calculator.pl

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/********************************************************************
    Constraint-based Graphical Programming in B-Prolog
    %
    draw a calculator keyboard
*********************************************************************/
go:-
    Buttons=[B0,B1,B2,B3,B4,B5,B6,B7,B8,B9,Bc,Bdiv,Bmul,Bsub,Badd,Beq,Bdot],
    cgButtons(Buttons),
    B0^text #= '0',
    B1^text #= '1',
    B2^text #= '2',
    B3^text #= '3',
    B4^text #= '4',
    B5^text #= '5',
    B6^text #= '6',
    B7^text #= '7',
    B8^text #= '8',
    B9^text #= '9',
    %
    Bc^text #= 'C',
    Bdiv^text #= '/',
    Bmul^text #= '*',    
    Bsub^text #= '-',
    Badd^text #= '+',
    Beq^text #= '=',
    Bdot^text #= '.',
    %
    B0^fontSize #= 26,
    B0^fontStyle #= 'BOLD',
    B0^width #>50,
    cgSameFont(Buttons),
    cgGrid([[Bc,Bdiv,Bmul,Bsub],
	    [B7,B8,  B9,  Badd],
	    [B4,B5,  B6,  Badd],
	    [B1,B2,  B3,  Beq],
	    [B0,B0,  Bdot,Beq]],2,2),
    %
    cgDefaultWindow(Win),Win^leftMargin #= 50, Win^topMargin #= 50,
    cgStartRecord(calculator),
    cgShow(Buttons),
    cgStopRecord.