user manual

272 Chapter 10: Creating a File Writer
Example: TIFF File Writer iTool Developer’s Guide
Example: TIFF File Writer
This example creates a file writer to write TIFF format files.
Example Code
The code for this example file writer is included in the file
example1_writetiff__define.pro in the examples/doc/itools
subdirectory of the IDL distribution. Run the example procedure by entering
example1_writetiff__define at the IDL command prompt or view the file in
an IDL Editor window by entering
.EDIT
example1_writetiff__define.pro.
Note
The standard TIFF file writer included with the iTools contains additional features
not included in this example. In most cases, if a file writer is included in the
standard iTool distribution, there is no need to create your own writer for files of the
same type.
Class Definition File
The class definition for example1_writetiff consists of an Init method, a SetData
method, and a class structure definition routine. As with all object class definition
files, the class structure definition routine is the last routine in the file, and the file is
given the same name as the class definition routine (with the suffix
.pro appended).
Class Definition Discussion
PRO example1_writetiff__Define
struct = {example1_writetiff, $
inherits IDLitWriter $
}
END
Discussion
Our class definition routine is very simple. We create an IDL structure variable with
the name
example1_writetiff, specifying that the structure inherits from the
IDLitWriter class. The object has no instance data, and thus no instance data fields.
Init Method
FUNCTION example1_writetiff::Init, _REF_EXTRA = _extra