include/vcl/glyphitemcache.hxx

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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  17  *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
  18  */
  19
  20 #ifndef INCLUDED_VCL_GLYPHITEMCACHE_HXX
  21 #define INCLUDED_VCL_GLYPHITEMCACHE_HXX
  22
  23 #include <sal/types.h>
  24 #include <vcl/dllapi.h>
  25
  26 #include <o3tl/lru_map.hxx>
  27 #include <o3tl/hash_combine.hxx>
  28 #include <vcl/glyphitem.hxx>
  29 #include <vcl/metric.hxx>
  30 #include <vcl/outdev.hxx>
  31 #include <vcl/vclptr.hxx>
  32 #include <tools/gen.hxx>
  33
  34 #include <optional>
  35
  36 /**
  37 A cache for SalLayoutGlyphs objects.
  38
  39 Allows caching for OutputDevice::DrawText() and similar calls. Pass the text and the output device
  40 for the call to OutputDevice::ImplLayout(). Items are cached per output device and its font.
  41 If something more changes, call clear().
  42 */
  43 class VCL_DLLPUBLIC SalLayoutGlyphsCache final
  44 {
  45 public:
  46     // NOTE: The lifetime of the returned value is guaranteed only until the next call
  47     // to any function in this class.
  48     const SalLayoutGlyphs* GetLayoutGlyphs(VclPtr<const OutputDevice> outputDevice,
  49                                            const OUString& text,
  50                                            const vcl::text::TextLayoutCache* layoutCache = nullptr)
  51     {
  52         return GetLayoutGlyphs(outputDevice, text, 0, text.getLength(), 0, layoutCache);
  53     }
  54     const SalLayoutGlyphs* GetLayoutGlyphs(VclPtr<const OutputDevice> outputDevice,
  55                                            const OUString& text, sal_Int32 nIndex, sal_Int32 nLen,
  56                                            tools::Long nLogicWidth = 0,
  57                                            const vcl::text::TextLayoutCache* layoutCache = nullptr);
  58     void clear();
  59
  60     /// Normally, we cannot cache glyphs when doing font fallback, because the font fallbacks
  61     /// can cache during the lifetime of the cache, and they are not included in the cache key.
  62     /// But during some processes, we can turn this on, as long as we remember to turn it off
  63     /// at the end.
  64     void SetCacheGlyphsWhenDoingFallbackFonts(bool bOK);
  65
  66     static SalLayoutGlyphsCache* self();
  67     SalLayoutGlyphsCache(int size) // needs to be public for vcl::DeleteOnDeinit
  68         : mCachedGlyphs(size)
  69     {
  70     }
  71
  72 private:
  73     struct CachedGlyphsKey
  74     {
  75         OUString text;
  76         sal_Int32 index;
  77         sal_Int32 len;
  78         tools::Long logicWidth;
  79         FontMetric fontMetric;
  80         double fontScaleX;
  81         double fontScaleY;
  82         MapMode mapMode;
  83         bool rtl;
  84         bool disabledLigatures; // because of fixed pitch
  85         bool artificialItalic;
  86         bool artificialBold;
  87         vcl::text::ComplexTextLayoutFlags layoutMode;
  88         LanguageType digitLanguage;
  89         size_t hashValue;
  90         CachedGlyphsKey(const VclPtr<const OutputDevice>& dev, OUString t, sal_Int32 i, sal_Int32 l,
  91                         tools::Long w);
  92         bool operator==(const CachedGlyphsKey& other) const;
  93     };
  94     struct CachedGlyphsHash
  95     {
  96         size_t operator()(const CachedGlyphsKey& key) const { return key.hashValue; }
  97     };
  98     struct GlyphsCost
  99     {
 100         size_t operator()(const SalLayoutGlyphs&) const;
 101     };
 102     typedef o3tl::lru_map<CachedGlyphsKey, SalLayoutGlyphs, CachedGlyphsHash,
 103                           std::equal_to<CachedGlyphsKey>, GlyphsCost>
 104         GlyphsCache;
 105     GlyphsCache mCachedGlyphs;
 106     // Last temporary glyphs returned (pointer is returned, so the object needs to be kept somewhere).
 107     std::optional<CachedGlyphsKey> mLastTemporaryKey;
 108     SalLayoutGlyphs mLastTemporaryGlyphs;
 109     // If set, info about the last call which wanted a substring of the full text.
 110     std::optional<CachedGlyphsKey> mLastSubstringKey;
 111     bool mbCacheGlyphsWhenDoingFallbackFonts = false;
 112
 113     SalLayoutGlyphsCache(const SalLayoutGlyphsCache&) = delete;
 114     SalLayoutGlyphsCache& operator=(const SalLayoutGlyphsCache&) = delete;
 115 };
 116
 117 #endif // INCLUDED_VCL_GLYPHITEMCACHE_HXX
 118
 119 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */