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8.3 The General Raster API

The GR interface consists of routines for storing, retrieving and manipulating the data in general raster data sets.

8.3.1 GR API Routines

All C routine names in the general raster interface have the prefix "GR" and the equivalent Fortran-77 routine names are prefaced by "mg". All GR routines are classifiable within one of the following categories:

The GR function calls are listed in the following table and described further in the HDF Reference Guide.

TABLE 8A GR Library Routines
Purpose

Routine Name

Description

C

Fortran-77

Access

GRstart

mgstart

Initializes the GR interface for a given data file.

GRend

mgend

Terminates access to the file initialized by GRstart.

GRselect

mgselct

Selects the data set to perform operations on.

GRendaccess

mgendac

Terminates access to the data set selected by GRselect or GRcreate.

Read/write

GRreadimage

mgrdimg/

mgrcimg

Reads image data from a general raster data set.

GRwriteimage

mgwrimg/mgwcimg

Writes image data to a general raster data set.

GRidtoref

mgid2ref

Maps an general raster data set identifier to a reference number.

GRluttoref

None

Returns the reference number for the specified palette..

GRreftoindex

mgr2idx

Maps the reference number of a general raster data set to a data set index and returns the index.

GRnametoindex

mgn2ndx

Maps a raster image name to an index and returns the index.

GRreadlut

mgrdlut/

mgrclut

Reads palette data from a general raster data set.

GRwritelut

mgwrlut/

mgwclut

Writes palette data to a general raster data set.

GRsetattr

mgsnatt/

mgscatt

Writes the attribute of an object to a general raster data set.

GRgetattr

mggnatt/

mggcatt

Reads the attribute of an object from a general raster data set.

Maintenance

GRcreate

mgcreat

Creates a new general raster data set.

GRreqlutil

mgrltil

Sets the interlace mode for the next palette read from a general raster data set.

GRreqimageil

mgrimil

Sets the interlace mode for the next image read from a general raster data set.

GRgetlutid

mggltid

Allocates a palette id to a general raster data set.

GRsetexternalfile

mgsxfil

Specifies that the image data of a general raster data set is a special element of an external element.

GRsetaccesstype

mgsactp

Sets the access to a general raster data set to be either parallel or serial.

GRsetcompress

mgscomp

Makes the image data of a general raster data set a compressed special element.

Inquiry

GRfileinfo

mgfinfo

Returns global information on the specified GR data set.

GRgetiminfo

mggiinf

Returns information on the specified general raster data set.

GRgetlutinfo

mgglinf

Returns information on a given palette.

GRattrinfo

mgatinf

Returns attribute information on a given object.

GRfindattr

mgfndat

Returns the index of an attribute with the given name.



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HDF User's Guide - 06/04/97, NCSA HDF Development Group.