An elegant open-source calculator for Android

[Yaron 53]

I wrote a simple & elegant calculator for Android using Delphi Tokyo 10.2.3 and released the source code on GitHub:
https://github.com/bLightZP/ElegantCalculator

 

This sample demonstrates basic scalable Android UI, taking screen scale into account.

I wrote a basic string math formula parser since I couldn't find anything free that would compile for Android.

 

You can check out the compiled Elegant Calculator on the google play store:
https://play.google.com/store/apps/details?id=com.inmatrix.ElegantCalculator

 

Edited November 12, 2018 by Yaron

[jdredd 0]

With a few tweaks you can compile and install TArtFormula @ http://artsoft.tech/works.html

 

Download @ http://artsoft.tech/download.html

It works pretty well and supports quite a bit of things.

 

 

[Yaron 53]

I actually reviewed two other formula parser, one was strictly windows and the other I thought I could convert, but after a few hours of work with it working perfectly under windows and having odd crashes under Android, I decided to just write something simple myself.

Edited November 12, 2018 by Yaron

[Andrea Magni 75]

An easy way to implement formulas is to rely on FireDAC expressions.

It is very powerful (I built a simple spreadsheet-like application with very small effort!)

 

Sincerely

[Rollo62 539]

Another good expression parser is the one from LiveBindings, explained by Daniele Teti.

Not sure if that old XE2 sample still works, but it should give the basic idea.
I use the expression engine of LiveBindings for calculations in my projects, usable in runtime.

 

This is how I use it:

uses
    System.Rtti
  , System.Bindings.EvalSys
  , System.Bindings.EvalProtocol
  , System.Bindings.Evaluator
  , System.Bindings.Methods
  ;



function TTestCalculator.Evaluate(const AExpr: string) : Double;
var
  LScope: IScope;
  LCompiledExpr: ICompiledBinding;
  LResult: TValue;


begin
  Result := 0.0;

  try
      LScope := TNestedScope.Create(BasicOperators, BasicConstants);

      //add the registered methods
      LScope := TNestedScope.Create(LScope, TBindingMethodsFactory.GetMethodScope);

      LCompiledExpr := Compile(AExpr, LScope);
      LResult       := LCompiledExpr.Evaluate(LScope, nil, nil).GetValue;

      if not LResult.IsEmpty then
        Result := LResult.AsExtended;

  finally

    LCompiledExpr    := nil;
    LScope           := nil;
  end;

end;