Overview of iTool File Writers
A file writer is an iTool component object class that defines how data stored in the iTool data manager can be exported to a file. File writers have mechanisms for manipulating data stored in iTool data objects into the proper format for a given file type. Some examples of iTool file writers are:
- the ASCII file writer, which uses the IDL PRINTF procedure to write data to a text file.
- various image file writers, which allow the user to save data in JPEG, BMP, PNG, and other well-defined image format files,
- a generic binary file writer, which uses the IDL WRITEU procedure to write unformatted binary data to a file.
A number of standard file writers are predefined and included in the IDL iTools package; if none of the predefined file writers suits your needs, you can create your own file writer by subclassing either from the base IDLitWriter class on which all of the predefined file writers are based, or from one of the predefined file writers.
The File Writer Creation Process
To create a new iTool file writer, you will do the following:
- Choose an iTool file writer class on which your new operation will be based. In almost all cases, you will base your new operation on the IDLitWriter class, which handles registration of standard file properties and provides standard messaging features.
- Provide methods that extract the image data from the data object and create a file using IDL's output routines (PRINT, WRITE, or one of the IDL WRITE_* routines).
This chapter describes the process of creating a new file writer based on the IDLitWriter class.
