{ Unit to plot an expression on a canvas

Copyright (C) 2008 Michael Van Canneyt michael@freepascal.org

This library is free software; you can redistribute it and/or modify it

under the terms of the GNU Library General Public License as published by

the Free Software Foundation; either version 2 of the License, or (at your

option) any later version with the following modification:

As a special exception, the copyright holders of this library give you

permission to link this library with independent modules to produce an

executable, regardless of the license terms of these independent modules,and

to copy and distribute the resulting executable under terms of your choice,

provided that you also meet, for each linked independent module, the terms

and conditions of the license of that module. An independent module is a

module which is not derived from or based on this library. If you modify

this library, you may extend this exception to your version of the library,

but you are not obligated to do so. If you do not wish to do so, delete this

exception statement from your version.

This program is distributed in the hope that it will be useful, but WITHOUT

ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public License

for more details.

You should have received a copy of the GNU Library General Public License

along with this library; if not, write to the Free Software Foundation,

Inc., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1335, USA.

}

unit exprplotpanel;

{$mode objfpc}{$H+}

interface

uses

Classes, SysUtils, plotpanel, fpexprpars;

Type

{ TExpressionControlPlotter }

TExpressionControlPlotter = Class(TCanvasPlotter)

private

FParser : TFPExpressionParser;

FX : TFPExprIdentifierDef;

function GetExpression: String;

function GetIdentifiers: TFPExprIdentifierDefs;

procedure SetExpression(const AValue: String);

procedure SetIdentifiers(const AValue: TFPExprIdentifierDefs);

Protected

Function CalcFunction(X : TPlotFloat) : TPlotFloat; override;

Property Parser : TFPExpressionParser Read FParser;

Public

Constructor Create(AOwner : TComponent); override;

Destructor Destroy; override;

Property Expression : String Read GetExpression Write SetExpression;

Property Identifiers : TFPExprIdentifierDefs Read GetIdentifiers Write SetIdentifiers;

end;

{ TPlotFunctionPanel }

TPlotExpressionPanel = Class(TCustomPlotFunctionPanel)

private

function GetExpression: String;

function GetIdentifiers: TFPExprIdentifierDefs;

procedure SetExpression(const AValue: String);

procedure SetIdentifiers(const AValue: TFPExprIdentifierDefs);

Protected

Function CreatePlotter : TCanvasPlotter; override;

Published

Property Expression : String Read GetExpression Write SetExpression;

Property Identifiers : TFPExprIdentifierDefs Read GetIdentifiers Write SetIdentifiers;

Property Active;

Property Align;

Property Anchors;

Property BkColor;

Property BorderSpacing;

Property Color;

Property PlotColor;

property PlotLinewidth;

Property XAxis;

Property YAxis;

end;

implementation

resourcestring

SErrInvalidResultType = 'Expression result type must be integer or float. Got %s"';

{ TExpressionControlPlotter }

function TExpressionControlPlotter.GetIdentifiers: TFPExprIdentifierDefs;

begin

Result:=FParser.Identifiers;

end;

function TExpressionControlPlotter.GetExpression: String;

begin

Result:=FParser.Expression;

end;

procedure TExpressionControlPlotter.SetExpression(const AValue: String);

begin

FParser.Expression:=AValue;

If Not (FParser.ResultType in [rtInteger,rtFLoat]) then

Raise EExprParser.CreateFmt(SErrInvalidResultType,[ResultTypeName(FParser.ResultType)]);

Changed;

end;

procedure TExpressionControlPlotter.SetIdentifiers(

const AValue: TFPExprIdentifierDefs);

begin

FParser.Identifiers.Assign(AValue);

// Reassign...

FX:=FParser.IdentifierByName('X');

end;

function TExpressionControlPlotter.CalcFunction(X: TPlotFloat): TPlotFloat;

Var

E : TFPExpressionResult;

begin

FX.AsFloat:=X;

E:=FParser.Evaluate;

If E.ResultType=rtFloat then

result:=E.ResFloat

else If E.ResultType=rtInteger then

result:=E.ResInteger;

end;

constructor TExpressionControlPlotter.Create(AOwner: TComponent);

begin

inherited Create(AOwner);

FParser:=TFPExpressionParser.Create(Self);

FX:=FParser.Identifiers.AddFloatVariable('X',0.0);

end;

destructor TExpressionControlPlotter.Destroy;

begin

FX:=Nil;

FreeAndNil(FParser);

inherited Destroy;

end;

{ TPlotExpressionPanel }

function TPlotExpressionPanel.GetExpression: String;

begin

Result:=TExpressionControlPlotter(Plotter).Expression;

end;

function TPlotExpressionPanel.GetIdentifiers: TFPExprIdentifierDefs;

begin

Result:=TExpressionControlPlotter(Plotter).Identifiers;

end;

procedure TPlotExpressionPanel.SetExpression(const AValue: String);

begin

TExpressionControlPlotter(Plotter).Expression:=AValue;

end;

procedure TPlotExpressionPanel.SetIdentifiers(const AValue: TFPExprIdentifierDefs);

begin

TExpressionControlPlotter(Plotter).Identifiers:=AValue;

end;

function TPlotExpressionPanel.CreatePlotter: TCanvasPlotter;

begin

Result:=TExpressionControlPlotter.Create(Self);

end;

end.