math_keyboard is a Flutter package that allows editing math expressions using a typeset input field (so-called "math field") and a custom-made fully integrated math keyboard in Flutter only - no plugins, no web views.

The math_keyboard package provides a widget that behaves like a Flutter TextField with the same full integration, i.e. focus tree support, input decoration support, and both an on-screen software keyboard as well as physical keyboard input support. On top of that, the math field typesetting uses TeX and the package supports converting to math expressions (that e.g. can be used for calculation).

math_keyboard is an open source project with the aim of providing a way to edit math expression providing the best user experience in terms of input and UI as well as allowing accurate evaluation of the mathematical expressions entered by the user. This is used by the simpleclub app, hence, the association.


In the following, some high-level information regarding the implementation of the package is
described. This is useful in case you are curious or intend to contribute.

For information on implementing math_keyboard into your own app, please see the
package README.

Math expressions

Notice how the math_keyboard package includes a major feature that allows working with the input
expressions in a mathematical matter, i.e. by converting them into "math expressions" (this is how
we refer to the format in the context of this project).

We achieve this by essentially working with two formats:

  • The typeset display format, powered by TeX (see below).
  • A data format, i.e. math expressions.

This "data format" depends on the math_expressions package. Handling the
expressions in this format allows you to e.g. evaluate the expressions.

TeX typesetting

Both the math field content, i.e. the expressions typed by the user, as well as some symbols on the
keyboard itself are typeset using TeX. For TeX typesetting in Flutter, we created our own proof of
concept renderer in early 2020, called CaTeX. This project is on-hold for now and in the
meantime, we collaborated on the flutter_math package that aims to achieve something similar.
Due to lack of maintenance on that repo, we are currently using our forked version,
flutter_math_fork. Note that our ultimate goal is fully integrating the math_keyboard package
with the catex package, which would give us maximum control over the rendering of the typeset math.