ITT Rule IDL Version 7.0 User Manual download pdf (Page 104)

104 Chapter 5: Creating an iTool

Creating an iTool Launch Routine iTool Developer’s Guide

user to retrieve the newly-created iTool’s identifier in an IDL variable by including

the IDENTIFIER keyword in the call to the launch routine. The iTool identifier can

then be used to specify the iTool as the target for another operation, such as

overplotting.

The _EXTRA Keyword

Optionally, you can use IDL’s keyword inheritance mechanism to pass keyword

parameters that are not explicitly handled by your routine through to other routines.

See “Keyword Inheritance” (Chapter 5, Application Programming) for details on

IDL’s keyword inheritance mechanism.

Creating Data Objects

If your iTool launch routine allows users to specify data arguments (as opposed to

keywords that are passed through to the iTool component objects), you must process

those arguments and create an IDLitParameterSet object to be passed to the

IDLITSYS_CREATETOOL function. Parameter sets, data types, and general iTool

system data handling concepts are discussed in detail in Chapter 3, “Data

Management”.

Parameter Sets

Data is passed to a newly-created iTool instance by supplying an IDLitParameterSet

object as the value of the INITIAL_DATA keyword to the

IDLITSYS_CREATETOOL function. To create a parameter set object, use the

OBJ_NEW function:

oParameterSet

= OBJ_NEW('IDLitParameterSet', NAME =

paramSetName

)

where oParameterSet is a named variable that will hold the object reference to the

parameter set object and paramSetName is a string that will be used by the iTool user

interface to refer to the parameter set.

For example, if you are creating a data container to hold X and Y vectors to be plotted

in two-dimensions, you might use the following code:

oPlotData = OBJ_NEW('IDLitParameterSet', NAME = 'Plot data')

See Chapter 3, “Data Management”, and “IDLitParameterSet” (IDL Reference

Guide) for details.

Data Items

The parameter set object holds objects of type IDLitData, or objects of types derived

from IDLitData, such as IDLitDataImage or IDLitDataVector. These data objects, in

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ITT Rule IDL Version 7.0 User Manual Page 104