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https://github.com/tesseract-ocr/tesseract.git
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2c909702c9
git-svn-id: https://tesseract-ocr.googlecode.com/svn/trunk@877 d0cd1f9f-072b-0410-8dd7-cf729c803f20
160 lines
5.8 KiB
C++
160 lines
5.8 KiB
C++
/**********************************************************************
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* File: edgloop.c (Formerly edgeloop.c)
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* Description: Functions to clean up an outline before approximation.
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* Author: Ray Smith
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* Created: Tue Mar 26 16:56:25 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 "drawedg.h"
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#include "edgloop.h"
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// Include automatically generated configuration file if running autoconf.
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#ifdef HAVE_CONFIG_H
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#include "config_auto.h"
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#endif
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#define MINEDGELENGTH 8 // min decent length
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/**********************************************************************
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* complete_edge
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*
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* Complete the edge by cleaning it up.
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**********************************************************************/
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void complete_edge(CRACKEDGE *start, //start of loop
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C_OUTLINE_IT* outline_it) {
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ScrollView::Color colour; //colour to draw in
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inT16 looplength; //steps in loop
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ICOORD botleft; //bounding box
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ICOORD topright;
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C_OUTLINE *outline; //new outline
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//check length etc.
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colour = check_path_legal (start);
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if (colour == ScrollView::RED || colour == ScrollView::BLUE) {
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looplength = loop_bounding_box (start, botleft, topright);
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outline = new C_OUTLINE (start, botleft, topright, looplength);
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//add to list
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outline_it->add_after_then_move (outline);
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}
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}
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/**********************************************************************
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* check_path_legal
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*
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* Check that the outline is legal for length and for chaincode sum.
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* The return value is RED for a normal black-inside outline,
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* BLUE for a white-inside outline, MAGENTA if it is too short,
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* YELLOW if it is too long, and GREEN if it is illegal.
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* These colours are used to draw the raw outline.
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**********************************************************************/
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ScrollView::Color check_path_legal( //certify outline
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CRACKEDGE *start //start of loop
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) {
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int lastchain; //last chain code
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int chaindiff; //chain code diff
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inT32 length; //length of loop
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inT32 chainsum; //sum of chain diffs
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CRACKEDGE *edgept; //current point
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const ERRCODE ED_ILLEGAL_SUM = "Illegal sum of chain codes";
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length = 0;
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chainsum = 0; //sum of chain codes
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edgept = start;
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lastchain = edgept->prev->stepdir; //previous chain code
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do {
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length++;
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if (edgept->stepdir != lastchain) {
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//chain code difference
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chaindiff = edgept->stepdir - lastchain;
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if (chaindiff > 2)
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chaindiff -= 4;
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else if (chaindiff < -2)
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chaindiff += 4;
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chainsum += chaindiff; //sum differences
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lastchain = edgept->stepdir;
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}
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edgept = edgept->next;
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}
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while (edgept != start && length < C_OUTLINE::kMaxOutlineLength);
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if ((chainsum != 4 && chainsum != -4)
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|| edgept != start || length < MINEDGELENGTH) {
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if (edgept != start) {
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return ScrollView::YELLOW;
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} else if (length < MINEDGELENGTH) {
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return ScrollView::MAGENTA;
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} else {
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ED_ILLEGAL_SUM.error ("check_path_legal", TESSLOG, "chainsum=%d",
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chainsum);
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return ScrollView::GREEN;
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}
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}
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//colour on inside
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return chainsum < 0 ? ScrollView::BLUE : ScrollView::RED;
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}
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/**********************************************************************
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* loop_bounding_box
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*
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* Find the bounding box of the edge loop.
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**********************************************************************/
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inT16 loop_bounding_box( //get bounding box
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CRACKEDGE *&start, //edge loop
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ICOORD &botleft, //bounding box
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ICOORD &topright) {
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inT16 length; //length of loop
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inT16 leftmost; //on top row
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CRACKEDGE *edgept; //current point
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CRACKEDGE *realstart; //topleft start
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edgept = start;
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realstart = start;
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botleft = topright = ICOORD (edgept->pos.x (), edgept->pos.y ());
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leftmost = edgept->pos.x ();
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length = 0; //coutn length
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do {
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edgept = edgept->next;
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if (edgept->pos.x () < botleft.x ())
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//get bounding box
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botleft.set_x (edgept->pos.x ());
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else if (edgept->pos.x () > topright.x ())
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topright.set_x (edgept->pos.x ());
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if (edgept->pos.y () < botleft.y ())
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//get bounding box
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botleft.set_y (edgept->pos.y ());
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else if (edgept->pos.y () > topright.y ()) {
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realstart = edgept;
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leftmost = edgept->pos.x ();
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topright.set_y (edgept->pos.y ());
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}
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else if (edgept->pos.y () == topright.y ()
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&& edgept->pos.x () < leftmost) {
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//leftmost on line
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leftmost = edgept->pos.x ();
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realstart = edgept;
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}
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length++; //count elements
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}
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while (edgept != start);
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start = realstart; //shift it to topleft
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return length;
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}
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