ArcGIS Engine Developer Guide

WORKING WITH THE ARCGIS CONTROLS
methods and allow you, as a developer, to build an application with little or no
code.
ArcObjects
Each ArcGIS control simplifies the development process by encapsulating coarsegrained
ArcObjects while still providing access to finer-grained ArcObjects. For
example, the PageLayoutControl encapsulates the PageLayout object. The PageLayout
contains at least one MapFrame element containing a Map, and the Map may
contain multiple raster, feature, or custom Layer objects. Each ArcGIS control
provides shortcuts to frequently used properties and methods on the ArcObjects
they encapsulate. For example, the MapControl has a SpatialReference property that
is a shortcut to the SpatialReference property of the Map object. Each ArcGIS
control also has some helper methods that perform common tasks. For example,
the MapControl has an AddShapeFile method. The ArcGIS controls are typically a
starting point for developing applications because they provide not only a user
interface but also a direct route into the object model.
For more details on how the controls work
together, see the ‘TOCControl and
ToolbarControl’ section later in this chapter.
Events
Each ArcGIS control fires events in response to keyboard and mouse interactions
by the end user. Other events fire in response to actions occurring within the
controls. For example, when a map document is loaded into the MapControl, the
OnMapReplaced event is fired, or when an object is dragged over the MapControl
via drag and drop, the OnOleDrop event is fired.
Buddy Controls
The ToolbarControl and TOCControl each work in conjunction with one other
‘buddy control’. Typically, the buddy control is a MapControl, PageLayoutControl,
ReaderControl, SceneControl, or GlobeControl. The buddy control can be set at design
time through the control property pages (in development environments that
support property page capability) or programmatically using SetBuddyControl.
Map authoring
The ArcGIS Desktop applications can be used to preauthor documents that can
be loaded into the ArcGIS controls to quickly produce high-quality mapping. For
example, ArcMap can be used to author map documents that can be loaded into
the MapControl and PageLayoutControl. Preauthoring documents can substantially
reduce your development time as it saves having to programmatically build up
maps and symbology from scratch. Once a document is loaded into an ArcGIS
control, any layer, element, and symbol can be accessed programmatically through
the object model if its appearance subsequently needs changing.
You can also save the contents of your controls to map documents using the
MapDocument class with the MapControl or PageLayoutControl. The documents can
then be reopened by the control or by ArcMap. Using this technique it is possible
to share documents between your custom application and ArcGIS Desktop. For
Chapter 3 • Developing with ArcGIS controls • 43