static void
generate_boundary (PixelRegion *PR,
BoundaryType type,
gint x1,
gint y1,
gint x2,
gint y2)
{
gint scanline;
gint i;
gint start, end;
gint *tmp_segs;
gint num_empty_n = 0;
gint num_empty_c = 0;
gint num_empty_l = 0;
start = 0;
end = 0;
/* array for determining the vertical line segments which must be drawn */
allocate_vert_segs (PR);
/* make sure there is enough space for the empty segment array */
allocate_empty_segs (PR);
num_segs = 0;
if (type == WithinBounds)
{
start = y1;
end = y2;
}
else if (type == IgnoreBounds)
{
start = 0;
end = PR->h;
}
/* Find the empty segments for the previous and current scanlines */
find_empty_segs (PR, start - 1, empty_segs_l,
max_empty_segs, &num_empty_l,
type, x1, y1, x2, y2);
find_empty_segs (PR, start, empty_segs_c,
max_empty_segs, &num_empty_c,
type, x1, y1, x2, y2);
for (scanline = start; scanline < end; scanline++)
{
/* find the empty segment list for the next scanline */
find_empty_segs (PR, scanline + 1, empty_segs_n,
max_empty_segs, &num_empty_n,
type, x1, y1, x2, y2);
/* process the segments on the current scanline */
for (i = 1; i < num_empty_c - 1; i += 2)
{
make_horiz_segs (empty_segs_c [i], empty_segs_c [i+1],
scanline, empty_segs_l, num_empty_l, true);
make_horiz_segs (empty_segs_c [i], empty_segs_c [i+1],
scanline+1, empty_segs_n, num_empty_n, false);
}
/* get the next scanline of empty segments, swap others */
tmp_segs = empty_segs_l;
empty_segs_l = empty_segs_c;
num_empty_l = num_empty_c;
empty_segs_c = empty_segs_n;
num_empty_c = num_empty_n;
empty_segs_n = tmp_segs;
}
}
static Boundary *
generate_boundary (PixelRegion *PR,
BoundaryType type,
gint x1,
gint y1,
gint x2,
gint y2,
guchar threshold)
{
Boundary *boundary;
gint scanline;
gint i;
gint start, end;
gint *tmp_segs;
gint num_empty_n = 0;
gint num_empty_c = 0;
gint num_empty_l = 0;
boundary = boundary_new (PR);
start = 0;
end = 0;
if (type == BOUNDARY_WITHIN_BOUNDS)
{
start = y1;
end = y2;
}
else if (type == BOUNDARY_IGNORE_BOUNDS)
{
start = PR->y;
end = PR->y + PR->h;
}
/* Find the empty segments for the previous and current scanlines */
find_empty_segs (PR, start - 1, boundary->empty_segs_l,
boundary->max_empty_segs, &num_empty_l,
type, x1, y1, x2, y2,
threshold);
find_empty_segs (PR, start, boundary->empty_segs_c,
boundary->max_empty_segs, &num_empty_c,
type, x1, y1, x2, y2,
threshold);
for (scanline = start; scanline < end; scanline++)
{
/* find the empty segment list for the next scanline */
find_empty_segs (PR, scanline + 1, boundary->empty_segs_n,
boundary->max_empty_segs, &num_empty_n,
type, x1, y1, x2, y2,
threshold);
/* process the segments on the current scanline */
for (i = 1; i < num_empty_c - 1; i += 2)
{
make_horiz_segs (boundary,
boundary->empty_segs_c [i],
boundary->empty_segs_c [i+1],
scanline,
boundary->empty_segs_l, num_empty_l, 1);
make_horiz_segs (boundary,
boundary->empty_segs_c [i],
boundary->empty_segs_c [i+1],
scanline + 1,
boundary->empty_segs_n, num_empty_n, 0);
}
/* get the next scanline of empty segments, swap others */
tmp_segs = boundary->empty_segs_l;
boundary->empty_segs_l = boundary->empty_segs_c;
num_empty_l = num_empty_c;
boundary->empty_segs_c = boundary->empty_segs_n;
num_empty_c = num_empty_n;
boundary->empty_segs_n = tmp_segs;
}
return boundary;
}
