%D \module
%D   [       file=meta-imp-symbols,
%D        version=2019.10.01,
%D          title=\METAPOST\ Graphics,
%D       subtitle=Symbols,
%D         author=Hans Hagen,
%D           date=\currentdate,
%D      copyright={PRAGMA ADE \& \CONTEXT\ Development Team}]
%C
%C This module is part of the \CONTEXT\ macro||package and is
%C therefore copyrighted by \PRAGMA. See mreadme.pdf for
%C details.

%D This is an (experimental) prelude to more.

\startMPcalculation{simplefun}

    pen SymbolPen ; SymbolPen := pencircle scaled 1/4 ;

    vardef SymbolBullet        = fill   unitcircle      scaled  3       shifted (1.5,1.5) withpen SymbolPen          enddef ; % 0x2022 •
    vardef SymbolDash          = draw   (origin--right) scaled  3       shifted (1.5,3.0) withpen SymbolPen scaled 2 enddef ; % 0x2013 –
    vardef SymbolTriangle      = draw   unittriangle    scaled  3       shifted (1.5,1.5) withpen SymbolPen          enddef ; % 0x25B6 ⊳
    vardef SymbolCircle        = fill   unitcircle      scaled  3       shifted (1.5,1.5) withpen SymbolPen          enddef ; % 0x2218 ∘
    vardef SymbolSquare        = draw   unitsquare      scaled (3-1/16) shifted (1.5,1.5) withpen SymbolPen          enddef ; % 0x25A1 □
    vardef SymbolDiamond       = draw   unitdiamond     scaled  3       shifted (1.5,1.5) withpen SymbolPen          enddef ; % 0x22C4 ⋄
    vardef SymbolBlackTriangle = fillup unittriangle    scaled (3-1/16) shifted (1.5,1.5) withpen SymbolPen          enddef ; % 0x25B6 ▶
    vardef SymbolBlackSquare   = fillup unitsquare      scaled (3-1/16) shifted (1.5,1.5) withpen SymbolPen          enddef ; % 0x25A0 ■
    vardef SymbolBlackDiamond  = fillup unitdiamond     scaled (3-1/16) shifted (1.5,1.5) withpen SymbolPen          enddef ; % 0x25C6 ◆

    vardef SymbolNotDef =
        draw center unitcircle
            scaled 3
            shifted (1.5,1.5)
            withpen SymbolPen scaled 4
    enddef ;

    vardef SymbolStar =  % 0x22C6 % ⋆
        SymbolNotDef
    enddef ;

    vardef SymbolCheckmark =  % 0x2713 ✓
        SymbolNotDef
    enddef ;

    vardef SymbolAsterisk =  % 0x2217 ∗
        SymbolNotDef
    enddef ;

    % We could set code directly to the meaning of the macro.

    lmt_registerglyphs [
        name     = "symbols",
        units    = 10,
        usecolor = true,
        width    = 6,
        height   = 6,
        depth    = 0,
        code     = "SymbolNotDef ;",
    ] ;

    lmt_registerglyph [ category = "symbols", unicode = "0x2022", code  = "SymbolBullet ;"        ] ;
    lmt_registerglyph [ category = "symbols", unicode = "0x2013", code  = "SymbolDash ;"          ] ;
    lmt_registerglyph [ category = "symbols", unicode = "0x22C6" ] ; % , code  = "SymbolStar ;"          ] ;
    lmt_registerglyph [ category = "symbols", unicode = "0x22B3", code  = "SymbolTriangle ;"      ] ;
    lmt_registerglyph [ category = "symbols", unicode = "0x2218", code  = "SymbolCircle ;"        ] ;
    lmt_registerglyph [ category = "symbols", unicode = "0x25A1", code  = "SymbolSquare ;"        ] ;
    lmt_registerglyph [ category = "symbols", unicode = "0x22C4", code  = "SymbolDiamond ;"       ] ;
    lmt_registerglyph [ category = "symbols", unicode = "0x2713" ] ; % , code  = "SymbolCheckmark ;"     ] ;
    lmt_registerglyph [ category = "symbols", unicode = "0x2217" ] ; % , code  = "SymbolAsterisk ;"      ] ;
    lmt_registerglyph [ category = "symbols", unicode = "0x25B6", code  = "SymbolBlackTriangle ;" ] ;
    lmt_registerglyph [ category = "symbols", unicode = "0x25A0", code  = "SymbolBlackSquare ;"   ] ;
    lmt_registerglyph [ category = "symbols", unicode = "0x25C6", code  = "SymbolBlackDiamond ;"  ] ;

\stopMPcalculation

\continueifinputfile{meta-imp-symbols.mkxl}

\usemodule[article-basic] \setupbodyfont[pagella]

\starttext

\definefontfeature[metasymbols][metapost=symbols]

\definefont[MyFont] [Serif*default,metasymbols sa 1]

Some metasymbols:

\startitem {\MyFont                 • □ ◆}\quad Regular rendering. \stopitem
\startitem {\MyFont\red             • □ ◆}\quad Rendering with color. \stopitem
\startitem {\MyFont\blue\showglyphs • □ ◆}\quad Idem but with boundingboxes shown. \stopitem

And some more:

\startlines
    • – ⋆ ⊳ ∘ □ ⋄ ✓ ∗ ▶ ■ ◆
    {\MyFont • – ⋆ ⊳ ∘ □ ⋄ ✓ ∗ ▶ ■ ◆}
\stoplines

\stoptext