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///////////////////////////////////////////////////////////////////////
// File: alignedblob.h
// Description: A class to find vertically aligned blobs in a BBGrid,
// and a struct to hold control parameters.
// Author: Ray Smith
//
// (C) Copyright 2008, Google Inc.
// 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.
//
///////////////////////////////////////////////////////////////////////
#ifndef TESSERACT_TEXTORD_ALIGNEDBLOB_H_
#define TESSERACT_TEXTORD_ALIGNEDBLOB_H_
#include "bbgrid.h"
#include "blobbox.h"
#include "tabvector.h"
namespace tesseract {
extern INT_VAR_H(textord_debug_bugs, 0,
"Turn on output related to bugs in tab finding");
extern INT_VAR_H(textord_debug_tabfind, 2, "Debug tab finding");
extern BOOL_VAR_H(textord_debug_printable, false,
"Make debug windows printable");
// Simple structure to hold the search parameters for AlignedBlob.
// The members are mostly derived from constants, which are
// conditioned on the alignment parameter.
// For finding vertical lines, a different set of constants are
// used, conditioned on the different constructor.
struct AlignedBlobParams {
// Constructor to set the parameters for finding aligned and ragged tabs.
// Vertical_x and vertical_y are the current estimates of the true vertical
// direction (up) in the image. Height is the height of the starter blob.
// v_gap_multiple is the multiple of height that will be used as a limit
// on vertical gap before giving up and calling the line ended.
// resolution is the original image resolution, and align0 indicates the
// type of tab stop to be found.
AlignedBlobParams(int vertical_x, int vertical_y, int height,
int v_gap_multiple, int min_gutter_width, int resolution,
TabAlignment alignment0);
// Constructor to set the parameters for finding vertical lines.
// Vertical_x and vertical_y are the current estimates of the true vertical
// direction (up) in the image. Width is the width of the starter blob.
AlignedBlobParams(int vertical_x, int vertical_y, int width);
// Fit the vertical vector into an ICOORD, which is 16 bit.
void set_vertical(int vertical_x, int vertical_y);
double gutter_fraction; // Multiple of height used for min_gutter.
bool right_tab; // We are looking at right edges.
bool ragged; // We are looking for a ragged (vs aligned) edge.
TabAlignment alignment; // The type we are trying to produce.
TabType confirmed_type; // Type to flag blobs if accepted.
int max_v_gap; // Max vertical gap to be tolerated.
int min_gutter; // Minimum gutter between columns.
// Tolerances allowed on horizontal alignment of aligned edges.
int l_align_tolerance; // Left edges.
int r_align_tolerance; // Right edges.
// Conditions for accepting a line.
int min_points; // Minimum number of points to be OK.
int min_length; // Min length of completed line.
ICOORD vertical; // Current estimate of logical vertical.
};
// The AlignedBlob class contains code to find vertically aligned blobs.
// This is factored out into a separate class, so it can be used by both
// vertical line finding (LineFind) and tabstop finding (TabFind).
class TESS_API AlignedBlob : public BlobGrid {
public:
AlignedBlob(int gridsize, const ICOORD& bleft, const ICOORD& tright);
~AlignedBlob() override;
// Return true if the given coordinates are within the test rectangle
// and the debug level is at least the given detail level.
static bool WithinTestRegion(int detail_level, int x, int y);
// Display the tab codes of the BLOBNBOXes in this grid.
ScrollView* DisplayTabs(const char* window_name, ScrollView* tab_win);
// Finds a vector corresponding to a set of vertically aligned blob edges
// running through the given box. The type of vector returned and the
// search parameters are determined by the AlignedBlobParams.
// vertical_x and y are updated with an estimate of the real
// vertical direction. (skew finding.)
// Returns nullptr if no decent vector can be found.
TabVector* FindVerticalAlignment(AlignedBlobParams align_params,
BLOBNBOX* bbox,
int* vertical_x, int* vertical_y);
private:
// Find a set of blobs that are aligned in the given vertical
// direction with the given blob. Returns a list of aligned
// blobs and the number in the list.
// For other parameters see FindAlignedBlob below.
int AlignTabs(const AlignedBlobParams& params,
bool top_to_bottom, BLOBNBOX* bbox,
BLOBNBOX_CLIST* good_points, int* end_y);
// Search vertically for a blob that is aligned with the input bbox.
// The search parameters are determined by AlignedBlobParams.
// top_to_bottom tells whether to search down or up.
// The return value is nullptr if nothing was found in the search box
// or if a blob was found in the gutter. On a nullptr return, end_y
// is set to the edge of the search box or the leading edge of the
// gutter blob if one was found.
BLOBNBOX* FindAlignedBlob(const AlignedBlobParams& p,
bool top_to_bottom, BLOBNBOX* bbox,
int x_start, int* end_y);
};
} // namespace tesseract.
#endif // TESSERACT_TEXTORD_ALIGNEDBLOB_H_
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