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8.3 The GR Interface

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

8.3.1 GR Interface Routines

All C routine names in the GR 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 routines are listed in the following table and described further in subsequent sections of this chapter.

TABLE 8A - GR Library Routines

Purpose
Routine Name7
Description
C
FORTRAN-77
Access
 GRstart mgstart Initializes the GR interface (Section 8.5.1 on page 264)

GRcreate mgcreat Creates a new raster image (Section 8.5.1 on page 264)

GRselect mgselct Selects the raster image (Section 8.5.1 on page 264)

GRendaccess mgendac Terminates access to the raster image (Section 8.5.2 on page 264)

GRend mgend Terminates access to the GR interface (Section 8.5.2 on page 264)

Raster Image Manipulation
 GRgetattr mggnatt/ mggcatt Reads an attribute of a raster image or a file (Section 8.9.4 on page 276)

GRidtoref mgid2rf Maps a raster image identifier to a reference number (Section 8.8.3 on page 273)

GRnametoindex mgn2ndx Maps the name of a raster image name to an index (Section 8.8.3 on page 273)

GRreadimage mgrdimg/ mgrcimg Reads raster image data (Section 8.7.1 on page 270)

GRreftoindex mgr2idx Maps the reference number of a raster image to its index (Section 8.8.3 on page 273)

GRsetattr mgsnatt/ mgscatt Assigns an attribute to a raster image or a file (Section 8.9.2 on page 275)

GRwriteimage mgwrimg/mgwcimg Writes raster image data (Section 8.6.2 on page 268)

GRreqimageil mgrimil Sets the interlace mode of the image read for subsequent read operations (Section 8.7.2 on page 271)

LUT Manipulation
 GRgetlutid mggltid Gets a palette identifier given the palette's index (Section 8.10.1 on page 277)

GRluttoref mglt2rf Maps a palette identifier to a reference number (Section 8.10.2 on page 278)

GRreadlut mgrdlut/ mgrclut Reads palette data from a raster image (Section 8.10.6 on page 279)

GRwritelut mgwrlut/ mgwclut Writes palette data to a raster image (Section 8.10.4 on page 278)

GRreqlutil mgrltil Sets the interlace mode of the next palette for subsequent read operations (Section 8.7.2 on page 271)

Maintenance
 GRsetcompress mgscomp Specifies whether the raster image will be stored in a file as a compressed raster image (Section 8.6.2 on page 268)

GRsetexternalfile mgsxfil Specifies that the raster image will be written to an external file (Section 8.6.3.1 on page 268)

Inquiry
 GRattrinfo mgatinf Retrieves information about an attribute (Section 8.9.3 on page 275)

GRfindattr mgfndat Finds the index of a data object's attribute given an attribute name (Section 8.9.3 on page 275)

GRfileinfo mgfinfo Retrieves the number of raster images and the number of global attributes in the file (Section 8.8.1 on page 272)

GRgetiminfo mggiinf Retrieves general information about a raster image (Section 8.8.2 on page 272)

GRgetlutinfo mgglinf Retrieves information about a palette (Section 8.10.3 on page 278)

Chunking
 GRsetchunk mgschnk Creates chunked raster image (Section 8.11.2 on page 282)

GRgetchunkinfo mggichnk Retrieves information about a chunked raster image (Section 8.11.3 on page 283)

GRsetchunkcache mgscchnk Sets maximum number of chunks to be cached (Section 8.11.4 on page 284)


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HDF User's Guide - 05/19/99, NCSA HDF Development Group.