Работа с коллекциями - сохранение и загрузка





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.


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.

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