds, &start->ccw))
return TRUE;
_cairo_box_add_point (&box, &start->ccw);
if (_cairo_box_contains_point (&stroker->tight_bounds, &end->cw))
return TRUE;
_cairo_box_add_point (&box, &end->cw);
if (_cairo_box_contains_point (&stroker->tight_bounds, &end->ccw))
return TRUE;
_cairo_box_add_point (&box, &end->ccw);
return (box.p2.x > stroker->tight_bounds.p1.x &&
box.p1.x < stroker->tight_bounds.p2.x &&
box.p2.y > stroker->tight_bounds.p1.y &&
box.p1.y < stroker->tight_bounds.p2.y);
}
static void
add_sub_edge (struct stroker *stroker,
const cairo_point_t *p1, const cairo_point_t *p2,
const cairo_slope_t *dev_slope,
cairo_stroke_face_t *start, cairo_stroke_face_t *end)
{
cairo_point_t rectangle[4];
compute_face (p1, dev_slope, stroker, start);
*end = *start;
end->point = *p2;
rectangle[0].x = p2->x - p1->x;
rectangle[0].y = p2->y - p1->y;
translate_point (&end->ccw, &rectangle[0]);
translate_point (&end->cw, &rectangle[0]);
if (p1->x == p2->x && p1->y == p2->y)
return;
if (! stroker_intersects_edge (stroker, start, end))
return;
rectangle[0] = start->cw;
rectangle[1] = start->ccw;
rectangle[2] = end->ccw;
rectangle[3] = end->cw;
_cairo_traps_tessellate_convex_quad (stroker->traps, rectangle);
}
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->first_point = *point;
stroker->current_face.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
move_to_dashed (void *closure, const cairo_point_t *point)
{
/* reset the dash pattern for new sub paths */
struct stroker *stroker = closure;
_cairo_stroker_dash_start (&stroker->dash);
return move_to (closure, point);
}
static cairo_status_t
line_to (void *closure, const cairo_point_t *point)
{
struct stroker *stroker = closure;
cairo_stroke_face_t start, end;
const cairo_point_t *p1 = &stroker->current_face.point;
const cairo_point_t *p2 = point;
cairo_slope_t dev_slope;
stroker->has_initial_sub_path = TRUE;
if (p1->x == p2->x && p1->y == p2->y)
return CAIRO_STATUS_SUCCESS;
_cairo_slope_init (&dev_slope, p1, p2);
add_sub_edge (stroker, p1, p2, &dev_slope, &start, &end);
if (stroker->has_current_face) {
/* Join with final face from previous segment */
join (stroker, &stroker->current_face, &start);
} 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;
return CAIRO_STATUS_SUCCESS;
}
/*
* Dashed lines. Cap each dash end, join around turns when on
*/
static cairo_status_t
line_to_dashed (void *closure, const cairo_point_t *point)
{
struct stroker *stroker = closure;
double mag, remain, step_length = 0;
double slope_dx, slope_dy;
double dx2, dy2;
cairo_stroke_face_t sub_start, sub_end;
const cairo_point_t *p1 = &stroker->current_face.point;
const cairo_point_t *p2 = point;
cairo_slope_t dev_slope;
cairo_line_t segment;
cairo_bool_t fully_in_bounds;
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->join_bounds, p1) ||
! _cairo_box_contains_point (&stroker->join_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 (stroker->ctm_inverse)
cairo_matrix_transform_distance (stroker->ctm_inverse, &slope_dx, &slope_dy);
mag = normalize_slope (&slope_dx, &slope_dy);
if (mag <= DBL_EPSILON)
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->join_bounds, &segment)))
{
add_sub_edge (stroker,
&segment.p1, &segment.p2,
&dev_slope,
&sub_start, &sub_end);
if (stroker->has_current_face) {
/* Join with final face from previous segment */
join (stroker, &stroker->current_face, &sub_start);
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 */
add_leading_cap (stroker, &sub_start);
}
if (remain) {
/* Cap dash end if not at end of segment */
add_trailing_cap (stroker, &sub_end);
} else {
stroker->current_face = sub_end;
stroker->has_current_face = TRUE;
}
} else {
if (stroker->has_current_face) {
/* Cap final face from previous segment */
add_trailing_cap (stroker, &stroker->current_face);
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 (point, &dev_slope, stroker, &stroker->current_face);
add_leading_cap (stroker, &stroker->current_face);
stroker->has_current_face = TRUE;
} else
stroker->current_face.point = *point;
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 ((tangent->dx | tangent->dy) == 0) {
cairo_point_t t;
face = stroker->current_face;
face.usr_vector.x = -face.usr_vector.x;
face.usr_vector.y = -face.usr_vector.y;
face.dev_slope.x = -face.dev_slope.x;
face.dev_slope.y = -face.dev_slope.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;
join (stroker, &stroker->current_face, &face);
} else {
cairo_point_t rectangle[4];
compute_face (&stroker->current_face.point, tangent, stroker, &face);
join (stroker, &stroker->current_face, &face);
rectangle[0] = face.cw;
rectangle[1] = face.ccw;
rectangle[2].x = point->x - face.point.x;
rectangle[2].y = point->y - face.point.y;
face.point = *point;
translate_point (&face.ccw, &rectangle[2]);
translate_point (&face.cw, &rectangle[2]);
rectangle[2] = face.ccw;
rectangle[3] = face.cw;
_cairo_traps_tessellate_convex_quad (stroker->traps, rectangle);
}
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_line_join_t line_join_save;
cairo_spline_t spline;
cairo_stroke_face_t face;
cairo_status_t status;
if (stroker->has_bounds &&
! _cairo_spline_intersects (&stroker->current_face.point, b, c, d,
&stroker->line_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) {
/* Join with final face from previous segment */
join (stroker, &stroker->current_face, &face);
} 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;
}
stroker->current_face = face;
/* Temporarily modify the stroker to use round joins to guarantee
* smooth stroked curves. */
line_join_save = stroker->line_join;
stroker->line_join = CAIRO_LINE_JOIN_ROUND;
status = _cairo_spline_decompose (&spline, stroker->tolerance);
stroker->line_join = line_join_save;
return status;
}
static cairo_status_t
curve_to_dashed (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_line_join_t line_join_save;
cairo_spline_add_point_func_t func;
cairo_status_t status;
func = (cairo_spline_add_point_func_t)line_to_dashed;
if (stroker->has_bounds &&
! _cairo_spline_intersects (&stroker->current_face.point, b, c, d,
&stroker->line_bounds))
return func (closure, d, NULL);
if (! _cairo_spline_init (&spline, func, stroker,
&stroker->current_face.point, b, c, d))
return func (closure, d, NULL);
/* Temporarily modify the stroker to use round joins to guarantee
* smooth stroked curves. */
line_join_save = stroker->line_join;
stroker->line_join = CAIRO_LINE_JOIN_ROUND;
status = _cairo_spline_decompose (&spline, stroker->tolerance);
stroker->line_join = line_join_save;
return status;
}
static cairo_status_t
_close_path (struct stroker *stroker)
{
if (stroker->has_first_face && stroker->has_current_face) {
/* Join first and final faces of sub path */
join (stroker, &stroker->current_face, &stroker->first_face);
} 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 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;
return _close_path (stroker);
}
static cairo_status_t
close_path_dashed (void *closure)
{
struct stroker *stroker = closure;
cairo_status_t status;
status = line_to_dashed (stroker, &stroker->first_point);
if (unlikely (status))
return status;
return _close_path (stroker);
}
cairo_int_status_t
_cairo_path_fixed_stroke_to_traps (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_traps_t *traps)
{
struct stroker stroker;
cairo_status_t status;
status = stroker_init (&stroker, path, style,
ctm, ctm_inverse, tolerance,
traps);
if (unlikely (status))
return status;
if (stroker.dash.dashed)
status = _cairo_path_fixed_interpret (path,
move_to_dashed,
line_to_dashed,
curve_to_dashed,
close_path_dashed,
&stroker);
else
status = _cairo_path_fixed_interpret (path,
move_to,
line_to,
curve_to,
close_path,
&stroker);
assert(status == CAIRO_STATUS_SUCCESS);
add_caps (&stroker);
stroker_fini (&stroker);
return traps->status;
}