Convert HGlobal into a Stream

[Cartoper]

I have an image stored in a HGlobal and would like to load it into a
System::Image via the System::Image::FromStream(). How do I convert
the HGlobal into a stream?

[Michael Phillips, Jr.]

>I have an image stored in a HGlobal and would like to load it into a

System::Image via the System::Image::FromStream(). How do I convert
the HGlobal into a stream?

CreateStreamOnHGlobal

See MSDN:
http://msdn2.microsoft.com/en-us/library/aa378980.aspx

"Cartoper" <ca******@gmail.comwrote in message
news:8c**********************************@d27g2000 prf.googlegroups.com...

>I have an image stored in a HGlobal and would like to load it into a
System::Image via the System::Image::FromStream(). How do I convert
the HGlobal into a stream?

[Cartoper]

On Dec 11, 2:41 pm, "Michael Phillips, Jr."
<[e-mail]0.c0mwrote:

I have an image stored in a HGlobal and would like to load it into a
System::Image via the System::Image::FromStream(). How do I convert
the HGlobal into a stream?

CreateStreamOnHGlobal

Ok, how do I convert the 'IStream *' to 'System::IO::Stream __gc *' so
I can use it in the .Net world?

[Michael Phillips, Jr.]

Ok, how do I convert the 'IStream *' to 'System::IO::Stream __gc *' so

I can use it in the .Net world?

You can't convert the unmanaged COM IStream to a managed System:IO::Stream.

If you want a Net solution use a MemoryStream.

Marshal the unmanaged memory represented by your HGlobal to a managed buffer
of type byte.
Create a MemoryStream object from this buffer and pass the MemoryStream
object to Image::FromStream.
"Cartoper" <ca******@gmail.comwrote in message
news:a5**********************************@y5g2000h sf.googlegroups.com...

On Dec 11, 2:41 pm, "Michael Phillips, Jr."
<[e-mail]0.c0mwrote:

>I have an image stored in a HGlobal and would like to load it into a
System::Image via the System::Image::FromStream(). How do I convert
the HGlobal into a stream?

CreateStreamOnHGlobal

Ok, how do I convert the 'IStream *' to 'System::IO::Stream __gc *' so
I can use it in the .Net world?

[Carl Daniel [VC++ MVP]]

Michael Phillips, Jr. wrote:

>Ok, how do I convert the 'IStream *' to 'System::IO::Stream __gc *'
so I can use it in the .Net world?

You can't convert the unmanaged COM IStream to a managed
System:IO::Stream.
If you want a Net solution use a MemoryStream.

Marshal the unmanaged memory represented by your HGlobal to a managed
buffer of type byte.
Create a MemoryStream object from this buffer and pass the
MemoryStream object to Image::FromStream.

Or if copying the memory backed by the HGLOBAL is unacceptable, write your
own implementation of System::IO::Stream that reads (and writes?) the
memory. It's not a lot of code to write.

-cd

[Mattias Sjögren]

>Or if copying the memory backed by the HGLOBAL is unacceptable, write your

>own implementation of System::IO::Stream that reads (and writes?) the
memory. It's not a lot of code to write.

Or just use the UnmanagedMemoryStream class (assuming .NET 2.0 or
later).
Mattias

--
Mattias Sjögren [C# MVP] mattias @ mvps.org
http://www.msjogren.net/dotnet/ | http://www.dotnetinterop.com
Please reply only to the newsgroup.

[Carl Daniel [VC++ MVP]]

Mattias Sjögren wrote:

>Or if copying the memory backed by the HGLOBAL is unacceptable,
write your own implementation of System::IO::Stream that reads (and
writes?) the memory. It's not a lot of code to write.

Or just use the UnmanagedMemoryStream class (assuming .NET 2.0 or
later).

Even better! (I knew it was in there somewhere - just couldn't remember the
name!)

-cd

[Cartoper]

On Dec 13, 12:26 am, "Carl Daniel [VC++ MVP]"
<[e-mail] ote:

Mattias Sjögren wrote:

Or just use the UnmanagedMemoryStream class (assuming .NET 2.0 or
later).

Even better! (I knew it was in there somewhere - just couldn't remember the
name!)

But I am using .Net 1.1 :(

[Michael Phillips, Jr.]

But I am using .Net 1.1 :(

The MemoryStream class is available with Net 1.1 to Net 3.5.

Marshaling the unmanaged HGlobal memory to a managed byte array is not
difficult.

"Cartoper" <ca******@gmail.comwrote in message
news:cb**********************************@a35g2000 prf.googlegroups.com...
On Dec 13, 12:26 am, "Carl Daniel [VC++ MVP]"
<[e-mail] ote:

Mattias Sjögren wrote:

Or just use the UnmanagedMemoryStream class (assuming .NET 2.0 or
later).

Even better! (I knew it was in there somewhere - just couldn't remember
the
name!)

But I am using .Net 1.1 :(