ITT Rule IDL Version 7.0 User Manual download pdf (Page 194)

194 Chapter 8: Creating a Manipulator

Overview of iTool Manipulators iTool Developer’s Guide

Overview of iTool Manipulators

A manipulator is an iTool component object class that defines a way the user can

interact with visualizations in the iTool window using the mouse or keyboard. Some

examples of iTool manipulators are:

• The translation/scaling manipulator, which allows the user to interactively

move visualizations around in an iTools window and change their size

• The rotation manipulator, which allows the user to change the orientation of

visualizations in two or three dimensions

• The annotation manipulators, which allow the user to insert text, line, polygon,

and other annotations

The majority of manipulators are associated with an operation that modifies the data

of the selected visualization in some manner. While a manipulator need not specify

an associated operation, this is required to support undo/redo functionality as

described in “Manipulators and the Undo/Redo System” on page 202.

A number of standard manipulators and manipulator containers are predefined and

included in the IDL iTools package as described in “Predefined iTool Manipulators”

on page 198. If none of the predefined manipulators suit your needs, you can create

your own manipulator by subclassing either from the base IDLitManipulator class, on

which all of the predefined manipulators are based, or from one of the predefined

manipulators.

Manipulators and Manipulator Containers

A manipulator is activated when the user clicks on the manipulator’s associated

toolbar icon. A manipulator typically modifies attributes of a target object (e.g. scales

an image), or records a sequence of values (e.g. creates an annotation). For a given

iTool, there is always a single active manipulator.

Manipulator containers (subclassed from IDLitManipulatorContainer) are used to

create hierarchies of manipulators, among which the current or active manipulator

can be defined. The child manipulator (subclassed from IDLitManipulator) can be

automatically changed based on the selection and what portion of a selection visual is

hit during a mouse-down operation. See the AUTO_SWITCH property of

“IDLitManipulatorContainer” (IDL Reference Guide) for details. See the following

section for information on selection visuals.

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ITT Rule IDL Version 7.0 User Manual Page 194