include/vcl/vcllayout.hxx

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