In order to calculate label layouts on the server (either using integrated or generic labeling), some prerequisites have to be met:
- A label model has to be used that can be converted to
a corresponding yFiles Java label model on the server. For edge labels, the
SliderEdgeLabelModel
or
FreeEdgeLabelModel should be
chosen. For node labels, use InteriorLabelModel
or ExteriorLabelModel.
-
The label data has to be transfered between client and server.
When using a RoundtripHandler on the client,
this can be configured using the
updateOptions
and
sendOptions
properties. At least GraphCanvasComponent.OPTION_COPY_LABEL_STYLE
should be used in order to transfer the label data.
When using a custom GraphMLIOHandler, the
readLabels
and
writeLabels
properties allow to configure reading and writing of label data.
- On the server, class
GraphRoundtripSupport
has to be used for graph reading and writing. Also,
setMapLabelModels(boolean)
has to be set to true (the default). This guarantees that the I/O handler used by
the roundtrip support will be properly configured to map the client label models
to yFiles Java label models and vice versa when the graph is transferred back
to the client.
If label mapping is enabled, the label layout data calculated by the layout
algorithm will be committed to the label data objects when the graph is
written back to the client. If the label has to be accessed/changed before
the graph is written back, but after the layout, this can be triggered manually
using
copyLabelLayouts(y.layout.LayoutGraph).
Label instances can be added on the server using
addLabel(y.base.Node, com.yworks.yfiles.server.graphml.flexio.data.Label)
and
addLabel(y.base.Edge, com.yworks.yfiles.server.graphml.flexio.data.Label),
or by adding the Label instances manually to the list of labels returned by
getLabels(y.base.Node)
and
getLabels(y.base.Edge).
When a label is added on the server, the layout graph is not automatically updated.
This shouldn't be a problem, as long as no label layout is calculated before sending
the graph back to the client. In order to synchronize the list of labels with
the layout graph, methods
syncLabels(y.base.Node, boolean)
and
syncLabels(y.base.Edge, boolean)
can be used.
Note that a reasonable preferred size should be set on the new labels before calling the synchronize methods. The synchronize methods don't try to calculate the label's size. If no preferred size is set, a default size (40,40) is used. If no preferred size is set and the synchronize methods are not used, the correct preferred size will be calculated on the client when the new label is parsed.