As you import different data source types a layer hierarchy
is built up consisting of layers and sublayers. Data sources of the
same type are grouped as sublayers of a parent layer.
In the following figure, the ESRI/Shape (see
Shapefile format) and GeoTIFF (see
GeoTIFF format) files are grouped as sublayers under their
parent layers. The last layer in the hierarchy becomes the front layer
in the Map View pane. For example, the Labels layer is displayed
in front of the GeoTIFF layer in the Map View pane.
You can rename layers and sublayers to make the name
more meaningful, (see
Renaming a map layer).
For example, San Francisco Streets would be more meaningful than SF_Streets.shp.
You can also set up your own layer hierarchy by creating
new layers and sublayers, (see
Creating a map layer hierarchy).
You can then fill them with one or more of the data sources you have
already imported.
The following figure shows an example of a new parent
layer called Top Layer
into which the SF_Streets.shp
file
has been placed.
Map layers can also be hidden from the layer tree, (see
Hiding and showing a map layer in the tree).
For example, in a case where users can add more map layers to an application
that has a fixed background map, the application developer may want
to ensure that the user cannot alter or remove this background map.
The solution to this problem is to hide those layers from the tree
so that they cannot be modified.
You also have the possibility to move layers to different
positions in the hierarchy and to split layers or create filters on
layers that contain metadata (see
Splitting or filtering a map layer).
You can send layers to the front (top) or back (bottom) of the hierarchy,
or change the position of a layer within the hierarchy.
The filtering mechanism allows you to create a layer
that displays only the objects that match a filter. You can also split
a layer by grouping together the objects that match the same value
for selected metadata. In both cases, the split/filtered layers are
added to the map layer hierarchy.
The following figure shows an example of an ESRI/Shape
file displayed according to a CONTINENT filter.