ArcGIS Engine Developer Guide

BUILDING APPLICATIONS WITH THE ARCGIS CONTROLS
The current tool to
zoom in on the page
A single click
command to
open a map
with the ToolbarControl using the Buddy property. For example, if a command
hosted on the ToolbarControl only works with the ReaderControl and the
ToolbarControl buddy is a MapControl, the command should disable itself.
To help you create custom commands to work with the ArcGIS controls and the
ArcGIS Desktop applications, HookHelper, GlobeHookHelper, and SceneHookHelper
objects exist.
• The HookHelper is used for custom commands that work with the MapControl,
PageLayoutControl, ToolbarControl, and ArcMap Desktop application.
• The SceneHookHelper is used for custom commands that work with the
SceneControl, ToolbarControl, and ArcScene Desktop application.
• The GlobeHookHelper is used for custom commands that work with the
GlobeControl, ToolbarControl, and ArcGlobe Desktop application.
Rather than requiring you to add code into a command’s OnCreate method to
determine the type of hook passed to the command, the helper object handles
this. The helper objects are used to hold onto the hook and return ActiveView,
PageLayout, Map, Globe, and Scene objects (depending on the type of helper object)
regardless of the type of hook that is passed. Refer to the ‘Building applications’
scenarios in Chapter 6, ‘Developer scenarios’, to see how to build a custom
command using the HookHelper object that works with a MapControl,
PageLayoutControl, and ToolbarControl.
The ICommand::OnClick method is called when the end user clicks a command
item hosted on the ToolbarControl. Depending on the type of command, it will
typically do some work using the hook to access the required objects from the
buddy control. There are three types of commands:
• A single-click command implementing the ICommand interface that responds
to a single click. A click results in a call to the ICommand::OnClick method, and
an action is performed. By changing the ICommand::Checked value, simple
command items can behave like a toggle. Single-click commands are the only
types of commands that can be hosted on a menu.
• A command item or tool implementing both the ICommand and ITool interfaces
that requires end user interaction with
the display of the buddy control. The
A tool control displaying the
current page percentage
A menu
containing
single
click map
commands
ToolbarControl maintains one
CurrentTool. When the end user clicks
the tool on the ToolbarControl, it
becomes the CurrentTool, and the
previous tool is deactivated. The
ToolbarControl will set the CurrentTool
of the buddy control. While the tool
is the CurrentTool, it will receive
mouse and key events from the buddy
control.
Chapter 3 • Developing with ArcGIS controls • 51