I have an application that generates a replay of Air Traffic and I need to allow the user to capture parts of the canvas so it can be exported as a BMP of GIF. I did this in VB6, but not sure how to do it in WPF. I plan on drawing a rectangle around the intended capture area following the mouse till the user triggers the capture.
You might also check out the RenderTargetBitmap class to copy the selected region.
Hope this helps.