ITT Rule IDL Version 7.0 User Manual download pdf (Page 189)

Chapter 7: Creating an Operation 189

iTool Developer’s Guide Example: Data Resample Operation

INTERP = interp, CUBIC = cubic)

; CONGRID always uses linear interp with 3D

3: data = CONGRID(data, newdims[0], newdims[1], newdims[2])

ENDCASE

RETURN, 1

END

Discussion

The Execute method does the work of our operation. Since example1_opresample is

based on the IDLitDataOperation class, when the operation is requested by a user the

Execute method is automatically called with each of the currently selected data

objects as the data argument.

First, we use the SIZE function to determine the number of dimensions of the input

data item. We use a CASE statement to create a new array (

newdims) that stores the

number of elements of each dimension multiplied by the scale factor for each

dimension. The number of elements in each dimension cannot be less than one.

Next we use the ARRAY_EQUAL function to compare the number of elements of

each dimension of the input data with the number of elements of each dimension of

our

newdims array. If these numbers are equal, no resampling will take place, so we

stop processing and return 1 for success.

If our newdims array contains a different number of elements than the original input

data, some resampling will take place. We check the value of the METHOD property

(stored in the instance data field _method) to determine what type of resampling we

should perform.

Finally, we call the CONGRID function with the appropriate arguments and

keywords, depending on the dimensionality of the input data and the resampling

method specified. We then return 1 for success.

GetProperty Method

PRO example1_opresample::GetProperty, $

X = x, $

Y = y, $

Z = z, $

METHOD = method, $

_REF_EXTRA = _extra

; My properties.

IF ARG_PRESENT(x) THEN $

x = self._x

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ITT Rule IDL Version 7.0 User Manual Page 189