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polygon: Assert that we add edges that are wholly contained by the clip

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Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
This commit is contained in:
Chris Wilson 2011-12-06 14:44:57 +00:00
parent 6b472e12ae
commit 19dd6e7e53
1 changed files with 42 additions and 1 deletions
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43
src/cairo-polygon.c
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@ -41,6 +41,38 @@
#include "cairo-contour-private.h"
#include "cairo-error-private.h"
#define DEBUG_POLYGON 0
#if DEBUG_POLYGON && !NDEBUG
static void
assert_last_edge_is_valid(cairo_polygon_t *polygon,
const cairo_box_t *limit)
{
cairo_edge_t *edge;
cairo_fixed_t x;
edge = &polygon->edges[polygon->num_edges-1];
assert (edge->bottom > edge->top);
assert (edge->top >= limit->p1.y);
assert (edge->bottom <= limit->p2.y);
x = _cairo_edge_compute_intersection_x_for_y (&edge->line.p1,
&edge->line.p2,
edge->top);
assert (x >= limit->p1.x);
assert (x <= limit->p2.x);
x = _cairo_edge_compute_intersection_x_for_y (&edge->line.p1,
&edge->line.p2,
edge->bottom);
assert (x >= limit->p1.x);
assert (x <= limit->p2.x);
}
#else
#define assert_last_edge_is_valid(p, l)
#endif
static void
_cairo_polygon_add_edge (cairo_polygon_t *polygon,
const cairo_point_t *p1,
@ -340,16 +372,19 @@ _add_clipped_edge (cairo_polygon_t *polygon,
* clip vertically by restricting top and bottom */
_add_edge (polygon, p1, p2, top_y, bot_y, dir);
assert_last_edge_is_valid (polygon, limits);
} else if (pright <= limits->p1.x) {
/* Projection of the edge to the left of the box:
* replace with the left side of the box (clipped top/bottom) */
_add_edge (polygon, &limits->p1, &bot_left, top_y, bot_y, dir);
assert_last_edge_is_valid (polygon, limits);
} else if (limits->p2.x <= pleft) {
/* Projection of the edge to the right of the box:
* replace with the right side of the box (clipped top/bottom) */
_add_edge (polygon, &top_right, &limits->p2, top_y, bot_y, dir);
assert_last_edge_is_valid (polygon, limits);
} else {
/* The edge and the box intersect in a generic way */
cairo_fixed_t left_y, right_y;
@ -392,6 +427,7 @@ _add_clipped_edge (cairo_polygon_t *polygon,
if (top_y < left_y) {
_add_edge (polygon, &limits->p1, &bot_left,
top_y, left_y, dir);
assert_last_edge_is_valid (polygon, limits);
top_y = left_y;
}
@ -399,6 +435,7 @@ _add_clipped_edge (cairo_polygon_t *polygon,
if (bot_y > right_y) {
_add_edge (polygon, &top_right, &limits->p2,
right_y, bot_y, dir);
assert_last_edge_is_valid (polygon, limits);
bot_y = right_y;
}
} else {
@ -406,6 +443,7 @@ _add_clipped_edge (cairo_polygon_t *polygon,
if (top_y < right_y) {
_add_edge (polygon, &top_right, &limits->p2,
top_y, right_y, dir);
assert_last_edge_is_valid (polygon, limits);
top_y = right_y;
}
@ -413,12 +451,15 @@ _add_clipped_edge (cairo_polygon_t *polygon,
if (bot_y > left_y) {
_add_edge (polygon, &limits->p1, &bot_left,
left_y, bot_y, dir);
assert_last_edge_is_valid (polygon, limits);
bot_y = left_y;
}
}
if (top_y != bot_y)
if (top_y != bot_y) {
_add_edge (polygon, p1, p2, top_y, bot_y, dir);
assert_last_edge_is_valid (polygon, limits);
}
}
}
}