source: trunk/UFile1.pas

unit UFile1;

{$mode delphi}{$H+}

interface

uses
  Classes, SysUtils, Contnrs, UStreamHelper;

type
  TFile1 = class;
  TArrayOfByte = array of Byte;

  { TFile1Block }

  TFile1Block = class
    Parent: TFile1;
    Name: string;
    Start: Integer;
    Size: Integer;
    function Read: TArrayOfByte;
  end;

  { TFile1 }

  TFile1 = class
  private
    function GetOpenned: Boolean;
  public
    FileData: TFileStream;
    Blocks: TObjectList; // TObjectList<TFile1Block>
    InternalSize: Cardinal;
    InternalName: string;
    procedure Open(FileName: string);
    procedure Close;
    constructor Create;
    destructor Destroy; override;
    property Openned: Boolean read GetOpenned;
  end;

implementation

{ TFile1Block }

function TFile1Block.Read: TArrayOfByte;
begin
  SetLength(Result, Size);
  Parent.FileData.Position := Start;
  Parent.FileData.Read(Result[0], Size);
end;

{ TFile1 }

function TFile1.GetOpenned: Boolean;
begin
  Result := Assigned(FileData);
end;

procedure TFile1.Open(FileName: string);
var
  Helper: TStreamHelper;
  MagicString: string;
  NewBlock: TFile1Block;
begin
  Close;
  FileData := TFileStream.Create(FileName, fmOpenRead);
  Helper := TStreamHelper.Create(FileData);
  Helper.Endianness := enBig;
  MagicString := Helper.ReadString(4);
  if MagicString = 'FORM' then begin
    InternalSize := Helper.ReadCardinal;
    InternalName := Helper.ReadString(4);
    while Helper.Position < Helper.Size do begin
      NewBlock := TFile1Block.Create;
      NewBlock.Name := Helper.ReadString(4);
      NewBlock.Size := Helper.ReadCardinal;
      NewBlock.Start := Helper.Position;
      NewBlock.Parent := Self;
      Helper.Position := NewBlock.Start + NewBlock.Size;
      Blocks.Add(NewBlock);
    end;
  end;
  Helper.Free;
end;

procedure TFile1.Close;
begin
  if Openned then begin
    Blocks.Count := 0;
    FreeAndNil(FileData);
  end;
end;

constructor TFile1.Create;
begin
  FileData := nil;
  Blocks := TObjectList.Create;
end;

destructor TFile1.Destroy;
begin
  Close;
  FreeAndNil(Blocks);
  inherited Destroy;
end;

end.