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/* -*- Mode: c; tab-width: 8; c-basic-offset: 4; indent-tabs-mode: t; -*- */
/*
* Copyright © 2002 Keith Packard
* Copyright © 2007 Red Hat, Inc.
*
* 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
*
* 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 Keith Packard
*
* Contributor(s):
* Keith R. Packard <keithp@keithp.com>
* Carl D. Worth <cworth@cworth.org>
*
* 2002-07-15: Converted from XRenderCompositeDoublePoly to #cairo_trap_t. Carl D. Worth
*/
#include "cairoint.h"
#include "cairo-box-inline.h"
#include "cairo-boxes-private.h"
#include "cairo-error-private.h"
#include "cairo-line-private.h"
#include "cairo-region-private.h"
#include "cairo-slope-private.h"
#include "cairo-traps-private.h"
#include "cairo-spans-private.h"
/* private functions */
void
_cairo_traps_init (cairo_traps_t *traps)
{
VG (VALGRIND_MAKE_MEM_UNDEFINED (traps, sizeof (cairo_traps_t)));
traps->status = CAIRO_STATUS_SUCCESS;
traps->maybe_region = 1;
traps->is_rectilinear = 0;
traps->is_rectangular = 0;
traps->num_traps = 0;
traps->traps_size = ARRAY_LENGTH (traps->traps_embedded);
traps->traps = traps->traps_embedded;
traps->num_limits = 0;
traps->has_intersections = FALSE;
}
void
_cairo_traps_limit (cairo_traps_t *traps,
const cairo_box_t *limits,
int num_limits)
{
int i;
traps->limits = limits;
traps->num_limits = num_limits;
traps->bounds = limits[0];
for (i = 1; i < num_limits; i++)
_cairo_box_add_box (&traps->bounds, &limits[i]);
}
void
_cairo_traps_init_with_clip (cairo_traps_t *traps,
const cairo_clip_t *clip)
{
_cairo_traps_init (traps);
if (clip)
_cairo_traps_limit (traps, clip->boxes, clip->num_boxes);
}
void
_cairo_traps_clear (cairo_traps_t *traps)
{
traps->status = CAIRO_STATUS_SUCCESS;
traps->maybe_region = 1;
traps->is_rectilinear = 0;
traps->is_rectangular = 0;
traps->num_traps = 0;
traps->has_intersections = FALSE;
}
void
_cairo_traps_fini (cairo_traps_t *traps)
{
if (traps->traps != traps->traps_embedded)
free (traps->traps);
VG (VALGRIND_MAKE_MEM_UNDEFINED (traps, sizeof (cairo_traps_t)));
}
/* make room for at least one more trap */
static cairo_bool_t
_cairo_traps_grow (cairo_traps_t *traps)
{
cairo_trapezoid_t *new_traps;
int new_size = 4 * traps->traps_size;
if (CAIRO_INJECT_FAULT ()) {
traps->status = _cairo_error (CAIRO_STATUS_NO_MEMORY);
return FALSE;
}
if (traps->traps == traps->traps_embedded) {
new_traps = _cairo_malloc_ab (new_size, sizeof (cairo_trapezoid_t));
if (new_traps != NULL)
memcpy (new_traps, traps->traps, sizeof (traps->traps_embedded));
} else {
new_traps = _cairo_realloc_ab (traps->traps,
new_size, sizeof (cairo_trapezoid_t));
}
if (unlikely (new_traps == NULL)) {
traps->status = _cairo_error (CAIRO_STATUS_NO_MEMORY);
return FALSE;
}
traps->traps = new_traps;
traps->traps_size = new_size;
return TRUE;
}
void
_cairo_traps_add_trap (cairo_traps_t *traps,
cairo_fixed_t top, cairo_fixed_t bottom,
const cairo_line_t *left,
const cairo_line_t *right)
{
cairo_trapezoid_t *trap;
assert (left->p1.y != left->p2.y);
assert (right->p1.y != right->p2.y);
assert (bottom > top);
if (unlikely (traps->num_traps == traps->traps_size)) {
if (unlikely (! _cairo_traps_grow (traps)))
return;
}
trap = &traps->traps[traps->num_traps++];
trap->top = top;
trap->bottom = bottom;
trap->left = *left;
trap->right = *right;
}
static void
_cairo_traps_add_clipped_trap (cairo_traps_t *traps,
cairo_fixed_t _top, cairo_fixed_t _bottom,
const cairo_line_t *_left,
const cairo_line_t *_right)
{
/* Note: With the goofy trapezoid specification, (where an
* arbitrary two points on the lines can specified for the left
* and right edges), these limit checks would not work in
* general. For example, one can imagine a trapezoid entirely
* within the limits, but with two points used to specify the left
* edge entirely to the right of the limits. Fortunately, for our
* purposes, cairo will never generate such a crazy
* trapezoid. Instead, cairo always uses for its points the
* extreme positions of the edge that are visible on at least some
* trapezoid. With this constraint, it's impossible for both
* points to be outside the limits while the relevant edge is
* entirely inside the limits.
*/
if (traps->num_limits) {
const cairo_box_t *b = &traps->bounds;
cairo_fixed_t top = _top, bottom = _bottom;
cairo_line_t left = *_left, right = *_right;
/* Trivially reject if trapezoid is entirely to the right or
* to the left of the limits. */
if (left.p1.x >= b->p2.x && left.p2.x >= b->p2.x)
return;
if (right.p1.x <= b->p1.x && right.p2.x <= b->p1.x)
return;
/* And reject if the trapezoid is entirely above or below */
if (top >= b->p2.y || bottom <= b->p1.y)
return;
/* Otherwise, clip the trapezoid to the limits. We only clip
* where an edge is entirely outside the limits. If we wanted
* to be more clever, we could handle cases where a trapezoid
* edge intersects the edge of the limits, but that would
* require slicing this trapezoid into multiple trapezoids,
* and I'm not sure the effort would be worth it. */
if (top < b->p1.y)
top = b->p1.y;
if (bottom > b->p2.y)
bottom = b->p2.y;
if (left.p1.x <= b->p1.x && left.p2.x <= b->p1.x)
left.p1.x = left.p2.x = b->p1.x;
if (right.p1.x >= b->p2.x && right.p2.x >= b->p2.x)
right.p1.x = right.p2.x = b->p2.x;
/* Trivial discards for empty trapezoids that are likely to
* be produced by our tessellators (most notably convex_quad
* when given a simple rectangle).
*/
if (top >= bottom)
return;
/* cheap colinearity check */
if (right.p1.x <= left.p1.x && right.p1.y == left.p1.y &&
right.p2.x <= left.p2.x && right.p2.y == left.p2.y)
return;
_cairo_traps_add_trap (traps, top, bottom, &left, &right);
} else
_cairo_traps_add_trap (traps, _top, _bottom, _left, _right);
}
static int
_compare_point_fixed_by_y (const void *av, const void *bv)
{
const cairo_point_t *a = av, *b = bv;
int ret = a->y - b->y;
if (ret == 0)
ret = a->x - b->x;
return ret;
}
void
_cairo_traps_tessellate_convex_quad (cairo_traps_t *traps,
const cairo_point_t q[4])
{
int a, b, c, d;
int i;
cairo_slope_t ab, ad;
cairo_bool_t b_left_of_d;
cairo_line_t left;
cairo_line_t right;
/* Choose a as a point with minimal y */
a = 0;
for (i = 1; i < 4; i++)
if (_compare_point_fixed_by_y (&q[i], &q[a]) < 0)
a = i;
/* b and d are adjacent to a, while c is opposite */
b = (a + 1) % 4;
c = (a + 2) % 4;
d = (a + 3) % 4;
/* Choose between b and d so that b.y is less than d.y */
if (_compare_point_fixed_by_y (&q[d], &q[b]) < 0) {
b = (a + 3) % 4;
d = (a + 1) % 4;
}
/* Without freedom left to choose anything else, we have four
* cases to tessellate.
*
* First, we have to determine the Y-axis sort of the four
* vertices, (either abcd or abdc). After that we need to determine
* which edges will be "left" and which will be "right" in the
* resulting trapezoids. This can be determined by computing a
* slope comparison of ab and ad to determine if b is left of d or
* not.
*
* Note that "left of" here is in the sense of which edges should
* be the left vs. right edges of the trapezoid. In particular, b
* left of d does *not* mean that b.x is less than d.x.
*
* This should hopefully be made clear in the lame ASCII art
* below. Since the same slope comparison is used in all cases, we
* compute it before testing for the Y-value sort. */
/* Note: If a == b then the ab slope doesn't give us any
* information. In that case, we can replace it with the ac (or
* equivalenly the bc) slope which gives us exactly the same
* information we need. At worst the names of the identifiers ab
* and b_left_of_d are inaccurate in this case, (would be ac, and
* c_left_of_d). */
if (q[a].x == q[b].x && q[a].y == q[b].y)
_cairo_slope_init (&ab, &q[a], &q[c]);
else
_cairo_slope_init (&ab, &q[a], &q[b]);
_cairo_slope_init (&ad, &q[a], &q[d]);
b_left_of_d = _cairo_slope_compare (&ab, &ad) > 0;
if (q[c].y <= q[d].y) {
if (b_left_of_d) {
/* Y-sort is abcd and b is left of d, (slope(ab) > slope (ad))
*
* top bot left right
* _a a a
* / / /| |\ a.y b.y ab ad
* b / b | b \
* / / | | \ \ b.y c.y bc ad
* c / c | c \
* | / \| \ \ c.y d.y cd ad
* d d d
*/
left.p1 = q[a]; left.p2 = q[b];
right.p1 = q[a]; right.p2 = q[d];
_cairo_traps_add_clipped_trap (traps, q[a].y, q[b].y, &left, &right);
left.p1 = q[b]; left.p2 = q[c];
_cairo_traps_add_clipped_trap (traps, q[b].y, q[c].y, &left, &right);
left.p1 = q[c]; left.p2 = q[d];
_cairo_traps_add_clipped_trap (traps, q[c].y, q[d].y, &left, &right);
} else {
/* Y-sort is abcd and b is right of d, (slope(ab) <= slope (ad))
*
* a a a_
* /| |\ \ \ a.y b.y ad ab
* / b | b \ b
* / / | | \ \ b.y c.y ad bc
* / c | c \ c
* / / |/ \ | c.y d.y ad cd
* d d d
*/
left.p1 = q[a]; left.p2 = q[d];
right.p1 = q[a]; right.p2 = q[b];
_cairo_traps_add_clipped_trap (traps, q[a].y, q[b].y, &left, &right);
right.p1 = q[b]; right.p2 = q[c];
_cairo_traps_add_clipped_trap (traps, q[b].y, q[c].y, &left, &right);
right.p1 = q[c]; right.p2 = q[d];
_cairo_traps_add_clipped_trap (traps, q[c].y, q[d].y, &left, &right);
}
} else {
if (b_left_of_d) {
/* Y-sort is abdc and b is left of d, (slope (ab) > slope (ad))
*
* a a a
* // / \ |\ a.y b.y ab ad
* /b/ b \ b \
* / / \ \ \ \ b.y d.y bc ad
* /d/ \ d \ d
* // \ / \| d.y c.y bc dc
* c c c
*/
left.p1 = q[a]; left.p2 = q[b];
right.p1 = q[a]; right.p2 = q[d];
_cairo_traps_add_clipped_trap (traps, q[a].y, q[b].y, &left, &right);
left.p1 = q[b]; left.p2 = q[c];
_cairo_traps_add_clipped_trap (traps, q[b].y, q[d].y, &left, &right);
right.p1 = q[d]; right.p2 = q[c];
_cairo_traps_add_clipped_trap (traps, q[d].y, q[c].y, &left, &right);
} else {
/* Y-sort is abdc and b is right of d, (slope (ab) <= slope (ad))
*
* a a a
* /| / \ \\ a.y b.y ad ab
* / b / b \b\
* / / / / \ \ b.y d.y ad bc
* d / d / \d\
* |/ \ / \\ d.y c.y dc bc
* c c c
*/
left.p1 = q[a]; left.p2 = q[d];
right.p1 = q[a]; right.p2 = q[b];
_cairo_traps_add_clipped_trap (traps, q[a].y, q[b].y, &left, &right);
right.p1 = q[b]; right.p2 = q[c];
_cairo_traps_add_clipped_trap (traps, q[b].y, q[d].y, &left, &right);
left.p1 = q[d]; left.p2 = q[c];
_cairo_traps_add_clipped_trap (traps, q[d].y, q[c].y, &left, &right);
}
}
}
static void add_tri (cairo_traps_t *traps,
int y1, int y2,
const cairo_line_t *left,
const cairo_line_t *right)
{
if (y2 < y1) {
int tmp = y1;
y1 = y2;
y2 = tmp;
}
if (_cairo_lines_compare_at_y (left, right, y1) > 0) {
const cairo_line_t *tmp = left;
left = right;
right = tmp;
}
_cairo_traps_add_clipped_trap (traps, y1, y2, left, right);
}
void
_cairo_traps_tessellate_triangle_with_edges (cairo_traps_t *traps,
const cairo_point_t t[3],
const cairo_point_t edges[4])
{
cairo_line_t lines[3];
if (edges[0].y <= edges[1].y) {
lines[0].p1 = edges[0];
lines[0].p2 = edges[1];
} else {
lines[0].p1 = edges[1];
lines[0].p2 = edges[0];
}
if (edges[2].y <= edges[3].y) {
lines[1].p1 = edges[2];
lines[1].p2 = edges[3];
} else {
lines[1].p1 = edges[3];
lines[1].p2 = edges[2];
}
if (t[1].y == t[2].y) {
add_tri (traps, t[0].y, t[1].y, &lines[0], &lines[1]);
return;
}
if (t[1].y <= t[2].y) {
lines[2].p1 = t[1];
lines[2].p2 = t[2];
} else {
lines[2].p1 = t[2];
lines[2].p2 = t[1];
}
if (((t[1].y - t[0].y) < 0) ^ ((t[2].y - t[0].y) < 0)) {
add_tri (traps, t[0].y, t[1].y, &lines[0], &lines[2]);
add_tri (traps, t[0].y, t[2].y, &lines[1], &lines[2]);
} else if (abs(t[1].y - t[0].y) < abs(t[2].y - t[0].y)) {
add_tri (traps, t[0].y, t[1].y, &lines[0], &lines[1]);
add_tri (traps, t[1].y, t[2].y, &lines[2], &lines[1]);
} else {
add_tri (traps, t[0].y, t[2].y, &lines[1], &lines[0]);
add_tri (traps, t[1].y, t[2].y, &lines[2], &lines[0]);
}
}
/**
* _cairo_traps_init_boxes:
* @traps: a #cairo_traps_t
* @box: an array box that will each be converted to a single trapezoid
* to store in @traps.
*
* Initializes a #cairo_traps_t to contain an array of rectangular
* trapezoids.
**/
cairo_status_t
_cairo_traps_init_boxes (cairo_traps_t *traps,
const cairo_boxes_t *boxes)
{
cairo_trapezoid_t *trap;
const struct _cairo_boxes_chunk *chunk;
_cairo_traps_init (traps);
while (traps->traps_size < boxes->num_boxes) {
if (unlikely (! _cairo_traps_grow (traps))) {
_cairo_traps_fini (traps);
return _cairo_error (CAIRO_STATUS_NO_MEMORY);
}
}
traps->num_traps = boxes->num_boxes;
traps->is_rectilinear = TRUE;
traps->is_rectangular = TRUE;
traps->maybe_region = boxes->is_pixel_aligned;
trap = &traps->traps[0];
for (chunk = &boxes->chunks; chunk != NULL; chunk = chunk->next) {
const cairo_box_t *box;
int i;
box = chunk->base;
for (i = 0; i < chunk->count; i++) {
trap->top = box->p1.y;
trap->bottom = box->p2.y;
trap->left.p1 = box->p1;
trap->left.p2.x = box->p1.x;
trap->left.p2.y = box->p2.y;
trap->right.p1.x = box->p2.x;
trap->right.p1.y = box->p1.y;
trap->right.p2 = box->p2;
box++, trap++;
}
}
return CAIRO_STATUS_SUCCESS;
}
cairo_status_t
_cairo_traps_tessellate_rectangle (cairo_traps_t *traps,
const cairo_point_t *top_left,
const cairo_point_t *bottom_right)
{
cairo_line_t left;
cairo_line_t right;
cairo_fixed_t top, bottom;
if (top_left->y == bottom_right->y)
return CAIRO_STATUS_SUCCESS;
if (top_left->x == bottom_right->x)
return CAIRO_STATUS_SUCCESS;
left.p1.x = left.p2.x = top_left->x;
left.p1.y = right.p1.y = top_left->y;
right.p1.x = right.p2.x = bottom_right->x;
left.p2.y = right.p2.y = bottom_right->y;
top = top_left->y;
bottom = bottom_right->y;
if (traps->num_limits) {
cairo_bool_t reversed;
int n;
if (top >= traps->bounds.p2.y || bottom <= traps->bounds.p1.y)
return CAIRO_STATUS_SUCCESS;
/* support counter-clockwise winding for rectangular tessellation */
reversed = top_left->x > bottom_right->x;
if (reversed) {
right.p1.x = right.p2.x = top_left->x;
left.p1.x = left.p2.x = bottom_right->x;
}
if (left.p1.x >= traps->bounds.p2.x || right.p1.x <= traps->bounds.p1.x)
return CAIRO_STATUS_SUCCESS;
for (n = 0; n < traps->num_limits; n++) {
const cairo_box_t *limits = &traps->limits[n];
cairo_line_t _left, _right;
cairo_fixed_t _top, _bottom;
if (top >= limits->p2.y)
continue;
if (bottom <= limits->p1.y)
continue;
/* Trivially reject if trapezoid is entirely to the right or
* to the left of the limits. */
if (left.p1.x >= limits->p2.x)
continue;
if (right.p1.x <= limits->p1.x)
continue;
/* Otherwise, clip the trapezoid to the limits. */
_top = top;
if (_top < limits->p1.y)
_top = limits->p1.y;
_bottom = bottom;
if (_bottom > limits->p2.y)
_bottom = limits->p2.y;
if (_bottom <= _top)
continue;
_left = left;
if (_left.p1.x < limits->p1.x) {
_left.p1.x = limits->p1.x;
_left.p1.y = limits->p1.y;
_left.p2.x = limits->p1.x;
_left.p2.y = limits->p2.y;
}
_right = right;
if (_right.p1.x > limits->p2.x) {
_right.p1.x = limits->p2.x;
_right.p1.y = limits->p1.y;
_right.p2.x = limits->p2.x;
_right.p2.y = limits->p2.y;
}
if (left.p1.x >= right.p1.x)
continue;
if (reversed)
_cairo_traps_add_trap (traps, _top, _bottom, &_right, &_left);
else
_cairo_traps_add_trap (traps, _top, _bottom, &_left, &_right);
}
} else {
_cairo_traps_add_trap (traps, top, bottom, &left, &right);
}
return traps->status;
}
void
_cairo_traps_translate (cairo_traps_t *traps, int x, int y)
{
cairo_fixed_t xoff, yoff;
cairo_trapezoid_t *t;
int i;
/* Ugh. The cairo_composite/(Render) interface doesn't allow
an offset for the trapezoids. Need to manually shift all
the coordinates to align with the offset origin of the
intermediate surface. */
xoff = _cairo_fixed_from_int (x);
yoff = _cairo_fixed_from_int (y);
for (i = 0, t = traps->traps; i < traps->num_traps; i++, t++) {
t->top += yoff;
t->bottom += yoff;
t->left.p1.x += xoff;
t->left.p1.y += yoff;
t->left.p2.x += xoff;
t->left.p2.y += yoff;
t->right.p1.x += xoff;
t->right.p1.y += yoff;
t->right.p2.x += xoff;
t->right.p2.y += yoff;
}
}
void
_cairo_trapezoid_array_translate_and_scale (cairo_trapezoid_t *offset_traps,
cairo_trapezoid_t *src_traps,
int num_traps,
double tx, double ty,
double sx, double sy)
{
int i;
cairo_fixed_t xoff = _cairo_fixed_from_double (tx);
cairo_fixed_t yoff = _cairo_fixed_from_double (ty);
if (sx == 1.0 && sy == 1.0) {
for (i = 0; i < num_traps; i++) {
offset_traps[i].top = src_traps[i].top + yoff;
offset_traps[i].bottom = src_traps[i].bottom + yoff;
offset_traps[i].left.p1.x = src_traps[i].left.p1.x + xoff;
offset_traps[i].left.p1.y = src_traps[i].left.p1.y + yoff;
offset_traps[i].left.p2.x = src_traps[i].left.p2.x + xoff;
offset_traps[i].left.p2.y = src_traps[i].left.p2.y + yoff;
offset_traps[i].right.p1.x = src_traps[i].right.p1.x + xoff;
offset_traps[i].right.p1.y = src_traps[i].right.p1.y + yoff;
offset_traps[i].right.p2.x = src_traps[i].right.p2.x + xoff;
offset_traps[i].right.p2.y = src_traps[i].right.p2.y + yoff;
}
} else {
cairo_fixed_t xsc = _cairo_fixed_from_double (sx);
cairo_fixed_t ysc = _cairo_fixed_from_double (sy);
for (i = 0; i < num_traps; i++) {
offset_traps[i].top = _cairo_fixed_mul (src_traps[i].top + yoff, ysc);
offset_traps[i].bottom = _cairo_fixed_mul (src_traps[i].bottom + yoff, ysc);
offset_traps[i].left.p1.x = _cairo_fixed_mul (src_traps[i].left.p1.x + xoff, xsc);
offset_traps[i].left.p1.y = _cairo_fixed_mul (src_traps[i].left.p1.y + yoff, ysc);
offset_traps[i].left.p2.x = _cairo_fixed_mul (src_traps[i].left.p2.x + xoff, xsc);
offset_traps[i].left.p2.y = _cairo_fixed_mul (src_traps[i].left.p2.y + yoff, ysc);
offset_traps[i].right.p1.x = _cairo_fixed_mul (src_traps[i].right.p1.x + xoff, xsc);
offset_traps[i].right.p1.y = _cairo_fixed_mul (src_traps[i].right.p1.y + yoff, ysc);
offset_traps[i].right.p2.x = _cairo_fixed_mul (src_traps[i].right.p2.x + xoff, xsc);
offset_traps[i].right.p2.y = _cairo_fixed_mul (src_traps[i].right.p2.y + yoff, ysc);
}
}
}
static cairo_bool_t
_cairo_trap_contains (cairo_trapezoid_t *t, cairo_point_t *pt)
{
cairo_slope_t slope_left, slope_pt, slope_right;
if (t->top > pt->y)
return FALSE;
if (t->bottom < pt->y)
return FALSE;
_cairo_slope_init (&slope_left, &t->left.p1, &t->left.p2);
_cairo_slope_init (&slope_pt, &t->left.p1, pt);
if (_cairo_slope_compare (&slope_left, &slope_pt) < 0)
return FALSE;
_cairo_slope_init (&slope_right, &t->right.p1, &t->right.p2);
_cairo_slope_init (&slope_pt, &t->right.p1, pt);
if (_cairo_slope_compare (&slope_pt, &slope_right) < 0)
return FALSE;
return TRUE;
}
cairo_bool_t
_cairo_traps_contain (const cairo_traps_t *traps,
double x, double y)
{
int i;
cairo_point_t point;
point.x = _cairo_fixed_from_double (x);
point.y = _cairo_fixed_from_double (y);
for (i = 0; i < traps->num_traps; i++) {
if (_cairo_trap_contains (&traps->traps[i], &point))
return TRUE;
}
return FALSE;
}
static cairo_fixed_t
_line_compute_intersection_x_for_y (const cairo_line_t *line,
cairo_fixed_t y)
{
return _cairo_edge_compute_intersection_x_for_y (&line->p1, &line->p2, y);
}
void
_cairo_traps_extents (const cairo_traps_t *traps,
cairo_box_t *extents)
{
int i;
if (traps->num_traps == 0) {
extents->p1.x = extents->p1.y = 0;
extents->p2.x = extents->p2.y = 0;
return;
}
extents->p1.x = extents->p1.y = INT32_MAX;
extents->p2.x = extents->p2.y = INT32_MIN;
for (i = 0; i < traps->num_traps; i++) {
const cairo_trapezoid_t *trap = &traps->traps[i];
if (trap->top < extents->p1.y)
extents->p1.y = trap->top;
if (trap->bottom > extents->p2.y)
extents->p2.y = trap->bottom;
if (trap->left.p1.x < extents->p1.x) {
cairo_fixed_t x = trap->left.p1.x;
if (trap->top != trap->left.p1.y) {
x = _line_compute_intersection_x_for_y (&trap->left,
trap->top);
if (x < extents->p1.x)
extents->p1.x = x;
} else
extents->p1.x = x;
}
if (trap->left.p2.x < extents->p1.x) {
cairo_fixed_t x = trap->left.p2.x;
if (trap->bottom != trap->left.p2.y) {
x = _line_compute_intersection_x_for_y (&trap->left,
trap->bottom);
if (x < extents->p1.x)
extents->p1.x = x;
} else
extents->p1.x = x;
}
if (trap->right.p1.x > extents->p2.x) {
cairo_fixed_t x = trap->right.p1.x;
if (trap->top != trap->right.p1.y) {
x = _line_compute_intersection_x_for_y (&trap->right,
trap->top);
if (x > extents->p2.x)
extents->p2.x = x;
} else
extents->p2.x = x;
}
if (trap->right.p2.x > extents->p2.x) {
cairo_fixed_t x = trap->right.p2.x;
if (trap->bottom != trap->right.p2.y) {
x = _line_compute_intersection_x_for_y (&trap->right,
trap->bottom);
if (x > extents->p2.x)
extents->p2.x = x;
} else
extents->p2.x = x;
}
}
}
static cairo_bool_t
_mono_edge_is_vertical (const cairo_line_t *line)
{
return _cairo_fixed_integer_round_down (line->p1.x) == _cairo_fixed_integer_round_down (line->p2.x);
}
static cairo_bool_t
_traps_are_pixel_aligned (cairo_traps_t *traps,
cairo_antialias_t antialias)
{
int i;
if (antialias == CAIRO_ANTIALIAS_NONE) {
for (i = 0; i < traps->num_traps; i++) {
if (! _mono_edge_is_vertical (&traps->traps[i].left) ||
! _mono_edge_is_vertical (&traps->traps[i].right))
{
traps->maybe_region = FALSE;
return FALSE;
}
}
} else {
for (i = 0; i < traps->num_traps; i++) {
if (traps->traps[i].left.p1.x != traps->traps[i].left.p2.x ||
traps->traps[i].right.p1.x != traps->traps[i].right.p2.x ||
! _cairo_fixed_is_integer (traps->traps[i].top) ||
! _cairo_fixed_is_integer (traps->traps[i].bottom) ||
! _cairo_fixed_is_integer (traps->traps[i].left.p1.x) ||
! _cairo_fixed_is_integer (traps->traps[i].right.p1.x))
{
traps->maybe_region = FALSE;
return FALSE;
}
}
}
return TRUE;
}
/**
* _cairo_traps_extract_region:
* @traps: a #cairo_traps_t
* @region: a #cairo_region_t
*
* Determines if a set of trapezoids are exactly representable as a
* cairo region. If so, the passed-in region is initialized to
* the area representing the given traps. It should be finalized
* with cairo_region_fini(). If not, %CAIRO_INT_STATUS_UNSUPPORTED
* is returned.
*
* Return value: %CAIRO_STATUS_SUCCESS, %CAIRO_INT_STATUS_UNSUPPORTED
* or %CAIRO_STATUS_NO_MEMORY
**/
cairo_int_status_t
_cairo_traps_extract_region (cairo_traps_t *traps,
cairo_antialias_t antialias,
cairo_region_t **region)
{
cairo_rectangle_int_t stack_rects[CAIRO_STACK_ARRAY_LENGTH (cairo_rectangle_int_t)];
cairo_rectangle_int_t *rects = stack_rects;
cairo_int_status_t status;
int i, rect_count;
/* we only treat this a hint... */
if (antialias != CAIRO_ANTIALIAS_NONE && ! traps->maybe_region)
return CAIRO_INT_STATUS_UNSUPPORTED;
if (! _traps_are_pixel_aligned (traps, antialias)) {
traps->maybe_region = FALSE;
return CAIRO_INT_STATUS_UNSUPPORTED;
}
if (traps->num_traps > ARRAY_LENGTH (stack_rects)) {
rects = _cairo_malloc_ab (traps->num_traps, sizeof (cairo_rectangle_int_t));
if (unlikely (rects == NULL))
return _cairo_error (CAIRO_STATUS_NO_MEMORY);
}
rect_count = 0;
for (i = 0; i < traps->num_traps; i++) {
int x1, y1, x2, y2;
if (antialias == CAIRO_ANTIALIAS_NONE) {
x1 = _cairo_fixed_integer_round_down (traps->traps[i].left.p1.x);
y1 = _cairo_fixed_integer_round_down (traps->traps[i].top);
x2 = _cairo_fixed_integer_round_down (traps->traps[i].right.p1.x);
y2 = _cairo_fixed_integer_round_down (traps->traps[i].bottom);
} else {
x1 = _cairo_fixed_integer_part (traps->traps[i].left.p1.x);
y1 = _cairo_fixed_integer_part (traps->traps[i].top);
x2 = _cairo_fixed_integer_part (traps->traps[i].right.p1.x);
y2 = _cairo_fixed_integer_part (traps->traps[i].bottom);
}
if (x2 > x1 && y2 > y1) {
rects[rect_count].x = x1;
rects[rect_count].y = y1;
rects[rect_count].width = x2 - x1;
rects[rect_count].height = y2 - y1;
rect_count++;
}
}
*region = cairo_region_create_rectangles (rects, rect_count);
status = (*region)->status;
if (rects != stack_rects)
free (rects);
return status;
}
cairo_bool_t
_cairo_traps_to_boxes (cairo_traps_t *traps,
cairo_antialias_t antialias,
cairo_boxes_t *boxes)
{
int i;
for (i = 0; i < traps->num_traps; i++) {
if (traps->traps[i].left.p1.x != traps->traps[i].left.p2.x ||
traps->traps[i].right.p1.x != traps->traps[i].right.p2.x)
return FALSE;
}
_cairo_boxes_init (boxes);
boxes->num_boxes = traps->num_traps;
boxes->chunks.base = (cairo_box_t *) traps->traps;
boxes->chunks.count = traps->num_traps;
boxes->chunks.size = traps->num_traps;
if (antialias != CAIRO_ANTIALIAS_NONE) {
for (i = 0; i < traps->num_traps; i++) {
/* Note the traps and boxes alias so we need to take the local copies first. */
cairo_fixed_t x1 = traps->traps[i].left.p1.x;
cairo_fixed_t x2 = traps->traps[i].right.p1.x;
cairo_fixed_t y1 = traps->traps[i].top;
cairo_fixed_t y2 = traps->traps[i].bottom;
boxes->chunks.base[i].p1.x = x1;
boxes->chunks.base[i].p1.y = y1;
boxes->chunks.base[i].p2.x = x2;
boxes->chunks.base[i].p2.y = y2;
if (boxes->is_pixel_aligned) {
boxes->is_pixel_aligned =
_cairo_fixed_is_integer (x1) && _cairo_fixed_is_integer (y1) &&
_cairo_fixed_is_integer (x2) && _cairo_fixed_is_integer (y2);
}
}
} else {
boxes->is_pixel_aligned = TRUE;
for (i = 0; i < traps->num_traps; i++) {
/* Note the traps and boxes alias so we need to take the local copies first. */
cairo_fixed_t x1 = traps->traps[i].left.p1.x;
cairo_fixed_t x2 = traps->traps[i].right.p1.x;
cairo_fixed_t y1 = traps->traps[i].top;
cairo_fixed_t y2 = traps->traps[i].bottom;
/* round down here to match Pixman's behavior when using traps. */
boxes->chunks.base[i].p1.x = _cairo_fixed_round_down (x1);
boxes->chunks.base[i].p1.y = _cairo_fixed_round_down (y1);
boxes->chunks.base[i].p2.x = _cairo_fixed_round_down (x2);
boxes->chunks.base[i].p2.y = _cairo_fixed_round_down (y2);
}
}
return TRUE;
}
/* moves trap points such that they become the actual corners of the trapezoid */
static void
_sanitize_trap (cairo_trapezoid_t *t)
{
cairo_trapezoid_t s = *t;
#define FIX(lr, tb, p) \
if (t->lr.p.y != t->tb) { \
t->lr.p.x = s.lr.p2.x + _cairo_fixed_mul_div_floor (s.lr.p1.x - s.lr.p2.x, s.tb - s.lr.p2.y, s.lr.p1.y - s.lr.p2.y); \
t->lr.p.y = s.tb; \
}
FIX (left, top, p1);
FIX (left, bottom, p2);
FIX (right, top, p1);
FIX (right, bottom, p2);
}
cairo_private cairo_status_t
_cairo_traps_path (const cairo_traps_t *traps,
cairo_path_fixed_t *path)
{
int i;
for (i = 0; i < traps->num_traps; i++) {
cairo_status_t status;
cairo_trapezoid_t trap = traps->traps[i];
if (trap.top == trap.bottom)
continue;
_sanitize_trap (&trap);
status = _cairo_path_fixed_move_to (path, trap.left.p1.x, trap.top);
if (unlikely (status)) return status;
status = _cairo_path_fixed_line_to (path, trap.right.p1.x, trap.top);
if (unlikely (status)) return status;
status = _cairo_path_fixed_line_to (path, trap.right.p2.x, trap.bottom);
if (unlikely (status)) return status;
status = _cairo_path_fixed_line_to (path, trap.left.p2.x, trap.bottom);
if (unlikely (status)) return status;
status = _cairo_path_fixed_close_path (path);
if (unlikely (status)) return status;
}
return CAIRO_STATUS_SUCCESS;
}
void
_cairo_debug_print_traps (FILE *file, const cairo_traps_t *traps)
{
cairo_box_t extents;
int n;
#if 0
if (traps->has_limits) {
printf ("%s: limits=(%d, %d, %d, %d)\n",
filename,
traps->limits.p1.x, traps->limits.p1.y,
traps->limits.p2.x, traps->limits.p2.y);
}
#endif
_cairo_traps_extents (traps, &extents);
fprintf (file, "extents=(%d, %d, %d, %d)\n",
extents.p1.x, extents.p1.y,
extents.p2.x, extents.p2.y);
for (n = 0; n < traps->num_traps; n++) {
fprintf (file, "%d %d L:(%d, %d), (%d, %d) R:(%d, %d), (%d, %d)\n",
traps->traps[n].top,
traps->traps[n].bottom,
traps->traps[n].left.p1.x,
traps->traps[n].left.p1.y,
traps->traps[n].left.p2.x,
traps->traps[n].left.p2.y,
traps->traps[n].right.p1.x,
traps->traps[n].right.p1.y,
traps->traps[n].right.p2.x,
traps->traps[n].right.p2.y);
}
}
struct cairo_trap_renderer {
cairo_span_renderer_t base;
cairo_traps_t *traps;
};
static cairo_status_t
span_to_traps (void *abstract_renderer, int y, int h,
const cairo_half_open_span_t *spans, unsigned num_spans)
{
struct cairo_trap_renderer *r = abstract_renderer;
cairo_fixed_t top, bot;
if (num_spans == 0)
return CAIRO_STATUS_SUCCESS;
top = _cairo_fixed_from_int (y);
bot = _cairo_fixed_from_int (y + h);
do {
if (spans[0].coverage) {
cairo_fixed_t x0 = _cairo_fixed_from_int(spans[0].x);
cairo_fixed_t x1 = _cairo_fixed_from_int(spans[1].x);
cairo_line_t left = { { x0, top }, { x0, bot } },
right = { { x1, top }, { x1, bot } };
_cairo_traps_add_trap (r->traps, top, bot, &left, &right);
}
spans++;
} while (--num_spans > 1);
return CAIRO_STATUS_SUCCESS;
}
cairo_int_status_t
_cairo_rasterise_polygon_to_traps (cairo_polygon_t *polygon,
cairo_fill_rule_t fill_rule,
cairo_antialias_t antialias,
cairo_traps_t *traps)
{
struct cairo_trap_renderer renderer;
cairo_scan_converter_t *converter;
cairo_int_status_t status;
cairo_rectangle_int_t r;
TRACE ((stderr, "%s: fill_rule=%d, antialias=%d\n",
__FUNCTION__, fill_rule, antialias));
assert(antialias == CAIRO_ANTIALIAS_NONE);
renderer.traps = traps;
renderer.base.render_rows = span_to_traps;
_cairo_box_round_to_rectangle (&polygon->extents, &r);
converter = _cairo_mono_scan_converter_create (r.x, r.y,
r.x + r.width,
r.y + r.height,
fill_rule);
status = _cairo_mono_scan_converter_add_polygon (converter, polygon);
if (likely (status == CAIRO_INT_STATUS_SUCCESS))
status = converter->generate (converter, &renderer.base);
converter->destroy (converter);
return status;
}