fpspreadsheet: Finishes the basic support for date reading

git-svn-id: https://svn.code.sf.net/p/lazarus-ccr/svn@2263 8e941d3f-bd1b-0410-a28a-d453659cc2b4

components/fpspreadsheet/fpspreadsheet.pas

@@ -603,6 +603,7 @@ begin
   //cctFormula
   cctNumber:     Result := FloatToStr(ACell^.NumberValue);
   cctUTF8String: Result := ACell^.UTF8StringValue;
+  cctDateTime:   Result := SysUtils.DateToStr(ACell^.DateTimeValue);
   else
     Result := '';
   end;

components/fpspreadsheet/xlsbiff8.pas

@@ -52,7 +52,7 @@ unit xlsbiff8;
 interface
 
 uses
-  Classes, SysUtils, fpcanvas,
+  Classes, SysUtils, fpcanvas, DateUtils,
   fpspreadsheet, xlscommon,
   {$ifdef USE_NEW_OLE}
   fpolebasic,
@@ -104,7 +104,7 @@ type
     procedure ReadXF(const AStream: TStream);
     procedure ReadFormat(const AStream: TStream);
     function  FindFormatRecordForCell(const AFXIndex: Integer): TFormatRecordData;
-    class function ConvertExcelDateToTDateTime(const AExcelDateNum: Integer): TDateTime;
+    class function ConvertExcelDateToTDateTime(const AExcelDateNum: Double; ABaseDate: TDateTime): TDateTime;
 
     // Workbook Globals records
     // procedure ReadCodepage in xlscommon
@@ -1472,6 +1472,7 @@ begin
        INT_EXCEL_ID_FONT:       ReadFont(AStream);
        INT_EXCEL_ID_XF:         ReadXF(AStream);
        INT_EXCEL_ID_FORMAT:     ReadFormat(AStream);
+       INT_EXCEL_ID_DATEMODE:   ReadDateMode(AStream);
       else
         // nothing
       end;
@@ -1557,6 +1558,7 @@ var
   ARow, ACol, XF: WORD;
   Number: Double;
   lFormatData: TFormatRecordData;
+  lDateTime: TDateTime;
 begin
   ReadRowColXF(AStream,ARow,ACol,XF);
 
@@ -1570,14 +1572,17 @@ begin
   // See: http://www.gaia-gis.it/FreeXL/freexl-1.0.0a-doxy-doc/Format.html
   // Unfornately Excel doesnt give us a direct way to find this,
   // we need to guess by the FORMAT field
-{  lFormatData := FindFormatRecordForCell(XF);
+  lFormatData := FindFormatRecordForCell(XF);
   if lFormatData <> nil then
   begin
     // Dates have /
     if Pos('/', lFormatData.FormatString) > 0 then
     begin
+      lDateTime := ConvertExcelDateToTDateTime(Number, FBaseDate);
+      FWorksheet.WriteDateTime(ARow,ACol,lDateTime);
+      Exit;
+    end;
   end;
-  end;}
 
   FWorksheet.WriteNumber(ARow,ACol,Number);
 end;
@@ -1963,9 +1968,9 @@ begin
 end;
 
 class function TsSpreadBIFF8Reader.ConvertExcelDateToTDateTime(
-  const AExcelDateNum: Integer): TDateTime;
+  const AExcelDateNum: Double; ABaseDate: TDateTime): TDateTime;
 begin
-
+  Result := IncDay(ABaseDate, Round(AExcelDateNum));
 end;
 
 procedure TsSpreadBIFF8Reader.ReadFont(const AStream: TStream);

components/fpspreadsheet/xlscommon.pas

@@ -7,13 +7,14 @@ unit xlscommon;
 interface
 
 uses
-  Classes, SysUtils,
+  Classes, SysUtils, DateUtils,
   fpspreadsheet,
   fpsutils, lconvencoding;
 
 const
   { RECORD IDs which didn't change across versions 2-8 }
   INT_EXCEL_ID_CODEPAGE   = $0042;
+  INT_EXCEL_ID_DATEMODE   = $0022;
 
   { Formula constants TokenID values }
 
@@ -104,9 +105,12 @@ type
   TsSpreadBIFFReader = class(TsCustomSpreadReader)
   protected
     FCodepage: string;
+    FBaseDate: TDateTime;
+    constructor Create; override;
     // Here we can add reading of records which didn't change across BIFF2-8 versions
     // Workbook Globals records
     procedure ReadCodePage(AStream: TStream);
+    procedure ReadDateMode(AStream: TStream);
   end;
 
   { TsSpreadBIFFWriter }
@@ -130,6 +134,14 @@ implementation
 
 { TsSpreadBIFFReader }
 
+constructor TsSpreadBIFFReader.Create;
+begin
+  inherited Create;
+  // Initial base date in case it wont be informed
+  FBaseDate := DateUtils.EncodeDateDay(1900, 1);
+  FBaseDate := DateUtils.IncDay(FBaseDate, -1);
+end;
+
 // In BIFF 8 it seams to always use the UTF-16 codepage
 procedure TsSpreadBIFFReader.ReadCodePage(AStream: TStream);
 var
@@ -181,6 +193,30 @@ begin
   end;
 end;
 
+procedure TsSpreadBIFFReader.ReadDateMode(AStream: TStream);
+var
+  lBaseMode: Word;
+begin
+  //5.28 DATEMODE
+  //BIFF2 BIFF3 BIFF4 BIFF5 BIFF8
+  //0022H 0022H 0022H 0022H 0022H
+  //This record specifies the base date for displaying date values. All dates are stored as count of days past this base date. In
+  //BIFF2-BIFF4 this record is part of the Calculation Settings Block (➜4.3). In BIFF5-BIFF8 it is stored in the Workbook
+  //Globals Substream.
+  //Record DATEMODE, BIFF2-BIFF8:
+  //Offset Size Contents
+  //0 2 0 = Base date is 1899-Dec-31 (the cell value 1 represents 1900-Jan-01)
+  //    1 = Base date is 1904-Jan-01 (the cell value 1 represents 1904-Jan-02)
+  lBaseMode := WordLEtoN(AStream.ReadWord);
+  if lBaseMode = 0 then
+  begin
+    FBaseDate := DateUtils.EncodeDateDay(1900, 1);
+    FBaseDate := DateUtils.IncDay(FBaseDate, -1);
+  end
+  else
+    FBaseDate := DateUtils.EncodeDateDay(1904, 1);
+end;
+
 function TsSpreadBIFFWriter.FPSColorToEXCELPallete(AColor: TsColor): Word;
 begin
   case AColor of