////////////////////////////////////////////////////////////////////////////////
// TMultiDataFile2                                                            //
////////////////////////////////////////////////////////////////////////////////
// Handles a file that consists of a sequence of other files, seperated by a  //
// 3byte header containing the size of the following segment, terminated by   //
// 3 byte with value 0.                                                       //
// VERSION 2 - LSB FIRST!!!!!                                                 //
////////////////////////////////////////////////////////////////////////////////
//  version 2.1 / August 2001                                                 //
//  (C) 1999,2000 by Werner Bailer (werner@wbailer.com)                       //
////////////////////////////////////////////////////////////////////////////////
unit MultiDataFile;

interface

uses Classes, SysUtils
{$IFDEF CLX}
, QGraphics
, QDialogs
{$ELSE}
, Graphics
, Dialogs
{$ENDIF}
;

type
  TMultiDataFile = class
  protected
    Stream:           TMemoryStream;
    function GetOffset(Index: Integer): Longint;
  public
    constructor Create;
    destructor Destroy; override;
    procedure ReadFile(Name: String);
    procedure Flush;
    function GetSize: Longint;
    function GetSegmentAsStream(Index: Integer; var outStream: TStream): Longint;
    function GetSegmentAsBitmap(Index: Integer; var Image: TBitmap): Boolean;
    //function GetSegmentAsJPEG(Index: Integer; var Image: TJPEGImage): Boolean;
    //function GetJPEGSegmentAsBitmap(Index: Integer; var Image: TBitmap): Boolean;
    function GetSegmentAsString(Index: Integer): String;
  end;

implementation

  // TMultiDataFile

  constructor TMultiDataFile.Create;
  begin
    inherited Create;
    Stream:=TMemoryStream.Create;
  end;

  destructor TMultiDataFile.Destroy;
  begin
    Stream.Free;
    inherited Destroy;
  end;

  procedure TMultiDataFile.ReadFile(Name: String);
  var
    inStream:       TFileStream;
  begin
    if FileExists(Name) then begin
     try
      inStream:=TFileStream.Create(Name,fmOpenRead);
      Stream.Clear;
      Stream.Seek(0,soFromBeginning);
      Stream.CopyFrom(inStream,inStream.Size);
      FileClose(inStream.Handle);
     finally
     // inStream.Free;
     end;
    end
    else raise Exception.Create('File '+Name+' not found.');
  end;

  procedure TMultiDataFile.Flush;
  begin
    Stream.Clear;
  end;

  function TMultiDataFile.GetSize: Longint;
  begin
    GetSize:=Stream.Size;
  end;

  function TMultiDataFile.GetOffset(Index: Integer): Longint;
  var
    SegSz:         Array[0..2] of Byte;
    SegSize:       Longint;
    offs:          Longint;
    idx:           Integer;
  begin
    Stream.Seek(0,soFromBeginning);
    if GetSize>3 then begin
      idx:=-1;
      offs:=-3;
      SegSize:=0;
      repeat
        Inc(idx);
        offs:=offs+3+SegSize;
        Stream.Seek(offs,soFromBeginning);
        Stream.Read(SegSz,3);
        SegSize:=SegSz[0]+SegSz[1]*$100+SegSz[2]*$10000;
      until (SegSize=0) or (idx=Index);
      if (idx=Index) and (SegSize<>0) then GetOffset:=offs else GetOffset:=-1;
    end
    else GetOffset:=-1;
  end;

  function TMultiDataFile.GetSegmentAsStream(Index: Integer; var outStream: TStream): Longint;
  var
    SegSz:         Array[0..2] of Byte;
    Offs:          Longint;
    SegSize:       Longint;
  begin
    Offs:=GetOffset(Index);
    SegSize:=0;
    if Offs>-1 then begin
      Stream.Seek(Offs,soFromBeginning);
      Stream.Read(SegSz,3);
      SegSize:=SegSz[0]+SegSz[1]*$100+SegSz[2]*$10000;
      Stream.Seek(Offs+3,soFromBeginning);
      outStream.Seek(0,soFromBeginning);
      outStream.CopyFrom(Stream,SegSize);
    end;
    GetSegmentAsStream:=SegSize;
  end;

  function TMultiDataFile.GetSegmentAsBitmap(Index: Integer; var Image: TBitmap): Boolean;
  var
    bmpStream:       TStream;
    BytesRead:       Longint;
  begin
    bmpStream:=TMemoryStream.Create;
    BytesRead:=GetSegmentAsStream(Index,bmpStream);
    if BytesRead>0 then begin
      GetSegmentAsBitmap:=True;
      try
        bmpStream.Seek(0,soFromBeginning);
        Image.LoadFromStream(bmpStream);
       except
        on Exception do GetSegmentAsBitmap:=False;
      end;
    end
    else GetSegmentAsBitmap:=False;
    bmpStream.Free;
  end;
{
  function TMultiDataFile.GetSegmentAsJPEG(Index: Integer; var Image: TJPEGImage): Boolean;
  var
    jpegStream:       TStream;
    BytesRead:        Longint;
  begin
    jpegStream:=TMemoryStream.Create;
    BytesRead:=GetSegmentAsStream(Index,jpegStream);
    Image.JPEGNeeded;
    if BytesRead>0 then begin
      try
        GetSegmentAsJPEG:=True;
        jpegStream.Seek(0,soFromBeginning);
        Image.LoadFromStream(jpegStream);
      except
        on Exception do GetSegmentAsJPEG:=False;
      end;
    end
    else GetSegmentAsJPEG:=False;
    jpegStream.Free;
  end;

  function TMultiDataFile.GetJPEGSegmentAsBitmap(Index: Integer; var Image: TBitmap): Boolean;
  var
    jpegImage:    TJPEGImage;
    Success:      Boolean;
  begin
    jpegImage:=TJPEGImage.Create;
    Success:=GetSegmentAsJPEG(Index,jpegImage);
    if Success then begin
      try
        Image.Assign(jpegImage);
      except
        on Exception do Success:=False;
      end;
    end;
    jpegImage.Free;
    GetJPEGSegmentAsBitmap:=Success;
  end;
}
  function TMultiDataFile.GetSegmentAsString(Index: Integer): String;
  var
    DataStream:     TStream;
    StrStream:      TStringStream;
  begin
    try
      DataStream:=TMemoryStream.Create;
      StrStream:=TStringStream.Create('');
      GetSegmentAsStream(Index,DataStream);
      StrStream.CopyFrom(DataStream,0);
      GetSegmentAsString:=Copy(StrStream.DataString,1,StrStream.Size);
    finally
      StrStream.Free;
      DataStream.Free;  
    end;
  end;

end.