Disclaimer: this page is a work in progress describing about the Layers mechanism for Papyrus.
The Layers mechanism allows to build different views of an underlying UML diagrams by applying selections rules as well as graphical transformation operators. A view is the result of the rendering of a layer-stack that is composed of several layers of operations. Each layer can be associated to visual properties (color, font, isVisible ...). In this case, this properties are applied to the visual elements. This allows for example to color all the visual elements of a layer in a particular color, or to hide them.
Examples of possible usages of layers:
- Hide / show / highlight particular elements of an UML diagram. Associate such elements with a layer, and then set a particular color, font, or hide the elements. Here again, a layer with a query can select the element dynamically for you. You can then hide/show all this elements with a single click.
- Multi users review of a diagram. Each reviewers add its comments in its dedicated layer. Then, it is possible to hide and show all comments of a user, user by user. It is also possible to use a layer with a query to select dynamically particular comments.
- Zoom on a diagram details. Each layer show details of the elements in the layer on top of it. Thus, it is possible to select (zooming) the level of details in the diagram.
There is different kind of layers. In the basic one, the user add the visual elements and attach the required visual properties. A more sophisticated one allows the user to specify a query that automatically select the visual elements. This allows, as example, to attach all the uml::Classes whom name start with a particular letter, or uml::Classes that are abstract. So it is possible to color in red all abstract uml::Classes. We also provide a layer which is made of ... layers ! This later one is used to build complex expression of layers.
A simple example
Attaching a stack of Layers to a Diagram
To be able to use the layers, you first need to attach a Layers Stack to your diagram. First select your diagram, then in the contextual menu select Layer->Attach to Diagram.
Layers are available by installing the extra components of Papyrus modeler.