Hierarchic Layout with Edge Labeling
This demo shows how to configure the Hierarchic Layout
for automatic edge label placement.
Configuring label placement
Label models and their
parameters determine the position of a label. For
many interactive use cases, it makes sense to choose a model that restricts the available
positions in some way. However, for automatic label placement the opposite is true: Models
that do not impose restrictions on a label's position work best. Thus
FreeEdgeLabelModel and SmartEdgeLabelModel
are good choices for integrated label placement.
PreferredPlacementDescriptors may be associated with labels to control
automatic placement. Such a descriptor determines if the algorithm will place a label
close to its owner edge's source or target node, next to or on the edge, or even rotate
The demo configures several descriptors for placing each label in a way that matches its
text - with two notable exceptions: For the labels Upside down and
Upwards , the actual rotation does not match the implied rotation. This is
because, by default, Hierarchic Layout's labeling
algorithm ensures that a rotated label's up vector does not point downwards. Uncommenting
the corresponding line in the demo's source code will turn this feature off and enable
upside down labels.
You can copy the code snippet to configure the layout from
See the Edge Label Placement Demo for a more elaborate example regarding
automatic edge label placement.
The Labeling and
Automatic Label Placement sections in the Developer's
Guide contain in-depth discussions of the relevant concepts.
See the PreferredPlacementDescriptor API documentation for detailed
information on all available placement options.