src/fontcache/truetypefontcache.h

   1 /*
   2  * This file is part of OpenTTD.
   3  * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
   4  * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   5  * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
   6  */
   7
   8 /** @file truetypefontcache.h Common base definition for font file based font caches. */
   9
  10 #ifndef TRUETYPEFONTCACHE_H
  11 #define TRUETYPEFONTCACHE_H
  12
  13 #include "../fontcache.h"
  14
  15
  16 static const int MAX_FONT_SIZE = 72; ///< Maximum font size.
  17
  18 static const byte FACE_COLOUR = 1;
  19 static const byte SHADOW_COLOUR = 2;
  20
  21 /** Font cache for fonts that are based on a TrueType font. */
  22 class TrueTypeFontCache : public FontCache {
  23 protected:
  24         static constexpr int MAX_GLYPH_DIM = 256;          ///< Maximum glyph dimensions.
  25         static constexpr uint MAX_FONT_MIN_REC_SIZE = 20u; ///< Upper limit for the recommended font size in case a font file contains nonsensical values.
  26
  27         int req_size;  ///< Requested font size.
  28         int used_size; ///< Used font size.
  29
  30         using FontTable = std::map<uint32_t, std::pair<size_t, const void *>>; ///< Table with font table cache
  31         FontTable font_tables; ///< Cached font tables.
  32
  33         /** Container for information about a glyph. */
  34         struct GlyphEntry {
  35                 Sprite *sprite; ///< The loaded sprite.
  36                 byte width;     ///< The width of the glyph.
  37                 bool duplicate; ///< Whether this glyph entry is a duplicate, i.e. may this be freed?
  38         };
  39
  40         /**
  41          * The glyph cache. This is structured to reduce memory consumption.
  42          * 1) There is a 'segment' table for each font size.
  43          * 2) Each segment table is a discrete block of characters.
  44          * 3) Each block contains 256 (aligned) characters sequential characters.
  45          *
  46          * The cache is accessed in the following way:
  47          * For character 0x0041  ('A'): glyph_to_sprite[0x00][0x41]
  48          * For character 0x20AC (Euro): glyph_to_sprite[0x20][0xAC]
  49          *
  50          * Currently only 256 segments are allocated, "limiting" us to 65536 characters.
  51          * This can be simply changed in the two functions Get & SetGlyphPtr.
  52          */
  53         GlyphEntry **glyph_to_sprite;
  54
  55         GlyphEntry *GetGlyphPtr(GlyphID key);
  56         void SetGlyphPtr(GlyphID key, const GlyphEntry *glyph, bool duplicate = false);
  57
  58         virtual const void *InternalGetFontTable(uint32_t tag, size_t &length) = 0;
  59         virtual const Sprite *InternalGetGlyph(GlyphID key, bool aa) = 0;
  60
  61 public:
  62         TrueTypeFontCache(FontSize fs, int pixels);
  63         virtual ~TrueTypeFontCache();
  64         int GetFontSize() const override { return this->used_size; }
  65         void SetUnicodeGlyph(char32_t key, SpriteID sprite) override { this->parent->SetUnicodeGlyph(key, sprite); }
  66         void InitializeUnicodeGlyphMap() override { this->parent->InitializeUnicodeGlyphMap(); }
  67         const Sprite *GetGlyph(GlyphID key) override;
  68         const void *GetFontTable(uint32_t tag, size_t &length) override;
  69         void ClearFontCache() override;
  70         uint GetGlyphWidth(GlyphID key) override;
  71         bool GetDrawGlyphShadow() override;
  72         bool IsBuiltInFont() override { return false; }
  73 };
  74
  75 #endif /* TRUETYPEFONTCACHE_H */