X Windows Requirements and Use

Question:

What kind of X Windows environment do I need to run Ferret?

Explanation: A compilation of notes from various sources in the Ferret documentation

From the Users Guide:

When installing or updating Ferret, check the installation guide for your system, from the Ferret Downloads page for requirements and instructions regarding the x window and x server configuration.

To get graphical output from Ferret at your workstation, you must have the X Windows environment variable DISPLAY defined properly. Set the variable to point to the workstation screen where you want Ferret graphical output displayed. In the example below graphics output will be sent to the screen of workatation anorak.

% setenv DISPLAY anorak:0.0

If you are running X windows on the same system where Ferret is running, the setting is just :0.0

% setenv DISPLAY :0.0

You can also set this variable using the Control Panel of your PC. Open the control panel, open up System, and choose the Environment tab. At the bottom of the window add Variable DISPLAY and set its Value to anorak:0.0

Notes for Windows Systems:

The X display must be set for indexed color (a.k.a. PseudoColor) -- maximum 65K colors. This is relevant to PC and MAC X software and to systems that have 3D graphics hardware installed.

If a graphics window that was obscured by another window appears to be fully or partially blank after the obscuring window is moved, or if the graphics in a window are drawn incorrectly after the window is resized, then try typing:

yes? set mode refresh

Some items from the Ferret v4.90 Release notes:

• 24 bit system support

 Ferret displays colors correctly on X window servers configured to use a 24 bit color display. If you use such a display, note the following:

• You may have to click on a Ferret window to correctly display the colors in that window.
• Other windows may change color once the Ferret window becomes active. Clicking on the windows that change color will restore their original color.
• The X server must support multiple visuals, and at least one PseudoColor, or indexed, visual. Unfortunately, the X server available on most Linux machines only supports one visual at a time; Ferret will not work with 24 bit color displays on such machines.

 
• GIF mode - GIF output without X windows

 Ferret can now run in batch mode -- without an X server. Invoke batch mode by starting up Ferret with the -gif option:

ferret -gif

Graphical output is buffered, and can be stored in a GIF file by executing the FRAME command. For example:

yes? frame/file=picture.gif

sends the stored graphical output from Ferret to the GIF file picture.gif.

Please note the following when using batch mode:



• Window resizing only works if the window is cleared before resizing the window. For instance:

yes? set window/clear/size=0.25

will resize the window while

yes? set window/size=0.25/clear

will cause an error.


• Avoid metafile commands when running in batch mode. In particular,

yes? set mode meta

may cause problems.


• Don't create new Ferret windows when running without an X server. The following command:

yes? set window/new

will cause Ferret to crash.


• PostScript mode - PostScript output without X windows

 Ferret can also generate PostScript files without an X server. This is an experimental feature and not fully supported. If you wish to use this mode, start Ferret with the -batch option:

ferret -batch <file>.ps

where <file> is the name of the output file. Note that the filename must end with ".ps".

 Please note the following when using PostScript mode:

• The PostScript output will not be fully written to the output file until you exit from Ferret.
• Window sizing commands do not have any effect on PostScript output.
• Avoid metafile commands when running in PostScript mode.
• Don't create new Ferret windows when running without an X server. The following command:

yes? set window/new

will cause Ferret to crash.