kicad/common/font/outline_font.cpp

/*
 * This program source code file is part of KICAD, a free EDA CAD application.
 *
 * Copyright (C) 2021 Ola Rinta-Koski <gitlab@rinta-koski.net>
 * Copyright (C) 2021-2022 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, you may find one here:
 * http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
 * or you may search the http://www.gnu.org website for the version 2 license,
 * or you may write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
 */

#include <limits>
#include <pgm_base.h>
#include <settings/settings_manager.h>
#include <harfbuzz/hb-ft.h>
#include <bezier_curves.h>
#include <geometry/shape_poly_set.h>
#include <eda_text.h>
#include <font/outline_font.h>
#include FT_GLYPH_H
#include FT_BBOX_H
#include <trigo.h>
#include <font/fontconfig.h>
#include <convert_basic_shapes_to_polygon.h>

using namespace KIFONT;


// 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.
constexpr double OUTLINE_FONT_SIZE_COMPENSATION = 1.4;

// 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 SUBSCRIPT_SUPERSCRIPT_SIZE = 0.64;


FT_Library OUTLINE_FONT::m_freeType = nullptr;

OUTLINE_FONT::OUTLINE_FONT() :
        m_faceSize( 16 )
{
    if( !m_freeType )
        FT_Init_FreeType( &m_freeType );
}


OUTLINE_FONT* OUTLINE_FONT::LoadFont( const wxString& aFontName, bool aBold, bool aItalic )
{
    OUTLINE_FONT* font = new OUTLINE_FONT();

    wxString fontFile;
    wxString qualifiedFontName = aFontName;

    if( aBold )
        qualifiedFontName << ":Bold";

    if( aItalic )
        qualifiedFontName << ":Italic";

    if( Fontconfig()->FindFont( qualifiedFontName, fontFile ) )
        (void) font->loadFace( fontFile );

    font->m_fontName = aFontName;       // Keep asked-for name, even if we substituted.
    font->m_fontFileName = fontFile;

    return font;
}


FT_Error OUTLINE_FONT::loadFace( const wxString& aFontFileName )
{
    m_faceScaler = m_faceSize * 64;
    m_subscriptFaceScaler = KiROUND( m_faceSize * 64 * SUBSCRIPT_SUPERSCRIPT_SIZE );

    // TODO: check that going from wxString to char* with UTF-8
    // conversion for filename makes sense on any/all platforms
    FT_Error e = FT_New_Face( m_freeType, aFontFileName.mb_str( wxConvUTF8 ), 0, &m_face );

    if( !e )
    {
        FT_Select_Charmap( m_face, FT_Encoding::FT_ENCODING_UNICODE );
        FT_Set_Char_Size( m_face, 0, m_faceScaler, 0, 0 );

        e = FT_New_Face( m_freeType, aFontFileName.mb_str( wxConvUTF8 ), 0, &m_subscriptFace );

        if( !e )
        {
            FT_Select_Charmap( m_subscriptFace, FT_Encoding::FT_ENCODING_UNICODE );
            FT_Set_Char_Size( m_subscriptFace, 0, m_subscriptFaceScaler, 0, 0 );
        }
    }

    return e;
}


/**
 * Compute the vertical position of an overbar.  This is the distance between the text
 * baseline and the overbar.
 */
double OUTLINE_FONT::ComputeOverbarVerticalPosition( double aGlyphHeight ) const
{
    // The overbar on actual text is positioned above the bounding box of the glyphs.  However,
    // that's expensive to calculate so we use an estimation here (as this is only used for
    // calculating bounding boxes).
    return aGlyphHeight * OUTLINE_FONT_SIZE_COMPENSATION;
}


/**
 * Compute the distance (interline) between 2 lines of text (for multiline texts).  This is
 * the distance between baselines, not the space between line bounding boxes.
 */
double OUTLINE_FONT::GetInterline( double aGlyphHeight, double aLineSpacing ) const
{
    double pitch = INTERLINE_PITCH_RATIO;

    if( GetFace()->units_per_EM )
        pitch = GetFace()->height / GetFace()->units_per_EM;

    return ( aLineSpacing * aGlyphHeight * pitch * OUTLINE_FONT_SIZE_COMPENSATION );
}


static bool contourIsFilled( const CONTOUR& c )
{
    switch( c.orientation )
    {
    case FT_ORIENTATION_TRUETYPE:   return c.winding == 1;
    case FT_ORIENTATION_POSTSCRIPT: return c.winding == -1;
    default:                        return false;
    }
}


static bool contourIsHole( const CONTOUR& c )
{
    return !contourIsFilled( c );
}


BOX2I OUTLINE_FONT::getBoundingBox( const std::vector<std::unique_ptr<GLYPH>>& aGlyphs ) const
{
    int minX = INT_MAX;
    int minY = INT_MAX;
    int maxX = INT_MIN;
    int maxY = INT_MIN;

    for( const std::unique_ptr<KIFONT::GLYPH>& glyph : aGlyphs )
    {
        BOX2D bbox = glyph->BoundingBox();
        bbox.Normalize();

        if( minX > bbox.GetX() )
            minX = bbox.GetX();

        if( minY > bbox.GetY() )
            minY = bbox.GetY();

        if( maxX < bbox.GetRight() )
            maxX = bbox.GetRight();

        if( maxY < bbox.GetBottom() )
            maxY = bbox.GetBottom();
    }

    BOX2I ret;
    ret.SetOrigin( minX, minY );
    ret.SetEnd( maxX, maxY );
    return ret;
}


void OUTLINE_FONT::GetLinesAsGlyphs( std::vector<std::unique_ptr<GLYPH>>* aGlyphs,
                                     const EDA_TEXT* aText ) const
{
    wxArrayString         strings;
    std::vector<VECTOR2I> positions;
    std::vector<VECTOR2I> extents;
    TEXT_ATTRIBUTES       attrs = aText->GetAttributes();

    attrs.m_Angle = aText->GetDrawRotation();

    return GetLinesAsGlyphs( aGlyphs, aText->GetShownText(), aText->GetTextPos(), attrs );
}


void OUTLINE_FONT::GetLinesAsGlyphs( std::vector<std::unique_ptr<GLYPH>>* aGlyphs,
                                     const UTF8& aText, const VECTOR2I& aPosition,
                                     const TEXT_ATTRIBUTES& aAttrs ) const
{
    wxArrayString         strings;
    std::vector<VECTOR2I> positions;
    std::vector<VECTOR2I> extents;
    TEXT_STYLE_FLAGS      textStyle = 0;

    if( aAttrs.m_Italic )
        textStyle |= TEXT_STYLE::ITALIC;

    getLinePositions( aText, aPosition, strings, positions, extents, aAttrs );

    for( size_t i = 0; i < strings.GetCount(); i++ )
    {
        (void) drawMarkup( nullptr, aGlyphs, UTF8( strings.Item( i ) ), positions[i],
                           aAttrs.m_Size, aAttrs.m_Angle, aAttrs.m_Mirrored, aPosition, textStyle );
    }
}


VECTOR2I OUTLINE_FONT::GetTextAsGlyphs( BOX2I* aBBox, std::vector<std::unique_ptr<GLYPH>>* aGlyphs,
                                        const UTF8& aText, const VECTOR2D& aSize,
                                        const VECTOR2I& aPosition, const EDA_ANGLE& aAngle,
                                        bool aMirror, const VECTOR2I& aOrigin,
                                        TEXT_STYLE_FLAGS aTextStyle ) const
{
    hb_buffer_t* buf = hb_buffer_create();
    hb_buffer_add_utf8( buf, aText.c_str(), -1, 0, -1 );

    // guess direction, script, and language based on contents
    hb_buffer_guess_segment_properties( buf );

    unsigned int         glyphCount;
    hb_glyph_info_t*     glyphInfo = hb_buffer_get_glyph_infos( buf, &glyphCount );
    hb_glyph_position_t* glyphPos = hb_buffer_get_glyph_positions( buf, &glyphCount );
    hb_font_t*           referencedFont;

    VECTOR2D glyphSize = aSize;
    FT_Face  face = m_face;
    double   scaler = m_faceScaler / OUTLINE_FONT_SIZE_COMPENSATION;

    if( IsSubscript( aTextStyle ) || IsSuperscript( aTextStyle ) )
        face = m_subscriptFace;

    referencedFont = hb_ft_font_create_referenced( face );
    hb_ft_font_set_funcs( referencedFont );
    hb_shape( referencedFont, buf, nullptr, 0 );

    const VECTOR2D scaleFactor( glyphSize.x / scaler, -glyphSize.y / scaler );

    VECTOR2I cursor( 0, 0 );
    VECTOR2D topLeft( INT_MAX * 1.0, -INT_MAX * 1.0 );
    VECTOR2D topRight( -INT_MAX * 1.0, -INT_MAX * 1.0 );

    for( unsigned int i = 0; i < glyphCount; i++ )
    {
        hb_glyph_position_t& pos = glyphPos[i];
        int                  codepoint = glyphInfo[i].codepoint;

        if( aGlyphs )
        {
            FT_Load_Glyph( face, codepoint, FT_LOAD_NO_BITMAP );

            FT_GlyphSlot faceGlyph = face->glyph;

            // contours is a collection of all outlines in the glyph;
            // example: glyph for 'o' generally contains 2 contours,
            // one for the glyph outline and one for the hole
            CONTOURS contours;

            OUTLINE_DECOMPOSER decomposer( faceGlyph->outline );
            decomposer.OutlineToSegments( &contours );

            std::unique_ptr<OUTLINE_GLYPH> glyph = std::make_unique<OUTLINE_GLYPH>();
            std::vector<SHAPE_LINE_CHAIN>  holes;

            for( CONTOUR& c : contours )
            {
                GLYPH_POINTS     points = c.points;
                SHAPE_LINE_CHAIN shape;

                for( const VECTOR2D& v : points )
                {
                    VECTOR2D pt( v + cursor );

                    topLeft.x = std::min( topLeft.x, pt.x );
                    topLeft.y = std::max( topLeft.y, pt.y );
                    topRight.x = std::max( topRight.x, pt.x );
                    topRight.y = std::max( topRight.y, pt.y );

                    if( IsSubscript( aTextStyle ) )
                        pt.y -= 0.25 * scaler;
                    else if( IsSuperscript( aTextStyle ) )
                        pt.y += 0.45 * scaler;

                    pt *= scaleFactor;
                    pt += aPosition;

                    if( aMirror )
                        pt.x = aOrigin.x - ( pt.x - aOrigin.x );

                    if( !aAngle.IsZero() )
                        RotatePoint( pt, aOrigin, aAngle );

                    shape.Append( pt.x, pt.y );
                }

                shape.SetClosed( true );

                if( contourIsHole( c ) )
                    holes.push_back( std::move( shape ) );
                else
                    glyph->AddOutline( std::move( shape ) );
            }

            for( SHAPE_LINE_CHAIN& hole : holes )
            {
                if( hole.PointCount() )
                {
                    for( int ii = 0; ii < glyph->OutlineCount(); ++ii )
                    {
                        if( glyph->Outline( ii ).PointInside( hole.GetPoint( 0 ) ) )
                        {
                            glyph->AddHole( std::move( hole ), ii );
                            break;
                        }
                    }
                }
            }

            if( glyph->HasHoles() )
                glyph->Fracture( SHAPE_POLY_SET::PM_FAST ); // FONT TODO verify aFastMode

            aGlyphs->push_back( std::move( glyph ) );
        }

        cursor.x += pos.x_advance;
        cursor.y += pos.y_advance;
    }

    if( IsOverbar( aTextStyle ) && aGlyphs )
    {
        topLeft *= scaleFactor;
        topRight *= scaleFactor;

        topLeft.y -= aSize.y * 0.16;
        topRight.y -= aSize.y * 0.16;

        topLeft += aPosition;
        topRight += aPosition;

        if( !aAngle.IsZero() )
        {
            RotatePoint( topLeft, aOrigin, aAngle );
            RotatePoint( topRight, aOrigin, aAngle );
        }

        double         overbarHeight = aSize.y * 0.07;
        SHAPE_POLY_SET overbar;

        TransformOvalToPolygon( overbar, topLeft, topRight, overbarHeight, overbarHeight / 8,
                                ERROR_INSIDE );

        std::unique_ptr<OUTLINE_GLYPH> overbarGlyph = std::make_unique<OUTLINE_GLYPH>( overbar );
        aGlyphs->push_back( std::move( overbarGlyph ) );
    }

    hb_buffer_destroy( buf );

    VECTOR2I cursorDisplacement( cursor.x * scaleFactor.x, -cursor.y * scaleFactor.y );

    if( aBBox )
    {
        aBBox->SetOrigin( aPosition.x, aPosition.y );
        aBBox->SetEnd( cursorDisplacement );
    }

    return VECTOR2I( aPosition.x + cursorDisplacement.x, aPosition.y + cursorDisplacement.y );
}


#undef OUTLINEFONT_RENDER_AS_PIXELS
#ifdef OUTLINEFONT_RENDER_AS_PIXELS
/*
 * WIP: eeschema (and PDF output?) should use pixel rendering instead of linear segmentation
 */
void OUTLINE_FONT::RenderToOpenGLCanvas( KIGFX::OPENGL_GAL& aGal, const UTF8& aString,
                                         const VECTOR2D& aGlyphSize, const VECTOR2I& aPosition,
                                         const EDA_ANGLE& aOrientation, bool aIsMirrored ) const
{
    hb_buffer_t* buf = hb_buffer_create();
    hb_buffer_add_utf8( buf, aString.c_str(), -1, 0, -1 );

    // guess direction, script, and language based on contents
    hb_buffer_guess_segment_properties( buf );

    unsigned int         glyphCount;
    hb_glyph_info_t*     glyphInfo = hb_buffer_get_glyph_infos( buf, &glyphCount );
    hb_glyph_position_t* glyphPos = hb_buffer_get_glyph_positions( buf, &glyphCount );
    hb_font_t*           referencedFont = hb_ft_font_create_referenced( m_face );

    hb_ft_font_set_funcs( referencedFont );
    hb_shape( referencedFont, buf, nullptr, 0 );

    const double mirror_factor = ( aIsMirrored ? 1 : -1 );
    const double x_scaleFactor = mirror_factor * aGlyphSize.x / mScaler;
    const double y_scaleFactor = aGlyphSize.y / mScaler;

    hb_position_t cursor_x = 0;
    hb_position_t cursor_y = 0;

    for( unsigned int i = 0; i < glyphCount; i++ )
    {
        hb_glyph_position_t& pos = glyphPos[i];
        int                  codepoint = glyphInfo[i].codepoint;

        FT_Error e = FT_Load_Glyph( m_face, codepoint, FT_LOAD_DEFAULT );
        // TODO handle FT_Load_Glyph error

        FT_Glyph glyph;
        e = FT_Get_Glyph( m_face->glyph, &glyph );
        // TODO handle FT_Get_Glyph error

        wxPoint pt( aPosition );
        pt.x += ( cursor_x >> 6 ) * x_scaleFactor;
        pt.y += ( cursor_y >> 6 ) * y_scaleFactor;

        cursor_x += pos.x_advance;
        cursor_y += pos.y_advance;
    }

    hb_buffer_destroy( buf );
}
#endif //OUTLINEFONT_RENDER_AS_PIXELS