| /* |
| * 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 struct _cairo_bo_intersect_ordinate { |
| int32_t ordinate; |
| enum { EXCESS = -1, EXACT = 0, DEFAULT = 1 } approx; |
| } 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 = -1, |
| 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_bo_intersect_point_t point; |
| } cairo_bo_event_t; |
| |
| typedef struct _cairo_bo_start_event { |
| cairo_bo_event_type_t type; |
| cairo_bo_intersect_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_bo_intersect_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_intersect_point_t const *a, |
| cairo_bo_intersect_point_t const *b) |
| { |
| int cmp; |
| |
| cmp = a->y.ordinate - b->y.ordinate; |
| if (cmp) |
| return cmp; |
| |
| cmp = a->y.approx - b->y.approx; |
| if (cmp) |
| return cmp; |
| |
| return a->x.ordinate - b->x.ordinate; |
| } |
| |
| /* 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)); |
| } |
| |
| static inline cairo_bo_intersect_ordinate_t |
| round_to_nearest (cairo_quorem64_t d, |
| cairo_int64_t den) |
| { |
| cairo_bo_intersect_ordinate_t ordinate; |
| int32_t quo = d.quo; |
| cairo_int64_t drem_2 = _cairo_int64_mul (d.rem, _cairo_int32_to_int64 (2)); |
| |
| /* assert (! _cairo_int64_negative (den));*/ |
| |
| if (_cairo_int64_lt (drem_2, _cairo_int64_negate (den))) { |
| quo -= 1; |
| drem_2 = _cairo_int64_negate (drem_2); |
| } else if (_cairo_int64_le (den, drem_2)) { |
| quo += 1; |
| drem_2 = _cairo_int64_negate (drem_2); |
| } |
| |
| ordinate.ordinate = quo; |
| ordinate.approx = _cairo_int64_is_zero (drem_2) ? EXACT : _cairo_int64_negative (drem_2) ? EXCESS : DEFAULT; |
| |
| return ordinate; |
| } |
| |
| /* 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_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_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; |
| |
| intersection->x = round_to_nearest (qr, den_det); |
| |
| /* 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; |
| |
| intersection->y = round_to_nearest (qr, den_det); |
| |
| 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; |
| |
| return a.approx; /* == EXCESS ? -1 : a.approx == EXACT ? 0 : 1;*/ |
| } |
| |
| /* 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) |
| { |
| return _cairo_bo_intersect_ordinate_32_compare (point->y, |
| edge->edge.bottom) < 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_intersect_point_t *intersection) |
| { |
| if (! intersect_lines (a, b, intersection)) |
| return FALSE; |
| |
| if (! _cairo_bo_edge_contains_intersect_point (a, intersection)) |
| return FALSE; |
| |
| if (! _cairo_bo_edge_contains_intersect_point (b, intersection)) |
| return FALSE; |
| |
| 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 ? -1 : a == b ? 0 : 1; |
| } |
| |
| 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_bo_intersect_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_intersect_point_t point; |
| |
| point.y.ordinate = edge->edge.bottom; |
| point.y.approx = EXACT; |
| point.x.ordinate = _line_compute_intersection_x_for_y (&edge->edge.line, |
| point.y.ordinate); |
| point.x.approx = EXACT; |
| |
| 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_intersect_point_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.ordinate != sweep_line.current_y) { |
| active_edges (sweep_line.head, |
| sweep_line.current_y, |
| polygon); |
| sweep_line.current_y = event->point.y.ordinate; |
| } |
| |
| 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.ordinate = a->edges[i].top; |
| events[j].point.y.approx = EXACT; |
| events[j].point.x.ordinate = |
| _line_compute_intersection_x_for_y (&a->edges[i].line, |
| events[j].point.y.ordinate); |
| events[j].point.x.approx = EXACT; |
| |
| 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.ordinate = b->edges[i].top; |
| events[j].point.y.approx = EXACT; |
| events[j].point.x.ordinate = |
| _line_compute_intersection_x_for_y (&b->edges[i].line, |
| events[j].point.y.ordinate); |
| events[j].point.x.approx = EXACT; |
| |
| 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; |
| } |