Код определения свойств

unit PropDemo;

interface

uses
  SysUtils, WinTypes, WinProcs, Messages, Classes, Graphics, Controls,
  Forms, Dialogs;

type
  TDemoProps = class(TComponent)
  private
    { Private declarations }
    FStringThing: string;
    FThing: record
      i, j, k: integer;
      x, y: real;
      ch: char;
    end;
    procedure ReadStringThing(Reader: TReader);
    procedure WriteStringThing(Writer: TWriter);
    procedure ReadThing(Stream: TStream);
    procedure WriteThing(Stream: TStream);
  protected
    { Protected declarations }
    procedure DefineProperties(Filer: TFiler); override;
  public
    { Public declarations }
    constructor Create(AOwner: TComponent); override;
  published
    { Published declarations }
  end;

procedure Register;

implementation

constructor TDemoProps.Create(AOwner: TComponent);

begin
  inherited Create(AOwner);

  { создайте любые данные, чтобы было что передать в поток}
  FStringThing := 'Всем привет!';
  with FThing do
  begin
    i := 1;
    j := 2;
    k := 3;
    x := PI;
    y := 180 / PI;
    ch := '?';
  end;
end;

procedure TDemoProps.ReadStringThing(Reader: TReader);

begin
  FStringThing := Reader.ReadString;
end;

procedure TDemoProps.WriteStringThing(Writer: TWriter);

begin
  Writer.WriteString(FStringThing);
end;

procedure TDemoProps.ReadThing(Stream: TStream);

begin
  Stream.ReadBuffer(FThing, sizeof(FThing));
end;

procedure TDemoProps.WriteThing(Stream: TStream);

begin
  Stream.WriteBuffer(FThing, sizeof(FThing));
end;

procedure TDemoProps.DefineProperties(Filer: TFiler);

begin
  inherited DefineProperties(Filer);
  Filer.DefineProperty('StringThing', ReadStringThing, WriteStringThing,
    FStringThing <> '');
  Filer.DefineBinaryProperty('Thing', ReadThing, WriteThing, true);
end;

procedure Register;
begin
  RegisterComponents('Samples', [TDemoProps]);
end;

end.