ModeMath 0.1.0

ModeMath

Mathematical formula display and editing for .NET, rendered with SkiaSharp.

A formula is an MA: a tree of what is written, not of what it means. Layout places one at a font size, and Painter draws what was placed onto an SKCanvas.

open ModeMath

let formula =
    match Latex.Read @"\frac{-b \pm \sqrt{b^2 - 4ac}}{2a}" with
    | Ok ma -> ma
    | Error error -> failwith error.Message

let placed = (Layout 24f<px>).Of formula
use painter = Painter.Embedded()
painter.Draw(placed, canvas, 0f<px>, placed.Ascent, paint)

examples/ shows what renders, a picture of each formula against its name and size. The formulas themselves are in tools/RenderExamples/Examples.fs.

Editing

Editor holds a formula with a cursor in it. Every key reaches it through Press, which answers with a new editor rather than changing this one, so a caller keeps whichever it likes and undo costs nothing. ValueNone says the key had nothing to do here, leaving the caller free to pass it on.

let pressing(editor: Editor, key: MathKey) =
    editor.Press key |> ValueOption.defaultValue editor

let typed =
    [ MathKey.Character 'x'; MathKey.Superscript; MathKey.Character '2' ]
    |> List.fold (fun editor key -> pressing(editor, key)) (Editor(Layout 24f<px>, MA.Empty))

let clicked = typed.Click(x, y)

An opening bracket is drawn faint until its closing one is typed, a run of letters spelling a function name becomes that function, and a formula can be built from MA directly instead.

LaTeX

Latex.Read takes a math-mode string and Latex.Write gives one back, every argument in braces. What is not understood is refused with the position it stands at, rather than guessed at, and a character the font cannot draw is refused there too, so a formula that was read always lays out. One built from MA in code can hold a character the font has no glyph for, and MA.Undrawable is the characters it would fail on.

Fonts

Latin Modern Math, cut down to the glyphs ModeMath draws, and AMS Capital Blackboard Bold are carried inside the assembly along with the licences they are redistributed under. fonts/README.md says where each came from and how the metrics beside them are generated.

Acknowledgements

ModeMath is inspired by CSharpMath. Most of the formulas in examples/ are taken from its rendering tests, and the typesetting is checked against those. ModeMath has no plan to work with any text outside of math mode, so for a LaTeX renderer that includes both text and maths you should use CSharpMath.

Licence

MIT, in LICENSE. The two fonts keep their own: the GUST Font Licence and the SIL Open Font Licence, both carried in fonts/.