src/fontcache_internal.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 fontcache_internal.h Support types and functions for platform-specific font support. */
   9
  10 #ifndef FONTCACHE_INTERNAL_H
  11 #define FONTCACHE_INTERNAL_H
  12
  13 #include "core/smallmap_type.hpp"
  14 #include "fontcache.h"
  15
  16
  17 static const int MAX_FONT_SIZE = 72; ///< Maximum font size.
  18
  19 static const byte FACE_COLOUR = 1;
  20 static const byte SHADOW_COLOUR = 2;
  21
  22 /** Font cache for fonts that are based on a TrueType font. */
  23 class TrueTypeFontCache : public FontCache {
  24 protected:
  25         static constexpr int MAX_GLYPH_DIM = 256;          ///< Maximum glyph dimensions.
  26         static constexpr uint MAX_FONT_MIN_REC_SIZE = 20u; ///< Upper limit for the recommended font size in case a font file contains nonsensical values.
  27
  28         int req_size;  ///< Requested font size.
  29         int used_size; ///< Used font size.
  30
  31         typedef SmallMap<uint32, std::pair<size_t, const void *> > FontTable; ///< Table with font table cache
  32         FontTable font_tables; ///< Cached font tables.
  33
  34         /** Container for information about a glyph. */
  35         struct GlyphEntry {
  36                 Sprite *sprite; ///< The loaded sprite.
  37                 byte width;     ///< The width of the glyph.
  38                 bool duplicate; ///< Whether this glyph entry is a duplicate, i.e. may this be freed?
  39         };
  40
  41         /**
  42          * The glyph cache. This is structured to reduce memory consumption.
  43          * 1) There is a 'segment' table for each font size.
  44          * 2) Each segment table is a discrete block of characters.
  45          * 3) Each block contains 256 (aligned) characters sequential characters.
  46          *
  47          * The cache is accessed in the following way:
  48          * For character 0x0041  ('A'): glyph_to_sprite[0x00][0x41]
  49          * For character 0x20AC (Euro): glyph_to_sprite[0x20][0xAC]
  50          *
  51          * Currently only 256 segments are allocated, "limiting" us to 65536 characters.
  52          * This can be simply changed in the two functions Get & SetGlyphPtr.
  53          */
  54         GlyphEntry **glyph_to_sprite;
  55
  56         GlyphEntry *GetGlyphPtr(GlyphID key);
  57         void SetGlyphPtr(GlyphID key, const GlyphEntry *glyph, bool duplicate = false);
  58
  59         virtual const void *InternalGetFontTable(uint32 tag, size_t &length) = 0;
  60         virtual const Sprite *InternalGetGlyph(GlyphID key, bool aa) = 0;
  61
  62 public:
  63         TrueTypeFontCache(FontSize fs, int pixels);
  64         virtual ~TrueTypeFontCache();
  65         int GetFontSize() const override { return this->used_size; }
  66         SpriteID GetUnicodeGlyph(WChar key) override { return this->parent->GetUnicodeGlyph(key); }
  67         void SetUnicodeGlyph(WChar key, SpriteID sprite) override { this->parent->SetUnicodeGlyph(key, sprite); }
  68         void InitializeUnicodeGlyphMap() override { this->parent->InitializeUnicodeGlyphMap(); }
  69         const Sprite *GetGlyph(GlyphID key) override;
  70         const void *GetFontTable(uint32 tag, size_t &length) override;
  71         void ClearFontCache() override;
  72         uint GetGlyphWidth(GlyphID key) override;
  73         bool GetDrawGlyphShadow() override;
  74         bool IsBuiltInFont() override { return false; }
  75 };
  76
  77 #endif /* FONTCACHE_INTERNAL_H */