ITT Rule IDL Version 7.0 User Manual download pdf (Page 152)

152 Chapter 7: Creating an Operation

Creating a New Data-Centric Operation iTool Developer’s Guide

Creating a New Data-Centric Operation

iTool operations that act primarily on data are based on the IDLitDataOperation class.

The class definition file for an IDLitDataOperation object must (at the least) provide

methods to initialize the operation class, get and set property values, execute the

operation, and define the operation class structure. Complex operations will likely

provide additional methods.

How an IDLitDataOperation Works

When an IDLitDataOperation is requested by a user, the following things occur:

1. As with any operation, execution commences when the DoAction method is

called. When called, the IDLitDataOperation retrieves the currently-selected

items. If nothing is selected, the operation returns.

2. For each selected item, the data objects of the parameters registered as

“operation targets” are retrieved.

3. The data objects are queried for iTool data types that match the types

supported by the IDLitDataOperation.

For each data object that includes data of an iTool data type supported by the

IDLitDataOperation, the following things occur:

1. The data from the data object is retrieved.

2. If the IDLitDataOperation does not have the REVERSIBLE_OPERATION

property set, a copy of the data is created and placed into the undo-redo

command set.

3. The Execute method is called, with the retrieved data as its argument.

4. If the Execute method succeeds and the IDLitDataOperation has the

EXPENSIVE_COMPUTATION property set, a copy of the results is placed

into the undo-redo command set.

5. The result of the IDLitDataOperation is placed in the data object. This action

will cause all visualization items that use the data object to update when the

operation is completed.

Once all selected data items have been processed, the undo-redo command set is

placed into the system undo-redo buffer for later use.

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ITT Rule IDL Version 7.0 User Manual Page 152