include/vcl/vcllayout.hxx

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  19
  20 #pragma once
  21
  22 #include <basegfx/point/b2dpoint.hxx>
  23 #include <basegfx/polygon/b2dpolypolygon.hxx>
  24 #include <basegfx/range/b2drectangle.hxx>
  25 #include <i18nlangtag/languagetag.hxx>
  26 #include <tools/gen.hxx>
  27 #include <tools/degree.hxx>
  28
  29 #include <vcl/glyphitem.hxx>
  30 #include <vcl/dllapi.h>
  31
  32 class LogicalFontInstance;
  33 namespace vcl::text { class ImplLayoutArgs; }
  34 namespace vcl::font { class PhysicalFontFace; }
  35 class SalGraphics;
  36 class GlyphItem;
  37
  38 // all positions/widths are in font units
  39 // one exception: drawposition is in pixel units
  40
  41 // Unfortunately there is little documentation to help implementors of
  42 // new classes derived from SalLayout ("layout engines"), and the code
  43 // and data structures are far from obvious.
  44
  45 // For instance, I *think* the important virtual functions in the
  46 // layout engines are called in this order:
  47
  48 // * InitFont()
  49 // * LayoutText()
  50 // * AdjustLayout(), any number of times (but presumably
  51 // usually not at all or just once)
  52 // * Optionally, DrawText()
  53
  54 // Functions that just return information like GetTexWidth() and
  55 // FillDXArray() are called after LayoutText() and before DrawText().
  56
  57 // Another important questions is which parts of an ImplLayoutArgs can
  58 // be changed by callers between LayoutText() and AdjustLayout()
  59 // calls. It probably makes sense only if one assumes that the "string
  60 // related inputs" part are not changed after LayoutText().
  61
  62 // But why use the same ImplLayoutArgs structure as parameter for both
  63 // LayoutText() and AdjustLayout() in the first place? And why
  64 // duplicate some of the fields in both SalLayout and ImplLayoutArgs
  65 // (mnMinCharPos, mnEndCharPos, mnLayoutFlags==mnFlags,
  66 // mnOrientation)? Lost in history...
  67
  68 class VCL_DLLPUBLIC SalLayout
  69 {
  70 public:
  71     virtual         ~SalLayout();
  72     // used by upper layers
  73     basegfx::B2DPoint& DrawBase()                           { return maDrawBase; }
  74     const basegfx::B2DPoint& DrawBase() const               { return maDrawBase; }
  75     Point&          DrawOffset()                            { return maDrawOffset; }
  76     const Point&    DrawOffset() const                      { return maDrawOffset; }
  77     basegfx::B2DPoint GetDrawPosition( const basegfx::B2DPoint& rRelative = basegfx::B2DPoint(0,0) ) const;
  78
  79     virtual bool    LayoutText( vcl::text::ImplLayoutArgs&, const SalLayoutGlyphsImpl* ) = 0;  // first step of layouting
  80     virtual void    AdjustLayout( vcl::text::ImplLayoutArgs& );    // adjusting after fallback etc.
  81     virtual void    InitFont() const {}
  82     virtual void    DrawText( SalGraphics& ) const = 0;
  83
  84     Degree10        GetOrientation() const                  { return mnOrientation; }
  85
  86     void            SetSubpixelPositioning(bool bSubpixelPositioning)
  87     {
  88         mbSubpixelPositioning = bSubpixelPositioning;
  89     }
  90
  91     bool            GetSubpixelPositioning() const
  92     {
  93         return mbSubpixelPositioning;
  94     }
  95
  96     // methods using string indexing
  97     virtual sal_Int32 GetTextBreak(double nMaxWidth, double nCharExtra, int nFactor) const = 0;
  98     virtual double  FillDXArray( std::vector<double>* pDXArray, const OUString& rStr ) const = 0;
  99     virtual double  GetTextWidth() const { return FillDXArray( nullptr, {} ); }
 100     virtual void    GetCaretPositions( std::vector<double>& rCaretPositions, const OUString& rStr ) const = 0;
 101     virtual bool    IsKashidaPosValid ( int /*nCharPos*/, int /*nNextCharPos*/ ) const = 0; // i60594
 102
 103     // methods using glyph indexing
 104     virtual bool    GetNextGlyph(const GlyphItem** pGlyph, basegfx::B2DPoint& rPos, int& nStart,
 105                                  const LogicalFontInstance** ppGlyphFont = nullptr) const = 0;
 106     virtual bool GetOutline(basegfx::B2DPolyPolygonVector&) const;
 107     bool GetBoundRect(basegfx::B2DRectangle&) const;
 108
 109     static tools::Rectangle BoundRect2Rectangle(basegfx::B2DRectangle&);
 110
 111     virtual SalLayoutGlyphs GetGlyphs() const;
 112
 113 protected:
 114     // used by layout engines
 115     SalLayout();
 116
 117 private:
 118     SalLayout(const SalLayout&) = delete;
 119     SalLayout& operator=(const SalLayout&) = delete;
 120
 121 protected:
 122     int             mnMinCharPos;
 123     int             mnEndCharPos;
 124     LanguageTag     maLanguageTag;
 125
 126     Degree10        mnOrientation;
 127
 128     mutable Point   maDrawOffset;
 129     basegfx::B2DPoint maDrawBase;
 130
 131     bool            mbSubpixelPositioning;
 132 };
 133
 134 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */