tesseract 4.1.1
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tesseract::LigatureTable Class Reference

#include <ligature_table.h>

Public Member Functions

std::string AddLigatures (const std::string &str, const PangoFontInfo *font) const
 
std::string RemoveLigatures (const std::string &str) const
 
std::string RemoveCustomLigatures (const std::string &str) const
 
const LigHashnorm_to_lig_table () const
 
const LigHashlig_to_norm_table () const
 

Static Public Member Functions

static LigatureTableGet ()
 

Protected Member Functions

 LigatureTable ()
 
void Init ()
 

Protected Attributes

LigHash norm_to_lig_table_
 
LigHash lig_to_norm_table_
 
int min_lig_length_
 
int max_lig_length_
 
int min_norm_length_
 
int max_norm_length_
 

Static Protected Attributes

static std::unique_ptr< LigatureTableinstance_
 

Detailed Description

Definition at line 38 of file ligature_table.h.

Constructor & Destructor Documentation

◆ LigatureTable()

tesseract::LigatureTable::LigatureTable ( )
protected

Member Function Documentation

◆ AddLigatures()

std::string tesseract::LigatureTable::AddLigatures ( const std::string &  str,
const PangoFontInfo font 
) const

Definition at line 156 of file ligature_table.cpp.

157 {
158 std::string result;
159 int len = str.size();
160 int step = 0;
161 int i = 0;
162 for (i = 0; i < len - min_norm_length_ + 1; i += step) {
163 step = 0;
164 for (int liglen = max_norm_length_; liglen >= min_norm_length_; --liglen) {
165 if (i + liglen <= len) {
166 std::string lig_cand = str.substr(i, liglen);
167 LigHash::const_iterator it = norm_to_lig_table_.find(lig_cand);
168 if (it != norm_to_lig_table_.end()) {
169 tlog(3, "Considering %s -> %s\n", lig_cand.c_str(),
170 it->second.c_str());
171 if (font) {
172 // Test for renderability.
173 if (!font->CanRenderString(it->second.data(), it->second.length()))
174 continue; // Not renderable
175 }
176 // Found a match so convert it.
177 step = liglen;
178 result += it->second;
179 tlog(2, "Substituted %s -> %s\n", lig_cand.c_str(),
180 it->second.c_str());
181 break;
182 }
183 }
184 }
185 if (step == 0) {
186 result += str[i];
187 step = 1;
188 }
189 }
190 result += str.substr(i, len - i);
191 return result;
192}
#define tlog(level,...)
Definition: tlog.h:33

◆ Get()

LigatureTable * tesseract::LigatureTable::Get ( )
static

Definition at line 52 of file ligature_table.cpp.

52 {
53 if (instance_ == nullptr) {
54 instance_.reset(new LigatureTable());
55 instance_->Init();
56 }
57 return instance_.get();
58}
static std::unique_ptr< LigatureTable > instance_

◆ Init()

void tesseract::LigatureTable::Init ( )
protected

Definition at line 63 of file ligature_table.cpp.

63 {
64 if (norm_to_lig_table_.empty()) {
65 for (char32 lig = kMinLigature; lig <= kMaxLigature; ++lig) {
66 // For each char in the range, convert to utf8, nfkc normalize, and if
67 // the strings are different put the both mappings in the hash_maps.
68 std::string lig8 = EncodeAsUTF8(lig);
69 icu::UnicodeString unicode_lig8(static_cast<UChar32>(lig));
70 icu::UnicodeString normed8_result;
71 icu::ErrorCode status;
72 icu::Normalizer::normalize(unicode_lig8, UNORM_NFKC, 0, normed8_result,
73 status);
74 std::string normed8;
75 normed8_result.toUTF8String(normed8);
76 // The icu::Normalizer maps the "LONG S T" ligature to "st". Correct that
77 // here manually so that AddLigatures() will work as desired.
78 if (lig8 == "\uFB05")
79 normed8 = "ſt";
80 int lig_length = lig8.length();
81 int norm_length = normed8.size();
82 if (normed8 != lig8 && lig_length > 1 && norm_length > 1) {
83 norm_to_lig_table_[normed8] = lig8;
84 lig_to_norm_table_[lig8] = normed8;
85 if (min_lig_length_ == 0 || lig_length < min_lig_length_)
86 min_lig_length_ = lig_length;
87 if (lig_length > max_lig_length_)
88 max_lig_length_ = lig_length;
89 if (min_norm_length_ == 0 || norm_length < min_norm_length_)
90 min_norm_length_ = norm_length;
91 if (norm_length > max_norm_length_)
92 max_norm_length_ = norm_length;
93 }
94 }
95 // Add custom extra ligatures.
96 for (int i = 0; UNICHARSET::kCustomLigatures[i][0] != nullptr; ++i) {
99 int norm_length = strlen(UNICHARSET::kCustomLigatures[i][0]);
100 if (min_norm_length_ == 0 || norm_length < min_norm_length_)
101 min_norm_length_ = norm_length;
102 if (norm_length > max_norm_length_)
103 max_norm_length_ = norm_length;
104
107 }
108 }
109}
signed int char32
const int kMinLigature
const int kMaxLigature
static TESS_API const char * kCustomLigatures[][2]
Definition: unicharset.h:150

◆ lig_to_norm_table()

const LigHash & tesseract::LigatureTable::lig_to_norm_table ( ) const
inline

Definition at line 55 of file ligature_table.h.

55 {
56 return lig_to_norm_table_;
57 }

◆ norm_to_lig_table()

const LigHash & tesseract::LigatureTable::norm_to_lig_table ( ) const
inline

Definition at line 52 of file ligature_table.h.

52 {
53 return norm_to_lig_table_;
54 }

◆ RemoveCustomLigatures()

std::string tesseract::LigatureTable::RemoveCustomLigatures ( const std::string &  str) const

Definition at line 130 of file ligature_table.cpp.

130 {
131 std::string result;
132 UNICHAR::const_iterator it_begin = UNICHAR::begin(str.c_str(), str.length());
133 UNICHAR::const_iterator it_end = UNICHAR::end(str.c_str(), str.length());
134 char tmp[5];
135 int len;
136 int norm_ind;
137 for (UNICHAR::const_iterator it = it_begin; it != it_end; ++it) {
138 len = it.get_utf8(tmp);
139 tmp[len] = '\0';
140 norm_ind = -1;
141 for (int i = 0;
142 UNICHARSET::kCustomLigatures[i][0] != nullptr && norm_ind < 0; ++i) {
143 if (!strcmp(tmp, UNICHARSET::kCustomLigatures[i][1])) {
144 norm_ind = i;
145 }
146 }
147 if (norm_ind >= 0) {
148 result += UNICHARSET::kCustomLigatures[norm_ind][0];
149 } else {
150 result += tmp;
151 }
152 }
153 return result;
154}
static const_iterator begin(const char *utf8_str, int byte_length)
Definition: unichar.cpp:204
static const_iterator end(const char *utf8_str, int byte_length)
Definition: unichar.cpp:208

◆ RemoveLigatures()

std::string tesseract::LigatureTable::RemoveLigatures ( const std::string &  str) const

Definition at line 111 of file ligature_table.cpp.

111 {
112 std::string result;
113 UNICHAR::const_iterator it_begin = UNICHAR::begin(str.c_str(), str.length());
114 UNICHAR::const_iterator it_end = UNICHAR::end(str.c_str(), str.length());
115 char tmp[5];
116 int len;
117 for (UNICHAR::const_iterator it = it_begin; it != it_end; ++it) {
118 len = it.get_utf8(tmp);
119 tmp[len] = '\0';
120 LigHash::const_iterator lig_it = lig_to_norm_table_.find(tmp);
121 if (lig_it != lig_to_norm_table_.end()) {
122 result += lig_it->second;
123 } else {
124 result += tmp;
125 }
126 }
127 return result;
128}

Member Data Documentation

◆ instance_

std::unique_ptr< LigatureTable > tesseract::LigatureTable::instance_
staticprotected

Definition at line 65 of file ligature_table.h.

◆ lig_to_norm_table_

LigHash tesseract::LigatureTable::lig_to_norm_table_
protected

Definition at line 67 of file ligature_table.h.

◆ max_lig_length_

int tesseract::LigatureTable::max_lig_length_
protected

Definition at line 69 of file ligature_table.h.

◆ max_norm_length_

int tesseract::LigatureTable::max_norm_length_
protected

Definition at line 71 of file ligature_table.h.

◆ min_lig_length_

int tesseract::LigatureTable::min_lig_length_
protected

Definition at line 68 of file ligature_table.h.

◆ min_norm_length_

int tesseract::LigatureTable::min_norm_length_
protected

Definition at line 70 of file ligature_table.h.

◆ norm_to_lig_table_

LigHash tesseract::LigatureTable::norm_to_lig_table_
protected

Definition at line 66 of file ligature_table.h.


The documentation for this class was generated from the following files: