static cairo_int_status_t _draw_trap (cairo_gl_context_t *ctx, cairo_gl_composite_t *setup, cairo_trapezoid_t *trap) { cairo_point_t quad[4]; quad[0].x = _cairo_edge_compute_intersection_x_for_y (&trap->left.p1, &trap->left.p2, trap->top); quad[0].y = trap->top; quad[1].x = _cairo_edge_compute_intersection_x_for_y (&trap->left.p1, &trap->left.p2, trap->bottom); quad[1].y = trap->bottom; quad[2].x = _cairo_edge_compute_intersection_x_for_y (&trap->right.p1, &trap->right.p2, trap->bottom); quad[2].y = trap->bottom; quad[3].x = _cairo_edge_compute_intersection_x_for_y (&trap->right.p1, &trap->right.p2, trap->top); quad[3].y = trap->top; return _cairo_gl_composite_emit_quad_as_tristrip (ctx, setup, quad); }
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]; XASSERT (edge->bottom > edge->top); XASSERT (edge->top >= limit->p1.y); XASSERT (edge->bottom <= limit->p2.y); x = _cairo_edge_compute_intersection_x_for_y (&edge->line.p1, &edge->line.p2, edge->top); XASSERT (x >= limit->p1.x); XASSERT (x <= limit->p2.x); x = _cairo_edge_compute_intersection_x_for_y (&edge->line.p1, &edge->line.p2, edge->bottom); XASSERT (x >= limit->p1.x); XASSERT (x <= limit->p2.x); }
static void _add_edge (cairo_polygon_t *polygon, const cairo_point_t *p1, const cairo_point_t *p2, int top, int bottom, int dir) { cairo_edge_t *edge; XASSERT (top < bottom); if (unlikely (polygon->num_edges == polygon->edges_size)) { if (! _cairo_polygon_grow (polygon)) return; } edge = &polygon->edges[polygon->num_edges++]; edge->line.p1 = *p1; edge->line.p2 = *p2; edge->top = top; edge->bottom = bottom; edge->dir = dir; if (top < polygon->extents.p1.y) polygon->extents.p1.y = top; if (bottom > polygon->extents.p2.y) polygon->extents.p2.y = bottom; if (p1->x < polygon->extents.p1.x || p1->x > polygon->extents.p2.x) { cairo_fixed_t x = p1->x; if (top != p1->y) x = _cairo_edge_compute_intersection_x_for_y (p1, p2, top); if (x < polygon->extents.p1.x) polygon->extents.p1.x = x; if (x > polygon->extents.p2.x) polygon->extents.p2.x = x; } if (p2->x < polygon->extents.p1.x || p2->x > polygon->extents.p2.x) { cairo_fixed_t x = p2->x; if (bottom != p2->y) x = _cairo_edge_compute_intersection_x_for_y (p1, p2, bottom); if (x < polygon->extents.p1.x) polygon->extents.p1.x = x; if (x > polygon->extents.p2.x) polygon->extents.p2.x = x; } }
static void _add_clipped_edge (struct reduce *r, const cairo_point_t *p1, const cairo_point_t *p2, int y1, int y2) { cairo_fixed_t x; x = _cairo_edge_compute_intersection_x_for_y (p1, p2, y1); if (x < r->extents.p1.x) r->extents.p1.x = x; x = _cairo_edge_compute_intersection_x_for_y (p1, p2, y2); if (x > r->extents.p2.x) r->extents.p2.x = x; if (y1 < r->extents.p1.y) r->extents.p1.y = y1; if (y2 > r->extents.p2.y) r->extents.p2.y = y2; r->inside = TRUE; }
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); }
static void _add_clipped_edge (cairo_polygon_t *polygon, const cairo_point_t *p1, const cairo_point_t *p2, const int top, const int bottom, const int dir) { cairo_point_t bot_left, top_right; cairo_fixed_t top_y, bot_y; int n; for (n = 0; n < polygon->num_limits; n++) { const cairo_box_t *limits = &polygon->limits[n]; cairo_fixed_t pleft, pright; if (top >= limits->p2.y) continue; if (bottom <= limits->p1.y) continue; bot_left.x = limits->p1.x; bot_left.y = limits->p2.y; top_right.x = limits->p2.x; top_right.y = limits->p1.y; /* The useful region */ top_y = MAX (top, limits->p1.y); bot_y = MIN (bottom, limits->p2.y); /* The projection of the edge on the horizontal axis */ pleft = MIN (p1->x, p2->x); pright = MAX (p1->x, p2->x); if (limits->p1.x <= pleft && pright <= limits->p2.x) { /* Projection of the edge completely contained in the box: * 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; cairo_bool_t top_left_to_bottom_right; /* * The edge intersects the lines corresponding to the left * and right sides of the limit box at left_y and right_y, * but we need to add edges for the range from top_y to * bot_y. * * For both intersections, there are three cases: * * 1) It is outside the vertical range of the limit * box. In this case we can simply further clip the * edge we will be emitting (i.e. restrict its * top/bottom limits to those of the limit box). * * 2) It is inside the vertical range of the limit * box. In this case, we need to add the vertical edge * connecting the correct vertex to the intersection, * in order to preserve the winding count. * * 3) It is exactly on the box. In this case, do nothing. * * These operations restrict the active range (stored in * top_y/bot_y) so that the p1-p2 edge is completely * inside the box if it is clipped to this vertical range. */ top_left_to_bottom_right = (p1->x <= p2->x) == (p1->y <= p2->y); if (top_left_to_bottom_right) { if (pleft >= limits->p1.x) { left_y = top_y; } else { left_y = _cairo_edge_compute_intersection_y_for_x (p1, p2, limits->p1.x); if (_cairo_edge_compute_intersection_x_for_y (p1, p2, left_y) < limits->p1.x) left_y++; } left_y = MIN (left_y, bot_y); 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; } if (pright <= limits->p2.x) { right_y = bot_y; } else { right_y = _cairo_edge_compute_intersection_y_for_x (p1, p2, limits->p2.x); if (_cairo_edge_compute_intersection_x_for_y (p1, p2, right_y) > limits->p2.x) right_y--; } right_y = MAX (right_y, top_y); 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 { if (pright <= limits->p2.x) { right_y = top_y; } else { right_y = _cairo_edge_compute_intersection_y_for_x (p1, p2, limits->p2.x); if (_cairo_edge_compute_intersection_x_for_y (p1, p2, right_y) > limits->p2.x) right_y++; } right_y = MIN (right_y, bot_y); 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; } if (pleft >= limits->p1.x) { left_y = bot_y; } else { left_y = _cairo_edge_compute_intersection_y_for_x (p1, p2, limits->p1.x); if (_cairo_edge_compute_intersection_x_for_y (p1, p2, left_y) < limits->p1.x) left_y--; } left_y = MAX (left_y, top_y); 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) { _add_edge (polygon, p1, p2, top_y, bot_y, dir); assert_last_edge_is_valid (polygon, limits); } } } }