Работа с коллекциями - сохранение и загрузка

Code:

unit DelphiPt;

interface

uses

Classes, Graphics;

type

TDDHPoint = class (TCollectionItem)

private

   fX, fY: Integer;

public

   Text: string;

   procedure WriteText (Writer: TWriter);

   procedure ReadText (Reader: TReader);

   procedure DefineProperties (Filer: TFiler); override;

   procedure Paint (Canvas: TCanvas);

   procedure Assign (Pt: TPersistent); override;

published

   property X: Integer read fX write fX;

   property Y: Integer read fY write fY;

end;

TWrapper = class (TComponent)

private

   FColl: TCollection;

published

   property MyColl: TCollection read FColl write FColl;

public

   constructor Create (Owner: TComponent); override;

   destructor Destroy; override;

end;

implementation

// TWrapper constructor and destructor

constructor TWrapper.Create (Owner: TComponent);

begin

inherited Create (Owner);

FColl := TCollection.Create (TDDHPoint);

end;

destructor TWrapper.Destroy;

begin

FColl.Clear;

FColl.Free;

inherited Destroy;

end;

// class TDDHPoint methods

procedure TDDHPoint.WriteText (Writer: TWriter);

begin

Writer.WriteString (Text);

end;

procedure TDDHPoint.ReadText (Reader: TReader);

begin

Text := Reader.ReadString;

end;

procedure TDDHPoint.DefineProperties (Filer: TFiler);

begin

Filer.DefineProperty (

   'Text', ReadText, WriteText, (Text <> ''));

end;

procedure TDDHPoint.Paint (Canvas: TCanvas);

begin

Canvas.Ellipse (fX - 3, fY - 3, fX + 3, fY + 3);

Canvas.TextOut (fX + 5, fY + 5, Text);

end;

procedure TDDHPoint.Assign (Pt: TPersistent);

begin

if Pt is TDDHPoint then

begin

   fx := TDDHPoint (Pt).fX;

   fY := TDDHPoint (Pt).fY;

   Text := TDDHPoint (Pt).Text;

end

else

   // raise an exception

   inherited Assign (pt);

end;

//initialization

//RegisterClass (TWrapper);

end.

Code:

unit PersForm;

interface

uses

Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,

Buttons, StdCtrls, ExtCtrls;

type

TForm1 = class(TForm)

   Panel1: TPanel;

   Label1: TLabel;

   Edit1: TEdit;

   SpeedButtonLoad: TSpeedButton;

   SpeedButtonSave: TSpeedButton;

   OpenDialog1: TOpenDialog;

   SaveDialog1: TSaveDialog;

   procedure FormCreate(Sender: TObject);

   procedure SpeedButtonSaveClick(Sender: TObject);

   procedure SpeedButtonLoadClick(Sender: TObject);

   procedure FormMouseDown(Sender: TObject; Button: TMouseButton;

     Shift: TShiftState; X, Y: Integer);

   procedure FormDestroy(Sender: TObject);

   procedure FormPaint(Sender: TObject);

private

   PtList: TCollection;

end;

var

Form1: TForm1;

implementation

{$R *.DFM}

uses

DelphiPt;

procedure TForm1.FormCreate(Sender: TObject);

begin

PtList := TCollection.Create (TDDHPoint);

end;

procedure TForm1.SpeedButtonSaveClick(Sender: TObject);

var

Str1: TFileStream;

Wrap: TWrapper;

begin

if SaveDialog1.Execute then

begin

   Str1 := TFileStream.Create (SaveDialog1.FileName,

     fmOpenWrite or fmCreate);

   try

     Wrap := TWrapper.Create (self);

     try

       Wrap.MyColl.Assign (ptList);

       Str1.WriteComponent (Wrap);

     finally

       Wrap.Free;

     end;

   finally

     Str1.Free;

   end;

end;

end;

procedure TForm1.SpeedButtonLoadClick(Sender: TObject);

var

Str1: TFileStream;

Wrap: TWrapper;

begin

if OpenDialog1.Execute then

begin

   Str1 := TFileStream.Create (

     OpenDialog1.Filename, fmOpenRead);

   try

     Wrap := TWrapper.Create (self);

     try

       Wrap := Str1.ReadComponent (Wrap) as TWrapper;

       ptList.Assign (Wrap.MyColl);

     finally

       Wrap.Free;

     end;

   finally

     Str1.Free;

     Invalidate;

     Edit1.Text := 'Point ' + IntToStr (PtList.Count + 1);

   end;

end;

end;

procedure TForm1.FormMouseDown(Sender: TObject; Button: TMouseButton;

Shift: TShiftState; X, Y: Integer);

var

Pt: TDDHPoint;

begin

Pt := PtList.Add as TDDHPoint;

Pt.X := X;

Pt.Y := Y;

Pt.Text := Edit1.Text;

Edit1.Text := 'Point ' + IntToStr (PtList.Count + 1);

Invalidate;

end;

procedure TForm1.FormDestroy(Sender: TObject);

begin

// empty and destroy the list

PtList.Clear;

PtList.Free;

end;

procedure TForm1.FormPaint(Sender: TObject);

var

I: Integer;

begin

for I := 0 to PtList.Count - 1 do

   TDDHPoint (PtList.Items [I]).Paint (Canvas);

end;

end.