Tesseract  3.02
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boxread.cpp
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1 /**********************************************************************
2  * File: boxread.cpp
3  * Description: Read data from a box file.
4  * Author: Ray Smith
5  * Created: Fri Aug 24 17:47:23 PDT 2007
6  *
7  * (C) Copyright 2007, Google Inc.
8  ** Licensed under the Apache License, Version 2.0 (the "License");
9  ** you may not use this file except in compliance with the License.
10  ** You may obtain a copy of the License at
11  ** http://www.apache.org/licenses/LICENSE-2.0
12  ** Unless required by applicable law or agreed to in writing, software
13  ** distributed under the License is distributed on an "AS IS" BASIS,
14  ** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15  ** See the License for the specific language governing permissions and
16  ** limitations under the License.
17  *
18  **********************************************************************/
19 
20 #include "mfcpch.h"
21 #include "boxread.h"
22 #include <string.h>
23 
24 #include "rect.h"
25 #include "strngs.h"
26 #include "tprintf.h"
27 #include "unichar.h"
28 
29 // Special char code used to identify multi-blob labels.
30 static const char* kMultiBlobLabelCode = "WordStr";
31 
32 // Open the boxfile based on the given image filename.
33 FILE* OpenBoxFile(const STRING& fname) {
34  STRING filename = fname;
35  const char *lastdot = strrchr(filename.string(), '.');
36  if (lastdot != NULL)
37  filename[lastdot - filename.string()] = '\0';
38 
39  filename += ".box";
40  FILE* box_file = NULL;
41  if (!(box_file = fopen(filename.string(), "rb"))) {
42  CANTOPENFILE.error("read_next_box", TESSEXIT,
43  "Cant open box file %s",
44  filename.string());
45  }
46  return box_file;
47 }
48 
49 // Box files are used ONLY DURING TRAINING, but by both processes of
50 // creating tr files with tesseract, and unicharset_extractor.
51 // ReadNextBox factors out the code to interpret a line of a box
52 // file so that applybox and unicharset_extractor interpret the same way.
53 // This function returns the next valid box file utf8 string and coords
54 // and returns true, or false on eof (and closes the file).
55 // It ignores the utf8 file signature ByteOrderMark (U+FEFF=EF BB BF), checks
56 // for valid utf-8 and allows space or tab between fields.
57 // utf8_str is set with the unichar string, and bounding box with the box.
58 // If there are page numbers in the file, it reads them all.
59 bool ReadNextBox(int *line_number, FILE* box_file,
60  STRING* utf8_str, TBOX* bounding_box) {
61  return ReadNextBox(-1, line_number, box_file, utf8_str, bounding_box);
62 }
63 
64 // As ReadNextBox above, but get a specific page number. (0-based)
65 // Use -1 to read any page number. Files without page number all
66 // read as if they are page 0.
67 bool ReadNextBox(int target_page, int *line_number, FILE* box_file,
68  STRING* utf8_str, TBOX* bounding_box) {
69  int page = 0;
70  char buff[kBoxReadBufSize]; // boxfile read buffer
71  char *buffptr = buff;
72 
73  while (fgets(buff, sizeof(buff) - 1, box_file)) {
74  (*line_number)++;
75 
76  buffptr = buff;
77  const unsigned char *ubuf = reinterpret_cast<const unsigned char*>(buffptr);
78  if (ubuf[0] == 0xef && ubuf[1] == 0xbb && ubuf[2] == 0xbf)
79  buffptr += 3; // Skip unicode file designation.
80  // Check for blank lines in box file
81  while (*buffptr == ' ' || *buffptr == '\t')
82  buffptr++;
83  if (*buffptr != '\0') {
84  if (!ParseBoxFileStr(buffptr, &page, utf8_str, bounding_box)) {
85  tprintf("Box file format error on line %i; ignored\n", *line_number);
86  continue;
87  }
88  if (target_page >= 0 && target_page != page)
89  continue; // Not on the appropriate page.
90  return true; // Successfully read a box.
91  }
92  }
93  fclose(box_file);
94  return false; // EOF
95 }
96 
97 // Parses the given box file string into a page_number, utf8_str, and
98 // bounding_box. Returns true on a successful parse.
99 // The box file is assumed to contain box definitions, one per line, of the
100 // following format for blob-level boxes:
101 // <UTF8 str> <left> <bottom> <right> <top> <page id>
102 // and for word/line-level boxes:
103 // WordStr <left> <bottom> <right> <top> <page id> #<space-delimited word str>
104 // See applyybox.cpp for more information.
105 bool ParseBoxFileStr(const char* boxfile_str, int* page_number,
106  STRING* utf8_str, TBOX* bounding_box) {
107  *bounding_box = TBOX(); // Initialize it to empty.
108  *utf8_str = "";
109  char uch[kBoxReadBufSize];
110  const char *buffptr = boxfile_str;
111  // Read the unichar without messing up on Tibetan.
112  // According to issue 253 the utf-8 surrogates 85 and A0 are treated
113  // as whitespace by sscanf, so it is more reliable to just find
114  // ascii space and tab.
115  int uch_len = 0;
116  while (*buffptr != '\0' && *buffptr != ' ' && *buffptr != '\t' &&
117  uch_len < kBoxReadBufSize - 1) {
118  uch[uch_len++] = *buffptr++;
119  }
120  uch[uch_len] = '\0';
121  if (*buffptr != '\0') ++buffptr;
122  int x_min, y_min, x_max, y_max;
123  *page_number = 0;
124  int count = sscanf(buffptr, "%d %d %d %d %d",
125  &x_min, &y_min, &x_max, &y_max, page_number);
126  if (count != 5 && count != 4) {
127  tprintf("Bad box coordinates in boxfile string!\n");
128  return false;
129  }
130  // Test for long space-delimited string label.
131  if (strcmp(uch, kMultiBlobLabelCode) == 0 &&
132  (buffptr = strchr(buffptr, '#')) != NULL) {
133  strncpy(uch, buffptr + 1, kBoxReadBufSize);
134  chomp_string(uch);
135  uch_len = strlen(uch);
136  }
137  // Validate UTF8 by making unichars with it.
138  int used = 0;
139  while (used < uch_len) {
140  UNICHAR ch(uch + used, uch_len - used);
141  int new_used = ch.utf8_len();
142  if (new_used == 0) {
143  tprintf("Bad UTF-8 str %s starts with 0x%02x at col %d\n",
144  uch + used, uch[used], used + 1);
145  return false;
146  }
147  used += new_used;
148  }
149  *utf8_str = uch;
150  bounding_box->set_to_given_coords(x_min, y_min, x_max, y_max);
151  return true; // Successfully read a box.
152 }
153 
154 // Creates a box file string from a unichar string, TBOX and page number.
155 void MakeBoxFileStr(const char* unichar_str, const TBOX& box, int page_num,
156  STRING* box_str) {
157  *box_str = unichar_str;
158  box_str->add_str_int(" ", box.left());
159  box_str->add_str_int(" ", box.bottom());
160  box_str->add_str_int(" ", box.right());
161  box_str->add_str_int(" ", box.top());
162  box_str->add_str_int(" ", page_num);
163 }
164