Pitney Bowes MapXtreme - Manual (Page 61)

Chapter 3: Mapping Concepts
Mapping and MapXtreme
MapXtreme v7.1 61 Developer Guide
Layers
Maps are made up of layers. Layers contain map features, such as postal code boundaries, schools,
or streets networks. It is important to understand the order of the layers. The bottommost layer is
drawn first and the topmost layer drawn last. Layers containing features that would obscure the
features of other layers should be placed lower, respectively. For example, a layer of boundary
regions should be placed beneath a layer of points.
Layers in MapXtreme can represent more than features. Layers can be raster or grid images,
seamless maps (joined maps), contain labels or user-drawn features, or contain an object theme,
such as a pie theme. Layers can be grouped for easier positioning and to facilitate animation of their
features. The main interface is IMapLayer. For more information see
Layers .
Features
Features are described by their geometry, style, data source, key and attributes. Typically a feature
is a row in a table. Supported geometries include closed objects that cover a given area (Polygons,
MultiPolygons, Rings, Rectangle, RoundedRectangles, and Ellipses); point objects that represent
single locations of data (Points, MultiPoints); and line objects that cover a given distance (Curves,
MultiCurves and LegacyArcs).
One of the main uses of computerized maps is to gather information about the features. In
MapXtreme features are returned in FeatureCollections by any of several methods, either created
from scratch using a schema, selected using selection tools or methods or by searching the Catalog
for those that meet a specific set of criteria.
Feature classes are located in the MapInfo.Data namespace.
Labels and Legends
Maps without elements to describe what is displayed are not very useful. Maps need text such as
labels and legends. Labels have been mentioned above as belonging to a type of layer called a
LabelLayer. This allows you to control every aspect of a label’s visibility, position, style, and content.
MapXtreme classes for working with labels include LabelSource, LabelProperties, and
LabelModifiers. See
Introduction to the MapInfo.Mapping Namespace .