DWSTRING

[Richard Kelly]

I have a normal FB STRING that has been loaded with the contents of a JPEG file. When I set a DWSTRING = FB STRING the resulting DWSTRING is only 4 bytes long. Some code below. I have verified that sFileContents does have the contents of the JPEG file.

Code Select Expand

DIM sImageStream       AS DWSTRING
DIM sFileContents      AS STRING

' Get File Size

    uImageAttributes.ImageSize = oCFileSys.GetFileSize(szImageFile)

' Get Raw Stream

   sFileContents = STRING(uImageAttributes.ImageSize, 0)
   hFile = CreateFileW(@szImageFile, GENERIC_READ, FILE_SHARE_READ, NULL, _
                       OPEN_EXISTING, FILE_FLAG_SEQUENTIAL_SCAN, NULL)
   ReadFile(hFile, STRPTR(sFileContents), uImageAttributes.ImageSize, @dwBytesRead, NULL)
   CloseHandle(hFile)

' Save Image for reference

    sImageStream = sFileContents


[José Roca]

Never use DWSTRING or any other null-terminated string (WSTRING, ZSTRING) to store binary data. For that, use STRING or a buffer of bytes.

It does not make any sense to convert the contents of a JPEG file to Unicode.

[Richard Kelly]

It was my over zealous use of DWSTRING. I switched over to STRING and now another interesting issue has come up.

When I take a STRING that is already populated and then add my string with the jpeg file contents that seems to work. Then when I add CRLF, I lose the jpeg file contents. I think I'm hitting a chr(0) that is messing things up.

[Richard Kelly]

Using memcpy instead of adding strings together solved the chr(0) issue.

Here is the updated SUB.

Code Select Expand

Private SUB cPDF.BuildObject(BYREF sObject as STRING, BYVAL sObjectPart AS STRING)

DIM sCRLF       AS STRING = CRLF
DIM nObjectSize AS LONG = LEN(sObjectPart)
DIM sNewObject  AS STRING

   If nObjectSize > 0 Then

      sNewObject = SPACE(LEN(sObject) + nObjectSize + LEN(sCRLF))

      If LEN(sObject) > 0 Then
         memcpy(STRPTR(sNewObject), STRPTR(sObject), LEN(sObject))
         memcpy(STRPTR(sNewObject) + LEN(sObject), STRPTR(sObjectPart), LEN(sObjectPart))
      Else
         memcpy(STRPTR(sNewObject), STRPTR(sObjectPart), LEN(sObjectPart))
      End If

      memcpy(STRPTR(sNewObject) + LEN(sNewObject) - LEN(sCRLF), STRPTR(sCRLF), LEN(sCRLF))

   End If

   sObject = sNewObject

End Sub