Hi
I'm using the ScrollViewer to create a view port on a rather large canvas with many objects on it (it's part of a drawing application). I found that when using the ScrollViewer's scroll bars the performance on moving the view port horizontally / vertically is excellent and it works as expected.
However, I also want the user to be able to pan with the mouse, by clicking the canvas and drag the mouse. This functionality is implemented by capturing the MouseLeftButtonDown to start the panning and the MouseMove to actually move the view port. The view port offset then is moved by calling .ScrollToHorizontalOffset and .ScrollToVerticalOffset on the ScrollViewer.
This generally works fine. However, I found that when either the user moves the mouse really rapidly or if the rendering of the view port contents takes "longer than normally" (i.e. due to the amount of objects) at some point the .ScrollToHorizontalOffset
and .ScrollToVerticalOffset calls simply stop doing anything.
When this happens, also the ScrollChanged event no longer occurs (at least it's consistent).
It seems that there is some code somewhere in WPF, that stops accepting "ScrollTo" calls if the calls happen too frequently.
Is this know / expected behavior? Is there anything I can do to get around this behavior?
Thanks for any ideas
Oskar.
