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alignedblob.h
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1
2 // File: alignedblob.h
3 // Description: A class to find vertically aligned blobs in a BBGrid,
4 // and a struct to hold control parameters.
5 // Author: Ray Smith
6 // Created: Fri Mar 21 15:03:01 PST 2008
7 //
8 // (C) Copyright 2008, Google Inc.
9 // Licensed under the Apache License, Version 2.0 (the "License");
10 // you may not use this file except in compliance with the License.
11 // You may obtain a copy of the License at
12 // http://www.apache.org/licenses/LICENSE-2.0
13 // Unless required by applicable law or agreed to in writing, software
14 // distributed under the License is distributed on an "AS IS" BASIS,
15 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16 // See the License for the specific language governing permissions and
17 // limitations under the License.
18 //
20
21 #ifndef TESSERACT_TEXTORD_ALIGNEDBLOB_H__
22 #define TESSERACT_TEXTORD_ALIGNEDBLOB_H__
23
24 #include "bbgrid.h"
25 #include "blobbox.h"
26 #include "strngs.h"
27 #include "tabvector.h"
28
29 extern INT_VAR_H(textord_debug_bugs, 0,
30 "Turn on output related to bugs in tab finding");
31 extern INT_VAR_H(textord_debug_tabfind, 2, "Debug tab finding");
32 extern BOOL_VAR_H(textord_debug_images, false,
33 "Use greyed image background for debug");
34 extern BOOL_VAR_H(textord_debug_printable, false,
35 "Make debug windows printable");
36
37 namespace tesseract {
38
39 // Simple structure to hold the search parameters for AlignedBlob.
40 // The members are mostly derived from constants, which are
41 // conditioned on the alignment parameter.
42 // For finding vertical lines, a different set of constants are
43 // used, conditioned on the different constructor.
44 struct AlignedBlobParams {
45 // Constructor to set the parameters for finding aligned and ragged tabs.
46 // Vertical_x and vertical_y are the current estimates of the true vertical
47 // direction (up) in the image. Height is the height of the starter blob.
48 // v_gap_multiple is the multiple of height that will be used as a limit
49 // on vertical gap before giving up and calling the line ended.
50 // resolution is the original image resolution, and align0 indicates the
51 // type of tab stop to be found.
52 AlignedBlobParams(int vertical_x, int vertical_y, int height,
53 int v_gap_multiple, int min_gutter_width, int resolution,
54 TabAlignment alignment0);
55 // Constructor to set the parameters for finding vertical lines.
56 // Vertical_x and vertical_y are the current estimates of the true vertical
57 // direction (up) in the image. Width is the width of the starter blob.
58 AlignedBlobParams(int vertical_x, int vertical_y, int width);
59
60 // Fit the vertical vector into an ICOORD, which is 16 bit.
61 void set_vertical(int vertical_x, int vertical_y);
62
63 double gutter_fraction; // Multiple of height used for min_gutter.
64 bool right_tab; // We are looking at right edges.
65 bool ragged; // We are looking for a ragged (vs aligned) edge.
66 TabAlignment alignment; // The type we are trying to produce.
67 TabType confirmed_type; // Type to flag blobs if accepted.
68 int max_v_gap; // Max vertical gap to be tolerated.
69 int min_gutter; // Minimum gutter between columns.
70 // Tolerances allowed on horizontal alignment of aligned edges.
71 int l_align_tolerance; // Left edges.
72 int r_align_tolerance; // Right edges.
73 // Conditions for accepting a line.
74 int min_points; // Minimum number of points to be OK.
75 int min_length; // Min length of completed line.
76
77 ICOORD vertical; // Current estimate of logical vertical.
78 };
79
80 // The AlignedBlob class contains code to find vertically aligned blobs.
81 // This is factored out into a separate class, so it can be used by both
82 // vertical line finding (LineFind) and tabstop finding (TabFind).
83 class AlignedBlob : public BlobGrid {
84 public:
85 AlignedBlob(int gridsize, const ICOORD& bleft, const ICOORD& tright);
86 virtual ~AlignedBlob();
87
88 // Return true if the given coordinates are within the test rectangle
89 // and the debug level is at least the given detail level.
90 static bool WithinTestRegion(int detail_level, int x, int y);
91
92 // Display the tab codes of the BLOBNBOXes in this grid.
93 ScrollView* DisplayTabs(const char* window_name, ScrollView* tab_win);
94
95 // Finds a vector corresponding to a set of vertically aligned blob edges
96 // running through the given box. The type of vector returned and the
97 // search parameters are determined by the AlignedBlobParams.
98 // vertical_x and y are updated with an estimate of the real
99 // vertical direction. (skew finding.)
100 // Returns NULL if no decent vector can be found.
101 TabVector* FindVerticalAlignment(AlignedBlobParams align_params,
102 BLOBNBOX* bbox,
103 int* vertical_x, int* vertical_y);
104
105 // Increment the serial number counter and set the string to use
106 // for a filename if textord_debug_images is true.
107 static void IncrementDebugPix();
108
109 // Return the string to use for a filename if textord_debug_images is true.
110 // Use IncrementDebugPix first to set the filename, and each time is
111 // to be incremented.
112 static const STRING& textord_debug_pix() {
113 return textord_debug_pix_;
114 }
115
116 private:
117 // Find a set of blobs that are aligned in the given vertical
118 // direction with the given blob. Returns a list of aligned
119 // blobs and the number in the list.
120 // For other parameters see FindAlignedBlob below.
121 int AlignTabs(const AlignedBlobParams& params,
122 bool top_to_bottom, BLOBNBOX* bbox,
123 BLOBNBOX_CLIST* good_points, int* end_y);
124
125 // Search vertically for a blob that is aligned with the input bbox.
126 // The search parameters are determined by AlignedBlobParams.
127 // top_to_bottom tells whether to search down or up.
128 // The return value is NULL if nothing was found in the search box
129 // or if a blob was found in the gutter. On a NULL return, end_y
130 // is set to the edge of the search box or the leading edge of the
131 // gutter blob if one was found.
132 BLOBNBOX* FindAlignedBlob(const AlignedBlobParams& p,
133 bool top_to_bottom, BLOBNBOX* bbox,
134 int x_start, int* end_y);
135
136 // Name of image file to use if textord_debug_images is true.
137 static STRING textord_debug_pix_;
138 // Index to image file to use if textord_debug_images is true.
139 static int debug_pix_index_;
140 };
141
142 } // namespace tesseract.
143
144 #endif // TESSERACT_TEXTORD_ALIGNEDBLOB_H__
145