What's the best way of creation of thousands of controls in scrollable area using WPF

Question

Hi guys!

I'm using WPF and C#.

I have a problem. I need to create a lot of bindable templated controls in scrollable area (they are all of different types). For example 1000 textboxes, 1000 drop down lists, and 1000 checkboxes.

The problem is that when they are all created it works really slow.

The question is - whether it is possible to have so many controls simultaniously without lags and in what direction should I search for the solution? I'd like to save an ability to use Templates, Databinding and simple event handling like mouse clicking.

P.S. I tried lot's of things (rendering of geometry only, different base classes and so on) but currently the only approach that seems working for me (i haven't tried it yet) is to create only those controls that fit into the current viewport and update this list of controls on scrolling.

P.P.S I know that there is a mechanism in 3.5 SP1 that is used in ListBox when list items are reused during scrolling but such approach cannot be used here because all those items are of different types.

Thank's a lot.

Answer 1

First - I'd question the rationale in design of this type of requirement. Having thousands of controls in anything except a grid or list of some sort (where they are all constant, not changing, so the list-style approach would work fine) is going to be incredibly confusing to your user. You're basically forcing a non-obvious, changing interface with thousands of items at them.

That being said...

P.P.S I know that there is a mechanism in 3.5 SP1 that is used in ListBox when list items are reused during scrolling but such approach cannot be used here because all those items are of different types.

This actually is probably your best approach. This should work fine - although it won't be as simple as the list box mechanism. You can always pre-create the controls - just create enough of each type of control as required to fill the current container, and as you scroll, reassign the appropriate controls into the appropriate locations.

If you truly need thousands of controls, this will most likely be your best option.

Answer 2

The fact that you want ~3000 controls on a single screen is a problem and it is usually a sign that you are approaching you GUI from the wrong angle. I am not very experienced with WPF, but my WinForms knowledge tells me that 1000+ control instances is just asking for trouble. This is what ListBoxes, DataGrids, and other tabular/list format controls were designed for.

I gave a similar answer to a similar problem here: Super Slow C# Custom Control

Maybe if you explain what are you trying to do instead of what solution you are trying to implement someone here can push you in the right direction.