AdvancedDataGrid: how to tell how many rows are currently visible?

Question

Does anyone know how to query an ADG (or its rows) to figure out how many rows are currently visible (i.e. not collapsed) when displaying different levels of a hierarchical collection?

In other words I'd like a function that tells me that 7 lines are visible in this view enter image description here

and 1 line is available in this one enter image description here

I assume this is simple but can't seem to find the right keyword anywhere.

thank you!

To be more accurate, it's really the number of leaves that are expanded at any time. Visible is confusing in the sense that a leaf could be expanded but not currently on the screen because it's way down on a long list displayed on a short ADG). In other words, counting ItemRenderers currently being used on the ADG doesn't do the trick if the list is too long. — fred august, Mar 08 '11 at 21:47

score 2 · Answer 1 · answered Mar 08 '11 at 22:38

You'll need to write a recursive function to iterate through your data and make use of the AdvancedDataGrid's isItemOpen(item:Object):Boolean function. Something like this:

countOpenItems(root : Object) : int {
 var openCount : int = 0;
 if (grid.isItemOpen(item)) {
  openCount++;
  for each (var child : Object in item.children) {
   openCount += countOpenItems(child);
  }
 }
 return openCount;
}

This example assumes each of your items has a property called children that can be iterated over.

note: This will return only the number of open items -- even in your second example this function will return 0. If you want to include open roots you'll have to account for them separately.

thank you Sean. I implemented something at the same time, then found your answer which would have been of great help (isItemOpen is what I was looking for and calls openNodes, which is what I found in my search). I ended up posting my own answer as it seems to count things properly, but appreciate the help & upvoted you. — fred august, Mar 09 '11 at 00:07

fred august · Accepted Answer · 2011-03-09T00:13:23.230

the openNodes property in view:IHierarchicalCollectionView seems to be what I was looking for. Passing the root node to this seems to do the trick. I'm sure there's a more elegant way to write this ;-)

function recurse(o:Object):uint
{
    // grab the general list, for commodity
    var view:IHierarchicalCollectionView = adg.dataProvider as IHierarchicalCollectionView;

    // I count as 1 if we're recursing through me
    var total:uint = 1;

    // check if I'm open
    for each (var e:Object in view.openNodes)
    {
        if (e == o)
        {
            // if so I need to add my children and their families
            for each (var c:Object in o.children)
                total += recurse(c);
        }
    }
    // if not I'm done, just counting myself

    return total
}

Note: one thing I thought was interesting is that openNodes returns the list of open nodes, even if they are not visible like in the case of such nodes living inside a closed node.

AdvancedDataGrid: how to tell how many rows are currently visible?

2 Answers2