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{ 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.
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