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373 lines
13 KiB
C++
373 lines
13 KiB
C++
/**********************************************************************
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* File: scanedg.c (Formerly scanedge.c)
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* Description: Raster scanning crack based edge extractor.
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* Author: Ray Smith
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* Created: Fri Mar 22 16:11:50 GMT 1991
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*
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* (C) Copyright 1991, Hewlett-Packard Ltd.
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** Licensed under the Apache License, Version 2.0 (the "License");
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** you may not use this file except in compliance with the License.
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** You may obtain a copy of the License at
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** http://www.apache.org/licenses/LICENSE-2.0
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** Unless required by applicable law or agreed to in writing, software
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** distributed under the License is distributed on an "AS IS" BASIS,
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** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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** See the License for the specific language governing permissions and
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** limitations under the License.
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*
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**********************************************************************/
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#include "scanedg.h"
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#include "allheaders.h"
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#include "edgloop.h"
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#define WHITE_PIX 1 /*thresholded colours */
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#define BLACK_PIX 0
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/*W->B->W */
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#define FLIP_COLOUR(pix) (1-(pix))
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/**********************************************************************
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* block_edges
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*
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* Extract edges from a PDBLK.
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**********************************************************************/
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void block_edges(Pix *t_pix, // thresholded image
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PDBLK *block, // block in image
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C_OUTLINE_IT* outline_it) {
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ICOORD bleft; // bounding box
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ICOORD tright;
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BLOCK_LINE_IT line_it = block; // line iterator
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int width = pixGetWidth(t_pix);
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int height = pixGetHeight(t_pix);
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int wpl = pixGetWpl(t_pix);
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// lines in progress
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CRACKEDGE **ptrline = new CRACKEDGE*[width + 1];
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CRACKEDGE *free_cracks = NULL;
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block->bounding_box(bleft, tright); // block box
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int block_width = tright.x() - bleft.x();
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for (int x = block_width; x >= 0; x--)
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ptrline[x] = NULL; // no lines in progress
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uinT8* bwline = new uinT8[width];
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uinT8 margin = WHITE_PIX;
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for (int y = tright.y() - 1; y >= bleft.y() - 1; y--) {
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if (y >= bleft.y() && y < tright.y()) {
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// Get the binary pixels from the image.
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l_uint32* line = pixGetData(t_pix) + wpl * (height - 1 - y);
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for (int x = 0; x < block_width; ++x) {
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bwline[x] = GET_DATA_BIT(line, x + bleft.x()) ^ 1;
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}
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make_margins(block, &line_it, bwline, margin, bleft.x(), tright.x(), y);
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} else {
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memset(bwline, margin, block_width * sizeof(bwline[0]));
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}
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line_edges(bleft.x(), y, block_width,
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margin, bwline, ptrline, &free_cracks, outline_it);
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}
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free_crackedges(free_cracks); // really free them
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delete[] ptrline;
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delete[] bwline;
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}
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/**********************************************************************
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* make_margins
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*
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* Get an image line and set to margin non-text pixels.
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**********************************************************************/
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void make_margins( //get a line
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PDBLK *block, //block in image
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BLOCK_LINE_IT *line_it, //for old style
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uinT8 *pixels, //pixels to strip
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uinT8 margin, //white-out pixel
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inT16 left, //block edges
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inT16 right,
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inT16 y //line coord
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) {
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PB_LINE_IT *lines;
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ICOORDELT_LIST *segments; //bits of a line
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ICOORDELT_IT seg_it;
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inT32 start; //of segment
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inT16 xext; //of segment
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int xindex; //index to pixel
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if (block->poly_block () != NULL) {
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lines = new PB_LINE_IT (block->poly_block ());
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segments = lines->get_line (y);
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if (!segments->empty ()) {
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seg_it.set_to_list (segments);
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seg_it.mark_cycle_pt ();
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start = seg_it.data ()->x ();
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xext = seg_it.data ()->y ();
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for (xindex = left; xindex < right; xindex++) {
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if (xindex >= start && !seg_it.cycled_list ()) {
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xindex = start + xext - 1;
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seg_it.forward ();
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start = seg_it.data ()->x ();
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xext = seg_it.data ()->y ();
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}
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else
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pixels[xindex - left] = margin;
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}
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}
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else {
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for (xindex = left; xindex < right; xindex++)
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pixels[xindex - left] = margin;
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}
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delete segments;
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delete lines;
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}
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else {
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start = line_it->get_line (y, xext);
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for (xindex = left; xindex < start; xindex++)
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pixels[xindex - left] = margin;
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for (xindex = start + xext; xindex < right; xindex++)
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pixels[xindex - left] = margin;
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}
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}
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/**********************************************************************
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* line_edges
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*
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* Scan a line for edges and update the edges in progress.
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* When edges close into loops, send them for approximation.
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**********************************************************************/
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void line_edges(inT16 x, // coord of line start
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inT16 y, // coord of line
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inT16 xext, // width of line
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uinT8 uppercolour, // start of prev line
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uinT8 * bwpos, // thresholded line
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CRACKEDGE ** prevline, // edges in progress
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CRACKEDGE **free_cracks,
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C_OUTLINE_IT* outline_it) {
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CrackPos pos = {free_cracks, x, y };
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int xmax; // max x coord
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int colour; // of current pixel
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int prevcolour; // of previous pixel
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CRACKEDGE *current; // current h edge
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CRACKEDGE *newcurrent; // new h edge
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xmax = x + xext; // max allowable coord
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prevcolour = uppercolour; // forced plain margin
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current = NULL; // nothing yet
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// do each pixel
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for (; pos.x < xmax; pos.x++, prevline++) {
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colour = *bwpos++; // current pixel
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if (*prevline != NULL) {
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// changed above
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// change colour
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uppercolour = FLIP_COLOUR(uppercolour);
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if (colour == prevcolour) {
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if (colour == uppercolour) {
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// finish a line
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join_edges(current, *prevline, free_cracks, outline_it);
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current = NULL; // no edge now
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} else {
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// new horiz edge
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current = h_edge(uppercolour - colour, *prevline, &pos);
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}
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*prevline = NULL; // no change this time
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} else {
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if (colour == uppercolour)
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*prevline = v_edge(colour - prevcolour, *prevline, &pos);
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// 8 vs 4 connection
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else if (colour == WHITE_PIX) {
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join_edges(current, *prevline, free_cracks, outline_it);
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current = h_edge(uppercolour - colour, NULL, &pos);
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*prevline = v_edge(colour - prevcolour, current, &pos);
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} else {
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newcurrent = h_edge(uppercolour - colour, *prevline, &pos);
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*prevline = v_edge(colour - prevcolour, current, &pos);
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current = newcurrent; // right going h edge
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}
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prevcolour = colour; // remember new colour
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}
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} else {
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if (colour != prevcolour) {
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*prevline = current = v_edge(colour - prevcolour, current, &pos);
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prevcolour = colour;
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}
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if (colour != uppercolour)
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current = h_edge(uppercolour - colour, current, &pos);
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else
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current = NULL; // no edge now
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}
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}
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if (current != NULL) {
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// out of block
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if (*prevline != NULL) { // got one to join to?
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join_edges(current, *prevline, free_cracks, outline_it);
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*prevline = NULL; // tidy now
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} else {
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// fake vertical
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*prevline = v_edge(FLIP_COLOUR(prevcolour)-prevcolour, current, &pos);
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}
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} else if (*prevline != NULL) {
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//continue fake
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*prevline = v_edge(FLIP_COLOUR(prevcolour)-prevcolour, *prevline, &pos);
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}
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}
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/**********************************************************************
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* h_edge
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*
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* Create a new horizontal CRACKEDGE and join it to the given edge.
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**********************************************************************/
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CRACKEDGE *h_edge(int sign, // sign of edge
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CRACKEDGE* join, // edge to join to
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CrackPos* pos) {
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CRACKEDGE *newpt; // return value
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if (*pos->free_cracks != NULL) {
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newpt = *pos->free_cracks;
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*pos->free_cracks = newpt->next; // get one fast
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} else {
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newpt = new CRACKEDGE;
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}
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newpt->pos.set_y(pos->y + 1); // coords of pt
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newpt->stepy = 0; // edge is horizontal
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if (sign > 0) {
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newpt->pos.set_x(pos->x + 1); // start location
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newpt->stepx = -1;
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newpt->stepdir = 0;
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} else {
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newpt->pos.set_x(pos->x); // start location
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newpt->stepx = 1;
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newpt->stepdir = 2;
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}
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if (join == NULL) {
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newpt->next = newpt; // ptrs to other ends
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newpt->prev = newpt;
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} else {
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if (newpt->pos.x() + newpt->stepx == join->pos.x()
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&& newpt->pos.y() == join->pos.y()) {
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newpt->prev = join->prev; // update other ends
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newpt->prev->next = newpt;
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newpt->next = join; // join up
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join->prev = newpt;
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} else {
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newpt->next = join->next; // update other ends
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newpt->next->prev = newpt;
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newpt->prev = join; // join up
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join->next = newpt;
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}
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}
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return newpt;
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}
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/**********************************************************************
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* v_edge
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*
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* Create a new vertical CRACKEDGE and join it to the given edge.
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**********************************************************************/
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CRACKEDGE *v_edge(int sign, // sign of edge
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CRACKEDGE* join,
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CrackPos* pos) {
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CRACKEDGE *newpt; // return value
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if (*pos->free_cracks != NULL) {
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newpt = *pos->free_cracks;
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*pos->free_cracks = newpt->next; // get one fast
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} else {
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newpt = new CRACKEDGE;
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}
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newpt->pos.set_x(pos->x); // coords of pt
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newpt->stepx = 0; // edge is vertical
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if (sign > 0) {
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newpt->pos.set_y(pos->y); // start location
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newpt->stepy = 1;
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newpt->stepdir = 3;
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} else {
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newpt->pos.set_y(pos->y + 1); // start location
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newpt->stepy = -1;
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newpt->stepdir = 1;
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}
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if (join == NULL) {
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newpt->next = newpt; //ptrs to other ends
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newpt->prev = newpt;
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} else {
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if (newpt->pos.x() == join->pos.x()
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&& newpt->pos.y() + newpt->stepy == join->pos.y()) {
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newpt->prev = join->prev; // update other ends
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newpt->prev->next = newpt;
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newpt->next = join; // join up
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join->prev = newpt;
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} else {
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newpt->next = join->next; // update other ends
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newpt->next->prev = newpt;
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newpt->prev = join; // join up
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join->next = newpt;
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}
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}
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return newpt;
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}
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/**********************************************************************
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* join_edges
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*
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* Join 2 edges together. Send the outline for approximation when a
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* closed loop is formed.
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**********************************************************************/
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void join_edges(CRACKEDGE *edge1, // edges to join
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CRACKEDGE *edge2, // no specific order
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CRACKEDGE **free_cracks,
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C_OUTLINE_IT* outline_it) {
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if (edge1->pos.x() + edge1->stepx != edge2->pos.x()
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|| edge1->pos.y() + edge1->stepy != edge2->pos.y()) {
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CRACKEDGE *tempedge = edge1;
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edge1 = edge2; // swap around
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edge2 = tempedge;
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}
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if (edge1->next == edge2) {
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// already closed
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complete_edge(edge1, outline_it);
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// attach freelist to end
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edge1->prev->next = *free_cracks;
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*free_cracks = edge1; // and free list
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} else {
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// update opposite ends
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edge2->prev->next = edge1->next;
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edge1->next->prev = edge2->prev;
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edge1->next = edge2; // make joins
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edge2->prev = edge1;
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}
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}
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/**********************************************************************
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* free_crackedges
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*
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* Really free the CRACKEDGEs by giving them back to delete.
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**********************************************************************/
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void free_crackedges(CRACKEDGE *start) {
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CRACKEDGE *current; // current edge to free
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CRACKEDGE *next; // next one to free
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for (current = start; current != NULL; current = next) {
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next = current->next;
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delete current; // delete them all
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}
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}
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