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/*
* Copyright © 2004 Carl Worth
* Copyright © 2006 Red Hat, Inc.
* Copyright © 2007 David Turner
* Copyright © 2008 M Joonas Pihlaja
* Copyright © 2008 Chris Wilson
* Copyright © 2009 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 Carl Worth
* Contributor(s):
* Carl D. Worth <cworth@cworth.org>
* M Joonas Pihlaja <jpihlaja@cc.helsinki.fi>
* Chris Wilson <chris@chris-wilson.co.uk>
*/
/* Provide definitions for standalone compilation */
#include "cairoint.h"
#include "cairo-error-private.h"
#include "cairo-list-inline.h"
#include "cairo-freelist-private.h"
#include "cairo-combsort-inline.h"
#include <setjmp.h>
#define STEP_X CAIRO_FIXED_ONE
#define STEP_Y CAIRO_FIXED_ONE
#define UNROLL3(x) x x x
#define STEP_XY (2*STEP_X*STEP_Y) /* Unit area in the step. */
#define AREA_TO_ALPHA(c) (((c)*255 + STEP_XY/2) / STEP_XY)
typedef struct _cairo_bo_intersect_ordinate {
int32_t ordinate;
enum { EXACT, INEXACT } exactness;
} cairo_bo_intersect_ordinate_t;
typedef struct _cairo_bo_intersect_point {
cairo_bo_intersect_ordinate_t x;
cairo_bo_intersect_ordinate_t y;
} cairo_bo_intersect_point_t;
struct quorem {
cairo_fixed_t quo;
cairo_fixed_t rem;
};
struct run {
struct run *next;
int sign;
cairo_fixed_t y;
typedef struct edge {
cairo_list_t link;
cairo_edge_t edge;
/* Current x coordinate and advancement.
* Initialised to the x coordinate of the top of the
* edge. The quotient is in cairo_fixed_t units and the
* remainder is mod dy in cairo_fixed_t units.
cairo_fixed_t dy;
struct quorem x;
struct quorem dxdy;
struct quorem dxdy_full;
cairo_bool_t vertical;
unsigned int flags;
int current_sign;
struct run *runs;
} edge_t;
enum {
START = 0x1,
STOP = 0x2,
/* the parent is always given by index/2 */
#define PQ_PARENT_INDEX(i) ((i) >> 1)
#define PQ_FIRST_ENTRY 1
/* left and right children are index * 2 and (index * 2) +1 respectively */
#define PQ_LEFT_CHILD_INDEX(i) ((i) << 1)
typedef enum {
EVENT_TYPE_STOP,
EVENT_TYPE_INTERSECTION,
EVENT_TYPE_START
} event_type_t;
typedef struct _event {
event_type_t type;
} event_t;
typedef struct _start_event {
edge_t *edge;
} start_event_t;
typedef struct _queue_event {
edge_t *e1;
edge_t *e2;
} queue_event_t;
typedef struct _pqueue {
int size, max_size;
event_t **elements;
event_t *elements_embedded[1024];
} pqueue_t;
struct cell {
struct cell *prev;
struct cell *next;
int x;
int uncovered_area;
int covered_height;
typedef struct _sweep_line {
cairo_list_t active;
cairo_list_t stopped;
cairo_list_t *insert_cursor;
cairo_bool_t is_vertical;
cairo_fixed_t current_row;
cairo_fixed_t current_subrow;
struct coverage {
struct cell head;
struct cell tail;
struct cell *cursor;
int count;
cairo_freepool_t pool;
} coverage;
struct event_queue {
pqueue_t pq;
event_t **start_events;
} queue;
cairo_freepool_t runs;
jmp_buf unwind;
} sweep_line_t;
cairo_always_inline static struct quorem
floored_divrem (int a, int b)
{
struct quorem qr;
qr.quo = a/b;
qr.rem = a%b;
if ((a^b)<0 && qr.rem) {
qr.quo--;
qr.rem += b;
}
return qr;
static struct quorem
floored_muldivrem(int x, int a, int b)
long long xa = (long long)x*a;
qr.quo = xa/b;
qr.rem = xa%b;
if ((xa>=0) != (b>=0) && qr.rem) {
static cairo_fixed_t
line_compute_intersection_x_for_y (const cairo_line_t *line,
cairo_fixed_t y)
cairo_fixed_t x, dy;
if (y == line->p1.y)
return line->p1.x;
if (y == line->p2.y)
return line->p2.x;
x = line->p1.x;
dy = line->p2.y - line->p1.y;
if (dy != 0) {
x += _cairo_fixed_mul_div_floor (y - line->p1.y,
line->p2.x - line->p1.x,
dy);
return x;
* We need to compare the x-coordinates of a pair of lines for a particular y,
* without loss of precision.
* The x-coordinate along an edge for a given y is:
* X = A_x + (Y - A_y) * A_dx / A_dy
* So the inequality we wish to test is:
* A_x + (Y - A_y) * A_dx / A_dy ∘ B_x + (Y - B_y) * B_dx / B_dy,
* where ∘ is our inequality operator.
* By construction, we know that A_dy and B_dy (and (Y - A_y), (Y - B_y)) are
* all positive, so we can rearrange it thus without causing a sign change:
* A_dy * B_dy * (A_x - B_x) ∘ (Y - B_y) * B_dx * A_dy
* - (Y - A_y) * A_dx * B_dy
* Given the assumption that all the deltas fit within 32 bits, we can compute
* this comparison directly using 128 bit arithmetic. For certain, but common,
* input we can reduce this down to a single 32 bit compare by inspecting the
* deltas.
* (And put the burden of the work on developing fast 128 bit ops, which are
* required throughout the tessellator.)
* See the similar discussion for _slope_compare().
static int
edges_compare_x_for_y_general (const cairo_edge_t *a,
const cairo_edge_t *b,
int32_t y)
/* XXX: We're assuming here that dx and dy will still fit in 32
* bits. That's not true in general as there could be overflow. We
* should prevent that before the tessellation algorithm
* begins.
int32_t dx;
int32_t adx, ady;
int32_t bdx, bdy;
HAVE_NONE = 0x0,
HAVE_DX = 0x1,
HAVE_ADX = 0x2,
HAVE_DX_ADX = HAVE_DX | HAVE_ADX,
HAVE_BDX = 0x4,
HAVE_DX_BDX = HAVE_DX | HAVE_BDX,
HAVE_ADX_BDX = HAVE_ADX | HAVE_BDX,
HAVE_ALL = HAVE_DX | HAVE_ADX | HAVE_BDX
} have_dx_adx_bdx = HAVE_ALL;
/* don't bother solving for abscissa if the edges' bounding boxes
* can be used to order them. */
int32_t amin, amax;
int32_t bmin, bmax;
if (a->line.p1.x < a->line.p2.x) {
amin = a->line.p1.x;
amax = a->line.p2.x;
} else {
amin = a->line.p2.x;
amax = a->line.p1.x;
if (b->line.p1.x < b->line.p2.x) {
bmin = b->line.p1.x;
bmax = b->line.p2.x;
bmin = b->line.p2.x;
bmax = b->line.p1.x;
if (amax < bmin) return -1;
if (amin > bmax) return +1;
ady = a->line.p2.y - a->line.p1.y;
adx = a->line.p2.x - a->line.p1.x;
if (adx == 0)
have_dx_adx_bdx &= ~HAVE_ADX;
bdy = b->line.p2.y - b->line.p1.y;
bdx = b->line.p2.x - b->line.p1.x;
if (bdx == 0)
have_dx_adx_bdx &= ~HAVE_BDX;
dx = a->line.p1.x - b->line.p1.x;
if (dx == 0)
have_dx_adx_bdx &= ~HAVE_DX;
#define L _cairo_int64x32_128_mul (_cairo_int32x32_64_mul (ady, bdy), dx)
#define A _cairo_int64x32_128_mul (_cairo_int32x32_64_mul (adx, bdy), y - a->line.p1.y)
#define B _cairo_int64x32_128_mul (_cairo_int32x32_64_mul (bdx, ady), y - b->line.p1.y)
switch (have_dx_adx_bdx) {
default:
case HAVE_NONE:
return 0;
case HAVE_DX:
/* A_dy * B_dy * (A_x - B_x) ∘ 0 */
return dx; /* ady * bdy is positive definite */
case HAVE_ADX:
/* 0 ∘ - (Y - A_y) * A_dx * B_dy */
return adx; /* bdy * (y - a->top.y) is positive definite */
case HAVE_BDX:
/* 0 ∘ (Y - B_y) * B_dx * A_dy */
return -bdx; /* ady * (y - b->top.y) is positive definite */
case HAVE_ADX_BDX:
/* 0 ∘ (Y - B_y) * B_dx * A_dy - (Y - A_y) * A_dx * B_dy */
if ((adx ^ bdx) < 0) {
return adx;
} else if (a->line.p1.y == b->line.p1.y) { /* common origin */
cairo_int64_t adx_bdy, bdx_ady;
/* ∴ A_dx * B_dy ∘ B_dx * A_dy */
adx_bdy = _cairo_int32x32_64_mul (adx, bdy);
bdx_ady = _cairo_int32x32_64_mul (bdx, ady);
return _cairo_int64_cmp (adx_bdy, bdx_ady);
} else
return _cairo_int128_cmp (A, B);
case HAVE_DX_ADX:
/* A_dy * (A_x - B_x) ∘ - (Y - A_y) * A_dx */
if ((-adx ^ dx) < 0) {
return dx;
cairo_int64_t ady_dx, dy_adx;
ady_dx = _cairo_int32x32_64_mul (ady, dx);
dy_adx = _cairo_int32x32_64_mul (a->line.p1.y - y, adx);
return _cairo_int64_cmp (ady_dx, dy_adx);
case HAVE_DX_BDX:
/* B_dy * (A_x - B_x) ∘ (Y - B_y) * B_dx */
if ((bdx ^ dx) < 0) {
cairo_int64_t bdy_dx, dy_bdx;
bdy_dx = _cairo_int32x32_64_mul (bdy, dx);
dy_bdx = _cairo_int32x32_64_mul (y - b->line.p1.y, bdx);
return _cairo_int64_cmp (bdy_dx, dy_bdx);
case HAVE_ALL:
/* XXX try comparing (a->line.p2.x - b->line.p2.x) et al */
return _cairo_int128_cmp (L, _cairo_int128_sub (B, A));
#undef B
#undef A
#undef L
* We need to compare the x-coordinate of a line for a particular y wrt to a
* given x, without loss of precision.
* A_x + (Y - A_y) * A_dx / A_dy ∘ X
* By construction, we know that A_dy (and (Y - A_y)) are
* (Y - A_y) * A_dx ∘ (X - A_x) * A_dy
* this comparison directly using 64 bit arithmetic.
* See the similar discussion for _slope_compare() and
* edges_compare_x_for_y_general().
edge_compare_for_y_against_x (const cairo_edge_t *a,
int32_t y,
int32_t x)
int32_t dx, dy;
cairo_int64_t L, R;
if (a->line.p1.x <= a->line.p2.x) {
if (x < a->line.p1.x)
return 1;
if (x > a->line.p2.x)
return -1;
if (x < a->line.p2.x)
if (x > a->line.p1.x)
dx = x - a->line.p1.x;
return -dx;
if (dx == 0 || (adx ^ dx) < 0)
dy = y - a->line.p1.y;
L = _cairo_int32x32_64_mul (dy, adx);
R = _cairo_int32x32_64_mul (dx, ady);
return _cairo_int64_cmp (L, R);
edges_compare_x_for_y (const cairo_edge_t *a,
/* If the sweep-line is currently on an end-point of a line,
* then we know its precise x value (and considering that we often need to
* compare events at end-points, this happens frequently enough to warrant
* special casing).
HAVE_NEITHER = 0x0,
HAVE_AX = 0x1,
HAVE_BX = 0x2,
HAVE_BOTH = HAVE_AX | HAVE_BX
} have_ax_bx = HAVE_BOTH;
int32_t ax = 0, bx = 0;
/* XXX given we have x and dx? */
if (y == a->line.p1.y)
ax = a->line.p1.x;
else if (y == a->line.p2.y)
ax = a->line.p2.x;
else
have_ax_bx &= ~HAVE_AX;
if (y == b->line.p1.y)
bx = b->line.p1.x;
else if (y == b->line.p2.y)
bx = b->line.p2.x;
have_ax_bx &= ~HAVE_BX;
switch (have_ax_bx) {
case HAVE_NEITHER:
return edges_compare_x_for_y_general (a, b, y);
case HAVE_AX:
return -edge_compare_for_y_against_x (b, y, ax);
case HAVE_BX:
return edge_compare_for_y_against_x (a, y, bx);
case HAVE_BOTH:
return ax - bx;
static inline int
slope_compare (const edge_t *a,
const edge_t *b)
int cmp;
cmp = a->dxdy.quo - b->dxdy.quo;
if (cmp)
return cmp;
if (a->dxdy.rem == 0)
return -b->dxdy.rem;
if (b->dxdy.rem == 0)
return a->dxdy.rem;
L = _cairo_int32x32_64_mul (b->dy, a->dxdy.rem);
R = _cairo_int32x32_64_mul (a->dy, b->dxdy.rem);
line_equal (const cairo_line_t *a, const cairo_line_t *b)
return a->p1.x == b->p1.x && a->p1.y == b->p1.y &&
a->p2.x == b->p2.x && a->p2.y == b->p2.y;
sweep_line_compare_edges (const edge_t *a,
const edge_t *b,
if (line_equal (&a->edge.line, &b->edge.line))
cmp = edges_compare_x_for_y (&a->edge, &b->edge, y);
return slope_compare (a, b);
static inline cairo_int64_t
det32_64 (int32_t a, int32_t b,
int32_t c, int32_t d)
/* det = a * d - b * c */
return _cairo_int64_sub (_cairo_int32x32_64_mul (a, d),
_cairo_int32x32_64_mul (b, c));
static inline cairo_int128_t
det64x32_128 (cairo_int64_t a, int32_t b,
cairo_int64_t c, int32_t d)
return _cairo_int128_sub (_cairo_int64x32_128_mul (a, d),
_cairo_int64x32_128_mul (c, b));
/* Compute the intersection of two lines as defined by two edges. The
* result is provided as a coordinate pair of 128-bit integers.
* Returns %CAIRO_BO_STATUS_INTERSECTION if there is an intersection or
* %CAIRO_BO_STATUS_PARALLEL if the two lines are exactly parallel.
static cairo_bool_t
intersect_lines (const edge_t *a, const edge_t *b,
cairo_bo_intersect_point_t *intersection)
cairo_int64_t a_det, b_det;
* should prevent that before the tessellation algorithm begins.
* What we're doing to mitigate this is to perform clamping in
* cairo_bo_tessellate_polygon().
int32_t dx1 = a->edge.line.p1.x - a->edge.line.p2.x;
int32_t dy1 = a->edge.line.p1.y - a->edge.line.p2.y;
int32_t dx2 = b->edge.line.p1.x - b->edge.line.p2.x;
int32_t dy2 = b->edge.line.p1.y - b->edge.line.p2.y;
cairo_int64_t den_det;
cairo_int64_t R;
cairo_quorem64_t qr;
den_det = det32_64 (dx1, dy1, dx2, dy2);
/* Q: Can we determine that the lines do not intersect (within range)
* much more cheaply than computing the intersection point i.e. by
* avoiding the division?
* X = ax + t * adx = bx + s * bdx;
* Y = ay + t * ady = by + s * bdy;
* ∴ t * (ady*bdx - bdy*adx) = bdx * (by - ay) + bdy * (ax - bx)
* => t * L = R
* Therefore we can reject any intersection (under the criteria for
* valid intersection events) if:
* L^R < 0 => t < 0, or
* L<R => t > 1
* (where top/bottom must at least extend to the line endpoints).
* A similar substitution can be performed for s, yielding:
* s * (ady*bdx - bdy*adx) = ady * (ax - bx) - adx * (ay - by)
R = det32_64 (dx2, dy2,
b->edge.line.p1.x - a->edge.line.p1.x,
b->edge.line.p1.y - a->edge.line.p1.y);
if (_cairo_int64_negative (den_det)) {
if (_cairo_int64_ge (den_det, R))
return FALSE;
if (_cairo_int64_le (den_det, R))
R = det32_64 (dy1, dx1,
a->edge.line.p1.y - b->edge.line.p1.y,
a->edge.line.p1.x - b->edge.line.p1.x);
/* We now know that the two lines should intersect within range. */
a_det = det32_64 (a->edge.line.p1.x, a->edge.line.p1.y,
a->edge.line.p2.x, a->edge.line.p2.y);
b_det = det32_64 (b->edge.line.p1.x, b->edge.line.p1.y,
b->edge.line.p2.x, b->edge.line.p2.y);
/* x = det (a_det, dx1, b_det, dx2) / den_det */
qr = _cairo_int_96by64_32x64_divrem (det64x32_128 (a_det, dx1,
b_det, dx2),
den_det);
if (_cairo_int64_eq (qr.rem, den_det))
#if 0
intersection->x.exactness = _cairo_int64_is_zero (qr.rem) ? EXACT : INEXACT;
#else
intersection->x.exactness = EXACT;
if (! _cairo_int64_is_zero (qr.rem)) {
if (_cairo_int64_negative (den_det) ^ _cairo_int64_negative (qr.rem))
qr.rem = _cairo_int64_negate (qr.rem);
qr.rem = _cairo_int64_mul (qr.rem, _cairo_int32_to_int64 (2));
if (_cairo_int64_ge (qr.rem, den_det)) {
qr.quo = _cairo_int64_add (qr.quo,
_cairo_int32_to_int64 (_cairo_int64_negative (qr.quo) ? -1 : 1));
intersection->x.exactness = INEXACT;
#endif
intersection->x.ordinate = _cairo_int64_to_int32 (qr.quo);
/* y = det (a_det, dy1, b_det, dy2) / den_det */
qr = _cairo_int_96by64_32x64_divrem (det64x32_128 (a_det, dy1,
b_det, dy2),
intersection->y.exactness = _cairo_int64_is_zero (qr.rem) ? EXACT : INEXACT;
intersection->y.exactness = EXACT;
/* compute ceiling away from zero */
intersection->y.exactness = INEXACT;
intersection->y.ordinate = _cairo_int64_to_int32 (qr.quo);
return TRUE;
bo_intersect_ordinate_32_compare (int32_t a, int32_t b, int exactness)
/* First compare the quotient */
cmp = a - b;
/* With quotient identical, if remainder is 0 then compare equal */
/* Otherwise, the non-zero remainder makes a > b */
return -(INEXACT == exactness);
/* Does the given edge contain the given point. The point must already
* be known to be contained within the line determined by the edge,
* (most likely the point results from an intersection of this edge
* with another).
* If we had exact arithmetic, then this function would simply be a
* matter of examining whether the y value of the point lies within
* the range of y values of the edge. But since intersection points
* are not exact due to being rounded to the nearest integer within
* the available precision, we must also examine the x value of the
* point.
* The definition of "contains" here is that the given intersection
* point will be seen by the sweep line after the start event for the
* given edge and before the stop event for the edge. See the comments
* in the implementation for more details.
bo_edge_contains_intersect_point (const edge_t *edge,
cairo_bo_intersect_point_t *point)
int cmp_top, cmp_bottom;
/* XXX: When running the actual algorithm, we don't actually need to
* compare against edge->top at all here, since any intersection above
* top is eliminated early via a slope comparison. We're leaving these
* here for now only for the sake of the quadratic-time intersection
* finder which needs them.
cmp_top = bo_intersect_ordinate_32_compare (point->y.ordinate,
edge->edge.top,
point->y.exactness);
if (cmp_top < 0)
cmp_bottom = bo_intersect_ordinate_32_compare (point->y.ordinate,
edge->edge.bottom,
if (cmp_bottom > 0)
if (cmp_top > 0 && cmp_bottom < 0)
/* At this stage, the point lies on the same y value as either
* edge->top or edge->bottom, so we have to examine the x value in
* order to properly determine containment. */
/* If the y value of the point is the same as the y value of the
* top of the edge, then the x value of the point must be greater
* to be considered as inside the edge. Similarly, if the y value
* of the point is the same as the y value of the bottom of the
* edge, then the x value of the point must be less to be
* considered as inside. */
if (cmp_top == 0) {
cairo_fixed_t top_x;
top_x = line_compute_intersection_x_for_y (&edge->edge.line,
edge->edge.top);
return bo_intersect_ordinate_32_compare (top_x, point->x.ordinate, point->x.exactness) < 0;
} else { /* cmp_bottom == 0 */
cairo_fixed_t bot_x;
bot_x = line_compute_intersection_x_for_y (&edge->edge.line,
edge->edge.bottom);
return bo_intersect_ordinate_32_compare (point->x.ordinate, bot_x, point->x.exactness) < 0;
edge_intersect (const edge_t *a,
cairo_point_t *intersection)
cairo_bo_intersect_point_t quorem;
if (! intersect_lines (a, b, &quorem))
if (a->edge.top != a->edge.line.p1.y || a->edge.bottom != a->edge.line.p2.y) {
if (! bo_edge_contains_intersect_point (a, &quorem))
if (b->edge.top != b->edge.line.p1.y || b->edge.bottom != b->edge.line.p2.y) {
if (! bo_edge_contains_intersect_point (b, &quorem))
/* Now that we've correctly compared the intersection point and
* determined that it lies within the edge, then we know that we
* no longer need any more bits of storage for the intersection
* than we do for our edge coordinates. We also no longer need the
* remainder from the division. */
intersection->x = quorem.x.ordinate;
intersection->y = quorem.y.ordinate;
event_compare (const event_t *a, const event_t *b)
return a->y - b->y;
static void
pqueue_init (pqueue_t *pq)
pq->max_size = ARRAY_LENGTH (pq->elements_embedded);
pq->size = 0;
pq->elements = pq->elements_embedded;
pqueue_fini (pqueue_t *pq)
if (pq->elements != pq->elements_embedded)
free (pq->elements);
pqueue_grow (pqueue_t *pq)
event_t **new_elements;
pq->max_size *= 2;
if (pq->elements == pq->elements_embedded) {
new_elements = _cairo_malloc_ab (pq->max_size,
sizeof (event_t *));
if (unlikely (new_elements == NULL))
memcpy (new_elements, pq->elements_embedded,
sizeof (pq->elements_embedded));
new_elements = _cairo_realloc_ab (pq->elements,
pq->max_size,
pq->elements = new_elements;
static inline void
pqueue_push (sweep_line_t *sweep_line, event_t *event)
int i, parent;
if (unlikely (sweep_line->queue.pq.size + 1 == sweep_line->queue.pq.max_size)) {
if (unlikely (! pqueue_grow (&sweep_line->queue.pq))) {
longjmp (sweep_line->unwind,
_cairo_error (CAIRO_STATUS_NO_MEMORY));
elements = sweep_line->queue.pq.elements;
for (i = ++sweep_line->queue.pq.size;
i != PQ_FIRST_ENTRY &&
event_compare (event,
elements[parent = PQ_PARENT_INDEX (i)]) < 0;
i = parent)
elements[i] = elements[parent];
elements[i] = event;
pqueue_pop (pqueue_t *pq)
event_t **elements = pq->elements;
event_t *tail;
int child, i;
tail = elements[pq->size--];
if (pq->size == 0) {
elements[PQ_FIRST_ENTRY] = NULL;
return;
for (i = PQ_FIRST_ENTRY;
(child = PQ_LEFT_CHILD_INDEX (i)) <= pq->size;
i = child)
if (child != pq->size &&
event_compare (elements[child+1],
elements[child]) < 0)
child++;
if (event_compare (elements[child], tail) >= 0)
break;
elements[i] = elements[child];
elements[i] = tail;
event_insert (sweep_line_t *sweep_line,
event_type_t type,
edge_t *e1,
edge_t *e2,
queue_event_t *event;
event = _cairo_freepool_alloc (&sweep_line->queue.pool);
if (unlikely (event == NULL)) {
event->y = y;
event->type = type;
event->e1 = e1;
event->e2 = e2;
pqueue_push (sweep_line, (event_t *) event);
event_delete (sweep_line_t *sweep_line,
event_t *event)
_cairo_freepool_free (&sweep_line->queue.pool, event);
static inline event_t *
event_next (sweep_line_t *sweep_line)
event_t *event, *cmp;
event = sweep_line->queue.pq.elements[PQ_FIRST_ENTRY];
cmp = *sweep_line->queue.start_events;
if (event == NULL ||
(cmp != NULL && event_compare (cmp, event) < 0))
event = cmp;
sweep_line->queue.start_events++;
pqueue_pop (&sweep_line->queue.pq);
return event;
CAIRO_COMBSORT_DECLARE (start_event_sort, event_t *, event_compare)
event_insert_stop (sweep_line_t *sweep_line,
edge_t *edge)
event_insert (sweep_line,
edge, NULL,
event_insert_if_intersect_below_current_y (sweep_line_t *sweep_line,
edge_t *left,
edge_t *right)
cairo_point_t intersection;
/* start points intersect */
if (left->edge.line.p1.x == right->edge.line.p1.x &&
left->edge.line.p1.y == right->edge.line.p1.y)
/* end points intersect, process DELETE events first */
if (left->edge.line.p2.x == right->edge.line.p2.x &&
left->edge.line.p2.y == right->edge.line.p2.y)
if (slope_compare (left, right) <= 0)
if (! edge_intersect (left, right, &intersection))
left, right,
intersection.y);
static inline edge_t *
link_to_edge (cairo_list_t *link)
return (edge_t *) link;
sweep_line_insert (sweep_line_t *sweep_line,
cairo_list_t *pos;
cairo_fixed_t y = sweep_line->current_subrow;
pos = sweep_line->insert_cursor;
if (pos == &sweep_line->active)
pos = sweep_line->active.next;
if (pos != &sweep_line->active) {
cmp = sweep_line_compare_edges (link_to_edge (pos),
edge,
y);
if (cmp < 0) {
while (pos->next != &sweep_line->active &&
sweep_line_compare_edges (link_to_edge (pos->next),
y) < 0)
pos = pos->next;
} else if (cmp > 0) {
do {
pos = pos->prev;
} while (pos != &sweep_line->active &&
sweep_line_compare_edges (link_to_edge (pos),
y) > 0);
cairo_list_add (&edge->link, pos);
sweep_line->insert_cursor = &edge->link;
inline static void
coverage_rewind (struct coverage *cells)
cells->cursor = &cells->head;
coverage_init (struct coverage *cells)
_cairo_freepool_init (&cells->pool,
sizeof (struct cell));
cells->head.prev = NULL;
cells->head.next = &cells->tail;
cells->head.x = INT_MIN;
cells->tail.prev = &cells->head;
cells->tail.next = NULL;
cells->tail.x = INT_MAX;
cells->count = 0;
coverage_rewind (cells);
coverage_fini (struct coverage *cells)
_cairo_freepool_fini (&cells->pool);
coverage_reset (struct coverage *cells)
_cairo_freepool_reset (&cells->pool);
static struct cell *
coverage_alloc (sweep_line_t *sweep_line,
struct cell *tail,
int x)
struct cell *cell;
cell = _cairo_freepool_alloc (&sweep_line->coverage.pool);
if (unlikely (NULL == cell)) {
tail->prev->next = cell;
cell->prev = tail->prev;
cell->next = tail;
tail->prev = cell;
cell->x = x;
cell->uncovered_area = 0;
cell->covered_height = 0;
sweep_line->coverage.count++;
return cell;
inline static struct cell *
coverage_find (sweep_line_t *sweep_line, int x)
cell = sweep_line->coverage.cursor;
if (unlikely (cell->x > x)) {
if (cell->prev->x < x)
cell = cell->prev;
} while (TRUE);
if (cell->x == x)
UNROLL3({
cell = cell->next;
if (cell->x >= x)
});
if (cell->x != x)
cell = coverage_alloc (sweep_line, cell, x);
return sweep_line->coverage.cursor = cell;
coverage_render_cells (sweep_line_t *sweep_line,
cairo_fixed_t left, cairo_fixed_t right,
cairo_fixed_t y1, cairo_fixed_t y2,
int sign)
int fx1, fx2;
int ix1, ix2;
int dx, dy;
/* Orient the edge left-to-right. */
dx = right - left;
if (dx >= 0) {
ix1 = _cairo_fixed_integer_part (left);
fx1 = _cairo_fixed_fractional_part (left);
ix2 = _cairo_fixed_integer_part (right);
fx2 = _cairo_fixed_fractional_part (right);
dy = y2 - y1;
ix1 = _cairo_fixed_integer_part (right);
fx1 = _cairo_fixed_fractional_part (right);
ix2 = _cairo_fixed_integer_part (left);
fx2 = _cairo_fixed_fractional_part (left);
dx = -dx;
sign = -sign;
dy = y1 - y2;
y1 = y2 - dy;
y2 = y1 + dy;
/* Add coverage for all pixels [ix1,ix2] on this row crossed
* by the edge. */
struct quorem y = floored_divrem ((STEP_X - fx1)*dy, dx);
if (cell->x != ix1) {
if (unlikely (cell->x > ix1)) {
if (cell->prev->x < ix1)
} else do {
if (cell->x >= ix1)
if (cell->x != ix1)
cell = coverage_alloc (sweep_line, cell, ix1);
cell->uncovered_area += sign * y.quo * (STEP_X + fx1);
cell->covered_height += sign * y.quo;
y.quo += y1;
if (cell->x != ++ix1)
if (ix1 < ix2) {
struct quorem dydx_full = floored_divrem (STEP_X*dy, dx);
cairo_fixed_t y_skip = dydx_full.quo;
y.rem += dydx_full.rem;
if (y.rem >= dx) {
++y_skip;
y.rem -= dx;
y.quo += y_skip;
y_skip *= sign;
cell->covered_height += y_skip;
cell->uncovered_area += y_skip*STEP_X;
} while (ix1 != ix2);
cell->uncovered_area += sign*(y2 - y.quo)*fx2;
cell->covered_height += sign*(y2 - y.quo);
sweep_line->coverage.cursor = cell;
full_inc_edge (edge_t *edge)
edge->x.quo += edge->dxdy_full.quo;
edge->x.rem += edge->dxdy_full.rem;
if (edge->x.rem >= 0) {
++edge->x.quo;
edge->x.rem -= edge->dy;
full_add_edge (sweep_line_t *sweep_line, edge_t *edge, int sign)
cairo_fixed_t x1, x2;
int frac;
edge->current_sign = sign;
ix1 = _cairo_fixed_integer_part (edge->x.quo);
if (edge->vertical) {
frac = _cairo_fixed_fractional_part (edge->x.quo);
cell = coverage_find (sweep_line, ix1);
cell->covered_height += sign * STEP_Y;
cell->uncovered_area += sign * 2 * frac * STEP_Y;
x1 = edge->x.quo;
full_inc_edge (edge);
x2 = edge->x.quo;
ix2 = _cairo_fixed_integer_part (edge->x.quo);
/* Edge is entirely within a column? */
if (likely (ix1 == ix2)) {
frac = _cairo_fixed_fractional_part (x1) +
_cairo_fixed_fractional_part (x2);
cell->uncovered_area += sign * frac * STEP_Y;
coverage_render_cells (sweep_line, x1, x2, 0, STEP_Y, sign);
full_nonzero (sweep_line_t *sweep_line)
sweep_line->is_vertical = TRUE;
edge_t *left = link_to_edge (pos), *right;
int winding = left->edge.dir;
sweep_line->is_vertical &= left->vertical;
pos = left->link.next;
if (unlikely (pos == &sweep_line->active)) {
full_add_edge (sweep_line, left, +1);
right = link_to_edge (pos);
sweep_line->is_vertical &= right->vertical;
winding += right->edge.dir;
if (0 == winding) {
if (pos == &sweep_line->active ||
link_to_edge (pos)->x.quo != right->x.quo)
if (! right->vertical)
full_inc_edge (right);
full_add_edge (sweep_line, right, -1);
} while (pos != &sweep_line->active);
full_evenodd (sweep_line_t *sweep_line)
int winding = 0;
if (pos == &sweep_line->active) {
if (++winding & 1) {
render_rows (cairo_botor_scan_converter_t *self,
sweep_line_t *sweep_line,
int y, int height,
cairo_span_renderer_t *renderer)
cairo_half_open_span_t spans_stack[CAIRO_STACK_ARRAY_LENGTH (cairo_half_open_span_t)];
cairo_half_open_span_t *spans = spans_stack;
int prev_x, cover;
int num_spans;
cairo_status_t status;
if (unlikely (sweep_line->coverage.count == 0)) {
status = renderer->render_rows (renderer, y, height, NULL, 0);
if (unlikely (status))
longjmp (sweep_line->unwind, status);
/* Allocate enough spans for the row. */
num_spans = 2*sweep_line->coverage.count+2;
if (unlikely (num_spans > ARRAY_LENGTH (spans_stack))) {
spans = _cairo_malloc_ab (num_spans, sizeof (cairo_half_open_span_t));
if (unlikely (spans == NULL)) {
/* Form the spans from the coverage and areas. */
num_spans = 0;
prev_x = self->xmin;
cover = 0;
cell = sweep_line->coverage.head.next;
int x = cell->x;
int area;
if (x > prev_x) {
spans[num_spans].x = prev_x;
spans[num_spans].inverse = 0;
spans[num_spans].coverage = AREA_TO_ALPHA (cover);
++num_spans;
cover += cell->covered_height*STEP_X*2;
area = cover - cell->uncovered_area;
spans[num_spans].x = x;
spans[num_spans].coverage = AREA_TO_ALPHA (area);
prev_x = x + 1;
} while ((cell = cell->next) != &sweep_line->coverage.tail);
if (prev_x <= self->xmax) {
if (cover && prev_x < self->xmax) {
spans[num_spans].x = self->xmax;
spans[num_spans].inverse = 1;
spans[num_spans].coverage = 0;
status = renderer->render_rows (renderer, y, height, spans, num_spans);
if (unlikely (spans != spans_stack))
free (spans);
coverage_reset (&sweep_line->coverage);
full_repeat (sweep_line_t *sweep)
cairo_list_foreach_entry (edge, edge_t, &sweep->active, link) {
if (edge->current_sign)
full_add_edge (sweep, edge, edge->current_sign);
else if (! edge->vertical)
full_reset (sweep_line_t *sweep)
cairo_list_foreach_entry (edge, edge_t, &sweep->active, link)
edge->current_sign = 0;
full_step (cairo_botor_scan_converter_t *self,
cairo_fixed_t row,
int top, bottom;
top = _cairo_fixed_integer_part (sweep_line->current_row);
bottom = _cairo_fixed_integer_part (row);
if (cairo_list_is_empty (&sweep_line->active)) {
status = renderer->render_rows (renderer, top, bottom - top, NULL, 0);
if (self->fill_rule == CAIRO_FILL_RULE_WINDING)
full_nonzero (sweep_line);
full_evenodd (sweep_line);
if (sweep_line->is_vertical || bottom == top + 1) {
render_rows (self, sweep_line, top, bottom - top, renderer);
full_reset (sweep_line);
render_rows (self, sweep_line, top++, 1, renderer);
full_repeat (sweep_line);
render_rows (self, sweep_line, top, 1, renderer);
} while (++top != bottom);
cairo_always_inline static void
sub_inc_edge (edge_t *edge,
cairo_fixed_t height)
if (height == 1) {
edge->x.quo += edge->dxdy.quo;
edge->x.rem += edge->dxdy.rem;
edge->x.quo += height * edge->dxdy.quo;
edge->x.rem += height * edge->dxdy.rem;
int carry = edge->x.rem / edge->dy + 1;
edge->x.quo += carry;
edge->x.rem -= carry * edge->dy;
sub_add_run (sweep_line_t *sweep_line, edge_t *edge, int y, int sign)
struct run *run;
run = _cairo_freepool_alloc (&sweep_line->runs);
if (unlikely (run == NULL))
longjmp (sweep_line->unwind, _cairo_error (CAIRO_STATUS_NO_MEMORY));
run->y = y;
run->sign = sign;
run->next = edge->runs;
edge->runs = run;
inline static cairo_bool_t
edges_coincident (edge_t *left, edge_t *right, cairo_fixed_t y)
/* XXX is compare_x_for_y() worth executing during sub steps? */
return line_equal (&left->edge.line, &right->edge.line);
//edges_compare_x_for_y (&left->edge, &right->edge, y) >= 0;
sub_nonzero (sweep_line_t *sweep_line)
cairo_fixed_t fy = _cairo_fixed_fractional_part (y);
if (left->current_sign != +1)
sub_add_run (sweep_line, left, fy, +1);
! edges_coincident (right, link_to_edge (pos), y))
if (right->current_sign)
sub_add_run (sweep_line, right, fy, 0);
if (right->current_sign != -1)
sub_add_run (sweep_line, right, fy, -1);
sub_evenodd (sweep_line_t *sweep_line)
sub_step (cairo_botor_scan_converter_t *self,
sweep_line_t *sweep_line)
if (cairo_list_is_empty (&sweep_line->active))
sub_nonzero (sweep_line);
sub_evenodd (sweep_line);
coverage_render_runs (sweep_line_t *sweep, edge_t *edge,
cairo_fixed_t y1, cairo_fixed_t y2)
struct run tail;
struct run *run = &tail;
tail.next = NULL;
tail.y = y2;
/* Order the runs top->bottom */
while (edge->runs) {
struct run *r;
r = edge->runs;
edge->runs = r->next;
r->next = run;
run = r;
if (run->y > y1)
sub_inc_edge (edge, run->y - y1);
y1 = run->y;
y2 = run->next->y;
if (y2 - y1 == STEP_Y)
sub_inc_edge (edge, y2 - y1);
if (run->sign) {
ix1 = _cairo_fixed_integer_part (x1);
ix2 = _cairo_fixed_integer_part (x2);
cell = coverage_find (sweep, ix1);
cell->covered_height += run->sign * (y2 - y1);
cell->uncovered_area += run->sign * (y2 - y1) * frac;
coverage_render_cells (sweep, x1, x2, y1, y2, run->sign);
run = run->next;
} while (run->next != NULL);
coverage_render_vertical_runs (sweep_line_t *sweep, edge_t *edge, cairo_fixed_t y2)
int height = 0;
for (run = edge->runs; run != NULL; run = run->next) {
if (run->sign)
height += run->sign * (y2 - run->y);
y2 = run->y;
cell = coverage_find (sweep, _cairo_fixed_integer_part (edge->x.quo));
cell->covered_height += height;
cell->uncovered_area += 2 * _cairo_fixed_fractional_part (edge->x.quo) * height;
sub_emit (cairo_botor_scan_converter_t *self,
sweep_line_t *sweep,
sub_step (self, sweep);
/* convert the runs into coverages */
if (edge->runs == NULL) {
if (! edge->vertical) {
if (edge->flags & START) {
sub_inc_edge (edge,
STEP_Y - _cairo_fixed_fractional_part (edge->edge.top));
edge->flags &= ~START;
coverage_render_vertical_runs (sweep, edge, STEP_Y);
int y1 = 0;
y1 = _cairo_fixed_fractional_part (edge->edge.top);
coverage_render_runs (sweep, edge, y1, STEP_Y);
edge->runs = NULL;
cairo_list_foreach_entry (edge, edge_t, &sweep->stopped, link) {
int y2 = _cairo_fixed_fractional_part (edge->edge.bottom);
coverage_render_vertical_runs (sweep, edge, y2);
if (edge->flags & START)
coverage_render_runs (sweep, edge, y1, y2);
cairo_list_init (&sweep->stopped);
_cairo_freepool_reset (&sweep->runs);
render_rows (self, sweep,
_cairo_fixed_integer_part (sweep->current_row), 1,
renderer);
sweep_line_init (sweep_line_t *sweep_line,
event_t **start_events,
int num_events)
cairo_list_init (&sweep_line->active);
cairo_list_init (&sweep_line->stopped);
sweep_line->insert_cursor = &sweep_line->active;
sweep_line->current_row = INT32_MIN;
sweep_line->current_subrow = INT32_MIN;
coverage_init (&sweep_line->coverage);
_cairo_freepool_init (&sweep_line->runs, sizeof (struct run));
start_event_sort (start_events, num_events);
start_events[num_events] = NULL;
sweep_line->queue.start_events = start_events;
_cairo_freepool_init (&sweep_line->queue.pool,
sizeof (queue_event_t));
pqueue_init (&sweep_line->queue.pq);
sweep_line->queue.pq.elements[PQ_FIRST_ENTRY] = NULL;
sweep_line_delete (sweep_line_t *sweep_line,
if (sweep_line->insert_cursor == &edge->link)
sweep_line->insert_cursor = edge->link.prev;
cairo_list_del (&edge->link);
if (edge->runs)
cairo_list_add_tail (&edge->link, &sweep_line->stopped);
edge->flags |= STOP;
sweep_line_swap (sweep_line_t *sweep_line,
right->link.prev = left->link.prev;
left->link.next = right->link.next;
right->link.next = &left->link;
left->link.prev = &right->link;
left->link.next->prev = &left->link;
right->link.prev->next = &right->link;
sweep_line_fini (sweep_line_t *sweep_line)
pqueue_fini (&sweep_line->queue.pq);
_cairo_freepool_fini (&sweep_line->queue.pool);
coverage_fini (&sweep_line->coverage);
_cairo_freepool_fini (&sweep_line->runs);
static cairo_status_t
botor_generate (cairo_botor_scan_converter_t *self,
sweep_line_t sweep_line;
cairo_fixed_t ybot;
event_t *event;
cairo_list_t *left, *right;
edge_t *e1, *e2;
int bottom;
sweep_line_init (&sweep_line, start_events, self->num_edges);
if ((status = setjmp (sweep_line.unwind)))
goto unwind;
ybot = self->extents.p2.y;
sweep_line.current_subrow = self->extents.p1.y;
sweep_line.current_row = _cairo_fixed_floor (self->extents.p1.y);
event = *sweep_line.queue.start_events++;
/* Can we process a full step in one go? */
if (event->y >= sweep_line.current_row + STEP_Y) {
bottom = _cairo_fixed_floor (event->y);
full_step (self, &sweep_line, bottom, renderer);
sweep_line.current_row = bottom;
sweep_line.current_subrow = bottom;
if (event->y > sweep_line.current_subrow) {
sub_step (self, &sweep_line);
sweep_line.current_subrow = event->y;
/* Update the active list using Bentley-Ottmann */
switch (event->type) {
case EVENT_TYPE_START:
e1 = ((start_event_t *) event)->edge;
sweep_line_insert (&sweep_line, e1);
event_insert_stop (&sweep_line, e1);
left = e1->link.prev;
right = e1->link.next;
if (left != &sweep_line.active) {
event_insert_if_intersect_below_current_y (&sweep_line,
link_to_edge (left), e1);
if (right != &sweep_line.active) {
e1, link_to_edge (right));
case EVENT_TYPE_STOP:
e1 = ((queue_event_t *) event)->e1;
event_delete (&sweep_line, event);
sweep_line_delete (&sweep_line, e1);
if (left != &sweep_line.active &&
right != &sweep_line.active)
link_to_edge (left),
link_to_edge (right));
case EVENT_TYPE_INTERSECTION:
e2 = ((queue_event_t *) event)->e2;
if (e1->flags & STOP)
if (e2->flags & STOP)
/* skip this intersection if its edges are not adjacent */
if (&e2->link != e1->link.next)
right = e2->link.next;
sweep_line_swap (&sweep_line, e1, e2);
/* after the swap e2 is left of e1 */
link_to_edge (left), e2);
event = event_next (&sweep_line);
if (event == NULL)
goto end;
} while (event->y == sweep_line.current_subrow);
} while (event->y < sweep_line.current_row + STEP_Y);
bottom = sweep_line.current_row + STEP_Y;
sub_emit (self, &sweep_line, renderer);
sweep_line.current_row = sweep_line.current_subrow;
end:
/* flush any partial spans */
if (sweep_line.current_subrow != sweep_line.current_row) {
sweep_line.current_row += STEP_Y;
sweep_line.current_subrow = sweep_line.current_row;
/* clear the rest */
if (sweep_line.current_subrow < ybot) {
bottom = _cairo_fixed_integer_part (sweep_line.current_row);
status = renderer->render_rows (renderer,
bottom, _cairo_fixed_integer_ceil (ybot) - bottom,
NULL, 0);
unwind:
sweep_line_fini (&sweep_line);
return status;
_cairo_botor_scan_converter_generate (void *converter,
cairo_botor_scan_converter_t *self = converter;
start_event_t stack_events[CAIRO_STACK_ARRAY_LENGTH (start_event_t)];
start_event_t *events;
event_t *stack_event_ptrs[ARRAY_LENGTH (stack_events) + 1];
event_t **event_ptrs;
struct _cairo_botor_scan_converter_chunk *chunk;
int num_events;
int i, j;
num_events = self->num_edges;
if (unlikely (0 == num_events)) {
return renderer->render_rows (renderer,
_cairo_fixed_integer_floor (self->extents.p1.y),
_cairo_fixed_integer_ceil (self->extents.p2.y) -
events = stack_events;
event_ptrs = stack_event_ptrs;
if (unlikely (num_events >= ARRAY_LENGTH (stack_events))) {
events = _cairo_malloc_ab_plus_c (num_events,
sizeof (start_event_t) + sizeof (event_t *),
if (unlikely (events == NULL))
return _cairo_error (CAIRO_STATUS_NO_MEMORY);
event_ptrs = (event_t **) (events + num_events);
j = 0;
for (chunk = &self->chunks; chunk != NULL; chunk = chunk->next) {
edge = chunk->base;
for (i = 0; i < chunk->count; i++) {
event_ptrs[j] = (event_t *) &events[j];
events[j].y = edge->edge.top;
events[j].type = EVENT_TYPE_START;
events[j].edge = edge;
edge++, j++;
status = botor_generate (self, event_ptrs, renderer);
if (events != stack_events)
free (events);
static edge_t *
botor_allocate_edge (cairo_botor_scan_converter_t *self)
chunk = self->tail;
if (chunk->count == chunk->size) {
int size;
size = chunk->size * 2;
chunk->next = _cairo_malloc_ab_plus_c (size,
sizeof (edge_t),
sizeof (struct _cairo_botor_scan_converter_chunk));
if (unlikely (chunk->next == NULL))
return NULL;
chunk = chunk->next;
chunk->next = NULL;
chunk->count = 0;
chunk->size = size;
chunk->base = chunk + 1;
self->tail = chunk;
return (edge_t *) chunk->base + chunk->count++;
botor_add_edge (cairo_botor_scan_converter_t *self,
const cairo_edge_t *edge)
edge_t *e;
cairo_fixed_t dx, dy;
e = botor_allocate_edge (self);
if (unlikely (e == NULL))
cairo_list_init (&e->link);
e->edge = *edge;
dx = edge->line.p2.x - edge->line.p1.x;
dy = edge->line.p2.y - edge->line.p1.y;
e->dy = dy;
if (dx == 0) {
e->vertical = TRUE;
e->x.quo = edge->line.p1.x;
e->x.rem = 0;
e->dxdy.quo = 0;
e->dxdy.rem = 0;
e->dxdy_full.quo = 0;
e->dxdy_full.rem = 0;
e->vertical = FALSE;
e->dxdy = floored_divrem (dx, dy);
if (edge->top == edge->line.p1.y) {
e->x = floored_muldivrem (edge->top - edge->line.p1.y,
dx, dy);
e->x.quo += edge->line.p1.x;
if (_cairo_fixed_integer_part (edge->bottom) - _cairo_fixed_integer_part (edge->top) > 1) {
e->dxdy_full = floored_muldivrem (STEP_Y, dx, dy);
e->x.rem = -e->dy;
e->current_sign = 0;
e->runs = NULL;
e->flags = START;
self->num_edges++;
return CAIRO_STATUS_SUCCESS;
_cairo_botor_scan_converter_add_edge (void *converter,
const cairo_point_t *p1,
const cairo_point_t *p2,
int top, int bottom,
int dir)
edge.line.p1 = *p1;
edge.line.p2 = *p2;
edge.top = top;
edge.bottom = bottom;
edge.dir = dir;
return botor_add_edge (self, &edge);
cairo_status_t
_cairo_botor_scan_converter_add_polygon (cairo_botor_scan_converter_t *converter,
const cairo_polygon_t *polygon)
int i;
for (i = 0; i < polygon->num_edges; i++) {
status = botor_add_edge (self, &polygon->edges[i]);
_cairo_botor_scan_converter_destroy (void *converter)
struct _cairo_botor_scan_converter_chunk *chunk, *next;
for (chunk = self->chunks.next; chunk != NULL; chunk = next) {
next = chunk->next;
free (chunk);
void
_cairo_botor_scan_converter_init (cairo_botor_scan_converter_t *self,
const cairo_box_t *extents,
cairo_fill_rule_t fill_rule)
self->base.destroy = _cairo_botor_scan_converter_destroy;
self->base.generate = _cairo_botor_scan_converter_generate;
self->extents = *extents;
self->fill_rule = fill_rule;
self->xmin = _cairo_fixed_integer_floor (extents->p1.x);
self->xmax = _cairo_fixed_integer_ceil (extents->p2.x);
self->chunks.base = self->buf;
self->chunks.next = NULL;
self->chunks.count = 0;
self->chunks.size = sizeof (self->buf) / sizeof (edge_t);
self->tail = &self->chunks;
self->num_edges = 0;