Determine if an element is visible in a scrollable Spark DataGrid

By digging in the Flex 4.5 API docs I’ve found a way to determine if a certain element (object) of the spark.components.DataGrid.dataProvider is visible in the viewport of the spark.components.Scroller wrapping the DataGrid.

The spark.components.Grid offers a method

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isCellVisible(rowIndex:int = -1, columnIndex:int = -1):Boolean

Since the spark.components.Grid represents the grid part of the spark.components.DataGrid, the method can be called as follows:

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dataGrid.grid.isCellVisible(rowIndex);.

You can call this method in an event listener to determine if a row (element) is visible in the scroller:

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dataGrid.scroller.verticalScrollBar.addEventListener(
    TrackBaseEvent.THUMB_RELEASE,updateIsItemVisible
);
 
private function updateIsItemVisible( e:Event):void
{
    var visible:Boolean = dataGrid.grid.isCellVisible( _itemIndex );
}