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I need to change Visibility of all items in listbox in code based on changing some filters. I tried to loop the items using

    myListbox.ContainerFromIndex(i)

but only first a few didn't return null. The answer why I quickly found here:

Why ItemContainerGenerator.ContainerFromIndex() returns null and how to avoid this behavior?

Turning off virtualization doesn't look like respectable solution to me, also I don't feel well about scrolling every item to view before calling ContainerFromIndex, even if it could probably work.

I'm not very clever from the rest of topics dealing with bindings and dependency properties etc, maybe also because majority of them are written in xaml and not in code. But I'm pretty sure the answer should be there. I'm very new to c# and I didn't find any clear-cut solution to such a basic problem.

I will prepare something like this array of Visibilities

    Visibility[] visibilities=new Visibility[100]
    ...

and I want myListBox with 100 items to use these values. Either automatically with some c# magic or in a cycle as I used to do in Win32.

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hoacin
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  • So you want to 'filter' out some values from the collection that is in the ListBox? If so, why don't you filter the collection and rebind it to the listbox? – Depechie Mar 07 '16 at 21:51
  • I want to change (Visibility) property in code of all listboxitems based on values in local array. I have no binding to Visibility property of list box items at the moment, all items are visible. I don't know how to access single items of the (collection?), as ContainerFromIndex doesn't work well. – hoacin Mar 07 '16 at 22:31

1 Answers1

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Based on the comment of Depechie, I made a research targeted on collections and created a functional code. Here is what I did:

Instead of adding items directly to listbox by

  lbGames.Items.Add(...)

I created two collections:

    List<object> gameList=new List<object>();
    ObservableCollection<object> filteredGameList = new ObservableCollection<object>();

Adding items this way:

    gameList.Add(...); or filteredGameList.Add(...)

While gameList is holding all items (stack panels), filteredGameList is holding only those I want visible. I had some problems with using only one big collection using its Visibility property, maybe my mistake, maybe not.

Withouth ObservableCollection I wasn't able to redraw listbox, that was problem with another List<> holding filtered data. When I filter data, I first clear filteredGameList and then I add all items I want visible, never changing Visibility property. ObservableCollection always tells listbox when items change.

On the application init, I attach listbox to this filteredGamesList.

    lbGames.ItemsSource = filteredGameList;

Now everything works fine.

hoacin
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