Basic Layer Properties

A map contains one or more layers (AcMapLayer objects) that are rendered to create a composite image. The AcMapLayer class, which applies only to AutoCAD Map 3D, is derived from MgLayerBase, which is part of the common Geospatial Platform API shared between AutoCAD Map 3D and MapGuide.

Each layer has properties that determine how it displays in the map and map legend. Some of the properties are:

• Layer name: A unique identifier
• Visibility: whether the layer should be displayed in the map. Note that actual visibility is dependent on more than just the visibility setting for a layer. See Layer Visibility for further details.
• Selectable: Whether features in the layer are selectable. This only applies to layers containing feature data. It does not apply to layers containing raster data.

AcMapMap.GetLayers() returns an MgLayerCollection object that contains all the layers in the map. MgLayerCollection.GetItem() returns an individual MgLayerBase object, by either index number in the collection or layer name.

Layers in the collection are sorted by drawing order, with the top layers at the beginning of the collection.