ITT Rule IDL Version 7.0 User Manual download pdf (Page 386)

386 Appendix A: Controlling iTools from the IDL Command Line

Retrieving Property Information iTool Developer’s Guide

Property Attribute Information

Knowing the property identifier for the property you wish to change is often enough,

if you are already familiar with the property, its data type, and range of possible

values. For example, suppose you want to change the line thickness of a plot line.

You may already know that the value of the THICK property of a plot line is a

floating-point integer, so you can confidently call the DoSetProperty method as

described in “Changing Property Values” on page 389, specifying a floating-point

number for the new line thickness value.

But you may not always know the data type or range of allowed values for a given

property. If you have the property identifier, you can get additional information on

the property using the GetPropertyAttribute method of the IDLitComponent class.

For example, suppose we want to set the value of the WIDTH property of the Smooth

operation. The following statements will retrieve the text description, the data type,

and the range of allowed values for the WIDTH property:

objSmooth->GetPropertyAttribute, 'WIDTH', DESCRIPTION=desc, $

TYPE=type, VALID_RANGE=range

PRINT, desc, type, range

IDL prints:

Smooth Filter Width. 2 0

The first attribute (DESCRIPTION) is the text description of the property. The

second attribute (TYPE) is the data type accepted by the property; the description of

the TYPE attribute reveals that the value 2 indicates that the property accepts an

integer value. The third attribute (VALID_RANGE) is the range of accepted values;

the scalar value 0 indicates that there are no restrictions on the range of integer values

allowed.

See “IDLitComponent::GetPropertyAttribute” (IDL Reference Guide) for additional

information on retrieving property attributes. “An Example Property Information

Retrieval Routine” on page 387 discusses an example utility (included in the IDL

distribution) that uses these techniques.

Property Value Information

To retrieve the current value of a property, you must use the property identifier and

the GetPropertyByIdentifier method of the IDLitComponent class.

For example, the following statements will retrieve and print the current value of the

WIDTH property of the Smooth operation in the current iTool:

success = objSmooth->GetPropertyByIdentifier('WIDTH', width_value)

1 2 ... 381 382 383 384 385 386 387 388 389 390 391 ... 429 430

No comments

ITT Rule IDL Version 7.0 User Manual Page 386