Object tree visibility (EXPAND, COLLAPSE)

Object tree expansion and collapse operators provide control over the visibility of elements within a tree displayed on a form. As input to these operators, the object group to which the operation is applied is passed. It is also specified over which tree elements (each corresponding to a specific object collection in the mentioned group) the operation needs to be performed:

• current element
• specified set of elements
• all top-level elements of the specified object group

Possible operations include:

• expand or collapse an element
• expand or collapse an element and all its descendants
• expand all ancestors of an element

Language

To declare actions that implement the expansion and collapse operations of object tree elements, use the EXPAND and COLLAPSE operators.

Examples

FORM expandCollapseTest
    TREE elements e = NavigatorElement PARENT parent(e)
    PROPERTIES(e) READONLY BACKGROUND NOT e IS NavigatorFolder VALUE, canonicalName, caption
;

expandDown {
    EXPAND DOWN expandCollapseTest.e OBJECTS e = navigatorElementCanonicalName('System.administration');
}

expandAllTop {
    EXPAND ALL TOP expandCollapseTest.e;
}

collapseDown {
    COLLAPSE DOWN expandCollapseTest.e OBJECTS e = navigatorElementCanonicalName('System.administration');
}

EXTEND FORM expandCollapseTest
    PROPERTIES() expandDown, expandAllTop, collapseDown
;