60 lines
2.2 KiB
C
60 lines
2.2 KiB
C
/* edge.h: declarations for edge traversing.
|
|
*
|
|
* Copyright (C) 1992 Free Software Foundation, Inc.
|
|
*
|
|
* This program is free software: you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License as published by
|
|
* the Free Software Foundation; either version 3, or (at your option)
|
|
* any later version.
|
|
*
|
|
* This program is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with this program. If not, see <https://www.gnu.org/licenses/>.
|
|
*/
|
|
|
|
#ifndef EDGE_H
|
|
#define EDGE_H
|
|
|
|
#include "bitmap.h"
|
|
|
|
/* We consider each pixel to consist of four edges, and we travel along
|
|
edges, instead of through pixel centers. This is necessary for those
|
|
unfortunate times when a single pixel is on both an inside and an
|
|
outside outline.
|
|
|
|
The numbers chosen here are not arbitrary; the code that figures out
|
|
which edge to move to depends on particular values. See the
|
|
`TRY_PIXEL' macro in `edge.c'. To emphasize this, I've written in the
|
|
numbers we need for each edge value. */
|
|
|
|
typedef enum
|
|
{
|
|
top = 1, left = 2, bottom = 3, right = 0, no_edge = 4
|
|
} edge_type;
|
|
|
|
/* This choice is also not arbitrary: starting at the top edge makes the
|
|
code find outside outlines before inside ones, which is certainly
|
|
what we want. */
|
|
#define START_EDGE top
|
|
|
|
|
|
/* Return the next outline edge on B in EDGE, ROW, and COL. */
|
|
extern void next_outline_edge (edge_type *edge,
|
|
unsigned *row, unsigned *col);
|
|
|
|
/* Return the next edge after START on the pixel ROW/COL in B that is
|
|
unmarked, according to the MARKED array. */
|
|
extern edge_type next_unmarked_outline_edge (unsigned row, unsigned col,
|
|
edge_type start,
|
|
bitmap_type marked);
|
|
|
|
/* Mark the edge E at the pixel ROW/COL in MARKED. */
|
|
extern void mark_edge (edge_type e, unsigned row, unsigned col,
|
|
bitmap_type *marked);
|
|
|
|
#endif /* not EDGE_H */
|
