Grouped nodes added to Vbox - Height issue? Bug?

Question

Maybe you guys could try this out as well? I'm most probably doing something wrong but for demonstrative purposes, I've found an issue with a VBox incorrectly stating its height value when it consists of grouped nodes.
Take the following for example, albeit simple and incomplete (it's more or less what I've got going on in my code):
     var goupedNodesSequence : Node[];
        for(i in [0..30]){
            //Label
            var myLabel : Label = Label{               
                textFill: Color.WHITE
                text: "Lable Number: {i}"
         //Rectangle
            var myRectangle : Rectangle = Rectangle{
                width: 100
                height: 25
                fill: Color.BLUE
         //Grouped label and rectangle
            var nodeGroup : Group = Group{
                content: [myLabel , myRectangle ]
            insert nodeGroup into goupedNodesSequence
            }//forloop
            //VBox
            def groupedNodesVBox : VBox = VBox {
                    content: goupedNodesSequence
                    spacing: 3       
            }My code is slightly different in that the construction of the groupedNodesSequence is done in a forloop within a function that returns the sequence. The sequence of nodes is then assigned to the VBox.content property.
I've noticed that visually, it looks correct in that each node, within the VBox, is a rectangle with a label on top of it. This is fine. But when you want to know the height property of the VBox node, it seems to be overstated in that it appears to add the height of all nodes including spacing (approximately anyway) to the total height of the VBox.
I've even tried to use the Stack feature to place the nodes in a stack formation and messed around with the X/Y translations and layout features but a no go.
I wonder if this has anything to do with the "bug" some people (PhiLHo ?) have encountered with using VBoxes and Scrollbars and getting incorrect Scroller max values possibly due to this incorrect height reading of the VBox? Check out PhiLHo's response to this thread to know what I'm talking about over here
I simply compensated the incorrect height difference in my code as it was more efficient for me, but I thought I'd bring this up for discussion and see if anyone else is having the same issue.
Essentially, put a few nodes together and group them, then add the group node to another sequence, and place that sequence of grouped nodes into a VBox. See what kind of height you're getting for the VBox.

Answer 1

For me, the VBox height comes out to 865, which I think is correct. You have 31 groups in the VBox, and each group has a rect that's 25 tall. Add to this the 30 inter-item spacings of 3 gives: 31 x 25 + 30 x 3 = 865. [Edited to avoid confusion between the arithmetic expression and forum markup.]
But if you look at the heights of each of the nodes, it's something of a puzzle. The height of each Label is 14, the height of each rect is 25, and the height of each nodeGroup (each contains a label and a rect) is 36. Huh??? How can this be if the label overlaps the rect? (I puzzled over this for a bit as well.)
At issue is how you're finding the height of each item. If you use boundsInLocal or boundsInParent, you get the heights I listed above. If you look at the actual boundsInParent of each label and rect, though, you'll notice something odd: the boundsInParent of Label are something like:
BoundingBox [minX = -1.0, minY=-11.0, maxX=97.0, maxY=3.0, width=98.0, height=14.0]
So the bounds of the Label are mostly above the origin, and the bounds of the Rectangle extends below the origin. That's why, when you throw them into a Group, the height of the Group is almost the sum of the two heights, even though visually the Label and the Rectangle overlap.
You might ask why the bounds of the Label extend above the actual label text. Well, that might be a bug. I'll investigate it. If you look at the layoutBounds of a Label, it makes more sense.
Meanwhile, a great explanation of the various JavaFX bounds can be found on [Amy Fowler's blog|http://weblogs.java.net/blog/2009/07/09/javafx12-understanding-bounds].
Edited by: smarks on Jan 5, 2010 3:31 PM