如何由檔案內容判定為何種圖檔格式

[tim]

請參考:
http://www.lmc-mediaagentur.de/dpool/tips/1319.htm

How to determine the graphic format of a file

代碼: 選擇全部

     
    function PhysicalResolveFileType(AStream: TStream): Integer; 
    var 
      p: PChar; 
    begin 
      Result := 0; 
      if not Assigned(AStream) then 
        Exit; 
      GetMem(p, 10); 
      try 
        AStream.Position := 0; 
        AStream.Read(p[0], 10); 
        {bitmap format} 
        if (p[0] = #66) and (p[1] = #77) then 
          Result := 1; 
        {tiff format} 
        if ((p[0] = #73) and (p[1] = #73) and (p[2] = #42) and (p[3] = #0)) or 
            (( p[0] = #77) and (p[1] = #77) and (p[2] = #42) and ( p[3] = #0)) then 
          Result := 2; 
        {jpg format} 
        if (p[6] = #74) and (p[7] = #70) and (p[8] = #73) and (p[9] = #70) then 
          Result := 3; 
        {png format} 
        if (p[0] = #137) and (p[1] = #80) and (p[2] = #78) and (p[3] = #71) and 
            (p[4] = #13) and (p[5] = #10) and (p[6] = #26) and (p[7] = #10) then 
          Result := 4; 
        {dcx format} 
        if (p[0] = #177) and (p[1] = #104) and (p[2] = #222) and (p[3] = #58) then 
          Result := 5; 
        {pcx format} 
        if p[0] = #10 then 
          Result := 6; 
        {emf format} 
        if (p[0] = #215) and (p[1] = #205) and (p[2] = #198) and (p[3] = #154) then 
          Result := 7; 
        {emf format} 
        if (p[0] = #1) and (p[1] = #0) and (p[2] = #0) and (p[3] = #0) then 
          Result := 7; 
      finally 
        Freemem( p ); 
      end; 
    end;