Adding support for a new data format to Lucy involves multiple concepts:
If workspace support is required, the add-on also needs to provide
ALcyWorkspaceObjectCodeccodecs to store and restore the models and layers.
In addition, an add-on can provide
ILcyCustomizerPanelFactoryfactories for customizing the models, domain objects and layers created by the model decoders and layer factories.
All these concepts are grouped in the support classes of the
com.luciad.lucy.format package. This package provides an abstract factory definition,
ALcyFormat, and wrappers to implement some common functionalities.
ALcyFormat class follows the Abstract Factory design pattern. It defines several factory methods for concepts that are required to add
support for a new data format. You must implement or override these methods with a sub-class.
See the Support custom data documentation for an example of an
You can pass the concrete factory implementation to
TLcyFormatTool, which adds all the concepts created by the factory to the Lucy back-end.
There are several specializations of
ALcyFormat that already provide some functionality that is commonly required:
ALcyGeneralFormat: this specialization adds workspace support for the models and domain objects of the format. For this support, it assumes that the source name of the model can be retrieved from the model descriptor of the models and that the model decoder always decodes the model elements in the same order. There are some additional assumptions that are documented in the reference documentation of
The Lucy framework provides some common format-related functionality in the form of
ALcyFormatWrapper wrappers. The availability of wrappers allows add-ons to re-use format-supporting functionality by wrapping their
ALcyFormat. For instance, the
TLcyAsynchronousFormatWrapper wrapper provides asynchronous painting functionality for the wrapped
The Lucy Fundamentals sample illustrates the usage and purpose of a few of those format wrappers.
Each of the wrappers in the following
ALcyFormatWrapper list makes certain assumptions that are documented in the reference documentation of their classes. Make sure to read the
reference documentation of those wrappers to verify that your format corresponds to these assumptions:
TLcySafeGuardFormatWrapper: this wrapper ensures that all layer factories, encoders, type providers, workspace codecs, customizer panel factories and so on, operate only on layers and models created by the wrapped format. This means that you don’t need these checks in the wrapped
ALcyFormat, resulting in less cluttered and more maintainable code in the wrapped format.
TLcyAsynchronousFormatWrapper: this wrapper wraps all the necessary factories and providers of the wrapped format to support asynchronous painting of the layers. By using this class, you allow the base format to focus on the regular appearance of the layer, leaving the asynchronous painting work to this wrapper. By using this wrapper, you also ensures that all layer-related concepts are properly wrapped, so that the customizer panels, workspace codecs, layer selection transfer handlers, and so on, all work in conjunction with the asynchronous painting functionality.
TLcyMutableFileFormatWrapper: this wrapper adds workspace support for saving mutable models, for example data that can be graphically edited by the end user.