/********************************************************************** * File: pango_font_info.h * Description: Font-related objects and helper functions * Author: Ranjith Unnikrishnan * Created: Mon Nov 18 2013 * * (C) Copyright 2013, 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_TRAINING_PANGO_FONT_INFO_H_ #define TESSERACT_TRAINING_PANGO_FONT_INFO_H_ #include #include #include #include "hashfn.h" #include "host.h" #include "util.h" #include "pango/pango-font.h" typedef signed int char32; namespace tesseract { // Data holder class for a font, intended to avoid having to work with Pango or // FontConfig-specific objects directly. class PangoFontInfo { public: enum FontTypeEnum { UNKNOWN, SERIF, SANS_SERIF, DECORATIVE, }; PangoFontInfo(); // Initialize from parsing a font description name, defined as a string of the // format: // "FamilyName [FaceName] [PointSize]" // where a missing FaceName implies the default regular face. // eg. "Arial Italic 12", "Verdana" // // FaceName is a combination of: // [StyleName] [Variant] [Weight] [Stretch] // with (all optional) Pango-defined values of: // StyleName: Oblique, Italic // Variant : Small-Caps // Weight : Ultra-Light, Light, Medium, Semi-Bold, Bold, Ultra-Bold, Heavy // Stretch : Ultra-Condensed, Extra-Condensed, Condensed, Semi-Condensed, // Semi-Expanded, Expanded, Extra-Expanded, Ultra-Expanded. explicit PangoFontInfo(const string& name); bool ParseFontDescriptionName(const string& name); // Returns true if the font have codepoint coverage for the specified text. bool CoversUTF8Text(const char* utf8_text, int byte_length) const; // Modifies string to remove unicode points that are not covered by the // font. Returns the number of characters dropped. int DropUncoveredChars(string* utf8_text) const; // Returns true if the entire string can be rendered by the font with full // character coverage and no unknown glyph or dotted-circle glyph // substitutions on encountering a badly formed unicode sequence. // If true, returns individual graphemes. Any whitespace characters in the // original string are also included in the list. bool CanRenderString(const char* utf8_word, int len, vector* graphemes) const; bool CanRenderString(const char* utf8_word, int len) const; // Retrieves the x_bearing and x_advance for the given utf8 character in the // font. Returns false if the glyph for the character could not be found in // the font. // Ref: http://freetype.sourceforge.net/freetype2/docs/glyphs/glyphs-3.html bool GetSpacingProperties(const string& utf8_char, int* x_bearing, int* x_advance) const; // Initializes FontConfig by setting its environment variable and creating // a fonts.conf file that points to the given fonts_dir. Once initialized, // it is not re-initialized unless force_clear is true. static void InitFontConfig(bool force_clear, const string& fonts_dir); // Accessors string DescriptionName() const; // Font Family name eg. "Arial" const string& family_name() const { return family_name_; } // Size in points (1/72"), rounded to the nearest integer. int font_size() const { return font_size_; } bool is_bold() const { return is_bold_; } bool is_italic() const { return is_italic_; } bool is_smallcaps() const { return is_smallcaps_; } bool is_monospace() const { return is_monospace_; } bool is_fraktur() const { return is_fraktur_; } FontTypeEnum font_type() const { return font_type_; } int resolution() const { return resolution_; } void set_resolution(const int resolution) { resolution_ = resolution; } private: friend class FontUtils; void Clear(); bool ParseFontDescription(const PangoFontDescription* desc); // Returns the PangoFont structure corresponding to the closest available font // in the font map. PangoFont* ToPangoFont() const; // Font properties set automatically from parsing the font description name. string family_name_; int font_size_; bool is_bold_; bool is_italic_; bool is_smallcaps_; bool is_monospace_; bool is_fraktur_; FontTypeEnum font_type_; // The Pango description that was used to initialize the instance. PangoFontDescription* desc_; // Default output resolution to assume for GetSpacingProperties() and any // other methods that returns pixel values. int resolution_; // Fontconfig operates through an environment variable, so it intrinsically // cannot be thread-friendly, but you can serialize multiple independent // font configurations by calling InitFontConfig(true, path). static bool fontconfig_initialized_; private: PangoFontInfo(const PangoFontInfo&); void operator=(const PangoFontInfo&); }; // Static utility methods for querying font availability and font-selection // based on codepoint coverage. class FontUtils { public: // Returns true if the font of the given description name is available in the // target directory specified by --fonts_dir static bool IsAvailableFont(const char* font_desc) { return IsAvailableFont(font_desc, NULL); } // Returns true if the font of the given description name is available in the // target directory specified by --fonts_dir. If false is returned, and // best_match is not NULL, the closest matching font is returned there. static bool IsAvailableFont(const char* font_desc, string* best_match); // Outputs description names of available fonts. static const vector& ListAvailableFonts(); // Picks font among available fonts that covers and can render the given word, // and returns the font description name and the decomposition of the word to // graphemes. Returns false if no suitable font was found. static bool SelectFont(const char* utf8_word, const int utf8_len, string* font_name, vector* graphemes); // Picks font among all_fonts that covers and can render the given word, // and returns the font description name and the decomposition of the word to // graphemes. Returns false if no suitable font was found. static bool SelectFont(const char* utf8_word, const int utf8_len, const vector& all_fonts, string* font_name, vector* graphemes); // Returns a bitmask where the value of true at index 'n' implies that unicode // value 'n' is renderable by at least one available font. static void GetAllRenderableCharacters(vector* unichar_bitmap); // Variant of the above function that inspects only the provided font names. static void GetAllRenderableCharacters(const vector& font_names, vector* unichar_bitmap); static void GetAllRenderableCharacters(const string& font_name, vector* unichar_bitmap); // NOTE: The following utilities were written to be backward compatible with // StringRender. // BestFonts returns a font name and a bit vector of the characters it // can render for the fonts that score within some fraction of the best // font on the characters in the given hash map. // In the flags vector, each flag is set according to whether the // corresponding character (in order of iterating ch_map) can be rendered. // The return string is a list of the acceptable fonts that were used. static string BestFonts(const unordered_map& ch_map, vector > >* font_flag); // FontScore returns the weighted renderability score of the given // hash map character table in the given font. The unweighted score // is also returned in raw_score. // The values in the bool vector ch_flags correspond to whether the // corresponding character (in order of iterating ch_map) can be rendered. static int FontScore(const unordered_map& ch_map, const string& fontname, int* raw_score, vector* ch_flags); // PangoFontInfo is reinitialized, so clear the static list of fonts. static void ReInit(); private: static vector available_fonts_; // cache list }; } // namespace tesseract #endif // TESSERACT_TRAINING_PANGO_FONT_INFO_H_