Setting visible/invisible when menu item is contained/not contained

Question

Hello All,
I have a vertical rectangle (the containerButtonsRect) that contains menu items (text). The items slide up and down when using up and down keys. When the items go out the container I want to make them invisible. When they come back in the containerButtonsRect I want to make them visible. The following code does not work:
override public function create(): Node {
        for (i in [0..sizeof labelButtons - 1]) {
            def menuItem:MenuItem = MenuItem {
                        x: bind containerButtonsRect.x
                        y: bind (containerButtonsRect.y + (i+1)*ySpacing + i*maxButtonHeight)
                        width: bind containerButtonsRect.width
                        height: bind maxButtonHeight
                        content: labelButtons[i]
                        translateY: bind tracker*deltaY
                        visible: bind ((menuItem.y + translateY > containerButtonsRect.y) and ((menuItem.y + translateY + maxButtonHeight) < (containerButtonsRect.y + containerButtonsRect.height)))
            insert menuItem into menuItems;
            if (i == focusedIndexItem) {
                menuItems[focusedIndexItem].selected = true;
            updateMaxSize(menuItem);
        return Group {
            content: bind [
                containerButtonsRect,
                selectionRect,
                menuItems
    }It is strange that the following line:
visible: bind ((menuItem.y + translateY > containerButtonsRect.y) and ((menuItem.y + translateY + maxButtonHeight) < (containerButtonsRect.y + containerButtonsRect.height)))does not do the job.
Is there a better way to set the visible attribute based on the logic described above?
Thanks.
Edited by: sacchett88 on Jun 9, 2010 2:10 PM

Answer 1

Thank for the response.
The translateY is set to provide vertical motion. A time line is controlling the tracker variable. So when I move arrow up/down the items scroll up/down.
I agree JavaFX have way complicated the different variables you can set to position components and retrieve width and height. This cause a lot of problems hard to debug.
Interesting your ideas of setting the clip of the group. I am not to familiar with that attribute as well the description in the docs: http://java.sun.com/javafx/1.3/docs/api/javafx.scene/javafx.scene.Group.html is poor:
"Specifies a Node to use to define the the clipping shape for this Node."
Is there any example you could point me out to ?
Thanks.