Send HWND Over Network

Question

Is there an API to capture an HWND and send it over the network to another desktop application on a different PC?

We have a 3rd party program that will accept an HWND and stream video to that. We want to have that 3rd party program send the video to a different computer but the only parameter it accepts is an HWND.

Basically we want to do something like Zoom desktop capture but only a specific window. We are willing to write an app to relay the data over the network. Something like this:

The program running on PC2 is an existing MFC C++ app but the relay program on PC1 hasn't been created yet and can be C++, C# or whatever is needed.

Answer 1

No. An HWND is meaningful only on the machine that created it. There are several applications that can do window capture and stream it over a network. You could then use something like VLC to show it on PC2.

Answer 2

Generally the way to do it is either write your own display driver filter to log any change to display and send it to remote computer, or to add a GDI+ subsystem level filter to capture the GDI+ API commands and send it to remote computer to replay it (much like what WMF/EMF do, it let you replay the sequence of command you used to draw the image on another device context)