ITT Rule IDL Version 7.0 User Manual download pdf (Page 213)

Chapter 8: Creating a Manipulator 213

iTool Developer’s Guide Creating a New Manipulator

required. It is always safest, however, to create a Cleanup method that calls the

superclass’ Cleanup method.

See “IDLitManipulator::Cleanup” (IDL Reference Guide) for additional details.

Example Cleanup Method

The following example code shows a very simple Cleanup method for the

ExampleManip manipulator:

PRO ExampleManip::Cleanup

; Clean up superclass.

self->IDLitManipulator::Cleanup

END

Discussion

Since our manipulator’s instance data does not include any pointers or object

references, the Cleanup method simply calls the superclass Cleanup method.

Creating Mouse Event Methods

Manipulators based on the IDLitManipulator class have the ability to respond to

mouse events generated by the user. The OnMouseDown, OnMouseMotion, and

OnMouseUp methods are invoked in response to mouse events in the iTool window.

The functionality of an interactive manipulator can be divided among these events.

Implementing an OnMouseDown Method

The manipulator class OnMouseDown method is called when a mouse down event

occurs on the target window. Calling the superclass

IDLitManipulator::OnMouseDown method selects items at the mouse location and

fills in the values of the

ButtonPress, nSelectionList and pSelectionList

instance data fields. See “Using Manipulator Public Instance Data” on page 204 for

more information on these fields. The

window coordinates of the cursor, which

button is depressed when the mouse button is clicked, and related information are

also provided through method parameters. Details on these method parameter values

are provided in “IDLitManipulator::OnMouseDown” (IDL Reference Guide).

The actual processing performed by the OnMouseDown method depends entirely on

the manipulator. If the manipulator action does not rely on mouse movements, the

majority of your processing may occur in the OnMouseDown method. Regardless,

you can use this method to determine if user selections meet requirements, or to set

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ITT Rule IDL Version 7.0 User Manual Page 213