Drawing Layers

   
As with the previous versions of the IRM application, the new IRM also includes the concept of drawing layers.
 
However, there are substantial differences between the previous and the new layer systems, including the following:
  • In the new IRM, Architecture (Lines and Arcs) and Text Layers are combined, meaning a single layer can contain both architecture and text objects.
  • Layers for graphical Managed Objects (Equipment, Cables, Pathways, Maintenance Holes, Locations and Spaces) work very differently in the new IRM.
     
Basically, while a given object could be in multiple Layers, at the time when it is drawn only one of those Layers is actually used. The UI provides mechanisms to effectively choose which Layer is “active”, as explained later in the following subsections.
 
NOTE: Circuits and Software have no graphical representation in the Design World (i.e., they are not drawn in the Design World). They will be excluded from the present discussion.
 
The following is a brief description of different types of Layers, while the subtopics cover more specifics about the IRM Layer system.
 

Architecture / decorative Layers

In both the previous and new version of IRM, each decorative drawing object (Line, Arc, Text) is in exactly one layer at any moment in time, and there are a “fixed” set of layers in the sense that layers are only created or destroyed as a result of explicit user action to do so, such as clicking a New or Delete button in the Layer Manager, or during a Decorative Drawing Import operation.
 

Managed object Layers

In the new IRM the layer mechanism for Managed objects  it is possible for an object to be in more than one layer at once, and layers can be implicitly created and deleted by user actions that are not directly connected with the layer system. In all cases, whenever there exists a “layer” from the user’s perspective, there is always a corresponding Layer object in IRMN, which holds the layer data (color, line thickness, etc.). That means that when we say that a layer is implicitly created, an actual Layer object is created. Layers for Managed objects cannot be explicitly created or deleted by the user. Instead, they are created implicitly based on data associated with the Managed Objects.
  

Layer Varieties

This layering flexibility allows the implicit object layers to be set based upon different properties associated with the object, such as:
  • By Type
  • By Category
  • By Grouping
  • By Field Value
 
These implicitly created Layer objects are of four varieties:
  • Type Layers - A Layer object is stored in each Type object (Equipment Type, Cable Type, etc.). This variety does not apply to Categorized objects.
  • Category Layers - there is an implicit layer for each Category of Managed Objects. A Layer object is stored in each Category object.
  • Grouping Layers - there is an implicit layer for each Grouping object. A Layer object is stored in each Grouping object.
  • Field Value Layers - there is an implicit layer for each possible value of each specially designated (Layer Creator) field in Managed Objects. A set of Layer objects are stored in each Field object that uses a (non-semantic) Field Specification with the Layer Creator property. There is one Layer object per value of the field. To avoid potentially large numbers of Layer objects from being created, IRM has the restriction that the Layer Creator property can only be set only for List fields.
 

Active Layer Variety

Since a single object can be in a given Category, Type, Grouping, and have a specially designated Layer field, it can clearly be in at least four layers at once. In fact, an object can be in more than four layers, because it can be in multiple Groupings, have multiple specially designated Layer fields, and even have more than one Category. Although an object can be in multiple Layers at once, only one of the layers can be “active” at a given point in time, which is necessary so that the drawing engine knows how to draw that object.
 
The user chooses a separate active layer variety for each one of the applicable super categories (Equipment, Cable, Pathways, Maintenance Holes, Locations, Spaces). That is, each of the applicable Super Categories has its own active layer variety. Therefore, Equipment may have the Type layer variety set as active, whereas Pathways may simultaneously have a Grouping layer variety set.
 
Given that a single draw-able object is in only one of the six listed Super Categories, this cannot lead to a single object having more than one active layer variety.
 
The following text and screenshots explain each of the layer varieties in more detail.
 
NOTE: IRM auto-saves a full User View, including Super Category visibility, Layer Precedence, and enabled state(s). In case the auto-saved view somehow gets corrupted, there is a "Reset View" button in the View Manager dialog, which closes all active Areas in the Design World and resets the User View.
 

Layer Categories

Note that a Layer is a Categorized Object. However, it is important to differentiate 
  • Layer Categories, for example, Categories of architecture Layer objects and
  • the Category variety of Layers, which is a particular variety of Layers different from architecture Layers.
 
Additional important notes about Layer Categories:
  • A Layer Category is automatically created by the server during CAD file import and all Layers created during the import are added to that Category. The name of the layer includes the name of the CAD file and the date of the import.
  • A Layer Category can be manually created and deleted by the user in the usual way
  • The user can manually add architecture Layers to a Category, using the usual mechanism in the Category and Types Tree
  • As usual for other Categorized Objects, a Layer can be in more than one Category