Before working with maps, its important to understand how they work. This section introduces the following topics.
The building blocks of every map are map shapes. Shapes in maps are referred to in this way to distinguish them from regular shape objects (see Other Corda® Objects). Map shapes can be grouped together in different ways to create a map. These shape collections are then layered together to form complete maps. Hence, these building blocks are also known as map layers. Each layer has its own data and formatting settings.
Maps can contain as many layers as necessary to accomplish their purpose. The various layer type is discussed below:
The Area layer is the foundation of a map. It is typically a collection of map shapes that forms the map background. For example, a map of the U.S. states starts with a Area layer of 50 shapes, each representing a state. Area layer shapes seldom change form or shape themselves because the shapes are critical to the meaning of the map. However, shape color and other aspects can change depending on the value of its data.
The Point layer overlays the Area layer to provide more specific data values on a map. Because it does not typically provide actual map structure, Point layers are more flexible in representing data, including the ability to modify shape. The size, shape, and color of Point layer shapes can vary according to the data. For example, a Point layer might graph data for cities, or to indicate where certain events took place.
Note: Area and Point map shapes do not necessarily have to represent data values. They may be used for geographical reference only. For example, a map where the data applies only to the Area layer might still display a Point layer without associated data, in order to provide additional data context, and vice versa.
Alternatively, a Point layer can be overlaid on a Area layer composed of a bitmap image. For example, a topographical image of the United States serves as the background below.
The Line layer is used, as its name indicates, to provide line shapes for use on a map. Lines can be used for roads, routes, or other such data items. Color, thickness, and type of line (solid, dashed, etc.) can all be modified based on the data value associated with the line shape.
The Decoration layer is not used to represent data values. Its sole purpose is to provide additional detail or context to the map. For example, lake and river shapes might be part of the decoration layer on a geographical map.
A map region is a special case of map layer that allows you to create overlays from existing Area map layers for the purpose of representing additional information. For more information on map regions, see Creating a Map Region Layer.
In most cases, the color of Area and Point layer map shapes change depending on the range of its data value. For example, in the Area and Point Map Layers image example above, the state (map shape) of Arizona has a value of 21, which puts it in the lightest colored range, and the state (map shape) of Nevada has a value of 98, which puts it in the darkest colored range. Additionally, Point map shapes may change depending on the data value. For example, the city of San Francisco shape has a value of 10, which puts it in the triangle range, and the city of Las Vegas shape has a value of 20, which puts it in the square range. Range behavior is defined separately for each map layer (see Map Ranges).
A map stores its data in a separate table for each layer. Each layer table contains a name for each data item and a corresponding data value. In this way, maps act differently than graphs because the number of data items is predetermined. New map data items must be defined explicitly in Corda Builder™. The image below illustrates how data from these tables is translated into the viewable map.
The previous section, Maps and Data, describes how the color of data items can vary according to the range of their data value. Point layer data items can also vary the actual shape of the data item according to its range. However, color and shape are not the only properties that can vary according to range. Just about any property, including fill, label, hover text, drilldown, and descriptive text can also vary according to range.
The way a map applies different types of formatting is an important aspect of map behavior. Each layer in a map has three levels of formatting that determine the look and feel of the layer's data items:
For each layer that comprises a map (Area, Point, Line, and Decoration), there is a set of default properties. In the first level of formatting, each shape in a given layer receives a look and feel based on these default properties.
If a data item in the layer doesn't fall in a range, and doesn't have any individual overrides, it looks exactly like the default shape.
Properties and attributes related to default layer properties are available from the Default Shape property in Object Properties. More information on these properties and attributes is available in the Corda® 7 Object Reference.
After formatting each data item according to the default layer properties, a map checks to see if the data item falls under a range override defined for that layer. For example, in the How Map Data Works example above, the map looks at the value for California and realizes that it falls in the 25-50 range.
If a data item does fall within a range, it looks to see if the range overrides any of the default data item's settings. Range overrides can override color or fill settings on Area layers, and in the case of Point layers, the shape definition. They can also be used to override other settings, such as drilldown or hover shapes and text.
Properties and attributes related to range overrides are available from the Ranges property in Object Properties. More information on these properties and attributes is available in the Corda 7 Object Reference.
Finally, a layer checks to see if the individual data item has any overrides. Typically, this answer is no because it is usually a bad practice to override settings for individual data items. An override decreases the flexibility of a project and makes it more difficult to update in the future. When using it as an Image Template file for Corda Server™, it may render the map unsuitable to display certain data sets.
However, there are some instances when it makes sense to override individual data item settings. For example, you might want to add hover items to a Area layer data item. Or the label on a certain shape might inconveniently overlap with the label of another shape, making it necessary to change the position of one of the labels.
Properties and attributes related to shape overrides are available from the Map Shape property in Object Properties. More information on these properties and attributes is available in the Corda 7 Object Reference.
Note: Because maps are just collections of shape objects, any characteristic of a shape can be overridden for a particular map shape as well.
Corda 7 offers a wide variety of world, country, U.S., state, and county maps. Some of these maps are included with the purchase of Corda Builder or OptiMap™. Other maps need to be purchased separately.
To keep the download size of Corda 7 small, the Corda 7 installer includes a small number of sample maps. Licensed Corda 7 users are entitled to a number of other maps, which can be downloaded from http://www.corda.com/download/maps.
For a catalog of available maps, see the Corda 7 Map Guide.
