AWARE SYSTEMS
TIFF and LibTiff Mail List Archive

Thread

1999.12.17 11:29 "TIFF previews in EPS files", by Flemming Bengtsson
1999.12.17 14:55 "Re: TIFF previews in EPS files", by Bjorn Brox
1999.12.17 15:54 "RE: TIFF previews in EPS files", by Dean Grimm

1999.12.17 15:54 "RE: TIFF previews in EPS files", by Dean Grimm

Hi Flemming,

I use the following C++ code on Windows:

#define EPS_BUFFER_LEN                  8192
#define EPS_THUMBTYPE_ERROR         -2
#define EPS_THUMBTYPE_NONE            -1
#define EPS_THUMBTYPE_TIFF            0
#define EPS_THUMBTYPE_META             1
const BYTE EPS_HDR_MAGIC_PS_ASCII[] = "%!";
const BYTE EPS_HDR_MAGIC_PS_WIN[] = {0xc5,0xd0,0xd3,0xc6};
typedef struct tagEPSHEADER {
     BYTE magic[4];
  DWORD offPS;
    DWORD lenPS;
    DWORD offMeta;
  DWORD lenMeta;
  DWORD offTiff;
  DWORD lenTiff;
  WORD checksum;
}EPSHEADER;

int ExtractEPSThumbnail(LPCTSTR pszEPSPath, LPCTSTR pszOutPath)
{
       int result = EPS_THUMBTYPE_NONE;
        HANDLE hf;

      // open the EPS file
    if ((hf=FOPEN(pszEPSPath)) != INVALID_HANDLE_VALUE)
     {
               EPSHEADER hdr;
          DWORD dwRead, dwOffset=0, dwLength=0;

           // read the header
              if (!ReadFile(hf, &hdr, sizeof(EPSHEADER), &dwRead, NULL)
                       || dwRead != sizeof(EPSHEADER))
         {
                       CloseHandle(hf);
                        return EPS_THUMBTYPE_NONE;
              }

               // check the type
               if (hdr.magic[0] == EPS_HDR_MAGIC_PS_ASCII[0]
                   && hdr.magic[1] == EPS_HDR_MAGIC_PS_ASCII[1])
           {
                       result = EPS_THUMBTYPE_NONE;
            }
               else if (hdr.magic[0] == EPS_HDR_MAGIC_PS_WIN[0]
                        && hdr.magic[1] == EPS_HDR_MAGIC_PS_WIN[1]
                      && hdr.magic[2] == EPS_HDR_MAGIC_PS_WIN[2]
                      && hdr.magic[3] == EPS_HDR_MAGIC_PS_WIN[3])
             {
                       // thumbnail is TIFF
                    if (hdr.lenTiff>0)
                      {
                               result = EPS_THUMBTYPE_TIFF;
                            dwOffset = hdr.offTiff;
                         dwLength = hdr.lenTiff;
                 }
                       // thumbnail is metafile
                        else if (hdr.lenMeta>0)
                 {
                               result = EPS_THUMBTYPE_META;
                            dwOffset = hdr.offMeta;
                         dwLength = hdr.lenMeta;
                 }
                       else
                            result = EPS_THUMBTYPE_NONE;

                    // extract the file
                     if (dwLength > 0)
                       {
                               HANDLE hfOut;
                           DWORD dwOut = 0, dwSize, dwWrite;
                               
                                // open the EPS file
                            if ((hfOut=FOPEN(pszOutPath, GENERIC_WRITE, CREATE_ALWAYS)) != INVALID_HANDLE_VALUE)
                            {
                                       char buf[EPS_BUFFER_LEN];

                                       // seek to the thumbnail offset
                                 if (SetFilePointer(hf, dwOffset, NULL, FILE_BEGIN) != 0xFFFFFFFF)
                                       {
                                               while (dwOut < dwLength)
                                                {
                                                       // read, at most, bufferlen bytes from input file
                                                       dwSize = min(EPS_BUFFER_LEN, dwLength-dwOut);
                                                   if (!ReadFile(hf, buf, dwSize, &dwRead, NULL)
                                                           || dwRead != dwSize)
                                                    {
                                                               result = EPS_THUMBTYPE_ERROR;
                                                           break;
                                                  }

                                                       // write bytes to output file
                                                   if (!WriteFile(hfOut, buf, dwRead, &dwWrite, NULL)
                                                              || dwWrite != dwRead)
                                                   {
                                                               result = EPS_THUMBTYPE_ERROR;
                                                           break;
                                                  }
                                                       dwOut += dwSize;
                                                }
                                       }
                                       else
                                            result = EPS_THUMBTYPE_ERROR;

                                   CloseHandle(hfOut);
                             }
                       }
               }

               CloseHandle(hf);
        }

       return result;
}