outline_font.h

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/*
 * This program source code file is part of KICAD, a free EDA CAD application.
 *
 * Copyright (C) 2021 Ola Rinta-Koski
 * Copyright The KiCad Developers, see AUTHORS.txt for contributors.
 *
 * Outline font class
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */
 
#ifndef OUTLINE_FONT_H_
#define OUTLINE_FONT_H_
 
#include <gal/gal.h>
#include <geometry/shape_poly_set.h>
#ifdef _MSC_VER
#include <ft2build.h>
#else
#include <freetype2/ft2build.h>
#endif
#include FT_FREETYPE_H
#include FT_OUTLINE_H
 
#include <font/font.h>
#include <font/glyph.h>
#include <font/outline_decomposer.h>
#include <embedded_files.h>
 
#include <mutex>
 
namespace KIFONT
{
class GAL_API OUTLINE_FONT : public FONT
{
public:
 
    enum class EMBEDDING_PERMISSION
    {
        INSTALLABLE,
        EDITABLE,
        PRINT_PREVIEW_ONLY,
        RESTRICTED,
        INVALID
    };
 
    OUTLINE_FONT();
 
    bool IsOutline() const override { return true; }
 
    bool IsBold() const override
    {
        return m_face && ( m_fakeBold || ( m_face->style_flags & FT_STYLE_FLAG_BOLD ) );
    }
 
    bool IsItalic() const override
    {
        return m_face && ( m_fakeItal || ( m_face->style_flags & FT_STYLE_FLAG_ITALIC ) );
    }
 
    // Accessors to distinguish fake vs real style for diagnostics and rendering decisions
    bool IsFakeItalic() const { return m_fakeItal; }
    bool IsFakeBold() const { return m_fakeBold; }
 
    void SetFakeBold()
    {
        m_fakeBold = true;
    }
 
    void SetFakeItal()
    {
        m_fakeItal = true;
    }
 
    const wxString& GetFileName() const { return m_fontFileName; }
 
    EMBEDDING_PERMISSION GetEmbeddingPermission() const;

    static OUTLINE_FONT* LoadFont( const wxString& aFontFileName, bool aBold, bool aItalic,
                                   const std::vector<wxString>* aEmbeddedFiles,
                                   bool aForDrawingSheet );

    double GetInterline( double aGlyphHeight, const METRICS& aFontMetrics ) const override;
 
    double GetSuperSubSizeMultiplier() const override { return m_subscriptSuperscriptSize; }

    double GetEmSize( double aSize ) const { return aSize * m_outlineFontSizeCompensation; }
 
    double GetSuperSubBaselineOffset( TEXT_STYLE_FLAGS aTextStyle ) const override
    {
        double offset = 0.0;
 
        if( IsSubscript( aTextStyle ) )
            offset = m_subscriptVerticalOffset;
        else if( IsSuperscript( aTextStyle ) )
            offset = m_superscriptVerticalOffset;
 
        // The stored offsets are y-up face units carrying the size compensation.
        return -offset * m_outlineFontSizeCompensation;
    }
 
    VECTOR2I GetTextAsGlyphs( BOX2I* aBoundingBox, std::vector<std::unique_ptr<GLYPH>>* aGlyphs,
                              const wxString& aText, const VECTOR2I& aSize,
                              const VECTOR2I& aPosition, const EDA_ANGLE& aAngle, bool aMirror,
                              const VECTOR2I& aOrigin, TEXT_STYLE_FLAGS aTextStyle ) const override;
 
    void GetLinesAsGlyphs( std::vector<std::unique_ptr<GLYPH>>* aGlyphs, const wxString& aText,
                           const VECTOR2I& aPosition, const TEXT_ATTRIBUTES& aAttrs,
                           const METRICS& aFontMetrics ) const;
 
    const FT_Face& GetFace() const { return m_face; }

    bool LoadGlyphContours( unsigned int aGlyphIndex, std::vector<CONTOUR>& aContours ) const;

    static void SelectCharmap( FT_Face aFace );
 
protected:
    FT_Error loadFace( const wxString& aFontFileName, int aFaceIndex );
 
    BOX2I getBoundingBox( const std::vector<std::unique_ptr<GLYPH>>& aGlyphs ) const;
 
    VECTOR2I getTextAsGlyphs( BOX2I* aBoundingBox, std::vector<std::unique_ptr<GLYPH>>* aGlyphs,
                              const wxString& aText, const VECTOR2I& aSize,
                              const VECTOR2I& aPosition, const EDA_ANGLE& aAngle, bool aMirror,
                              const VECTOR2I& aOrigin, TEXT_STYLE_FLAGS aTextStyle ) const;
 
private:
    VECTOR2I getTextAsGlyphsUnlocked( BOX2I* aBoundingBox,
                                      std::vector<std::unique_ptr<GLYPH>>* aGlyphs,
                                      const wxString& aText, const VECTOR2I& aSize,
                                      const VECTOR2I& aPosition, const EDA_ANGLE& aAngle,
                                      bool aMirror, const VECTOR2I& aOrigin,
                                      TEXT_STYLE_FLAGS aTextStyle ) const;
 
private:
    // FreeType variables

    static std::mutex m_freeTypeMutex;
    static FT_Library m_freeType;
    FT_Face           m_face;
 
    const int         m_faceSize;
    bool              m_fakeBold;
    bool              m_fakeItal;
 
    bool              m_forDrawingSheet;
 
    // cache for glyphs converted to straight segments
    // key is glyph index (FT_GlyphSlot field glyph_index)
    std::map<unsigned int, std::vector<std::vector<VECTOR2D>>> m_contourCache;
 
    // The height of the KiCad stroke font is the distance between stroke endpoints for a vertical
    // line of cap-height.  So the cap-height of the font is actually stroke-width taller than its
    // height.
    // Outline fonts are normally scaled on full-height (including ascenders and descenders), so we
    // need to compensate to keep them from being much smaller than their stroked counterparts.
    static constexpr double m_outlineFontSizeCompensation = 1.4;
 
    // FT_Set_Char_Size() gets character width and height specified in 1/64ths of a point
    static constexpr int m_charSizeScaler = 64;
 
    // The KiCad stroke font uses a subscript/superscript size ratio of 0.7.  This ratio is also
    // commonly used in LaTeX, but fonts with designed-in subscript and superscript glyphs are more
    // likely to use 0.58.
    // For auto-generated subscript and superscript glyphs in outline fonts we split the difference
    // with 0.64.
    static constexpr double m_subscriptSuperscriptSize = 0.64;
 
    static constexpr double m_underlineOffsetScaler = -0.16;
 
    int faceSize( int aSize ) const
    {
        return aSize * m_charSizeScaler * m_outlineFontSizeCompensation;
    };
 
    int faceSize() const { return faceSize( m_faceSize ); }
 
    // also for superscripts
    int subscriptSize( int aSize ) const
    {
        return KiROUND( faceSize( aSize ) * m_subscriptSuperscriptSize );
    }
    int subscriptSize() const { return subscriptSize( m_faceSize ); }
 
    static constexpr double m_subscriptVerticalOffset   = -0.25;
    static constexpr double m_superscriptVerticalOffset = 0.45;
};
 
} //namespace KIFONT
 
#endif // OUTLINE_FONT_H_