Delphi COM Passing ByteArray as OleVariant - c++

Question

I'm interfacing fingerprint reader via COM and i need help converting VB.NET and C++ Code to Delphi.
The API takes olevariant as parameter:
Function FingerPrint.GetData(var ImageData : OleVariant) : WordBool;
VB.NET example provided:
Dim imgData() as Byte
ReDim imgData(fingerPrint.ImageSize) as Byte
If fingerPrint.GetData(imgData) = True Then
'Success
End If
C++ example provided:
BYTE* dataBuff = new BYTE[fingerPrint.ImageSize];
VARIANT imgData;
imgData.vt = VT_BYREF|VT_UI1;
imgData.pbVal = dataBuff;
if(fingerPrint.getData(imgData) == TRUE) {
//Success
}
Here's my Delphi Code:
procedure GetImgData();
var varBuffer : OleVariant;
imgBuff : PByteArray;
begin
GetMem(imgBuff, fingerPrint.ImageSize);
try
tagVariant(varBuffer).vt := VT_UI1 or VT_BYREF; // 0x4011
tagVariant(varBuffer).pbVal := Pointer(imgBuff);
if fingerPrint.getData(varBuffer) then
begin
// success
end;
finally
FreeMem(imgBuff);
end;
end;
another approach:
procedure GetImgData();
var varBuffer : OleVariant;
tagV : TVariantArg;
imgBuff : PByteArray;
begin
GetMem(imgBuff, fingerPrint.ImageSize);
try
tagV.vt := VT_UI1 or VT_BYREF; // 0x4011
tagV.pbVal := Pointer(imgBuff);
varBuffer := OleVariant(tagV);
if fingerPrint.getData(varBuffer) then
begin
// success
end;
finally
FreeMem(imgBuff);
end;
end;
getData is not returning true using the parameter i'm sending. Sent my executable to support and told me that API is getting 0x400C (VT_VARIANT or VT_BYREF) instead of 0x4011.
Anything wrong with my Code?
Please Help!
UPDATE:
here's from dispinterface
function GetData(var ImageData: OleVariant): WordBool; dispid 23;
from Component Wrapper
..
function GetData(var ImageData : OleVariant): WordBool;
..
function TFingerPrint.GetData(var ImageData : OleVariant): WordBool;
begin
Result := DefaultInterface.GetData(ImageData);
end;
C++ declaration
BOOL getData(const VARIANT FAR& imgData)
UPDATE 20140313
Our supplier sent new OCX to handle data received from Delphi.

Answer 1

Are you sure it's 0x4011 and not 0x2011? Since varArray = $2000 and VarArrayCreate([0,size-1],varByte) would create an OleVariant with an array of varByte's like the VB code. If that works, use VarArrayLock and VarArrayUnlock to access the data.