Use this function to retrieve records from an EVF. After you open the EVF with ENVI_EVF_OPEN (or ENVI_EVF_DEFINE_CLOSE returns the EVF ID), you can retrieve the specified record. The function ENVI_EVF_INFO returns the number of records.
Syntax
Result = ENVI_EVF_READ_RECORD(EVF_ID, Record_number [, PARTS_PTR=value] [, TYPE=value])
Return Value
The return value is a [2, n] array of double-precision, floating-point values, where n is the number of points in the record. Result[0, *] contains the x values, and Result[1, *] contains the y values.
Arguments
EVF_ID
This is the EVF ID returned from ENVI_EVF_OPEN or ENVI_EVF_DEFINE_CLOSE.
Record_number
This is the record number for the vector to retrieve. Record_number is a long integer from 0 to the total number of records minus one. The NUM_RECS value is retrieved using ENVI_EVF_INFO.
Keywords
PARTS_PTR (optional)
If you are working with multipart vectors (for example, a polygon that contains holes), the value of this keyword is the output of the PARTS_PTR keyword in the ENVI_EVF_DEFINE_ADD_RECORD routine.
TYPE (optional)
If you are working with multipart vectors, the possible values that will be returned for TYPE are as follows:
- 1: Point
- 3: Polyline
- 5: Polygon
- 8: Multi-point
Example
See the code example under ENVI_EVF_CLOSE.
API Version
4.2