Type: Tips & Tricks

yFiles HierarchicLayouter provides no default means for specifying the alignment of nodes within a common layer but always places them in the center of the layer.
However the layout algorithm has been implemented in a modular fashion and different stages of the layout can be customized completely.
In order to modify the node alignment the drawer stage can be wrapped with a custom implementation.
Copy the attached java source file to your application, compile it and use the following lines of code to reconfigure HierarchicLayouter to work with the customization class:

// wrap the default drawer implemenation hierarchicLayouter.setDrawer( new AlignmentDrawer(hierarchicLayouter.getDrawer()));

The provided implementation provides different default alignment modes. For a top-level alignment (in LayoutOrientation.TOP_TO_BOTTOM style) you can use the following code to configure the customization:

//register a DataProvider, providing alignment data for each node graph.addDataProvider( AlignmentDrawer.NODE_ALIGNMENT_POINT_DPKEY, new AlignmentDrawer.TopAlignmentDataProvider());

Warning

These DataProvider implementations will only work properly if the layout is performed in buffered mode.

Note

Note that IncrementalHierarchicLayouter included in yFiles 2.3 offers this functionality by default. The behavior can be controlled for each node separately using the NodeLayoutDescriptor.setLayerAlignment(double) method.