X-windows

The most commonly used devices are X-windows. These can require a little preparation before you select a device. Starlink graphics use GWM to manage windows. It enables a window to persist between separate applications; or to be shared by different applications, potentially even running on different machines. See SUN/130 for details of GWM and how to change your X-defaults file ($HOME/.Xdefaults), but the salient points are given below.

If the window appears on a terminal or workstation other than the one running the KAPPA executables you will need to redirect output to your screen, if you have not already done so for some other software. You either use the xdisplay command

    % xdisplay myterm.mysite.mydomain.mycountry

or set the DISPLAY environment variable to point to the address of your screen.

    % setenv DISPLAY myterm.mysite.mydomain.mycountry:0

You substitute your machine's address or IP number. (Ask your computer manager.)

If you do not create the window before running KAPPA, the first graphics application to open an X-windows device will create the window, using certain defaults. The defaults control amongst others the foreground and background colours, the number of colours allocated, the size and location of the window. These defaults may be altered with an X-defaults file, or a window created with the GWM xmake command.

    % xmake xwindows -geom 600x450 -fg yellow -bg black

This example makes a window of dimension 600-by-450 pixels, the background colour is black and colour for the line graphics is yellow.

The following set up to place in your X-defaults file is a reasonable compromise, as it maximises the number of colour indices for the graphics window (xwindows), and has a second graphics window (x2windows). In the defaults file there are the following lines

     gwm*xwindows*colours:         80
     gwm*xwindows2*colours:        20

and you can also set the sizes of the windows too. Notice that the second device name is x2windows, but the window name is xwindows2. Don't ask why. This confusing name rule applies also to all but the first window of the maximum of four windows allowed.

The device names can be abbreviated, to give unambiguous names. Thus you can enter xw for the xwindows device; x2w for the x2windows device; and so on. This is the reason for having device names as they are.

The following tells KAPPA that this is the current device. This remains as a global parameter, so you probably will not need to issue this command that often.

     % gdset x2windows