Question

We’ve implemented our main code functionality in a C++ Dll then written a C# UI on top. This works fine most of the time, but in areas where we want the UI to report the progress of a function in C++ we’re having some performance problems.

We pass a pointer to a C# function down to the Dll to use for progress updates. When it’s called we use InvokeRequired and Invoke() to make sure the callback is thread-safe. Measured from the C++ side, this can take anything between 16ms and 180ms. Is there any way of reducing the time this takes?

One of these callbacks passes the location of a line to be drawn on the screen. This drawing currently very slow – I assume the invoked functions are queuing up and taking time to be drawn in C#. I can see two ways of dealing with this:
1. Change the callback to send a list of lines and allow the lines to queue up in C++ whilst waiting for the previous call to C# to complete.
2. Adding the lines to a queue in C# (preferably without calling Invoke) then drawing all lines that are available at once.
Any suggestions on how to do this, whether both options are required, or alternative methods?

Thanks for any and all help.

Answer 1

You can use BeginInvoke instead of Invoke. Invoke waits for the function to return, while BeginInvoke allows the function to run parallel to the current thread.