0,0 → 1,1532 |
/* |
* Copyright © 2004 Carl Worth |
* Copyright © 2006 Red Hat, Inc. |
* Copyright © 2008 Chris Wilson |
* |
* 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> |
* Chris Wilson <chris@chris-wilson.co.uk> |
*/ |
|
/* Provide definitions for standalone compilation */ |
#include "cairoint.h" |
|
#include "cairo-error-private.h" |
#include "cairo-freelist-private.h" |
#include "cairo-combsort-inline.h" |
|
typedef cairo_point_t cairo_bo_point32_t; |
|
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; |
|
typedef struct _cairo_bo_edge cairo_bo_edge_t; |
|
typedef struct _cairo_bo_deferred { |
cairo_bo_edge_t *other; |
int32_t top; |
} cairo_bo_deferred_t; |
|
struct _cairo_bo_edge { |
int a_or_b; |
cairo_edge_t edge; |
cairo_bo_edge_t *prev; |
cairo_bo_edge_t *next; |
cairo_bo_deferred_t deferred; |
}; |
|
/* 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 { |
CAIRO_BO_EVENT_TYPE_STOP, |
CAIRO_BO_EVENT_TYPE_INTERSECTION, |
CAIRO_BO_EVENT_TYPE_START |
} cairo_bo_event_type_t; |
|
typedef struct _cairo_bo_event { |
cairo_bo_event_type_t type; |
cairo_point_t point; |
} cairo_bo_event_t; |
|
typedef struct _cairo_bo_start_event { |
cairo_bo_event_type_t type; |
cairo_point_t point; |
cairo_bo_edge_t edge; |
} cairo_bo_start_event_t; |
|
typedef struct _cairo_bo_queue_event { |
cairo_bo_event_type_t type; |
cairo_point_t point; |
cairo_bo_edge_t *e1; |
cairo_bo_edge_t *e2; |
} cairo_bo_queue_event_t; |
|
typedef struct _pqueue { |
int size, max_size; |
|
cairo_bo_event_t **elements; |
cairo_bo_event_t *elements_embedded[1024]; |
} pqueue_t; |
|
typedef struct _cairo_bo_event_queue { |
cairo_freepool_t pool; |
pqueue_t pqueue; |
cairo_bo_event_t **start_events; |
} cairo_bo_event_queue_t; |
|
typedef struct _cairo_bo_sweep_line { |
cairo_bo_edge_t *head; |
int32_t current_y; |
cairo_bo_edge_t *current_edge; |
} cairo_bo_sweep_line_t; |
|
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; |
} |
|
static inline int |
_cairo_bo_point32_compare (cairo_bo_point32_t const *a, |
cairo_bo_point32_t const *b) |
{ |
int cmp; |
|
cmp = a->y - b->y; |
if (cmp) |
return cmp; |
|
return a->x - b->x; |
} |
|
/* Compare the slope of a to the slope of b, returning 1, 0, -1 if the |
* slope a is respectively greater than, equal to, or less than the |
* slope of b. |
* |
* For each edge, consider the direction vector formed from: |
* |
* top -> bottom |
* |
* which is: |
* |
* (dx, dy) = (line.p2.x - line.p1.x, line.p2.y - line.p1.y) |
* |
* We then define the slope of each edge as dx/dy, (which is the |
* inverse of the slope typically used in math instruction). We never |
* compute a slope directly as the value approaches infinity, but we |
* can derive a slope comparison without division as follows, (where |
* the ? represents our compare operator). |
* |
* 1. slope(a) ? slope(b) |
* 2. adx/ady ? bdx/bdy |
* 3. (adx * bdy) ? (bdx * ady) |
* |
* Note that from step 2 to step 3 there is no change needed in the |
* sign of the result since both ady and bdy are guaranteed to be |
* greater than or equal to 0. |
* |
* When using this slope comparison to sort edges, some care is needed |
* when interpreting the results. Since the slope compare operates on |
* distance vectors from top to bottom it gives a correct left to |
* right sort for edges that have a common top point, (such as two |
* edges with start events at the same location). On the other hand, |
* the sense of the result will be exactly reversed for two edges that |
* have a common stop point. |
*/ |
static inline int |
_slope_compare (const cairo_bo_edge_t *a, |
const cairo_bo_edge_t *b) |
{ |
/* 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 adx = a->edge.line.p2.x - a->edge.line.p1.x; |
int32_t bdx = b->edge.line.p2.x - b->edge.line.p1.x; |
|
/* Since the dy's are all positive by construction we can fast |
* path several common cases. |
*/ |
|
/* First check for vertical lines. */ |
if (adx == 0) |
return -bdx; |
if (bdx == 0) |
return adx; |
|
/* Then where the two edges point in different directions wrt x. */ |
if ((adx ^ bdx) < 0) |
return adx; |
|
/* Finally we actually need to do the general comparison. */ |
{ |
int32_t ady = a->edge.line.p2.y - a->edge.line.p1.y; |
int32_t bdy = b->edge.line.p2.y - b->edge.line.p1.y; |
cairo_int64_t adx_bdy = _cairo_int32x32_64_mul (adx, bdy); |
cairo_int64_t bdx_ady = _cairo_int32x32_64_mul (bdx, ady); |
|
return _cairo_int64_cmp (adx_bdy, bdx_ady); |
} |
} |
|
/* |
* 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_bo_edge_t *a, |
const cairo_bo_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; |
enum { |
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->edge.line.p1.x < a->edge.line.p2.x) { |
amin = a->edge.line.p1.x; |
amax = a->edge.line.p2.x; |
} else { |
amin = a->edge.line.p2.x; |
amax = a->edge.line.p1.x; |
} |
if (b->edge.line.p1.x < b->edge.line.p2.x) { |
bmin = b->edge.line.p1.x; |
bmax = b->edge.line.p2.x; |
} else { |
bmin = b->edge.line.p2.x; |
bmax = b->edge.line.p1.x; |
} |
if (amax < bmin) return -1; |
if (amin > bmax) return +1; |
} |
|
ady = a->edge.line.p2.y - a->edge.line.p1.y; |
adx = a->edge.line.p2.x - a->edge.line.p1.x; |
if (adx == 0) |
have_dx_adx_bdx &= ~HAVE_ADX; |
|
bdy = b->edge.line.p2.y - b->edge.line.p1.y; |
bdx = b->edge.line.p2.x - b->edge.line.p1.x; |
if (bdx == 0) |
have_dx_adx_bdx &= ~HAVE_BDX; |
|
dx = a->edge.line.p1.x - b->edge.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->edge.line.p1.y) |
#define B _cairo_int64x32_128_mul (_cairo_int32x32_64_mul (bdx, ady), y - b->edge.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->edge.line.p1.y == b->edge.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; |
} else { |
cairo_int64_t ady_dx, dy_adx; |
|
ady_dx = _cairo_int32x32_64_mul (ady, dx); |
dy_adx = _cairo_int32x32_64_mul (a->edge.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) { |
return dx; |
} else { |
cairo_int64_t bdy_dx, dy_bdx; |
|
bdy_dx = _cairo_int32x32_64_mul (bdy, dx); |
dy_bdx = _cairo_int32x32_64_mul (y - b->edge.line.p1.y, bdx); |
|
return _cairo_int64_cmp (bdy_dx, dy_bdx); |
} |
case HAVE_ALL: |
/* XXX try comparing (a->edge.line.p2.x - b->edge.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. |
* |
* 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 ∘ X |
* where ∘ is our inequality operator. |
* |
* By construction, we know that A_dy (and (Y - A_y)) are |
* all positive, so we can rearrange it thus without causing a sign change: |
* (Y - A_y) * A_dx ∘ (X - A_x) * A_dy |
* |
* Given the assumption that all the deltas fit within 32 bits, we can compute |
* this comparison directly using 64 bit arithmetic. |
* |
* See the similar discussion for _slope_compare() and |
* edges_compare_x_for_y_general(). |
*/ |
static int |
edge_compare_for_y_against_x (const cairo_bo_edge_t *a, |
int32_t y, |
int32_t x) |
{ |
int32_t adx, ady; |
int32_t dx, dy; |
cairo_int64_t L, R; |
|
if (x < a->edge.line.p1.x && x < a->edge.line.p2.x) |
return 1; |
if (x > a->edge.line.p1.x && x > a->edge.line.p2.x) |
return -1; |
|
adx = a->edge.line.p2.x - a->edge.line.p1.x; |
dx = x - a->edge.line.p1.x; |
|
if (adx == 0) |
return -dx; |
if (dx == 0 || (adx ^ dx) < 0) |
return adx; |
|
dy = y - a->edge.line.p1.y; |
ady = a->edge.line.p2.y - a->edge.line.p1.y; |
|
L = _cairo_int32x32_64_mul (dy, adx); |
R = _cairo_int32x32_64_mul (dx, ady); |
|
return _cairo_int64_cmp (L, R); |
} |
|
static int |
edges_compare_x_for_y (const cairo_bo_edge_t *a, |
const cairo_bo_edge_t *b, |
int32_t y) |
{ |
/* 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). |
*/ |
enum { |
HAVE_NEITHER = 0x0, |
HAVE_AX = 0x1, |
HAVE_BX = 0x2, |
HAVE_BOTH = HAVE_AX | HAVE_BX |
} have_ax_bx = HAVE_BOTH; |
int32_t ax, bx; |
|
if (y == a->edge.line.p1.y) |
ax = a->edge.line.p1.x; |
else if (y == a->edge.line.p2.y) |
ax = a->edge.line.p2.x; |
else |
have_ax_bx &= ~HAVE_AX; |
|
if (y == b->edge.line.p1.y) |
bx = b->edge.line.p1.x; |
else if (y == b->edge.line.p2.y) |
bx = b->edge.line.p2.x; |
else |
have_ax_bx &= ~HAVE_BX; |
|
switch (have_ax_bx) { |
default: |
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 |
_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; |
} |
|
static int |
_cairo_bo_sweep_line_compare_edges (cairo_bo_sweep_line_t *sweep_line, |
const cairo_bo_edge_t *a, |
const cairo_bo_edge_t *b) |
{ |
int cmp; |
|
/* compare the edges if not identical */ |
if (! _line_equal (&a->edge.line, &b->edge.line)) { |
cmp = edges_compare_x_for_y (a, b, sweep_line->current_y); |
if (cmp) |
return cmp; |
|
/* The two edges intersect exactly at y, so fall back on slope |
* comparison. We know that this compare_edges function will be |
* called only when starting a new edge, (not when stopping an |
* edge), so we don't have to worry about conditionally inverting |
* the sense of _slope_compare. */ |
cmp = _slope_compare (a, b); |
if (cmp) |
return cmp; |
} |
|
/* We've got two collinear edges now. */ |
return b->edge.bottom - a->edge.bottom; |
} |
|
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) |
{ |
/* det = a * d - b * c */ |
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 (cairo_bo_edge_t *a, |
cairo_bo_edge_t *b, |
cairo_bo_intersect_point_t *intersection) |
{ |
cairo_int64_t a_det, b_det; |
|
/* 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. |
* 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; |
} else { |
if (_cairo_int64_le (den_det, R)) |
return FALSE; |
} |
|
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); |
if (_cairo_int64_negative (den_det)) { |
if (_cairo_int64_ge (den_det, R)) |
return FALSE; |
} else { |
if (_cairo_int64_le (den_det, R)) |
return FALSE; |
} |
|
/* 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)) |
return FALSE; |
#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)); |
} else |
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), |
den_det); |
if (_cairo_int64_eq (qr.rem, den_det)) |
return FALSE; |
#if 0 |
intersection->y.exactness = _cairo_int64_is_zero (qr.rem) ? EXACT : INEXACT; |
#else |
intersection->y.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)); |
} else |
intersection->y.exactness = INEXACT; |
} |
#endif |
intersection->y.ordinate = _cairo_int64_to_int32 (qr.quo); |
|
return TRUE; |
} |
|
static int |
_cairo_bo_intersect_ordinate_32_compare (cairo_bo_intersect_ordinate_t a, |
int32_t b) |
{ |
/* First compare the quotient */ |
if (a.ordinate > b) |
return +1; |
if (a.ordinate < b) |
return -1; |
/* With quotient identical, if remainder is 0 then compare equal */ |
/* Otherwise, the non-zero remainder makes a > b */ |
return INEXACT == a.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. |
*/ |
static cairo_bool_t |
_cairo_bo_edge_contains_intersect_point (cairo_bo_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 = _cairo_bo_intersect_ordinate_32_compare (point->y, |
edge->edge.top); |
cmp_bottom = _cairo_bo_intersect_ordinate_32_compare (point->y, |
edge->edge.bottom); |
|
if (cmp_top < 0 || cmp_bottom > 0) |
{ |
return FALSE; |
} |
|
if (cmp_top > 0 && cmp_bottom < 0) |
{ |
return TRUE; |
} |
|
/* 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 _cairo_bo_intersect_ordinate_32_compare (point->x, top_x) > 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 _cairo_bo_intersect_ordinate_32_compare (point->x, bot_x) < 0; |
} |
} |
|
/* Compute the intersection of two edges. The result is provided as a |
* coordinate pair of 128-bit integers. |
* |
* Returns %CAIRO_BO_STATUS_INTERSECTION if there is an intersection |
* that is within both edges, %CAIRO_BO_STATUS_NO_INTERSECTION if the |
* intersection of the lines defined by the edges occurs outside of |
* one or both edges, and %CAIRO_BO_STATUS_PARALLEL if the two edges |
* are exactly parallel. |
* |
* Note that when determining if a candidate intersection is "inside" |
* an edge, we consider both the infinitesimal shortening and the |
* infinitesimal tilt rules described by John Hobby. Specifically, if |
* the intersection is exactly the same as an edge point, it is |
* effectively outside (no intersection is returned). Also, if the |
* intersection point has the same |
*/ |
static cairo_bool_t |
_cairo_bo_edge_intersect (cairo_bo_edge_t *a, |
cairo_bo_edge_t *b, |
cairo_bo_point32_t *intersection) |
{ |
cairo_bo_intersect_point_t quorem; |
|
if (! intersect_lines (a, b, &quorem)) |
return FALSE; |
|
if (! _cairo_bo_edge_contains_intersect_point (a, &quorem)) |
return FALSE; |
|
if (! _cairo_bo_edge_contains_intersect_point (b, &quorem)) |
return FALSE; |
|
/* 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; |
|
return TRUE; |
} |
|
static inline int |
cairo_bo_event_compare (const cairo_bo_event_t *a, |
const cairo_bo_event_t *b) |
{ |
int cmp; |
|
cmp = _cairo_bo_point32_compare (&a->point, &b->point); |
if (cmp) |
return cmp; |
|
cmp = a->type - b->type; |
if (cmp) |
return cmp; |
|
return a - b; |
} |
|
static inline void |
_pqueue_init (pqueue_t *pq) |
{ |
pq->max_size = ARRAY_LENGTH (pq->elements_embedded); |
pq->size = 0; |
|
pq->elements = pq->elements_embedded; |
} |
|
static inline void |
_pqueue_fini (pqueue_t *pq) |
{ |
if (pq->elements != pq->elements_embedded) |
free (pq->elements); |
} |
|
static cairo_status_t |
_pqueue_grow (pqueue_t *pq) |
{ |
cairo_bo_event_t **new_elements; |
pq->max_size *= 2; |
|
if (pq->elements == pq->elements_embedded) { |
new_elements = _cairo_malloc_ab (pq->max_size, |
sizeof (cairo_bo_event_t *)); |
if (unlikely (new_elements == NULL)) |
return _cairo_error (CAIRO_STATUS_NO_MEMORY); |
|
memcpy (new_elements, pq->elements_embedded, |
sizeof (pq->elements_embedded)); |
} else { |
new_elements = _cairo_realloc_ab (pq->elements, |
pq->max_size, |
sizeof (cairo_bo_event_t *)); |
if (unlikely (new_elements == NULL)) |
return _cairo_error (CAIRO_STATUS_NO_MEMORY); |
} |
|
pq->elements = new_elements; |
return CAIRO_STATUS_SUCCESS; |
} |
|
static inline cairo_status_t |
_pqueue_push (pqueue_t *pq, cairo_bo_event_t *event) |
{ |
cairo_bo_event_t **elements; |
int i, parent; |
|
if (unlikely (pq->size + 1 == pq->max_size)) { |
cairo_status_t status; |
|
status = _pqueue_grow (pq); |
if (unlikely (status)) |
return status; |
} |
|
elements = pq->elements; |
|
for (i = ++pq->size; |
i != PQ_FIRST_ENTRY && |
cairo_bo_event_compare (event, |
elements[parent = PQ_PARENT_INDEX (i)]) < 0; |
i = parent) |
{ |
elements[i] = elements[parent]; |
} |
|
elements[i] = event; |
|
return CAIRO_STATUS_SUCCESS; |
} |
|
static inline void |
_pqueue_pop (pqueue_t *pq) |
{ |
cairo_bo_event_t **elements = pq->elements; |
cairo_bo_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 && |
cairo_bo_event_compare (elements[child+1], |
elements[child]) < 0) |
{ |
child++; |
} |
|
if (cairo_bo_event_compare (elements[child], tail) >= 0) |
break; |
|
elements[i] = elements[child]; |
} |
elements[i] = tail; |
} |
|
static inline cairo_status_t |
_cairo_bo_event_queue_insert (cairo_bo_event_queue_t *queue, |
cairo_bo_event_type_t type, |
cairo_bo_edge_t *e1, |
cairo_bo_edge_t *e2, |
const cairo_point_t *point) |
{ |
cairo_bo_queue_event_t *event; |
|
event = _cairo_freepool_alloc (&queue->pool); |
if (unlikely (event == NULL)) |
return _cairo_error (CAIRO_STATUS_NO_MEMORY); |
|
event->type = type; |
event->e1 = e1; |
event->e2 = e2; |
event->point = *point; |
|
return _pqueue_push (&queue->pqueue, (cairo_bo_event_t *) event); |
} |
|
static void |
_cairo_bo_event_queue_delete (cairo_bo_event_queue_t *queue, |
cairo_bo_event_t *event) |
{ |
_cairo_freepool_free (&queue->pool, event); |
} |
|
static cairo_bo_event_t * |
_cairo_bo_event_dequeue (cairo_bo_event_queue_t *event_queue) |
{ |
cairo_bo_event_t *event, *cmp; |
|
event = event_queue->pqueue.elements[PQ_FIRST_ENTRY]; |
cmp = *event_queue->start_events; |
if (event == NULL || |
(cmp != NULL && cairo_bo_event_compare (cmp, event) < 0)) |
{ |
event = cmp; |
event_queue->start_events++; |
} |
else |
{ |
_pqueue_pop (&event_queue->pqueue); |
} |
|
return event; |
} |
|
CAIRO_COMBSORT_DECLARE (_cairo_bo_event_queue_sort, |
cairo_bo_event_t *, |
cairo_bo_event_compare) |
|
static void |
_cairo_bo_event_queue_init (cairo_bo_event_queue_t *event_queue, |
cairo_bo_event_t **start_events, |
int num_events) |
{ |
_cairo_bo_event_queue_sort (start_events, num_events); |
start_events[num_events] = NULL; |
|
event_queue->start_events = start_events; |
|
_cairo_freepool_init (&event_queue->pool, |
sizeof (cairo_bo_queue_event_t)); |
_pqueue_init (&event_queue->pqueue); |
event_queue->pqueue.elements[PQ_FIRST_ENTRY] = NULL; |
} |
|
static cairo_status_t |
event_queue_insert_stop (cairo_bo_event_queue_t *event_queue, |
cairo_bo_edge_t *edge) |
{ |
cairo_bo_point32_t point; |
|
point.y = edge->edge.bottom; |
point.x = _line_compute_intersection_x_for_y (&edge->edge.line, |
point.y); |
return _cairo_bo_event_queue_insert (event_queue, |
CAIRO_BO_EVENT_TYPE_STOP, |
edge, NULL, |
&point); |
} |
|
static void |
_cairo_bo_event_queue_fini (cairo_bo_event_queue_t *event_queue) |
{ |
_pqueue_fini (&event_queue->pqueue); |
_cairo_freepool_fini (&event_queue->pool); |
} |
|
static inline cairo_status_t |
event_queue_insert_if_intersect_below_current_y (cairo_bo_event_queue_t *event_queue, |
cairo_bo_edge_t *left, |
cairo_bo_edge_t *right) |
{ |
cairo_bo_point32_t intersection; |
|
if (_line_equal (&left->edge.line, &right->edge.line)) |
return CAIRO_STATUS_SUCCESS; |
|
/* The names "left" and "right" here are correct descriptions of |
* the order of the two edges within the active edge list. So if a |
* slope comparison also puts left less than right, then we know |
* that the intersection of these two segments has already |
* occurred before the current sweep line position. */ |
if (_slope_compare (left, right) <= 0) |
return CAIRO_STATUS_SUCCESS; |
|
if (! _cairo_bo_edge_intersect (left, right, &intersection)) |
return CAIRO_STATUS_SUCCESS; |
|
return _cairo_bo_event_queue_insert (event_queue, |
CAIRO_BO_EVENT_TYPE_INTERSECTION, |
left, right, |
&intersection); |
} |
|
static void |
_cairo_bo_sweep_line_init (cairo_bo_sweep_line_t *sweep_line) |
{ |
sweep_line->head = NULL; |
sweep_line->current_y = INT32_MIN; |
sweep_line->current_edge = NULL; |
} |
|
static cairo_status_t |
sweep_line_insert (cairo_bo_sweep_line_t *sweep_line, |
cairo_bo_edge_t *edge) |
{ |
if (sweep_line->current_edge != NULL) { |
cairo_bo_edge_t *prev, *next; |
int cmp; |
|
cmp = _cairo_bo_sweep_line_compare_edges (sweep_line, |
sweep_line->current_edge, |
edge); |
if (cmp < 0) { |
prev = sweep_line->current_edge; |
next = prev->next; |
while (next != NULL && |
_cairo_bo_sweep_line_compare_edges (sweep_line, |
next, edge) < 0) |
{ |
prev = next, next = prev->next; |
} |
|
prev->next = edge; |
edge->prev = prev; |
edge->next = next; |
if (next != NULL) |
next->prev = edge; |
} else if (cmp > 0) { |
next = sweep_line->current_edge; |
prev = next->prev; |
while (prev != NULL && |
_cairo_bo_sweep_line_compare_edges (sweep_line, |
prev, edge) > 0) |
{ |
next = prev, prev = next->prev; |
} |
|
next->prev = edge; |
edge->next = next; |
edge->prev = prev; |
if (prev != NULL) |
prev->next = edge; |
else |
sweep_line->head = edge; |
} else { |
prev = sweep_line->current_edge; |
edge->prev = prev; |
edge->next = prev->next; |
if (prev->next != NULL) |
prev->next->prev = edge; |
prev->next = edge; |
} |
} else { |
sweep_line->head = edge; |
} |
|
sweep_line->current_edge = edge; |
|
return CAIRO_STATUS_SUCCESS; |
} |
|
static void |
_cairo_bo_sweep_line_delete (cairo_bo_sweep_line_t *sweep_line, |
cairo_bo_edge_t *edge) |
{ |
if (edge->prev != NULL) |
edge->prev->next = edge->next; |
else |
sweep_line->head = edge->next; |
|
if (edge->next != NULL) |
edge->next->prev = edge->prev; |
|
if (sweep_line->current_edge == edge) |
sweep_line->current_edge = edge->prev ? edge->prev : edge->next; |
} |
|
static void |
_cairo_bo_sweep_line_swap (cairo_bo_sweep_line_t *sweep_line, |
cairo_bo_edge_t *left, |
cairo_bo_edge_t *right) |
{ |
if (left->prev != NULL) |
left->prev->next = right; |
else |
sweep_line->head = right; |
|
if (right->next != NULL) |
right->next->prev = left; |
|
left->next = right->next; |
right->next = left; |
|
right->prev = left->prev; |
left->prev = right; |
} |
|
static inline cairo_bool_t |
edges_colinear (const cairo_bo_edge_t *a, const cairo_bo_edge_t *b) |
{ |
if (_line_equal (&a->edge.line, &b->edge.line)) |
return TRUE; |
|
if (_slope_compare (a, b)) |
return FALSE; |
|
/* The choice of y is not truly arbitrary since we must guarantee that it |
* is greater than the start of either line. |
*/ |
if (a->edge.line.p1.y == b->edge.line.p1.y) { |
return a->edge.line.p1.x == b->edge.line.p1.x; |
} else if (a->edge.line.p1.y < b->edge.line.p1.y) { |
return edge_compare_for_y_against_x (b, |
a->edge.line.p1.y, |
a->edge.line.p1.x) == 0; |
} else { |
return edge_compare_for_y_against_x (a, |
b->edge.line.p1.y, |
b->edge.line.p1.x) == 0; |
} |
} |
|
static void |
edges_end (cairo_bo_edge_t *left, |
int32_t bot, |
cairo_polygon_t *polygon) |
{ |
cairo_bo_deferred_t *l = &left->deferred; |
cairo_bo_edge_t *right = l->other; |
|
assert(right->deferred.other == NULL); |
if (likely (l->top < bot)) { |
_cairo_polygon_add_line (polygon, &left->edge.line, l->top, bot, 1); |
_cairo_polygon_add_line (polygon, &right->edge.line, l->top, bot, -1); |
} |
|
l->other = NULL; |
} |
|
static inline void |
edges_start_or_continue (cairo_bo_edge_t *left, |
cairo_bo_edge_t *right, |
int top, |
cairo_polygon_t *polygon) |
{ |
assert (right->deferred.other == NULL); |
|
if (left->deferred.other == right) |
return; |
|
if (left->deferred.other != NULL) { |
if (right != NULL && edges_colinear (left->deferred.other, right)) { |
cairo_bo_edge_t *old = left->deferred.other; |
|
/* continuation on right, extend right to cover both */ |
assert (old->deferred.other == NULL); |
assert (old->edge.line.p2.y > old->edge.line.p1.y); |
|
if (old->edge.line.p1.y < right->edge.line.p1.y) |
right->edge.line.p1 = old->edge.line.p1; |
if (old->edge.line.p2.y > right->edge.line.p2.y) |
right->edge.line.p2 = old->edge.line.p2; |
left->deferred.other = right; |
return; |
} |
|
edges_end (left, top, polygon); |
} |
|
if (right != NULL && ! edges_colinear (left, right)) { |
left->deferred.top = top; |
left->deferred.other = right; |
} |
} |
|
#define is_zero(w) ((w)[0] == 0 || (w)[1] == 0) |
|
static inline void |
active_edges (cairo_bo_edge_t *left, |
int32_t top, |
cairo_polygon_t *polygon) |
{ |
cairo_bo_edge_t *right; |
int winding[2] = {0, 0}; |
|
/* Yes, this is naive. Consider this a placeholder. */ |
|
while (left != NULL) { |
assert (is_zero (winding)); |
|
do { |
winding[left->a_or_b] += left->edge.dir; |
if (! is_zero (winding)) |
break; |
|
if unlikely ((left->deferred.other)) |
edges_end (left, top, polygon); |
|
left = left->next; |
if (! left) |
return; |
} while (1); |
|
right = left->next; |
do { |
if unlikely ((right->deferred.other)) |
edges_end (right, top, polygon); |
|
winding[right->a_or_b] += right->edge.dir; |
if (is_zero (winding)) { |
if (right->next == NULL || |
! edges_colinear (right, right->next)) |
break; |
} |
|
right = right->next; |
} while (1); |
|
edges_start_or_continue (left, right, top, polygon); |
|
left = right->next; |
} |
} |
|
static cairo_status_t |
intersection_sweep (cairo_bo_event_t **start_events, |
int num_events, |
cairo_polygon_t *polygon) |
{ |
cairo_status_t status = CAIRO_STATUS_SUCCESS; /* silence compiler */ |
cairo_bo_event_queue_t event_queue; |
cairo_bo_sweep_line_t sweep_line; |
cairo_bo_event_t *event; |
cairo_bo_edge_t *left, *right; |
cairo_bo_edge_t *e1, *e2; |
|
_cairo_bo_event_queue_init (&event_queue, start_events, num_events); |
_cairo_bo_sweep_line_init (&sweep_line); |
|
while ((event = _cairo_bo_event_dequeue (&event_queue))) { |
if (event->point.y != sweep_line.current_y) { |
active_edges (sweep_line.head, |
sweep_line.current_y, |
polygon); |
sweep_line.current_y = event->point.y; |
} |
|
switch (event->type) { |
case CAIRO_BO_EVENT_TYPE_START: |
e1 = &((cairo_bo_start_event_t *) event)->edge; |
|
status = sweep_line_insert (&sweep_line, e1); |
if (unlikely (status)) |
goto unwind; |
|
status = event_queue_insert_stop (&event_queue, e1); |
if (unlikely (status)) |
goto unwind; |
|
left = e1->prev; |
right = e1->next; |
|
if (left != NULL) { |
status = event_queue_insert_if_intersect_below_current_y (&event_queue, left, e1); |
if (unlikely (status)) |
goto unwind; |
} |
|
if (right != NULL) { |
status = event_queue_insert_if_intersect_below_current_y (&event_queue, e1, right); |
if (unlikely (status)) |
goto unwind; |
} |
|
break; |
|
case CAIRO_BO_EVENT_TYPE_STOP: |
e1 = ((cairo_bo_queue_event_t *) event)->e1; |
_cairo_bo_event_queue_delete (&event_queue, event); |
|
if (e1->deferred.other) |
edges_end (e1, sweep_line.current_y, polygon); |
|
left = e1->prev; |
right = e1->next; |
|
_cairo_bo_sweep_line_delete (&sweep_line, e1); |
|
if (left != NULL && right != NULL) { |
status = event_queue_insert_if_intersect_below_current_y (&event_queue, left, right); |
if (unlikely (status)) |
goto unwind; |
} |
|
break; |
|
case CAIRO_BO_EVENT_TYPE_INTERSECTION: |
e1 = ((cairo_bo_queue_event_t *) event)->e1; |
e2 = ((cairo_bo_queue_event_t *) event)->e2; |
_cairo_bo_event_queue_delete (&event_queue, event); |
|
/* skip this intersection if its edges are not adjacent */ |
if (e2 != e1->next) |
break; |
|
if (e1->deferred.other) |
edges_end (e1, sweep_line.current_y, polygon); |
if (e2->deferred.other) |
edges_end (e2, sweep_line.current_y, polygon); |
|
left = e1->prev; |
right = e2->next; |
|
_cairo_bo_sweep_line_swap (&sweep_line, e1, e2); |
|
/* after the swap e2 is left of e1 */ |
|
if (left != NULL) { |
status = event_queue_insert_if_intersect_below_current_y (&event_queue, left, e2); |
if (unlikely (status)) |
goto unwind; |
} |
|
if (right != NULL) { |
status = event_queue_insert_if_intersect_below_current_y (&event_queue, e1, right); |
if (unlikely (status)) |
goto unwind; |
} |
|
break; |
} |
} |
|
unwind: |
_cairo_bo_event_queue_fini (&event_queue); |
|
return status; |
} |
|
cairo_status_t |
_cairo_polygon_intersect (cairo_polygon_t *a, int winding_a, |
cairo_polygon_t *b, int winding_b) |
{ |
cairo_status_t status; |
cairo_bo_start_event_t stack_events[CAIRO_STACK_ARRAY_LENGTH (cairo_bo_start_event_t)]; |
cairo_bo_start_event_t *events; |
cairo_bo_event_t *stack_event_ptrs[ARRAY_LENGTH (stack_events) + 1]; |
cairo_bo_event_t **event_ptrs; |
int num_events; |
int i, j; |
|
/* XXX lazy */ |
if (winding_a != CAIRO_FILL_RULE_WINDING) { |
status = _cairo_polygon_reduce (a, winding_a); |
if (unlikely (status)) |
return status; |
} |
|
if (winding_b != CAIRO_FILL_RULE_WINDING) { |
status = _cairo_polygon_reduce (b, winding_b); |
if (unlikely (status)) |
return status; |
} |
|
if (unlikely (0 == a->num_edges)) |
return CAIRO_STATUS_SUCCESS; |
|
if (unlikely (0 == b->num_edges)) { |
a->num_edges = 0; |
return CAIRO_STATUS_SUCCESS; |
} |
|
events = stack_events; |
event_ptrs = stack_event_ptrs; |
num_events = a->num_edges + b->num_edges; |
if (num_events > ARRAY_LENGTH (stack_events)) { |
events = _cairo_malloc_ab_plus_c (num_events, |
sizeof (cairo_bo_start_event_t) + |
sizeof (cairo_bo_event_t *), |
sizeof (cairo_bo_event_t *)); |
if (unlikely (events == NULL)) |
return _cairo_error (CAIRO_STATUS_NO_MEMORY); |
|
event_ptrs = (cairo_bo_event_t **) (events + num_events); |
} |
|
j = 0; |
for (i = 0; i < a->num_edges; i++) { |
event_ptrs[j] = (cairo_bo_event_t *) &events[j]; |
|
events[j].type = CAIRO_BO_EVENT_TYPE_START; |
events[j].point.y = a->edges[i].top; |
events[j].point.x = |
_line_compute_intersection_x_for_y (&a->edges[i].line, |
events[j].point.y); |
|
events[j].edge.a_or_b = 0; |
events[j].edge.edge = a->edges[i]; |
events[j].edge.deferred.other = NULL; |
events[j].edge.prev = NULL; |
events[j].edge.next = NULL; |
j++; |
} |
|
for (i = 0; i < b->num_edges; i++) { |
event_ptrs[j] = (cairo_bo_event_t *) &events[j]; |
|
events[j].type = CAIRO_BO_EVENT_TYPE_START; |
events[j].point.y = b->edges[i].top; |
events[j].point.x = |
_line_compute_intersection_x_for_y (&b->edges[i].line, |
events[j].point.y); |
|
events[j].edge.a_or_b = 1; |
events[j].edge.edge = b->edges[i]; |
events[j].edge.deferred.other = NULL; |
events[j].edge.prev = NULL; |
events[j].edge.next = NULL; |
j++; |
} |
assert (j == num_events); |
|
#if 0 |
{ |
FILE *file = fopen ("clip_a.txt", "w"); |
_cairo_debug_print_polygon (file, a); |
fclose (file); |
} |
{ |
FILE *file = fopen ("clip_b.txt", "w"); |
_cairo_debug_print_polygon (file, b); |
fclose (file); |
} |
#endif |
|
a->num_edges = 0; |
status = intersection_sweep (event_ptrs, num_events, a); |
if (events != stack_events) |
free (events); |
|
#if 0 |
{ |
FILE *file = fopen ("clip_result.txt", "w"); |
_cairo_debug_print_polygon (file, a); |
fclose (file); |
} |
#endif |
|
return status; |
} |
|
cairo_status_t |
_cairo_polygon_intersect_with_boxes (cairo_polygon_t *polygon, |
cairo_fill_rule_t *winding, |
cairo_box_t *boxes, |
int num_boxes) |
{ |
cairo_polygon_t b; |
cairo_status_t status; |
int n; |
|
if (num_boxes == 0) { |
polygon->num_edges = 0; |
return CAIRO_STATUS_SUCCESS; |
} |
|
for (n = 0; n < num_boxes; n++) { |
if (polygon->extents.p1.x >= boxes[n].p1.x && |
polygon->extents.p2.x <= boxes[n].p2.x && |
polygon->extents.p1.y >= boxes[n].p1.y && |
polygon->extents.p2.y <= boxes[n].p2.y) |
{ |
return CAIRO_STATUS_SUCCESS; |
} |
} |
|
_cairo_polygon_init (&b, NULL, 0); |
for (n = 0; n < num_boxes; n++) { |
if (boxes[n].p2.x > polygon->extents.p1.x && |
boxes[n].p1.x < polygon->extents.p2.x && |
boxes[n].p2.y > polygon->extents.p1.y && |
boxes[n].p1.y < polygon->extents.p2.y) |
{ |
cairo_point_t p1, p2; |
|
p1.y = boxes[n].p1.y; |
p2.y = boxes[n].p2.y; |
|
p2.x = p1.x = boxes[n].p1.x; |
_cairo_polygon_add_external_edge (&b, &p1, &p2); |
|
p2.x = p1.x = boxes[n].p2.x; |
_cairo_polygon_add_external_edge (&b, &p2, &p1); |
} |
} |
|
status = _cairo_polygon_intersect (polygon, *winding, |
&b, CAIRO_FILL_RULE_WINDING); |
_cairo_polygon_fini (&b); |
|
*winding = CAIRO_FILL_RULE_WINDING; |
return status; |
} |