lazarus-ccr/components/fpspreadsheet/xlsbiff2.pas

{
xlsbiff2.pas

Writes an Excel 2.x file

Excel 2.x files support only one Worksheet per Workbook, so only the first
will be written.

An Excel file consists of a number of subsequent records.
To ensure a properly formed file, the following order must be respected:

1st record:        BOF
2nd to Nth record: Any record
Last record:       EOF

The row and column numbering in BIFF files is zero-based.

Excel file format specification obtained from:

http://sc.openoffice.org/excelfileformat.pdf

Encoding information: ISO_8859_1 is used, to have support to
other characters, please use a format which support unicode

AUTHORS: Felipe Monteiro de Carvalho
}
unit xlsbiff2;

{$ifdef fpc}
  {$mode delphi}
{$endif}

interface

uses
  Classes, SysUtils,
  fpspreadsheet, xlscommon, fpsutils, lconvencoding;
  
type

  { TsBIFF2NumFormatList }
  TsBIFF2NumFormatList = class(TsCustomNumFormatList)
  protected
    procedure AddBuiltinFormats; override;
    procedure ConvertBeforeWriting(var AFormatString: String;
      var ANumFormat: TsNumberFormat; var ADecimals: Byte; var ACurrencySymbol: String); override;
    function FindFormatOf(AFormatCell: PCell): Integer; override;
  public
    constructor Create(AWorkbook: TsWorkbook);
    function FormatStringForWriting(AIndex: Integer): String; override;
  end;

  { TsSpreadBIFF2Reader }

  TsSpreadBIFF2Reader = class(TsSpreadBIFFReader)
  private
    WorkBookEncoding: TsEncoding;
    FWorksheet: TsWorksheet;
    FFont: TsFont;
  protected
    procedure ApplyCellFormatting(ARow, ACol: Cardinal; XFIndex: Word); override;
    procedure CreateNumFormatList; override;
    procedure ExtractNumberFormat(AXFIndex: WORD;
      out ANumberFormat: TsNumberFormat; out ANumberFormatStr: String); override;
    procedure ReadBlank(AStream: TStream); override;
    procedure ReadColWidth(AStream: TStream);
    procedure ReadFont(AStream: TStream);
    procedure ReadFontColor(AStream: TStream);
    procedure ReadFormula(AStream: TStream); override;
    procedure ReadInteger(AStream: TStream);
    procedure ReadLabel(AStream: TStream); override;
    procedure ReadNumber(AStream: TStream); override;
    procedure ReadRowColXF(AStream: TStream; out ARow, ACol: Cardinal; out AXF: Word); override;
    procedure ReadRowInfo(AStream: TStream); override;
    function ReadRPNFunc(AStream: TStream): Word; override;
    function ReadRPNTokenArraySize(AStream: TStream): Word; override;
    procedure ReadStringRecord(AStream: TStream); override;
    procedure ReadWindow2(AStream: TStream); override;
    procedure ReadXF(AStream: TStream);
  public
    { General reading methods }
    procedure ReadFromStream(AStream: TStream; AData: TsWorkbook); override;
  end;

  { TsSpreadBIFF2Writer }

  TsSpreadBIFF2Writer = class(TsSpreadBIFFWriter)
  private
    function FindXFIndex(ACell: PCell): Word;
    { Record writing methods }
    procedure WriteBOF(AStream: TStream);
    procedure WriteCellFormatting(AStream: TStream; ACell: PCell; XFIndex: Word);
    procedure WriteColWidth(AStream: TStream; ACol: PCol);
    procedure WriteColWidths(AStream: TStream);
    procedure WriteEOF(AStream: TStream);
    procedure WriteFont(AStream: TStream; AFontIndex: Integer);
    procedure WriteFonts(AStream: TStream);
    procedure WriteFormatCount(AStream: TStream);
    procedure WriteIXFE(AStream: TStream; XFIndex: Word);
    procedure WriteXF(AStream: TStream; AFontIndex, AFormatIndex: byte;
      ABorders: TsCellBorders = []; AHorAlign: TsHorAlignment = haLeft;
      AddBackground: Boolean = false);
    procedure WriteXFFieldsForFormattingStyles(AStream: TStream);
    procedure WriteXFRecords(AStream: TStream);
  protected
    procedure CreateNumFormatList; override;
    procedure ListAllFormattingStyles; override;
    procedure ListAllNumFormats; override;
    procedure WriteBlank(AStream: TStream; const ARow, ACol: Cardinal; ACell: PCell); override;
    procedure WriteFormat(AStream: TStream; AFormatData: TsNumFormatData;
      AListIndex: Integer); override;
    procedure WriteLabel(AStream: TStream; const ARow, ACol: Cardinal; const AValue: string; ACell: PCell); override;
    procedure WriteNumber(AStream: TStream; const ARow, ACol: Cardinal; const AValue: double; ACell: PCell); override;
    procedure WriteRow(AStream: TStream; ASheet: TsWorksheet;
      ARowIndex, AFirstColIndex, ALastColIndex: Cardinal; ARow: PRow); override;
    procedure WriteRPNFormula(AStream: TStream; const ARow, ACol: Cardinal; const AFormula: TsRPNFormula; ACell: PCell); override;
    procedure WriteWindow1(AStream: TStream); override;
    procedure WriteWindow2(AStream: TStream; ASheet: TsWorksheet);
  public
    { General writing methods }
    procedure WriteToStream(AStream: TStream); override;
  end;

var
  { the palette of the default BIFF2 colors as "big-endian color" values }
  PALETTE_BIFF2: array[$0..$07] of TsColorValue = (
    $000000,  // $00: black
    $FFFFFF,  // $01: white
    $FF0000,  // $02: red
    $00FF00,  // $03: green
    $0000FF,  // $04: blue
    $FFFF00,  // $05: yellow
    $FF00FF,  // $06: magenta
    $00FFFF   // $07: cyan
  );


implementation

uses
  Math, fpsNumFormatParser;

const
  { Excel record IDs }
  INT_EXCEL_ID_BLANK      = $0001;
  INT_EXCEL_ID_INTEGER    = $0002;
  INT_EXCEL_ID_NUMBER     = $0003;
  INT_EXCEL_ID_LABEL      = $0004;
  INT_EXCEL_ID_ROW        = $0008;
  INT_EXCEL_ID_BOF        = $0009;
  INT_EXCEL_ID_INDEX      = $000B;
  INT_EXCEL_ID_FORMAT     = $001E;
  INT_EXCEL_ID_FORMATCOUNT= $001F;
  INT_EXCEL_ID_COLWIDTH   = $0024;
  INT_EXCEL_ID_WINDOW2    = $003E;
  INT_EXCEL_ID_XF         = $0043;
  INT_EXCEL_ID_IXFE       = $0044;
  INT_EXCEL_ID_FONTCOLOR  = $0045;

  { BOF record constants }
  INT_EXCEL_SHEET         = $0010;
  INT_EXCEL_CHART         = $0020;
  INT_EXCEL_MACRO_SHEET   = $0040;


{ TsBIFF2NumFormatList }

constructor TsBIFF2NumFormatList.Create(AWorkbook: TsWorkbook);
begin
  inherited Create(AWorkbook);
end;

procedure TsBIFF2NumFormatList.AddBuiltinFormats;
var
  fs: TFormatSettings;
  ds, ts, cs: string;
begin
  fs := Workbook.FormatSettings;
  ds := fs.DecimalSeparator;
  ts := fs.ThousandSeparator;
  cs := fs.CurrencyString;
  AddFormat( 0, '', nfGeneral);
  AddFormat( 1, '0', nfFixed);
  AddFormat( 2, '0'+ds+'00', nfFixed);                     // 0.00
  AddFormat( 3, '#'+ts+'##0', nfFixedTh);                  // #,##0
  AddFormat( 4, '#'+ts+'##0'+ds+'00', nfFixedTh);          // #,##0.00
  AddFormat( 5, UTF8ToAnsi('"'+cs+'"#'+ts+'##0_);("'+cs+'"#'+ts+'##0)'), nfCurrency);
  AddFormat( 6, UTF8ToAnsi('"'+cs+'"#'+ts+'##0_);[Red]("'+cs+'"#'+ts+'##0)'), nfCurrencyRed);
  AddFormat( 7, UTF8ToAnsi('"'+cs+'"#'+ts+'##0'+ds+'00_);("'+cs+'"#'+ts+'##0'+ds+'00)'), nfCurrency);
  AddFormat( 8, UTF8ToAnsi('"'+cs+'"#'+ts+'##0'+ds+'00_);[Red]("'+cs+'"#'+ts+'##0'+ds+'00)'), nfCurrency);
  AddFormat( 9, '0%', nfPercentage);
  AddFormat(10, '0'+ds+'00%', nfPercentage);
  AddFormat(11, '0'+ds+'00E+00', nfExp);
  AddFormat(12, fs.ShortDateFormat, nfShortDate);
  AddFormat(13, fs.LongDateFormat, nfLongDate);
  AddFormat(14, 'd/mmm', nfCustom);
  AddFormat(15, 'mmm/yy', nfCustom);
  //AddFormat(14, SpecialDateTimeFormat('dm', fs, true), nfFmtDateTime);
  //AddFormat(15, SpecialDateTimeFormat('my', fs, true), nfFmtDateTime);
  AddFormat(16, AddAMPM(fs.ShortTimeFormat, fs), nfShortTimeAM);
  AddFormat(17, AddAMPM(fs.LongTimeFormat, fs), nfLongTimeAM);
  AddFormat(18, fs.ShortTimeFormat, nfShortTime);
  AddFormat(19, fs.LongTimeFormat, nfLongTime);
  AddFormat(20, fs.ShortDateFormat + ' ' + fs.ShortTimeFormat, nfShortDateTime);

  FFirstFormatIndexInFile := 0;  // BIFF2 stores built-in formats to file.
  FNextFormatIndex := 21;    // not needed - there are not user-defined formats
end;


procedure TsBIFF2NumFormatList.ConvertBeforeWriting(var AFormatString: String;
  var ANumFormat: TsNumberFormat; var ADecimals: Byte; var ACurrencySymbol: String);
var
  fmt: String;
begin
  case ANumFormat of
    nfGeneral:
      ;
    nfFixed, nfFixedTh, nfPercentage, nfExp,
    nfCurrency, nfCurrencyRed, nfAccounting, nfAccountingRed:
      if ADecimals > 0 then ADecimals := 2;
    nfSci:
      begin
        if ADecimals > 0 then ADecimals := 2;
        ANumFormat := nfExp;
      end;
    {
    nfFmtDateTime:
      begin
        fmt := lowercase(AFormatString);
        if (fmt = 'd-mm') or (fmt = 'd/mm') or
           (fmt = 'dd-mm') or (fmt = 'dd/mm') or
           (fmt = 'dd-mmm') or (fmt = 'dd/mmm')
        then
          AFormatString := SpecialDateTimeFormat('dm', Workbook.FormatSettings, true)
        else
        if (fmt = 'm-yy') or (fmt = 'm/yy') or
           (fmt = 'mm-yy') or (fmt = 'mm/yy') or
           (fmt = 'mmm-yy') or (fmt = 'mmm/yy') or
           (fmt = 'm-yyyy') or (fmt = 'm/yyyy') or
           (fmt = 'mm-yyyy') or (fmt = 'mm/yyyy') or
           (fmt = 'mmm-yyyy') or (fmt = 'mmm-yyyy')
        then
          AFormatString := SpecialDateTimeFormat('my', Workbook.FormatSettings, true)
        else
        if (copy(fmt, 1, 5) = 'nn:ss') or (copy(fmt, 1, 5) = 'mm:ss') or
           (copy(fmt, 1, 4) = 'n:ss') or (copy(fmt, 1, 4) = 'm:ss')
        then
          ANumFormat := nfLongTime
        else
          ANumFormat := nfShortDateTime;
      end;
      }
    nfCustom, nfTimeInterval:
      begin
        ANumFormat := nfGeneral;
        AFormatString := '';
        ADecimals := 0;
      end;
  end;
end;


function TsBIFF2NumFormatList.FindFormatOf(AFormatCell: PCell): Integer;
var
  fmt: String;
  parser: TsNumFormatParser;
  decs: Integer;
  dt: string;
begin
  parser := TsNumFormatParser.Create(Workbook, AFormatCell^.NumberFormatStr);
  try
    decs := parser.Decimals;
    dt := parser.GetDateTimeCode(0);
  finally
    parser.Free;
  end;

  case AFormatCell^.NumberFormat of
    nfGeneral,
    nfTimeInterval  : Result := 0;
    nfFixed         : Result := IfThen(decs = 0, 1, 2);
    nfFixedTh       : Result := IfThen(decs = 0, 3, 4);
    nfCurrency,
    nfAccounting    : Result := IfThen(decs = 0, 5, 7);
    nfCurrencyRed,
    nfAccountingRed : Result := IfThen(decs = 0, 6, 8);
    nfPercentage    : Result := IfThen(decs = 0, 9, 10);
    nfExp, nfSci    : Result := 11;
    nfShortDate     : Result := 12;
    nfLongDate      : Result := 13;
    nfShortTimeAM   : Result := 16;
    nfLongTimeAM    : Result := 17;
    nfShortTime     : Result := 18;
    nfLongTime      : Result := 19;
    nfShortDateTime : Result := 20;
    nfCustom        : if dt = 'dm' then Result := 14 else
                      if dt = 'my' then Result := 15;
  end;
end;

 { Creates formatting strings that are written into the file. These are the
   strings in the format list. The only exception is the nfGeneral entry which
   is written as "General". }
 function TsBIFF2NumFormatList.FormatStringForWriting(AIndex: Integer): String;
begin
  Result := inherited FormatStringForWriting(AIndex);
  if Result = '' then
    Result := 'General';
end;


{ TsSpreadBIFF2Reader }

procedure TsSpreadBIFF2Reader.ApplyCellFormatting(ARow, ACol: Cardinal;
  XFIndex: Word);
var
  lCell: PCell;
  xfData: TXFListData;
  style: Byte;
begin
  lCell := FWorksheet.GetCell(ARow, ACol);

  if Assigned(lCell) then begin
    xfData := TXFListData(FXFList.items[XFIndex]);

    // Font index, "bold" attribute
    if xfData.FontIndex = 1 then
      Include(lCell^.UsedFormattingFields, uffBold)
    else
      Include(lCell^.UsedFormattingFields, uffFont);
    lCell^.FontIndex := xfData.FontIndex;

    // Alignment
    lCell^.HorAlignment := xfData.HorAlignment;
    lCell^.VertAlignment := xfData.VertAlignment;

    // Wordwrap not supported by BIFF2
    Exclude(lCell^.UsedFormattingFields, uffWordwrap);
    // Text rotation not supported by BIFF2
    Exclude(lCell^.UsedFormattingFields, uffTextRotation);

    // Border
    if xfData.Borders <> [] then begin
      Include(lCell^.UsedFormattingFields, uffBorder);
      lCell^.Border := xfData.Borders;
    end else
      Exclude(lCell^.UsedFormattingFields, uffBorder);

    // Background, only shaded, color is ignored
    if xfData.BackgroundColor <> 0 then
      Include(lCell^.UsedFormattingFields, uffBackgroundColor)
    else
      Exclude(lCell^.UsedFormattingFields, uffBackgroundColor);
  end;
end;

{ Creates the correct version of the number format list.
  It is for BIFF2 and BIFF3 file formats. }
procedure TsSpreadBIFF2Reader.CreateNumFormatList;
begin
  FreeAndNil(FNumFormatList);
  FNumFormatList := TsBIFF2NumFormatList.Create(Workbook);
end;

{ Extracts the number format data from an XF record indexed by AXFIndex.
  Note that BIFF2 supports only 21 formats. }
procedure TsSpreadBIFF2Reader.ExtractNumberFormat(AXFIndex: WORD;
  out ANumberFormat: TsNumberFormat; out ANumberFormatStr: String);
var
  lNumFormatData: TsNumFormatData;
begin
  lNumFormatData := FindNumFormatDataForCell(AXFIndex);
  if lNumFormatData <> nil then begin
    ANumberFormat := lNumFormatData.NumFormat;
    ANumberFormatStr := lNumFormatData.FormatString;
  end else begin
    ANumberFormat := nfGeneral;
    ANumberFormatStr := '';
  end;
end;

procedure TsSpreadBIFF2Reader.ReadBlank(AStream: TStream);
var
  ARow, ACol: Cardinal;
  XF: Word;
begin
  ReadRowColXF(AStream, ARow, ACol, XF);
  ApplyCellFormatting(ARow, ACol, XF);
end;

procedure TsSpreadBIFF2Reader.ReadColWidth(AStream: TStream);
var
  c, c1, c2: Cardinal;
  w: Word;
  col: TCol;
  sheet: TsWorksheet;
begin
  sheet := Workbook.GetFirstWorksheet;
  // read column start and end index of column range
  c1 := AStream.ReadByte;
  c2 := AStream.ReadByte;
  // read col width in 1/256 of the width of "0" character
  w := WordLEToN(AStream.ReadWord);
  // calculate width in units of "characters"
  col.Width := w / 256;
  // assign width to columns
  for c := c1 to c2 do
    sheet.WriteColInfo(c, col);
end;

procedure TsSpreadBIFF2Reader.ReadFont(AStream: TStream);
var
  lHeight: Word;
  lOptions: Word;
  Len: Byte;
  lFontName: UTF8String;
begin
  FFont := TsFont.Create;

  { Height of the font in twips = 1/20 of a point }
  lHeight := WordLEToN(AStream.ReadWord);
  FFont.Size := lHeight/20;

  { Option flags }
  lOptions := WordLEToN(AStream.ReadWord);
  FFont.Style := [];
  if lOptions and $0001 <> 0 then Include(FFont.Style, fssBold);
  if lOptions and $0002 <> 0 then Include(FFont.Style, fssItalic);
  if lOptions and $0004 <> 0 then Include(FFont.Style, fssUnderline);
  if lOptions and $0008 <> 0 then Include(FFont.Style, fssStrikeout);

  { Font name: Unicodestring, char count in 1 byte }
  Len := AStream.ReadByte();
  SetLength(lFontName, Len);
  AStream.ReadBuffer(lFontName[1], Len);
  FFont.FontName := lFontName;

  { Add font to workbook's font list }
  FWorkbook.AddFont(FFont);
end;

procedure TsSpreadBIFF2Reader.ReadFontColor(AStream: TStream);
begin
  FFont.Color := WordLEToN(AStream.ReadWord);
end;

procedure TsSpreadBIFF2Reader.ReadFromStream(AStream: TStream; AData: TsWorkbook);
var
  BIFF2EOF: Boolean;
  RecordType: Word;
  CurStreamPos: Int64;
begin
  // Clear existing fonts. They will be replaced by those from the file.
  FWorkbook.RemoveAllFonts;

  { Store some data about the workbook that other routines need }
  WorkBookEncoding := AData.Encoding;

  BIFF2EOF := False;

  { In BIFF2 files there is only one worksheet, let's create it }
  FWorksheet := AData.AddWorksheet('');

  { Read all records in a loop }
  while not BIFF2EOF do
  begin
    { Read the record header }
    RecordType := WordLEToN(AStream.ReadWord);
    RecordSize := WordLEToN(AStream.ReadWord);

    CurStreamPos := AStream.Position;

    case RecordType of
      INT_EXCEL_ID_BLANK     : ReadBlank(AStream);
      INT_EXCEL_ID_FONT      : ReadFont(AStream);
      INT_EXCEL_ID_FONTCOLOR : ReadFontColor(AStream);
      INT_EXCEL_ID_INTEGER   : ReadInteger(AStream);
      INT_EXCEL_ID_NUMBER    : ReadNumber(AStream);
      INT_EXCEL_ID_LABEL     : ReadLabel(AStream);
      INT_EXCEL_ID_FORMULA   : ReadFormula(AStream);
      INT_EXCEL_ID_STRING    : ReadStringRecord(AStream);
      INT_EXCEL_ID_COLWIDTH  : ReadColWidth(AStream);
      INT_EXCEL_ID_ROW       : ReadRowInfo(AStream);
      INT_EXCEL_ID_WINDOW2   : ReadWindow2(AStream);
      INT_EXCEL_ID_PANE      : ReadPane(AStream);
      INT_EXCEL_ID_XF        : ReadXF(AStream);
      INT_EXCEL_ID_BOF       : ;
      INT_EXCEL_ID_EOF       : BIFF2EOF := True;
    else
      // nothing
    end;

    // Make sure we are in the right position for the next record
    AStream.Seek(CurStreamPos + RecordSize, soFromBeginning);

    if AStream.Position >= AStream.Size then BIFF2EOF := True;
  end;
end;

procedure TsSpreadBIFF2Reader.ReadFormula(AStream: TStream);
var
  ARow, ACol: Cardinal;
  XF: Word;
  ok: Boolean;
  formulaResult: Double;
//  rpnFormula: TsRPNFormula;
  Data: array [0..7] of byte;
  dt: TDateTime;
  nf: TsNumberFormat;
  nd: Byte;
  ncs: String;
  nfs: String;
  err: TsErrorValue;
  cell: PCell;
begin
  { BIFF Record row/column/style }
  ReadRowColXF(AStream, ARow, ACol, XF);

  { Result of the formula result in IEEE 754 floating-point value }
  AStream.ReadBuffer(Data, Sizeof(Data));

  { Recalculation byte - currently not used }
  AStream.ReadByte;

  // Now determine the type of the formula result
  if (Data[6] = $FF) and (Data[7] = $FF) then
    case Data[0] of
      0: // String -> Value is found in next record (STRING)
         FIncompleteCell := FWorksheet.GetCell(ARow, ACol);
      1: // Boolean value
         FWorksheet.WriteBoolValue(ARow, ACol, Data[2] = 1);
      2: begin  // Error value
           case Data[2] of
             ERR_INTERSECTION_EMPTY   : err := errEmptyIntersection;
             ERR_DIVIDE_BY_ZERO       : err := errDivideByZero;
             ERR_WRONG_TYPE_OF_OPERAND: err := errWrongType;
             ERR_ILLEGAL_REFERENCE    : err := errIllegalRef;
             ERR_WRONG_NAME           : err := errWrongName;
             ERR_OVERFLOW             : err := errOverflow;
             ERR_ARG_ERROR            : err := errArgError;
           end;
           FWorksheet.WriteErrorValue(ARow, ACol, err);
         end;
      3: // Empty cell
         FWorksheet.WriteBlank(ARow, ACol);
    end
  else begin
    if SizeOf(Double) <> 8 then
      raise Exception.Create('Double is not 8 bytes');

    // Result is a number or a date/time
    Move(Data[0], formulaResult, SizeOf(Data));

    {Find out what cell type, set content type and value}
    ExtractNumberFormat(XF, nf, nfs);
    if IsDateTime(formulaResult, nf, nfs, dt) then
      FWorksheet.WriteDateTime(ARow, ACol, dt, nf, nfs)
    else
      FWorksheet.WriteNumber(ARow, ACol, formulaResult, nf, nfs);
  end;

  { Formula token array }
  if FWorkbook.ReadFormulas then begin
    cell := FWorksheet.FindCell(ARow, ACol);
    ok := ReadRPNTokenArray(AStream, cell^.RPNFormulaValue);
    if not ok then FWorksheet.WriteErrorValue(cell, errFormulaNotSupported);
  end;

  { Apply formatting to cell }
  ApplyCellFormatting(ARow, ACol, XF);
end;

procedure TsSpreadBIFF2Reader.ReadLabel(AStream: TStream);
var
  L: Byte;
  ARow, ACol: Cardinal;
  XF: Word;
  AValue: array[0..255] of Char;
  AStrValue: UTF8String;
begin
  { BIFF Record row/column/style }
  ReadRowColXF(AStream, ARow, ACol, XF);

  { String with 8-bit size }
  L := AStream.ReadByte();
  AStream.ReadBuffer(AValue, L);
  AValue[L] := #0;

  { Save the data }
  case WorkBookEncoding of
    seLatin2:   AStrValue := CP1250ToUTF8(AValue);
    seCyrillic: AStrValue := CP1251ToUTF8(AValue);
    seGreek:    AStrValue := CP1253ToUTF8(AValue);
    seTurkish:  AStrValue := CP1254ToUTF8(AValue);
    seHebrew:   AStrValue := CP1255ToUTF8(AValue);
    seArabic:   AStrValue := CP1256ToUTF8(AValue);
  else
    // Latin 1 is the default
    AStrValue := CP1252ToUTF8(AValue);
  end;
  FWorksheet.WriteUTF8Text(ARow, ACol, AStrValue);

  { Apply formatting to cell }
  ApplyCellFormatting(ARow, ACol, XF);
end;

procedure TsSpreadBIFF2Reader.ReadNumber(AStream: TStream);
var
  ARow, ACol: Cardinal;
  XF: Word;
  value: Double;
  dt: TDateTime;
  nf: TsNumberFormat;
  nd: Byte;
  ncs: String;
  nfs: String;
begin
  { BIFF Record row/column/style }
  ReadRowColXF(AStream, ARow, ACol, XF);

  { IEE 754 floating-point value }
  AStream.ReadBuffer(value, 8);

  {Find out what cell type, set content type and value}
  ExtractNumberFormat(XF, nf, nfs);
  if IsDateTime(value, nf, nfs, dt) then
    FWorksheet.WriteDateTime(ARow, ACol, dt, nf, nfs)
  else
    FWorksheet.WriteNumber(ARow, ACol, value, nf, nfs);

  { Apply formatting to cell }
  ApplyCellFormatting(ARow, ACol, XF);
end;

procedure TsSpreadBIFF2Reader.ReadInteger(AStream: TStream);
var
  ARow, ACol: Cardinal;
  XF: Word;
  AWord  : Word;
begin
  { BIFF Record row/column/style }
  ReadRowColXF(AStream, ARow, ACol, XF);

  { 16 bit unsigned integer }
  AStream.ReadBuffer(AWord, 2);

  { Save the data }
  FWorksheet.WriteNumber(ARow, ACol, AWord);

  { Apply formatting to cell }
  ApplyCellFormatting(ARow, ACol, XF);
end;

// Read the row, column and xf index
procedure TsSpreadBIFF2Reader.ReadRowColXF(AStream: TStream;
  out ARow, ACol: Cardinal; out AXF: WORD);
begin
  { BIFF Record data for row and column}
  ARow := WordLEToN(AStream.ReadWord);
  ACol := WordLEToN(AStream.ReadWord);

  { Index to XF record }
  AXF := AStream.ReadByte;

  { Index to format and font record, Cell style - ignored because contained in XF
    Must read to keep the record in sync. }
  AStream.ReadWord;
end;

procedure TsSpreadBIFF2Reader.ReadRowInfo(AStream: TStream);
type
  TRowRecord = packed record
    RowIndex: Word;
    Col1: Word;
    Col2: Word;
    Height: Word;
  end;
var
  rowrec: TRowRecord;
  lRow: PRow;
  h: word;
begin
  AStream.ReadBuffer(rowrec, SizeOf(TRowRecord));
  h := WordLEToN(rowrec.Height);
  if h and $8000 = 0 then begin // if this bit were set, rowheight would be default
    lRow := FWorksheet.GetRow(WordLEToN(rowrec.RowIndex));
    // Row height is encoded into the 15 remaining bits in units "twips" (1/20 pt)
    // We need it in "lines" units.
    lRow^.Height := TwipsToPts(h and $7FFF) / Workbook.GetFont(0).Size;
    if lRow^.Height > ROW_HEIGHT_CORRECTION then
      lRow^.Height := lRow^.Height - ROW_HEIGHT_CORRECTION
    else
      lRow^.Height := 0;
  end;
end;

{ Reads the identifier for an RPN function with fixed argument count.
  Valid for BIFF2-BIFF3. }
function TsSpreadBIFF2Reader.ReadRPNFunc(AStream: TStream): Word;
var
  b: Byte;
begin
  b := AStream.ReadByte;
  Result := b;
end;

{ Helper funtion for reading of the size of the token array of an RPN formula.
  Is overridden because BIFF2 uses 1 byte only. }
function TsSpreadBIFF2Reader.ReadRPNTokenArraySize(AStream: TStream): Word;
begin
  Result := AStream.ReadByte;
end;

{ Reads a STRING record which contains the result of string formula. }
procedure TsSpreadBIFF2Reader.ReadStringRecord(AStream: TStream);
var
  len: Byte;
  s: ansistring;
begin
  // The string is a byte-string with 16 bit length
  len := AStream.ReadByte;
  if len > 0 then begin
    SetLength(s, Len);
    AStream.ReadBuffer(s[1], len);
    if (FIncompleteCell <> nil) and (s <> '') then begin
      FIncompleteCell^.UTF8StringValue := s;
      FIncompleteCell^.ContentType := cctUTF8String;
    end;
  end;
  FIncompleteCell := nil;
end;

{ Reads the WINDOW2 record containing information like "show grid lines",
  "show sheet headers", "panes are frozen", etc. }
procedure TsSpreadBIFF2Reader.ReadWindow2(AStream: TStream);
var
  b: byte;
  w: Word;
  rgb: DWord;
begin
  // Show formulas, not results
  b := AStream.ReadByte;

  // Show grid lines
  if AStream.ReadByte <> 0 then
    FWorksheet.Options := FWorksheet.Options + [soShowGridLines]
  else
    FWorksheet.Options := FWorksheet.Options - [soShowGridLines];

  // Show sheet headers
  if AStream.ReadByte <> 0 then
    FWorksheet.Options := FWorksheet.Options + [soShowHeaders]
  else
    FWorksheet.Options := FWorksheet.Options - [soShowHeaders];

  // Panes are frozen
  if AStream.ReadByte <> 0 then
    FWorksheet.Options := FWorksheet.Options + [soHasFrozenPanes]
  else
    FWorksheet.Options := FWorksheet.Options - [soHasFrozenPanes];

  // Show zero values
  b := AStream.ReadByte;

  // Index to first visible row
  w := WordLEToN(AStream.ReadWord);

  // Indoex to first visible column
  w := WordLEToN(AStream.ReadWord);

  // Use automatic grid line color (0= manual)
  b := AStream.ReadByte;

  // Manual grid line line color (rgb)
  rgb := DWordToLE(AStream.ReadDWord);
end;

procedure TsSpreadBIFF2Reader.ReadXF(AStream: TStream);
{ Offset Size Contents
    0      1   Index to FONT record (➜5.45)
    1      1   Not used
    2      1   Number format and cell flags:
                 Bit  Mask  Contents
                 5-0  3FH   Index to FORMAT record (➜5.49)
                  6   40H   1 = Cell is locked
                  7   80H   1 = Formula is hidden
    3      1   Horizontal alignment, border style, and background:
                 Bit  Mask  Contents
                 2-0  07H   XF_HOR_ALIGN – Horizontal alignment
                              0 General, 1 Left, 2 Center, 3 Right, 4 Filled
                  3   08H   1 = Cell has left black border
                  4   10H   1 = Cell has right black border
                  5   20H   1 = Cell has top black border
                  6   40H   1 = Cell has bottom black border
                  7   80H   1 = Cell has shaded background }
type
  TXFRecord = packed record
    FontIndex: byte;
    NotUsed: byte;
    NumFormat_Flags: byte;
    HorAlign_Border_BackGround: Byte;
  end;
var
  lData: TXFListData;
  xf: TXFRecord;
  b: Byte;
begin
  AStream.ReadBuffer(xf, SizeOf(xf));

  lData := TXFListData.Create;

  // Font index
  lData.FontIndex := xf.FontIndex;

  // Format index
  lData.FormatIndex := xf.NumFormat_Flags and $3F;

  // Horizontal alignment
  b := xf.HorAlign_Border_Background and MASK_XF_HOR_ALIGN;
  if (b <= ord(High(TsHorAlignment))) then
    lData.HorAlignment := TsHorAlignment(b)
  else
    lData.HorAlignment := haDefault;

  // Vertical alignment - not used in BIFF2
  lData.VertAlignment := vaBottom;

  // Word wrap - not used in BIFF2
  lData.WordWrap := false;

  // Text rotation - not used in BIFF2
  lData.TextRotation := trHorizontal;

  // Borders
  lData.Borders := [];
  if xf.HorAlign_Border_Background and $08 <> 0 then
    Include(lData.Borders, cbWest);
  if xf.HorAlign_Border_Background and $10 <> 0 then
    Include(lData.Borders, cbEast);
  if xf.HorAlign_Border_Background and $20 <> 0 then
    Include(lData.Borders, cbNorth);
  if xf.HorAlign_Border_Background and $40 <> 0 then
    Include(lData.Borders, cbSouth);

  // Background color not supported, only shaded background
  if xf.HorAlign_Border_Background and $80 <> 0 then
    lData.BackgroundColor := 1    // shaded background = "true"
  else
    ldata.BackgroundColor := 0;   // shaded background = "false"

  // Add the decoded data to the list
  FXFList.Add(lData);

  ldata := TXFListData(FXFList.Items[FXFList.Count-1]);
end;


{ TsSpreadBIFF2Writer }

{ Creates the correct version of the number format list.
  It is for BIFF2 and BIFF3 file formats. }
procedure TsSpreadBIFF2Writer.CreateNumFormatList;
begin
  FreeAndNil(FNumFormatList);
  FNumFormatList := TsBIFF2NumFormatList.Create(Workbook);
end;

function TsSpreadBIFF2Writer.FindXFIndex(ACell: PCell): Word;
var
  lIndex: Integer;
  lCell: TCell;
begin
  // First try the fast methods for default formats
  if ACell^.UsedFormattingFields = [] then
    Result := 15
  else begin
    // If not, then we need to search in the list of dynamic formats
    // But we have to consider that the number formats of the cell is in fpc syntax,
    // but the number format list of the writer is in Excel syntax.
    // And for BIFF2, there is only a limited number of formats.
    lCell := ACell^;
    {
    with lCell do begin
      if IsDateTimeFormat(NumberFormat) then
        NumberFormatStr := BuildDateTimeFormatString(NumberFormat,
          Workbook.FormatSettings, NumberFormatStr)
      else
        NumberFormatStr := BuildNumberFormatString(NumberFormat,
          Workbook.FormatSettings, Decimals, CurrencySymbol);
      NumFormatList.ConvertBeforeWriting(NumberFormatStr, NumberFormat, Decimals, CurrencyString);
    end;
    }
    lIndex := FindFormattingInList(@lCell);

    // Carefully check the index
    if (lIndex < 0) or (lIndex > Length(FFormattingStyles)) then
      raise Exception.Create('[TsSpreadBIFF2Writer.WriteXFIndex] Invalid Index, this should not happen!');
    Result := FFormattingStyles[lIndex].Row;
  end;
end;

procedure TsSpreadBIFF2Writer.ListAllFormattingStyles;
var
  i: Integer;
begin
  inherited ListAllFormattingStyles;
  {
  for i:=0 to High(FFormattingStyles) do
    FNumFormatList.ConvertBeforeWriting(
      FFormattingStyles[i].NumberFormatStr,
      FFormattingStyles[i].NumberFormat
    );
    }
end;

{ Builds up the list of number formats to be written to the biff2 file.
  Unlike biff5+ no formats are added here because biff2 supports only 21
  standard formats; these formats have been added by the NumFormatList's
  AddBuiltInFormats. }
procedure TsSpreadBIFF2Writer.ListAllNumFormats;
begin
  // Nothing to do here.
end;

{ Attaches cell formatting data for the given cell to the current record.
  Is called from all writing methods of cell contents. }
procedure TsSpreadBIFF2Writer.WriteCellFormatting(AStream: TStream; ACell: PCell;
  XFIndex: Word);
var
  b: Byte;
  xf: Word;
  i: Integer;
begin
  if ACell^.UsedFormattingFields = [] then
  begin
    AStream.WriteByte($0);
    AStream.WriteByte($0);
    AStream.WriteByte($0);
    Exit;
  end;

  // 1st byte:
  //   Mask $3F: Index to XF record
  //   Mask $40: 1 = Cell is locked
  //   Mask $80: 1 = Formula is hidden
  AStream.WriteByte(Min(XFIndex, $3F) and $3F);

  // 2nd byte:
  //   Mask $3F: Index to FORMAT record
  //   Mask $C0: Index to FONT record
  b := ACell.FontIndex shl 6;
  AStream.WriteByte(b);

  // 3rd byte
  //   Mask $07: horizontal alignment
  //   Mask $08: Cell has left border
  //   Mask $10: Cell has right border
  //   Mask $20: Cell has top border
  //   Mask $40: Cell has bottom border
  //   Mask $80: Cell has shaded background
  b := 0;
  if uffHorAlign in ACell^.UsedFormattingFields then
    b := ord (ACell^.HorAlignment);
  if uffBorder in ACell^.UsedFormattingFields then begin
    if cbNorth in ACell^.Border then b := b or $20;
    if cbWest in ACell^.Border then b := b or $08;
    if cbEast in ACell^.Border then b := b or $10;
    if cbSouth in ACell^.Border then b := b or $40;
  end;
  if uffBackgroundColor in ACell^.UsedFormattingFields then
    b := b or $80;
  AStream.WriteByte(b);
end;

{
  Writes an Excel 2 COLWIDTH record
}
procedure TsSpreadBIFF2Writer.WriteColWidth(AStream: TStream; ACol: PCol);
var
  w: Integer;
begin
  if Assigned(ACol) then begin
    { BIFF Record header }
    AStream.WriteWord(WordToLE(INT_EXCEL_ID_COLWIDTH));  // BIFF record header
    AStream.WriteWord(WordToLE(4));                      // Record size
    AStream.WriteByte(ACol^.Col);                        // start column
    AStream.WriteByte(ACol^.Col);                        // end column
    { calculate width to be in units of 1/256 of pixel width of character "0" }
    w := round(ACol^.Width * 256);
    AStream.WriteWord(WordToLE(w));                     // write width
  end;
end;

{
  Write COLWIDTH records for all columns
}
procedure TsSpreadBIFF2Writer.WriteColWidths(AStream: TStream);
var
  j: Integer;
  sheet: TsWorksheet;
  col: PCol;
begin
  sheet := Workbook.GetFirstWorksheet;
  for j := 0 to sheet.Cols.Count-1 do begin
    col := PCol(sheet.Cols[j]);
    WriteColWidth(AStream, col);
  end;
end;

{
  Writes an Excel 2 IXFE record
  This record contains the "real" XF index if it is > 62.
}
procedure TsSpreadBIFF2Writer.WriteIXFE(AStream: TStream; XFIndex: Word);
begin
  { BIFF Record header }
  AStream.WriteWord(WordToLE(INT_EXCEL_ID_IXFE));
  AStream.WriteWord(WordToLE(2));
  AStream.WriteWord(WordToLE(XFIndex));
end;

{
  Writes an Excel 2 file to a stream

  Excel 2.x files support only one Worksheet per Workbook,
  so only the first will be written.
}
procedure TsSpreadBIFF2Writer.WriteToStream(AStream: TStream);
var
  sheet: TsWorksheet;
begin
  sheet := Workbook.GetFirstWorksheet;

  WriteBOF(AStream);
    WriteFonts(AStream);
    WriteFormatCount(AStream);
    WriteFormats(AStream);
    WriteXFRecords(AStream);
    WriteColWidths(AStream);
    WriteRows(AStream, sheet);
    WriteCellsToStream(AStream, sheet.Cells);

    WriteWindow1(AStream);
    //  { -- currently not working
    WriteWindow2(AStream, sheet);
    WritePane(AStream, sheet, false);  // false for "is not BIFF5 or BIFF8"
    WriteSelections(AStream, sheet);
      //}
  WriteEOF(AStream);
end;

{
  Writes an Excel 2 WINDOW1 record
}
procedure TsSpreadBIFF2Writer.WriteWindow1(AStream: TStream);
begin
  { BIFF Record header }
  AStream.WriteWord(WordToLE(INT_EXCEL_ID_WINDOW1));
  AStream.WriteWord(WordToLE(9));

  { Horizontal position of the document window, in twips = 1 / 20 of a point }
  AStream.WriteWord(WordToLE(0));

  { Vertical position of the document window, in twips = 1 / 20 of a point }
  AStream.WriteWord(WordToLE($0069));

  { Width of the document window, in twips = 1 / 20 of a point }
  AStream.WriteWord(WordToLE($339F));

  { Height of the document window, in twips = 1 / 20 of a point }
  AStream.WriteWord(WordToLE($1B5D));

  { Window is visible (1) / hidden (0) }
  AStream.WriteByte(WordToLE(0));
end;

{
  Writes an Excel 2 WINDOW2 record
}
procedure TsSpreadBIFF2Writer.WriteWindow2(AStream: TStream;
 ASheet: TsWorksheet);
var
  b: Byte;
begin
  { BIFF Record header }
  AStream.WriteWord(WordToLE(INT_EXCEL_ID_WINDOW2));
  AStream.WriteWord(WordToLE(14));

  { Show formulas, not results }
  AStream.WriteByte(0);

  { Show grid lines }
  b := IfThen(soShowGridLines in ASheet.Options, 1, 0);
  AStream.WriteByte(b);

  { Show sheet headers }
  b := IfThen(soShowHeaders in ASheet.Options, 1, 0);
  AStream.WriteByte(b);

  { Panes are frozen? }
  b := IfThen(soHasFrozenPanes in ASheet.Options, 1, 0);
  AStream.WriteByte(b);

  { Show zero values as zeros, not empty cells }
  AStream.WriteByte(1);

  { Index to first visible row }
  AStream.WriteWord(0);

  { Index to first visible column }
  AStream.WriteWord(0);

  { Use automatic grid line color }
  AStream.WriteByte(1);

  { RGB of manual grid line color }
  AStream.WriteDWord(0);
end;

procedure TsSpreadBIFF2Writer.WriteXF(AStream: TStream;
  AFontIndex, AFormatIndex: byte; ABorders: TsCellBorders = [];
  AHorAlign: TsHorAlignment = haLeft; AddBackground: Boolean = false);
var
  b: Byte;
begin
  { BIFF Record header }
  AStream.WriteWord(WordToLE(INT_EXCEL_ID_XF));
  AStream.WriteWord(WordToLE(4));

  { Index to FONT record }
  AStream.WriteByte(AFontIndex);

  { not used }
  AStream.WriteByte(0);

  { Number format index and cell flags }
  b := AFormatIndex and $3F;
  AStream.WriteByte(b);

  { Horizontal alignment, border style, and background }
  b := byte(AHorAlign);
  if cbWest in ABorders then b := b or $08;
  if cbEast in ABorders then b := b or $10;
  if cbNorth in ABorders then b := b or $20;
  if cbSouth in ABorders then b := b or $40;
  if AddBackground then b := b or $80;
  AStream.WriteByte(b);
end;

procedure TsSpreadBIFF2Writer.WriteXFFieldsForFormattingStyles(AStream: TStream);
var
  i, j: Integer;
  lFontIndex: Word;
  lFormatIndex: Word; //number format
  lBorders: TsCellBorders;
  lAddBackground: Boolean;
  lHorAlign: TsHorAlignment;
  fmt: String;
begin
  // The loop starts with the first style added manually.
  // First style was already added  (see AddDefaultFormats)
  for i := 1 to Length(FFormattingStyles) - 1 do begin
    // Default styles
    lFontIndex := 0;
    lFormatIndex := 0; //General format (one of the built-in number formats)
    lBorders := [];
    lHorAlign := FFormattingStyles[i].HorAlignment;

    // Now apply the modifications.
    if uffNumberFormat in FFormattingStyles[i].UsedFormattingFields then begin
      j := NumFormatList.FindFormatOf(@FFormattingStyles[i]);
      if j > -1 then
        lFormatIndex := NumFormatList[j].Index;
    end;

    if uffBorder in FFormattingStyles[i].UsedFormattingFields then
      lBorders := FFormattingStyles[i].Border;

    if uffBold in FFormattingStyles[i].UsedFormattingFields then
      lFontIndex := 1;   // must be before uffFont which overrides uffBold

    if uffFont in FFormattingStyles[i].UsedFormattingFields then
      lFontIndex := FFormattingStyles[i].FontIndex;

    lAddBackground := (uffBackgroundColor in FFormattingStyles[i].UsedFormattingFields);

    // And finally write the style
    WriteXF(AStream, lFontIndex, lFormatIndex, lBorders, lHorAlign, lAddBackground);
  end;
end;

procedure TsSpreadBIFF2Writer.WriteXFRecords(AStream: TStream);
begin
  WriteXF(AStream, 0, 0);  // XF0
  WriteXF(AStream, 0, 0);  // XF1
  WriteXF(AStream, 0, 0);  // XF2
  WriteXF(AStream, 0, 0);  // XF3
  WriteXF(AStream, 0, 0);  // XF4
  WriteXF(AStream, 0, 0);  // XF5
  WriteXF(AStream, 0, 0);  // XF6
  WriteXF(AStream, 0, 0);  // XF7
  WriteXF(AStream, 0, 0);  // XF8
  WriteXF(AStream, 0, 0);  // XF9
  WriteXF(AStream, 0, 0);  // XF10
  WriteXF(AStream, 0, 0);  // XF11
  WriteXF(AStream, 0, 0);  // XF12
  WriteXF(AStream, 0, 0);  // XF13
  WriteXF(AStream, 0, 0);  // XF14
  WriteXF(AStream, 0, 0);  // XF15 - Default, no formatting

   // Add all further non-standard/built-in formatting styles
  ListAllFormattingStyles;
  WriteXFFieldsForFormattingStyles(AStream);
end;

{
  Writes an Excel 2 BOF record

  This must be the first record on an Excel 2 stream
}
procedure TsSpreadBIFF2Writer.WriteBOF(AStream: TStream);
begin
  { BIFF Record header }
  AStream.WriteWord(WordToLE(INT_EXCEL_ID_BOF));
  AStream.WriteWord(WordToLE($0004));

  { Unused }
  AStream.WriteWord($0000);

  { Data type }
  AStream.WriteWord(WordToLE(INT_EXCEL_SHEET));
end;

{
  Writes an Excel 2 EOF record

  This must be the last record on an Excel 2 stream
}
procedure TsSpreadBIFF2Writer.WriteEOF(AStream: TStream);
begin
  { BIFF Record header }
  AStream.WriteWord(WordToLE(INT_EXCEL_ID_EOF));
  AStream.WriteWord($0000);
end;

{
  Writes an Excel 2 font record
  The font data is passed as font index.
}
procedure TsSpreadBIFF2Writer.WriteFont(AStream: TStream; AFontIndex: Integer);
var
  Len: Byte;
  lFontName: AnsiString;
  optn: Word;
  font: TsFont;
begin
  font := Workbook.GetFont(AFontIndex);
  if font = nil then  // this happens for FONT4 in case of BIFF
    exit;

  if font.FontName = '' then
    raise Exception.Create('Font name not specified.');
  if font.Size <= 0.0 then
    raise Exception.Create('Font size not specified.');

  lFontName := font.FontName;
  Len := Length(lFontName);

  { BIFF Record header }
  AStream.WriteWord(WordToLE(INT_EXCEL_ID_FONT));
  AStream.WriteWord(WordToLE(4 + 1 + Len * Sizeof(AnsiChar)));

  { Height of the font in twips = 1/20 of a point }
  AStream.WriteWord(WordToLE(round(font.Size*20)));

  { Option flags }
  optn := 0;
  if fssBold in font.Style then optn := optn or $0001;
  if fssItalic in font.Style then optn := optn or $0002;
  if fssUnderline in font.Style then optn := optn or $0004;
  if fssStrikeout in font.Style then optn := optn or $0008;
  AStream.WriteWord(WordToLE(optn));

  { Font name: Unicodestring, char count in 1 byte }
  AStream.WriteByte(Len);
  AStream.WriteBuffer(lFontName[1], Len * Sizeof(AnsiChar));

  { Font color: goes into next record! }

  { BIFF Record header }
  AStream.WriteWord(WordToLE(INT_EXCEL_ID_FONTCOLOR));
  AStream.WriteWord(WordToLE(2));

  { Font color index, only first 8 palette entries allowed! }
  AStream.WriteWord(WordToLE(word(font.Color)));
end;

procedure TsSpreadBiff2Writer.WriteFonts(AStream: TStream);
var
  i: Integer;
begin
  for i:=0 to Workbook.GetFontCount-1 do
    WriteFont(AStream, i);
end;

procedure TsSpreadBiff2Writer.WriteFormat(AStream: TStream;
  AFormatData: TsNumFormatData; AListIndex: Integer);
var
  len: Integer;
  s: ansistring;
begin
  s := NumFormatList.FormatStringForWriting(AListIndex);
  len := Length(s);

  { BIFF Record header }
  AStream.WriteWord(WordToLE(INT_EXCEL_ID_FORMAT));
  AStream.WriteWord(WordToLE(1 + len));

  { Format string }
  AStream.WriteByte(len);          // AnsiString, char count in 1 byte
  AStream.WriteBuffer(s[1], len);  // String data
end;

procedure TsSpreadBIFF2Writer.WriteFormatCount(AStream: TStream);
begin
  AStream.WriteWord(WordToLE(INT_EXCEL_ID_FORMATCOUNT));
  AStream.WriteWord(WordToLE(2));
  AStream.WriteWord(WordToLE(21)); // there are 21 built-in formats
end;

{
  Writes an Excel 2 FORMULA record

  The formula needs to be converted from usual user-readable string
  to an RPN array

  // or, in RPN: A1, B1, +
  SetLength(MyFormula, 3);
  MyFormula[0].TokenID := INT_EXCEL_TOKEN_TREFV; A1
  MyFormula[0].Col := 0;
  MyFormula[0].Row := 0;
  MyFormula[1].TokenID := INT_EXCEL_TOKEN_TREFV; B1
  MyFormula[1].Col := 1;
  MyFormula[1].Row := 0;
  MyFormula[2].TokenID := INT_EXCEL_TOKEN_TADD;  +
}
procedure TsSpreadBIFF2Writer.WriteRPNFormula(AStream: TStream; const ARow,
  ACol: Cardinal; const AFormula: TsRPNFormula; ACell: PCell);
var
  FormulaResult: double;
  i: Integer;
  RPNLength: Word;
  TokenArraySizePos, RecordSizePos, FinalPos: Cardinal;
  FormulaKind, ExtraInfo: Word;
  r: Cardinal;
  len: Integer;
  s: ansistring;
  xf: Word;
begin
  RPNLength := 0;
  FormulaResult := 0.0;

  xf := FindXFIndex(ACell);
  if xf >= 63 then
    WriteIXFE(AStream, xf);

  { BIFF Record header }
  AStream.WriteWord(WordToLE(INT_EXCEL_ID_FORMULA));
  RecordSizePos := AStream.Position;
  AStream.WriteWord(WordToLE(17 + RPNLength));

  { Row and column }
  AStream.WriteWord(WordToLE(ARow));
  AStream.WriteWord(WordToLE(ACol));

  { BIFF2 Attributes }
  WriteCellFormatting(AStream, ACell, xf);

  { Result of the formula in IEEE 754 floating-point value }
  AStream.WriteBuffer(FormulaResult, 8);

  { 0 = Do not recalculate
    1 = Always recalculate }
  AStream.WriteByte($1);

  { Formula }

  { The size of the token array is written later,
    because it's necessary to calculate if first,
    and this is done at the same time it is written }
  TokenArraySizePos := AStream.Position;
  AStream.WriteByte(RPNLength);

  { Formula data (RPN token array) }
  for i := 0 to Length(AFormula) - 1 do
  begin

    { Token identifier }
    FormulaKind := FormulaElementKindToExcelTokenID(AFormula[i].ElementKind, ExtraInfo);
    AStream.WriteByte(FormulaKind);
    Inc(RPNLength);

    { Additional data }
    case FormulaKind of

    { binary operation tokens }

    INT_EXCEL_TOKEN_TADD, INT_EXCEL_TOKEN_TSUB, INT_EXCEL_TOKEN_TMUL,
     INT_EXCEL_TOKEN_TDIV, INT_EXCEL_TOKEN_TPOWER: begin end;

    INT_EXCEL_TOKEN_TNUM:
    begin
      AStream.WriteBuffer(AFormula[i].DoubleValue, 8);
      Inc(RPNLength, 8);
    end;

    INT_EXCEL_TOKEN_TSTR:
    begin
      s := ansistring(AFormula[i].StringValue);
      len := Length(s);
      AStream.WriteByte(len);
      AStream.WriteBuffer(s[1], len);
      Inc(RPNLength, len + 1);
    end;

    INT_EXCEL_TOKEN_TBOOL:
    begin
      AStream.WriteByte(ord(AFormula[i].DoubleValue <> 0.0));
      inc(RPNLength, 1);
    end;

    INT_EXCEL_TOKEN_TREFR, INT_EXCEL_TOKEN_TREFV, INT_EXCEL_TOKEN_TREFA:
    begin
      r := AFormula[i].Row and MASK_EXCEL_ROW;
      if (rfRelRow in AFormula[i].RelFlags) then r := r or MASK_EXCEL_RELATIVE_ROW;
      if (rfRelCol in AFormula[i].RelFlags) then r := r or MASK_EXCEL_RELATIVE_COL;
      AStream.WriteWord(r);
      AStream.WriteByte(AFormula[i].Col);
      Inc(RPNLength, 3);
    end;

    INT_EXCEL_TOKEN_TAREA_R: { fekCellRange }
    begin
      r := AFormula[i].Row and MASK_EXCEL_ROW;
      if (rfRelRow in AFormula[i].RelFlags) then r := r or MASK_EXCEL_RELATIVE_ROW;
      if (rfRelCol in AFormula[i].RelFlags) then r := r or MASK_EXCEL_RELATIVE_COL;
      AStream.WriteWord(WordToLE(r));

      r := AFormula[i].Row2 and MASK_EXCEL_ROW;
      if (rfRelRow2 in AFormula[i].RelFlags) then r := r or MASK_EXCEL_RELATIVE_ROW;
      if (rfRelCol2 in AFormula[i].RelFlags) then r := r or MASK_EXCEL_RELATIVE_COL;
      AStream.WriteWord(WordToLE(r));

      AStream.WriteByte(AFormula[i].Col);
      AStream.WriteByte(AFormula[i].Col2);
      Inc(RPNLength, 6);
    end;

    INT_EXCEL_TOKEN_FUNC_R, INT_EXCEL_TOKEN_FUNC_V, INT_EXCEL_TOKEN_FUNC_A:
    begin
      AStream.WriteByte(Lo(ExtraInfo));
      Inc(RPNLength, 1);
    end;

    INT_EXCEL_TOKEN_FUNCVAR_V:
    begin
      AStream.WriteByte(AFormula[i].ParamsNum);
      AStream.WriteByte(Lo(ExtraInfo));
      // taking only the low-bytes, the high-bytes are needed for compatibility
      // with other BIFF formats...
      Inc(RPNLength, 2);
    end;

    end;
  end;

  { Write sizes in the end, after we known them }
  FinalPos := AStream.Position;
  AStream.position := TokenArraySizePos;
  AStream.WriteByte(RPNLength);
  AStream.Position := RecordSizePos;
  AStream.WriteWord(WordToLE(17 + RPNLength));
  AStream.position := FinalPos;
end;

{*******************************************************************
*  TsSpreadBIFF2Writer.WriteBlank ()
*
*  DESCRIPTION:    Writes an Excel 2 record for an empty cell
*
*                  Required if this cell should contain formatting
*
*******************************************************************}
procedure TsSpreadBIFF2Writer.WriteBlank(AStream: TStream;
  const ARow, ACol: Cardinal; ACell: PCell);
var
  xf: Word;
begin
  xf := FindXFIndex(ACell);
  if xf >= 63 then
    WriteIXFE(AStream, xf);

  { BIFF Record header }
  AStream.WriteWord(WordToLE(INT_EXCEL_ID_BLANK));
  AStream.WriteWord(WordToLE(7));

  { BIFF Record data }
  AStream.WriteWord(WordToLE(ARow));
  AStream.WriteWord(WordToLE(ACol));

  { BIFF2 Attributes }
  WriteCellFormatting(AStream, ACell, xf);
end;

{*******************************************************************
*  TsSpreadBIFF2Writer.WriteLabel ()
*
*  DESCRIPTION:    Writes an Excel 2 LABEL record
*
*                  Writes a string to the sheet
*                  If the string length exceeds 255 bytes, the string
*                  will be truncated and an exception will be raised as
*                  a warning.
*
*******************************************************************}
procedure TsSpreadBIFF2Writer.WriteLabel(AStream: TStream; const ARow,
  ACol: Cardinal; const AValue: string; ACell: PCell);
const
  MaxBytes=255; //limit for this format
var
  L: Byte;
  AnsiText: ansistring;
  TextTooLong: boolean=false;
var
  xf: Word;
begin
  if AValue = '' then Exit; // Writing an empty text doesn't work

  AnsiText := UTF8ToISO_8859_1(AValue);

  if Length(AnsiText)>MaxBytes then
  begin
    // BIFF 5 does not support labels/text bigger than 255 chars,
    // so BIFF2 won't either
    // Rather than lose data when reading it, let the application programmer deal
    // with the problem or purposefully ignore it.
    TextTooLong:=true;
    AnsiText := Copy(AnsiText,1,MaxBytes);
  end;
  L := Length(AnsiText);

  xf := FindXFIndex(ACell);
  if xf >= 63 then
    WriteIXFE(AStream, xf);

  { BIFF Record header }
  AStream.WriteWord(WordToLE(INT_EXCEL_ID_LABEL));
  AStream.WriteWord(WordToLE(8 + L));

  { BIFF Record data }
  AStream.WriteWord(WordToLE(ARow));
  AStream.WriteWord(WordToLE(ACol));

  { BIFF2 Attributes }
  WriteCellFormatting(AStream, ACell, xf);

  { String with 8-bit size }
  AStream.WriteByte(L);
  AStream.WriteBuffer(AnsiText[1], L);

  {
  //todo: keep a log of errors and show with an exception after writing file or something.
  We can't just do the following
  if TextTooLong then
    Raise Exception.CreateFmt('Text value exceeds %d character limit in cell [%d,%d]. Text has been truncated.',[MaxBytes,ARow,ACol]);
    because the file wouldn't be written.
  }
end;

{*******************************************************************
*  TsSpreadBIFF2Writer.WriteNumber ()
*
*  DESCRIPTION:    Writes an Excel 2 NUMBER record
*
*                  Writes a number (64-bit IEE 754 floating point) to the sheet
*
*******************************************************************}
procedure TsSpreadBIFF2Writer.WriteNumber(AStream: TStream; const ARow,
  ACol: Cardinal; const AValue: double; ACell: PCell);
var
  xf: Word;
begin
  xf := FindXFIndex(ACell);
  if xf >= 63 then
    WriteIXFE(AStream, xf);

  { BIFF Record header }
  AStream.WriteWord(WordToLE(INT_EXCEL_ID_NUMBER));
  AStream.WriteWord(WordToLE(15));

  { BIFF Record data }
  AStream.WriteWord(WordToLE(ARow));
  AStream.WriteWord(WordToLE(ACol));

  { BIFF2 Attributes }
  WriteCellFormatting(AStream, ACell, xf);

  { IEE 754 floating-point value }
  AStream.WriteBuffer(AValue, 8);
end;

procedure TsSpreadBIFF2Writer.WriteRow(AStream: TStream; ASheet: TsWorksheet;
  ARowIndex, AFirstColIndex, ALastColIndex: Cardinal; ARow: PRow);
var
  containsXF: Boolean;
  rowheight: Word;
  w: Word;
  h: Single;
begin
  containsXF := false;

  { BIFF record header }
  AStream.WriteWord(WordToLE(INT_EXCEL_ID_ROW));
  AStream.WriteWord(WordToLE(IfThen(containsXF, 18, 13)));

  { Index of row }
  AStream.WriteWord(WordToLE(Word(ARowIndex)));

  { Index to column of the first cell which is described by a cell record }
  AStream.WriteWord(WordToLE(Word(AFirstColIndex)));

  { Index to column of the last cell which is described by a cell record, increased by 1 }
  AStream.WriteWord(WordToLE(Word(ALastColIndex) + 1));

  { Row height (in twips, 1/20 point) and info on custom row height }
  h := Workbook.GetFont(0).Size;
  if (ARow = nil) or (ARow^.Height = Workbook.DefaultRowHeight) then
    rowheight := PtsToTwips((Workbook.DefaultRowHeight + ROW_HEIGHT_CORRECTION) * h)
  else
  if (ARow^.Height = 0) then
    rowheight := 0
  else
    rowheight := PtsToTwips((ARow^.Height + ROW_HEIGHT_CORRECTION) * h);
  w := rowheight and $7FFF;
  AStream.WriteWord(WordToLE(w));

  { not used }
  AStream.WriteWord(0);

  { Contains row attribute field and XF index }
  AStream.WriteByte(ord(containsXF));

  { Relative offset to calculate stream position of the first cell record for this row }
  AStream.WriteWord(0);

  if containsXF then begin
    { Default row attributes }
    AStream.WriteByte(0);
    AStream.WriteByte(0);
    AStream.WriteByte(0);

    { Index to XF record }
    AStream.WriteWord(WordToLE(15));
  end;
end;

{*******************************************************************
*  Initialization section
*
*  Registers this reader / writer on fpSpreadsheet
*  Converts the palette to litte-endian
*
*******************************************************************}

initialization

  RegisterSpreadFormat(TsSpreadBIFF2Reader, TsSpreadBIFF2Writer, sfExcel2);
  MakeLEPalette(@PALETTE_BIFF2, Length(PALETTE_BIFF2));

end.