ITT Rule IDL Version 7.0 User Manual download pdf (Page 268)

268 Chapter 10: Creating a File Writer

Creating a New File Writer iTool Developer’s Guide

TITLE = 'Error', SEVERITY = 2

RETURN, 0 ; failure

ENDIF

; Get number of dimensions of image array.

ndim = SIZE(image, /N_DIMENSIONS)

; Write to a PPM file. Use REVERSE to make image appear

; with correct orientation.

WRITE_PPM, strFilename, REVERSE(image, ndim)

; Return 1 for success.

RETURN, 1

END

Discussion

The SetData method accepts an IDLitData object (oImageData) as its input

parameter. Before processing the input data, the method prompts the user for a file in

which to save the image, using the GetFilename method of the IDLitWriter object.

After securing a filename, the method proceeds to check the input data object. First it

checks to make sure that the input object is valid. Then it attempts to retrieve data of

an appropriate iTool data type from the data object; in this example, the method tries

to extract an data of one of the following types using the GetByType method of the

IDLitData class:

•IDLIMAGE

• IDLIMAGEPIXELS

• IDLARRAY2D

If no data of any of these types is found, the method displays an error message and

exits.

Once the method has obtained an appropriate data object, it checks to determine

whether the data object is an IDLitDataIDLImage object; if so, it attempts to retrieve

the image pixels from the data object; otherwise it simply retrieves the data array.

The data retrieved by the GetData method is stored in the variable

image. The

method then checks the return value from the GetData method to determine whether

the returned value is valid.

Using the valid image data, the method determines the number of dimensions and

then uses the WRITE_PPM procedure to create an image file. The image data must

be processed by the REVERSE function in order to make it appear in the output file

with the correct orientation.

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ITT Rule IDL Version 7.0 User Manual Page 268