include/vcl/vcllayout.hxx

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