Introduction

The MIDAS graphics package is designed to enable data representation in a reasonable flexible way. It can be used for graphical display of most of the MIDAS internal data structures: bulk data frames, table files, keywords, and image descriptors. The software consists of four layers:

• main programs and procedures, executed by the MIDAS graphics commands;
• high level MIDAS Graphics Interfaces ;
• low level MIDAS Graphics Interfaces;
• low level Astronet Graphics Library (AGL) .

This chapter is focused on the MIDAS Graphics Interfaces, a well defined set of high level graphics routines. These routines should be used by MIDAS programs for graphical applications. The name of the routines consist of six characters (all capital letters), from which the first two determine the language. These letters can be either PC (for C)  or PT (for Fortran 77) . The following four characters indicate the functionality of the routine.

Currently, the standard Graphics Interfaces cover the following functions:

• set up of graphics characteristics;
• open a device, set the clip values, etc.;
• plot the coordinate box;
• plot data;
• plot text;
• get the graphic cursor;
• close the graphics device and plot files.

This set of interfaces is intended to cover the basic needs for doing software development for graphical data representation in MIDAS. The lower level AGL library can be used to get more flexibility. However, when using this library, information about the graphics (e.g. graphics setup, coordinate box, etc.) is not stored in the MIDAS keywords structure. Hence, mixing calls to the MIDAS Graphics Interfaces and calls to the AGL library should be avoided.

In the following sections a general description of the Graphics Interfaces is presented. The detailed calling sequences are included in Appendix . Two program examples, one in C and one in Fortran, showing how to use the Graphics Interfaces are included in Appendix .

Information about using the graphics facilities in MIDAS can be found in the ESO-MIDAS Users Guide, Volume 1, Chapter 6.