Re: Drawing on another processes window

"Alex Blekhman" <>
Fri, 10 Aug 2007 17:42:21 +0300
"Cartoper" wrote:

I am working on a COM Server (EXE) that is to provide a
live image to
it's client. The client provides a HWND to the COM Server
in which to
draw. Considering the live view needs to keep up with
window changes
in size and position, my first thought is to simply
subclass the HWND
that the COM server receieved. I was reminded that that
code must be in the same process as the owner of the HWND.

My thought, now, is to have the COM Server inject the
subclass code
into the target process and have the two sides simply send
the image
via shared memory. The questions are:

1: Is there an example out there I can look at that does
like this?
2: Is there a better way to do this?

I don't know what your needs are, but HWND is a systemwide
handle (desktop-wide, actually). Once you have it you can
draw on the window from any process because HWND's are
public to all processes. However, if you want to handle
WM_PAINT notification, then, yes, you need to subclass.


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