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https://github.com/tesseract-ocr/tesseract.git
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5c8ad7ee72
git-svn-id: https://tesseract-ocr.googlecode.com/svn/trunk@384 d0cd1f9f-072b-0410-8dd7-cf729c803f20
483 lines
18 KiB
C++
483 lines
18 KiB
C++
/**********************************************************************
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* File: edgblob.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 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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#include "mfcpch.h"
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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 "edgblob.h"
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#define EXTERN
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// Control parameters used in outline_complexity(), which rejects an outline
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// if any one of the 3 conditions is satisfied:
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// - number of children exceeds edges_max_children_per_outline
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// - number of nested layers exceeds edges_max_children_layers
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// - joint complexity exceeds edges_children_count_limit(as in child_count())
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EXTERN BOOL_VAR(edges_use_new_outline_complexity, FALSE,
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"Use the new outline complexity module");
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EXTERN INT_VAR(edges_max_children_per_outline, 10,
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"Max number of children inside a character outline");
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EXTERN INT_VAR(edges_max_children_layers, 5,
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"Max layers of nested children inside a character outline");
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EXTERN BOOL_VAR(edges_debug, FALSE,
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"turn on debugging for this module");
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EXTERN INT_VAR(edges_children_per_grandchild, 10,
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"Importance ratio for chucking outlines");
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EXTERN INT_VAR(edges_children_count_limit, 45,
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"Max holes allowed in blob");
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EXTERN BOOL_VAR(edges_children_fix, FALSE,
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"Remove boxy parents of char-like children");
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EXTERN INT_VAR(edges_min_nonhole, 12,
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"Min pixels for potential char in box");
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EXTERN INT_VAR(edges_patharea_ratio, 40,
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"Max lensq/area for acceptable child outline");
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EXTERN double_VAR(edges_childarea, 0.5,
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"Min area fraction of child outline");
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EXTERN double_VAR(edges_boxarea, 0.875,
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"Min area fraction of grandchild for box");
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/**********************************************************************
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* OL_BUCKETS::OL_BUCKETS
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*
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* Construct an array of buckets for associating outlines into blobs.
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**********************************************************************/
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OL_BUCKETS::OL_BUCKETS(
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//// constructor
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ICOORD bleft, // corners
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ICOORD tright): bl(bleft), tr(tright) {
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bxdim =(tright.x() - bleft.x()) / BUCKETSIZE + 1;
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bydim =(tright.y() - bleft.y()) / BUCKETSIZE + 1;
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// make array
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buckets = new C_OUTLINE_LIST[bxdim * bydim];
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index = 0;
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}
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/**********************************************************************
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* OL_BUCKETS::operator(
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*
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* Return a pointer to a list of C_OUTLINEs corresponding to the
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* given pixel coordinates.
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**********************************************************************/
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C_OUTLINE_LIST *
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OL_BUCKETS::operator()( // array access
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inT16 x, // image coords
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inT16 y) {
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return &buckets[(y-bl.y()) / BUCKETSIZE * bxdim + (x-bl.x()) / BUCKETSIZE];
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}
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/**********************************************************************
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* OL_BUCKETS::outline_complexity
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*
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* This is the new version of count_child.
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*
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* The goal of this function is to determine if an outline and its
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* interiors could be part of a character blob. This is done by
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* computing a "complexity" index for the outline, which is the return
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* value of this function, and checking it against a threshold.
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* The max_count is used for short-circuiting the recursion and forcing
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* a rejection that guarantees to fail the threshold test.
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* The complexity F for outline X with N children X[i] is
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* F(X) = N + sum_i F(X[i]) * edges_children_per_grandchild
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* so each layer of nesting increases complexity exponentially.
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* An outline can be rejected as a text blob candidate if its complexity
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* is too high, has too many children(likely a container), or has too
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* many layers of nested inner loops. This has the side-effect of
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* flattening out boxed or reversed video text regions.
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**********************************************************************/
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inT32 OL_BUCKETS::outline_complexity(
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C_OUTLINE *outline, // parent outline
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inT32 max_count, // max output
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inT16 depth // recurion depth
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) {
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inT16 xmin, xmax; // coord limits
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inT16 ymin, ymax;
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inT16 xindex, yindex; // current bucket
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C_OUTLINE *child; // current child
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inT32 child_count; // no of children
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inT32 grandchild_count; // no of grandchildren
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C_OUTLINE_IT child_it; // search iterator
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TBOX olbox = outline->bounding_box();
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xmin =(olbox.left() - bl.x()) / BUCKETSIZE;
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xmax =(olbox.right() - bl.x()) / BUCKETSIZE;
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ymin =(olbox.bottom() - bl.y()) / BUCKETSIZE;
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ymax =(olbox.top() - bl.y()) / BUCKETSIZE;
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child_count = 0;
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grandchild_count = 0;
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if (++depth > edges_max_children_layers) // nested loops are too deep
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return max_count + depth;
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for (yindex = ymin; yindex <= ymax; yindex++) {
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for (xindex = xmin; xindex <= xmax; xindex++) {
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child_it.set_to_list(&buckets[yindex * bxdim + xindex]);
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if (child_it.empty())
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continue;
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for (child_it.mark_cycle_pt(); !child_it.cycled_list();
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child_it.forward()) {
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child = child_it.data();
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if (child == outline || !(*child < *outline))
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continue;
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child_count++;
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if (child_count > edges_max_children_per_outline) { // too fragmented
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if (edges_debug)
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tprintf("Discard outline on child_count=%d > "
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"max_children_per_outline=%d\n",
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child_count,
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static_cast<inT32>(edges_max_children_per_outline));
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return max_count + child_count;
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}
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// Compute the "complexity" of each child recursively
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inT32 remaining_count = max_count - child_count - grandchild_count;
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if (remaining_count > 0)
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grandchild_count += edges_children_per_grandchild *
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outline_complexity(child, remaining_count, depth);
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if (child_count + grandchild_count > max_count) { // too complex
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if (edges_debug)
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tprintf("Disgard outline on child_count=%d + grandchild_count=%d "
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"> max_count=%d\n",
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child_count, grandchild_count, max_count);
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return child_count + grandchild_count;
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}
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}
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}
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}
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return child_count + grandchild_count;
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}
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/**********************************************************************
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* OL_BUCKETS::count_children
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*
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* Find number of descendants of this outline.
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**********************************************************************/
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inT32 OL_BUCKETS::count_children( // recursive count
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C_OUTLINE *outline, // parent outline
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inT32 max_count // max output
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) {
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BOOL8 parent_box; // could it be boxy
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inT16 xmin, xmax; // coord limits
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inT16 ymin, ymax;
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inT16 xindex, yindex; // current bucket
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C_OUTLINE *child; // current child
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inT32 child_count; // no of children
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inT32 grandchild_count; // no of grandchildren
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inT32 parent_area; // potential box
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FLOAT32 max_parent_area; // potential box
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inT32 child_area; // current child
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inT32 child_length; // current child
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TBOX olbox;
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C_OUTLINE_IT child_it; // search iterator
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olbox = outline->bounding_box();
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xmin =(olbox.left() - bl.x()) / BUCKETSIZE;
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xmax =(olbox.right() - bl.x()) / BUCKETSIZE;
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ymin =(olbox.bottom() - bl.y()) / BUCKETSIZE;
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ymax =(olbox.top() - bl.y()) / BUCKETSIZE;
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child_count = 0;
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grandchild_count = 0;
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parent_area = 0;
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max_parent_area = 0;
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parent_box = TRUE;
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for (yindex = ymin; yindex <= ymax; yindex++) {
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for (xindex = xmin; xindex <= xmax; xindex++) {
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child_it.set_to_list(&buckets[yindex * bxdim + xindex]);
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if (child_it.empty())
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continue;
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for (child_it.mark_cycle_pt(); !child_it.cycled_list();
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child_it.forward()) {
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child = child_it.data();
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if (child != outline && *child < *outline) {
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child_count++;
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if (child_count <= max_count) {
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int max_grand =(max_count - child_count) /
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edges_children_per_grandchild;
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if (max_grand > 0)
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grandchild_count += count_children(child, max_grand) *
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edges_children_per_grandchild;
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else
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grandchild_count += count_children(child, 1);
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}
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if (child_count + grandchild_count > max_count) {
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if (edges_debug)
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tprintf("Discarding parent with child count=%d, gc=%d\n",
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child_count,grandchild_count);
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return child_count + grandchild_count;
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}
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if (parent_area == 0) {
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parent_area = outline->outer_area();
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if (parent_area < 0)
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parent_area = -parent_area;
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max_parent_area = outline->bounding_box().area() * edges_boxarea;
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if (parent_area < max_parent_area)
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parent_box = FALSE;
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}
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if (parent_box &&
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(!edges_children_fix ||
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child->bounding_box().height() > edges_min_nonhole)) {
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child_area = child->outer_area();
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if (child_area < 0)
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child_area = -child_area;
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if (edges_children_fix) {
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if (parent_area - child_area < max_parent_area) {
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parent_box = FALSE;
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continue;
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}
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if (grandchild_count > 0) {
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if (edges_debug)
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tprintf("Discarding parent of area %d, child area=%d, max%g "
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"with gc=%d\n",
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parent_area, child_area, max_parent_area,
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grandchild_count);
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return max_count + 1;
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}
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child_length = child->pathlength();
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if (child_length * child_length >
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child_area * edges_patharea_ratio) {
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if (edges_debug)
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tprintf("Discarding parent of area %d, child area=%d, max%g "
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"with child length=%d\n",
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parent_area, child_area, max_parent_area,
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child_length);
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return max_count + 1;
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}
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}
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if (child_area < child->bounding_box().area() * edges_childarea) {
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if (edges_debug)
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tprintf("Discarding parent of area %d, child area=%d, max%g "
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"with child rect=%d\n",
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parent_area, child_area, max_parent_area,
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child->bounding_box().area());
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return max_count + 1;
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}
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}
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}
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}
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}
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}
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return child_count + grandchild_count;
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}
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/**********************************************************************
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* OL_BUCKETS::extract_children
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*
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* Find number of descendants of this outline.
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**********************************************************************/
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void OL_BUCKETS::extract_children( // recursive count
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C_OUTLINE *outline, // parent outline
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C_OUTLINE_IT *it // destination iterator
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) {
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inT16 xmin, xmax; // coord limits
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inT16 ymin, ymax;
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inT16 xindex, yindex; // current bucket
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TBOX olbox;
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C_OUTLINE_IT child_it; // search iterator
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olbox = outline->bounding_box();
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xmin =(olbox.left() - bl.x()) / BUCKETSIZE;
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xmax =(olbox.right() - bl.x()) / BUCKETSIZE;
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ymin =(olbox.bottom() - bl.y()) / BUCKETSIZE;
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ymax =(olbox.top() - bl.y()) / BUCKETSIZE;
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for (yindex = ymin; yindex <= ymax; yindex++) {
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for (xindex = xmin; xindex <= xmax; xindex++) {
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child_it.set_to_list(&buckets[yindex * bxdim + xindex]);
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for (child_it.mark_cycle_pt(); !child_it.cycled_list();
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child_it.forward()) {
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if (*child_it.data() < *outline) {
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it->add_after_then_move(child_it.extract());
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}
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}
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}
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}
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}
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/**********************************************************************
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* extract_edges
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*
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* Run the edge detector over the block and return a list of blobs.
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**********************************************************************/
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void extract_edges( // find blobs
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#ifndef GRAPHICS_DISABLED
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ScrollView* window, // window for output
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#endif
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IMAGE *image, // image to scan
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IMAGE *t_image, // thresholded image
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ICOORD page_tr, // corner of page
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BLOCK *block // block to scan
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) {
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ICOORD bleft; // block box
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ICOORD tright;
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C_OUTLINE_LIST outlines; // outlines in block
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// iterator
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C_OUTLINE_IT out_it = &outlines;
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#ifndef GRAPHICS_DISABLED
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get_outlines(window, image, t_image, page_tr, (PDBLK *) block, &out_it);
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#else
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get_outlines(image, t_image, page_tr, (PDBLK *) block, &out_it);
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#endif
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// block box
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block->bounding_box(bleft, tright);
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// make blobs
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outlines_to_blobs(block, bleft, tright, &outlines);
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}
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/**********************************************************************
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* outlines_to_blobs
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*
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* Gather together outlines into blobs using the usual bucket sort.
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**********************************************************************/
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void outlines_to_blobs( // find blobs
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BLOCK *block, // block to scan
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ICOORD bleft,
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ICOORD tright,
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C_OUTLINE_LIST *outlines) {
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// make buckets
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OL_BUCKETS buckets(bleft, tright);
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fill_buckets(outlines, &buckets);
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empty_buckets(block, &buckets);
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}
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/**********************************************************************
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* fill_buckets
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*
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* Run the edge detector over the block and return a list of blobs.
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**********************************************************************/
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void fill_buckets( // find blobs
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C_OUTLINE_LIST *outlines, // outlines in block
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OL_BUCKETS *buckets // output buckets
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) {
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TBOX ol_box; // outline box
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C_OUTLINE_IT out_it = outlines; // iterator
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C_OUTLINE_IT bucket_it; // iterator in bucket
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C_OUTLINE *outline; // current outline
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for (out_it.mark_cycle_pt(); !out_it.cycled_list(); out_it.forward()) {
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outline = out_it.extract(); // take off list
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// get box
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ol_box = outline->bounding_box();
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bucket_it.set_to_list((*buckets) (ol_box.left(), ol_box.bottom()));
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bucket_it.add_to_end(outline);
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}
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}
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/**********************************************************************
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* empty_buckets
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*
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* Run the edge detector over the block and return a list of blobs.
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**********************************************************************/
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void empty_buckets( // find blobs
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BLOCK *block, // block to scan
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OL_BUCKETS *buckets // output buckets
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) {
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BOOL8 good_blob; // healthy blob
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C_OUTLINE_LIST outlines; // outlines in block
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// iterator
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C_OUTLINE_IT out_it = &outlines;
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C_OUTLINE_IT bucket_it = buckets->start_scan();
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C_OUTLINE_IT parent_it; // parent outline
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C_BLOB *blob; // new blob
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C_BLOB_IT good_blobs = block->blob_list();
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C_BLOB_IT junk_blobs = block->reject_blobs();
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while (!bucket_it.empty()) {
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out_it.set_to_list(&outlines);
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do {
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parent_it = bucket_it; // find outermost
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do
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bucket_it.forward();
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while (!bucket_it.at_first()
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&& !(*parent_it.data() < *bucket_it.data()));
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}
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while (!bucket_it.at_first());
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// move to new list
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out_it.add_after_then_move(parent_it.extract());
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good_blob = capture_children(buckets, &junk_blobs, &out_it);
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blob = new C_BLOB(&outlines);
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if (good_blob)
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good_blobs.add_after_then_move(blob);
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else
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junk_blobs.add_after_then_move(blob);
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bucket_it.set_to_list(buckets->scan_next());
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}
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}
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/**********************************************************************
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* capture_children
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*
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* Find all neighbouring outlines that are children of this outline
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* and either move them to the output list or declare this outline
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* illegal and return FALSE.
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**********************************************************************/
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BOOL8 capture_children( // find children
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OL_BUCKETS *buckets, // bucket sort clanss
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C_BLOB_IT *reject_it, // dead grandchildren
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C_OUTLINE_IT *blob_it // output outlines
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) {
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C_OUTLINE *outline; // master outline
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inT32 child_count; // no of children
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outline = blob_it->data();
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if (edges_use_new_outline_complexity)
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child_count = buckets->outline_complexity(outline,
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edges_children_count_limit,
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0);
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else
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child_count = buckets->count_children(outline,
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edges_children_count_limit);
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if (child_count > edges_children_count_limit)
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return FALSE;
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if (child_count > 0)
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buckets->extract_children(outline, blob_it);
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return TRUE;
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}
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