include/vcl/vcllayout.hxx

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
   2 /*
   3  * This file is part of the LibreOffice project.
   4  *
   5  * This Source Code Form is subject to the terms of the Mozilla Public
   6  * License, v. 2.0. If a copy of the MPL was not distributed with this
   7  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
   8  *
   9  * This file incorporates work covered by the following license notice:
  10  *
  11  *   Licensed to the Apache Software Foundation (ASF) under one or more
  12  *   contributor license agreements. See the NOTICE file distributed
  13  *   with this work for additional information regarding copyright
  14  *   ownership. The ASF licenses this file to you under the Apache
  15  *   License, Version 2.0 (the "License"); you may not use this file
  16  *   except in compliance with the License. You may obtain a copy of
  17  *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
  18  */
  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 <tools/degree.hxx>
  26 #include <vcl/devicecoordinate.hxx>
  27 #include <vcl/dllapi.h>
  28
  29 class ImplLayoutArgs;
  30 class PhysicalFontFace;
  31 class SalGraphics;
  32 class GlyphItem;
  33 class SalLayoutGlyphs;
  34
  35 // all positions/widths are in font units
  36 // one exception: drawposition is in pixel units
  37
  38 // Unfortunately there is little documentation to help implementors of
  39 // new classes derived from SalLayout ("layout engines"), and the code
  40 // and data structures are far from obvious.
  41
  42 // For instance, I *think* the important virtual functions in the
  43 // layout engines are called in this order:
  44
  45 // * InitFont()
  46 // * LayoutText()
  47 // * AdjustLayout(), any number of times (but presumably
  48 // usually not at all or just once)
  49 // * Optionally, DrawText()
  50
  51 // Functions that just return information like GetTexWidth() and
  52 // FillDXArray() are called after LayoutText() and before DrawText().
  53
  54 // Another important questions is which parts of an ImplLayoutArgs can
  55 // be changed by callers between LayoutText() and AdjustLayout()
  56 // calls. It probably makes sense only if one assumes that the "string
  57 // related inputs" part are not changed after LayoutText().
  58
  59 // But why use the same ImplLayoutArgs structure as parameter for both
  60 // LayoutText() and AdjustLayout() in the first place? And why
  61 // duplicate some of the fields in both SalLayout and ImplLayoutArgs
  62 // (mnMinCharPos, mnEndCharPos, mnLayoutFlags==mnFlags,
  63 // mnOrientation)? Lost in history...
  64
  65 class VCL_DLLPUBLIC SalLayout
  66 {
  67 public:
  68     virtual         ~SalLayout();
  69     // used by upper layers
  70     Point&          DrawBase()                              { return maDrawBase; }
  71     const Point&    DrawBase() const                        { return maDrawBase; }
  72     Point&          DrawOffset()                            { return maDrawOffset; }
  73     const Point&    DrawOffset() const                      { return maDrawOffset; }
  74     Point           GetDrawPosition( const Point& rRelative = Point(0,0) ) const;
  75
  76     virtual bool    LayoutText( ImplLayoutArgs&, const SalLayoutGlyphs* ) = 0;  // first step of layouting
  77     virtual void    AdjustLayout( ImplLayoutArgs& );    // adjusting after fallback etc.
  78     virtual void    InitFont() const {}
  79     virtual void    DrawText( SalGraphics& ) const = 0;
  80
  81     int             GetUnitsPerPixel() const                { return mnUnitsPerPixel; }
  82     Degree10        GetOrientation() const                  { return mnOrientation; }
  83
  84     // methods using string indexing
  85     virtual sal_Int32 GetTextBreak(DeviceCoordinate nMaxWidth, DeviceCoordinate nCharExtra, int nFactor) const = 0;
  86     virtual DeviceCoordinate FillDXArray( DeviceCoordinate* pDXArray ) const = 0;
  87     virtual DeviceCoordinate GetTextWidth() const { return FillDXArray( nullptr ); }
  88     virtual void    GetCaretPositions( int nArraySize, tools::Long* pCaretXArray ) const = 0;
  89     virtual bool    IsKashidaPosValid ( int /*nCharPos*/ ) const { return true; } // i60594
  90
  91     // methods using glyph indexing
  92     virtual bool    GetNextGlyph(const GlyphItem** pGlyph, Point& rPos, int& nStart,
  93                                  const PhysicalFontFace** pFallbackFont = 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     Degree10        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: */