I have a node with two ports: one to right and one to bottom. At the bottom port I have a TreeExpanderButton. This is expanding and collapsing sub trees coming out of both bottom and Right ports. How do I restrict this functionality to either one?
You’ll probably need to create a custom button that only expands/collapses from the bottom port. The default behavior is to call CommandHandler.collapseTree/CommandHandler.expandTree.
Here’s the implementation of the TreeExpanderButton, which you can probably customize to suit your use case:
go.GraphObject.defineBuilder('TreeExpanderButton', function (args) {
var button = /** @type {Panel} */ (
go.GraphObject.make('Button',
{ // set these values for the isTreeExpanded binding conversion
'_treeExpandedFigure': 'MinusLine',
'_treeCollapsedFigure': 'PlusLine'
},
go.GraphObject.make(go.Shape, // the icon
{
name: 'ButtonIcon',
figure: 'MinusLine', // default value for isTreeExpanded is true
stroke: '#424242',
strokeWidth: 2,
desiredSize: new go.Size(8, 8)
},
// bind the Shape.figure to the Node.isTreeExpanded value using this converter:
new go.Binding('figure', 'isTreeExpanded',
function (exp, shape) {
var but = shape.panel;
return exp ? but['_treeExpandedFigure'] : but['_treeCollapsedFigure'];
}
).ofObject()
),
// assume initially not visible because there are no links coming out
{ visible: false },
// bind the button visibility to whether it's not a leaf node
new go.Binding('visible', 'isTreeLeaf',
function (leaf) { return !leaf; }
).ofObject()
)
);
// tree expand/collapse behavior
button.click = function (e, btn) {
var node = btn.part;
if (node instanceof go.Adornment) node = node.adornedPart;
if (!(node instanceof go.Node)) return;
var diagram = node.diagram;
if (diagram === null) return;
var cmd = diagram.commandHandler;
if (node.isTreeExpanded) {
if (!cmd.canCollapseTree(node)) return;
} else {
if (!cmd.canExpandTree(node)) return;
}
e.handled = true;
if (node.isTreeExpanded) {
cmd.collapseTree(node);
} else {
cmd.expandTree(node);
}
};
return button;
});
Thanks Walter. Exactly what I was looking for.