XWindow display

  With the term XWindow display we refer to a bitmapped screen supporting the XWindow environment. These displays have less functionality provided in hardware than the ``classical'' peripheral image displays. On the other hand they offer much more flexibility via software. For example, display screens of different sizes may be created and different number of image channels may be connected to any one display.
Another important difference results from the way XWindows works: when an X application program terminates, all the connected windows and data structures disappear. Therefore, MIDAS starts up an independent server process, the display server, which owns all X11 related data structures. The MIDAS applications do not interact directly with the windows but send messages to the server which then performs the actual task. Like this we can keep the windows alive while the different applications are executed and terminated, one by one.
Also, keep in mind that all interaction with the display will only work while the input focus is in the display window (either enforced by clicking the mouse in that window or just moving the cursor into it -- that depends on how your window manager is set up).
Image displays are created on the screen via the CREATE/DISPLAY command. An ``image display'' is then represented by a window on the bitmapped screen. It may have one or several image channels associated with it. The image channels may have the same size as the display window or could be larger. These channels are not realised in hardware ( e.g. video memory) like the peripheral image displays, but exist as data structures in main memory. Also an overlay channel and an alphanumerics memory are emulated for each image display. Initially each display is provided with a grayscale LUT.
You may create several image displays at the same time on your bitmapped screen even though only one display can be the current active display at any time. With the command ASSIGN/DISPLAY you switch from one display to the next.
Each image channel has independent scroll (also emulated in software) but no zoom capabilities. There are special commands like GET/CURSOR and VIEW/IMAGE which provide zoom in a special zoom window. Also available is an intensity transformation table but only one per image display and not one per image memory since the ITTs are emulated by convolving the ITT values with the current LUT.

• Using Image Memories
• Using the Cursors
• Look--Up Tables
• Intensity Transformation Tables
• Graphics
• Alphanumerics
• Command Interruption
• Graphical User Interface -- XDisplay