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81 lines
2.7 KiB
C++
81 lines
2.7 KiB
C++
/**********************************************************************
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* File: ligature_table.h
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* Description: Class for adding and removing optional latin ligatures,
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* conditional on codepoint support by a specified font
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* (if specified).
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* Author: Ranjith Unnikrishnan
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* Created: Mon Nov 18 2013
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*
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* (C) Copyright 2013, Google Inc.
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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* http://www.apache.org/licenses/LICENSE-2.0
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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**********************************************************************/
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#ifndef TRAININGDATA_LIGATURE_TABLE_H_
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#define TRAININGDATA_LIGATURE_TABLE_H_
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#include <memory>
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#include <string>
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#include <unordered_map>
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#include "util.h"
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namespace tesseract {
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class PangoFontInfo; // defined in pango_font_info.h
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// Map to substitute strings for ligatures.
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using LigHash = std::unordered_map<std::string, std::string, StringHash>;
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class LigatureTable {
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public:
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// Get a static instance of this class.
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static LigatureTable* Get();
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// Convert the utf8 string so that ligaturizable sequences, such as "fi" get
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// replaced by the (utf8 code for) appropriate ligature characters. Only do so
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// if the corresponding ligature character is renderable in the current font.
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std::string AddLigatures(const std::string& str, const PangoFontInfo* font) const;
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// Remove all ligatures.
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std::string RemoveLigatures(const std::string& str) const;
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// Remove only custom ligatures (eg. "ct") encoded in the private-use-area.
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std::string RemoveCustomLigatures(const std::string& str) const;
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const LigHash& norm_to_lig_table() const {
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return norm_to_lig_table_;
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}
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const LigHash& lig_to_norm_table() const {
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return lig_to_norm_table_;
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}
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protected:
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LigatureTable();
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// Initialize the hash tables mapping between ligature strings and the
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// corresponding ligature characters.
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void Init();
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static std::unique_ptr<LigatureTable> instance_;
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LigHash norm_to_lig_table_;
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LigHash lig_to_norm_table_;
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int min_lig_length_;
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int max_lig_length_;
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int min_norm_length_;
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int max_norm_length_;
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private:
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LigatureTable(const LigatureTable&);
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void operator=(const LigatureTable&);
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};
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} // namespace tesseract
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#endif // OCR_TRAININGDATA_TYPESETTING_LIGATURE_TABLE_H_
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