Hi,
How I can a return "array of byte" from a COM object and put in a Stream? I use a OleVariant variable to get the return. But I can not convert in a string (the return is a XML).
Marcos Douglas
Mailing lists / fpc-pascal / 2011-06
Array of byte from a COM object
6 messages · 2 people · –
- Marcos Douglas 4
- Ludo Brands 2
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Marcos Douglas wrote 5 lines
Hi,
How I can a return "array of byte" from a COM object and put in a Stream?
I use a OleVariant variable to get the return. But I can not convert
in a string (the return is a XML).
I did using this function:
procedure VariantToStream(const V: OleVariant; const Stream: TStream);
var
P: Pointer;
L: Integer;
begin
Assert(VarType(V) = varByte or varArray);
Assert(VarArrayDimCount(V) = 1);
L := VarArrayHighBound(V, 1) - VarArrayLowBound(V, 1) + 1;
Stream.Size := L;
Stream.Position := 0;
P := VarArrayLock(V);
try
Stream.Write(P^, Stream.Size);
finally
VarArrayUnlock(V);
end;
end;Marcos Douglas
If the Assert(VarType(V) = varByte or varArray); is not raising an error then you are not getting a Safearray. VarArrayLock is for safearrays. If you are getting an array of byte, you should be able to access the bytes as V[i].
Do you have the interface definition for the method returning the "array of byte"?
Ludo
Show quoted text 45 lines
-----Message d'origine-----
De :
De la part
de Marcos Douglas
Envoyé : jeudi 9 juin 2011 17:21
À : FPC-Pascal users discussions
Objet : [fpc-pascal] Re: Array of byte from a COM object
On Thu, Jun 9, 2011 at 11:26 AM, Marcos Douglas
wrote:
>
> Hi,
> How I can a return "array of byte" from a COM object and put in a
> Stream? I use a OleVariant variable to get the return. But
I can not
> convert in a string (the return is a XML).
I did using this function:
procedure VariantToStream(const V: OleVariant; const Stream:
TStream); var
P: Pointer;
L: Integer;
begin
Assert(VarType(V) = varByte or varArray);
Assert(VarArrayDimCount(V) = 1);
L := VarArrayHighBound(V, 1) - VarArrayLowBound(V, 1) + 1;
Stream.Size := L;
Stream.Position := 0;
P := VarArrayLock(V);
try
Stream.Write(P^, Stream.Size);
finally
VarArrayUnlock(V);
end;
end;
Marcos Douglas
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Ludo Brands wrote 5 lines
If the Assert(VarType(V) = varByte or varArray); is not raising an error
then you are not getting a Safearray. VarArrayLock is for safearrays. If you
are getting an array of byte, you should be able to access the bytes as
V[i].
Yes, an array of bytes. I can use V[i].
Do you have the interface definition for the method returning the "array of byte"?
No. This method belongs a COM object. I don't have the definition, just know that is a array of byte.
Marcos Douglas
No. This method belongs a COM object. I don't have the definition, just know that is a array of byte.
Use OleView to get the IDL. It is part of MS platform SDK or can be downloaded separately from MS. Talking to COM objects without having the IDL is, well, "adventuruous".
Ludo
Ludo Brands wrote 8 lines
> No. This method belongs a COM object. I don't have the
> definition, just know that is a array of byte.
Use OleView to get the IDL. It is part of MS platform SDK or can be
downloaded separately from MS. Talking to COM objects without having the IDL
is, well, "adventuruous".
I didn't know about OleView (I will search for that, thanks). Well, the code is working perfectly.
Marcos Douglas