Question

In a ListView, I want the selected items to be always visible (in the current field of view).

Example:
I have six items in my ListView. Only (the top) five are visible.
I select the first item. When I scroll down, this item is not visible anymore, but it remains selected.

I want to DEselect any item that goes out of the current view.

Answer 1

I solved it manually, so it’s more a workaround.
I just keep track of the index…

public class ScrollIndexManager
{
private readonly int _viewableItemsCount;
private int _canScrollUpCount;
private int _canScrollDownCount;

public ScrollIndexManager(int viewableItemsCount)
{
    _viewableItemsCount = viewableItemsCount;
}

public bool HasChanged { get; set; }

public int BottomVisibleItemIndex
{
    get { return TopVisibleItemIndex + _viewableItemsCount - 1; }
}

private int _topVisibleItemIndex = 0;
public int TopVisibleItemIndex
{
    get { return _topVisibleItemIndex; }
    set
    {
        if (value < 0)
        {
            HasChanged = false;
            return;
        }
        _topVisibleItemIndex = value;

        HasChanged = true;
    }
}

public void SetCanScrollDown(int totalItemCount)
{
    _canScrollDownCount = totalItemCount - _viewableItemsCount;
}

public bool CanScrollUp()
{
    return _canScrollUpCount > 0;
}

public bool CanScrollDown()
{
    return _canScrollDownCount > 0;
}

public bool Increase()
{
    TopVisibleItemIndex--;
    return HasChanged;
}

public bool Decrease()
{
    TopVisibleItemIndex++;
    return HasChanged;
}

public void ScrolledUp()
{
    _canScrollUpCount--;
    _canScrollDownCount++;
}

public void ScrolledDown()
{
    _canScrollUpCount++;
    _canScrollDownCount--;
}
}