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tesseract/textord/underlin.cpp

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/**********************************************************************
* File: underlin.cpp (Formerly undrline.c)
* Description: Code to chop blobs apart from underlines.
* Author: Ray Smith
* Created: Mon Aug 8 11:14:00 BST 1994
*
* (C) Copyright 1994, Hewlett-Packard Ltd.
** Licensed under the Apache License, Version 2.0 (the "License");
** you may not use this file except in compliance with the License.
** You may obtain a copy of the License at
** http://www.apache.org/licenses/LICENSE-2.0
** Unless required by applicable law or agreed to in writing, software
** distributed under the License is distributed on an "AS IS" BASIS,
** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
** See the License for the specific language governing permissions and
** limitations under the License.
*
**********************************************************************/
#ifdef __UNIX__
#include <assert.h>
#endif
#include "underlin.h"
#define PROJECTION_MARGIN 10 //arbitrary
#define EXTERN
EXTERN double_VAR (textord_underline_offset, 0.1, "Fraction of x to ignore");
EXTERN BOOL_VAR (textord_restore_underlines, TRUE,
"Chop underlines & put back");
/**********************************************************************
* restore_underlined_blobs
*
* Find underlined blobs and put them back in the row.
**********************************************************************/
void restore_underlined_blobs( //get chop points
TO_BLOCK *block //block to do
) {
inT16 chop_coord; //chop boundary
TBOX blob_box; //of underline
BLOBNBOX *u_line; //underline bit
TO_ROW *row; //best row for blob
ICOORDELT_LIST chop_cells; //blobs to cut out
//real underlines
BLOBNBOX_LIST residual_underlines;
C_OUTLINE_LIST left_coutlines;
C_OUTLINE_LIST right_coutlines;
ICOORDELT_IT cell_it = &chop_cells;
//under lines
BLOBNBOX_IT under_it = &block->underlines;
BLOBNBOX_IT ru_it = &residual_underlines;
if (block->get_rows()->empty())
return; // Don't crash if there are no rows.
for (under_it.mark_cycle_pt (); !under_it.cycled_list ();
under_it.forward ()) {
u_line = under_it.extract ();
blob_box = u_line->bounding_box ();
row = most_overlapping_row (block->get_rows (), u_line);
if (row == NULL)
return; // Don't crash if there is no row.
find_underlined_blobs (u_line, &row->baseline, row->xheight,
row->xheight * textord_underline_offset,
&chop_cells);
cell_it.set_to_list (&chop_cells);
for (cell_it.mark_cycle_pt (); !cell_it.cycled_list ();
cell_it.forward ()) {
chop_coord = cell_it.data ()->x ();
if (cell_it.data ()->y () - chop_coord > textord_fp_chop_error + 1) {
split_to_blob (u_line, chop_coord,
textord_fp_chop_error + 0.5,
&left_coutlines,
&right_coutlines);
if (!left_coutlines.empty()) {
ru_it.add_after_then_move(new BLOBNBOX(new C_BLOB(&left_coutlines)));
}
chop_coord = cell_it.data ()->y ();
split_to_blob(NULL, chop_coord, textord_fp_chop_error + 0.5,
&left_coutlines, &right_coutlines);
if (!left_coutlines.empty()) {
row->insert_blob(new BLOBNBOX(new C_BLOB(&left_coutlines)));
}
u_line = NULL; //no more blobs to add
}
delete cell_it.extract();
}
if (!right_coutlines.empty ()) {
split_to_blob(NULL, blob_box.right(), textord_fp_chop_error + 0.5,
&left_coutlines, &right_coutlines);
if (!left_coutlines.empty())
ru_it.add_after_then_move(new BLOBNBOX(new C_BLOB(&left_coutlines)));
}
if (u_line != NULL) {
if (u_line->cblob() != NULL)
delete u_line->cblob();
delete u_line;
}
}
if (!ru_it.empty()) {
ru_it.move_to_first();
for (ru_it.mark_cycle_pt(); !ru_it.cycled_list(); ru_it.forward()) {
under_it.add_after_then_move(ru_it.extract());
}
}
}
/**********************************************************************
* most_overlapping_row
*
* Return the row which most overlaps the blob.
**********************************************************************/
TO_ROW *most_overlapping_row( //find best row
TO_ROW_LIST *rows, //list of rows
BLOBNBOX *blob //blob to place
) {
inT16 x = (blob->bounding_box ().left ()
+ blob->bounding_box ().right ()) / 2;
TO_ROW_IT row_it = rows; //row iterator
TO_ROW *row; //current row
TO_ROW *best_row; //output row
float overlap; //of blob & row
float bestover; //best overlap
best_row = NULL;
bestover = (float) -MAX_INT32;
if (row_it.empty ())
return NULL;
row = row_it.data ();
row_it.mark_cycle_pt ();
while (row->baseline.y (x) + row->descdrop > blob->bounding_box ().top ()
&& !row_it.cycled_list ()) {
best_row = row;
bestover =
blob->bounding_box ().top () - row->baseline.y (x) + row->descdrop;
row_it.forward ();
row = row_it.data ();
}
while (row->baseline.y (x) + row->xheight + row->ascrise
>= blob->bounding_box ().bottom () && !row_it.cycled_list ()) {
overlap = row->baseline.y (x) + row->xheight + row->ascrise;
if (blob->bounding_box ().top () < overlap)
overlap = blob->bounding_box ().top ();
if (blob->bounding_box ().bottom () >
row->baseline.y (x) + row->descdrop)
overlap -= blob->bounding_box ().bottom ();
else
overlap -= row->baseline.y (x) + row->descdrop;
if (overlap > bestover) {
bestover = overlap;
best_row = row;
}
row_it.forward ();
row = row_it.data ();
}
if (bestover < 0
&& row->baseline.y (x) + row->xheight + row->ascrise
- blob->bounding_box ().bottom () > bestover)
best_row = row;
return best_row;
}
/**********************************************************************
* find_underlined_blobs
*
* Find the start and end coords of blobs in the underline.
**********************************************************************/
void find_underlined_blobs( //get chop points
BLOBNBOX *u_line, //underlined unit
QSPLINE *baseline, //actual baseline
float xheight, //height of line
float baseline_offset, //amount to shrinke it
ICOORDELT_LIST *chop_cells //places to chop
) {
inT16 x, y; //sides of blob
ICOORD blob_chop; //sides of blob
TBOX blob_box = u_line->bounding_box ();
//cell iterator
ICOORDELT_IT cell_it = chop_cells;
STATS upper_proj (blob_box.left (), blob_box.right () + 1);
STATS middle_proj (blob_box.left (), blob_box.right () + 1);
STATS lower_proj (blob_box.left (), blob_box.right () + 1);
C_OUTLINE_IT out_it; //outlines of blob
ASSERT_HOST (u_line->cblob () != NULL);
out_it.set_to_list (u_line->cblob ()->out_list ());
for (out_it.mark_cycle_pt (); !out_it.cycled_list (); out_it.forward ()) {
vertical_cunderline_projection (out_it.data (),
baseline, xheight, baseline_offset,
&lower_proj, &middle_proj, &upper_proj);
}
for (x = blob_box.left (); x < blob_box.right (); x++) {
if (middle_proj.pile_count (x) > 0) {
for (y = x + 1;
y < blob_box.right () && middle_proj.pile_count (y) > 0; y++);
blob_chop = ICOORD (x, y);
cell_it.add_after_then_move (new ICOORDELT (blob_chop));
x = y;
}
}
}
/**********************************************************************
* vertical_cunderline_projection
*
* Compute the vertical projection of a outline from its outlines
* and add to the given STATS.
**********************************************************************/
void vertical_cunderline_projection( //project outlines
C_OUTLINE *outline, //outline to project
QSPLINE *baseline, //actual baseline
float xheight, //height of line
float baseline_offset, //amount to shrinke it
STATS *lower_proj, //below baseline
STATS *middle_proj, //centre region
STATS *upper_proj //top region
) {
ICOORD pos; //current point
ICOORD step; //edge step
inT16 lower_y, upper_y; //region limits
inT32 length; //of outline
inT16 stepindex; //current step
C_OUTLINE_IT out_it = outline->child ();
pos = outline->start_pos ();
length = outline->pathlength ();
for (stepindex = 0; stepindex < length; stepindex++) {
step = outline->step (stepindex);
if (step.x () > 0) {
lower_y =
(inT16) floor (baseline->y (pos.x ()) + baseline_offset + 0.5);
upper_y =
(inT16) floor (baseline->y (pos.x ()) + baseline_offset +
xheight + 0.5);
if (pos.y () >= lower_y) {
lower_proj->add (pos.x (), -lower_y);
if (pos.y () >= upper_y) {
middle_proj->add (pos.x (), lower_y - upper_y);
upper_proj->add (pos.x (), upper_y - pos.y ());
}
else
middle_proj->add (pos.x (), lower_y - pos.y ());
}
else
lower_proj->add (pos.x (), -pos.y ());
}
else if (step.x () < 0) {
lower_y =
(inT16) floor (baseline->y (pos.x () - 1) + baseline_offset +
0.5);
upper_y =
(inT16) floor (baseline->y (pos.x () - 1) + baseline_offset +
xheight + 0.5);
if (pos.y () >= lower_y) {
lower_proj->add (pos.x () - 1, lower_y);
if (pos.y () >= upper_y) {
middle_proj->add (pos.x () - 1, upper_y - lower_y);
upper_proj->add (pos.x () - 1, pos.y () - upper_y);
}
else
middle_proj->add (pos.x () - 1, pos.y () - lower_y);
}
else
lower_proj->add (pos.x () - 1, pos.y ());
}
pos += step;
}
for (out_it.mark_cycle_pt (); !out_it.cycled_list (); out_it.forward ()) {
vertical_cunderline_projection (out_it.data (),
baseline, xheight, baseline_offset,
lower_proj, middle_proj, upper_proj);
}
}
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