Multi-Monitor Configurations
IDL allows you to position windows on multiple monitors attached to the same computer. Such multi-monitor configurations may appear to the user (and to you as an IDL programmer) as a single extended desktop consisting of multiple physical monitors, or as a series of individual desktops appearing on multiple physical monitors.
IDL's support for multi-monitor configurations includes the following:
- The IDLsysMonitorInfo object, which allows you to query the system for the current monitor configuration and to determine the screen geometry of the various monitors.
- Keyword support for extended (or multiple) desktops within routines that draw a window on the monitor screen. For example, the XOFFSET, YOFFSET, and DISPLAY_NAME keywords to the WIDGET_BASE function and WIDGET_CONTROL procedure allow you to position widget applications anywhere on any available monitor. Similarly, the LOCATION and DISPLAY_NAME properties of the IDLgrWindow object afford you the same control for object graphics windows.
It is important to note that support for multi-monitor configurations is quite different on Windows and UNIX systems, and that as a result IDL's support varies by platform. By understanding how multi-monitor configurations are supported on each platform, you can create cross-platform IDL applications that will take advantage of multiple monitors when they are present. See the following sections for platform-specific details.
See Example: Multi-Monitor Window Positioning for example code that uses the IDL's multi-monitor support.
Multi-Monitor Terminology
In this discussion of IDL's multi-monitor support, the following terms are used with the meanings listed below.
Desktop
An onscreen user work area. Multiple desktops are generally managed either by the operating system itself or by a desktop management system and are dependant on the physical monitor configuration — that is, you can have multiple desktops on a single monitor.
Display
On UNIX systems, the word Display describes the connection between an X client and an X server. Do not confuse this with monitor.
Extended Desktop
A term for an onscreen user work area that may span multiple monitors. It is often used to describe the minimum bounding box that encloses the user work area defined by each monitor in the system. There may be "holes" in an extended desktop if two monitors with different display resolutions are used. Extended desktops are characterized by their ability to drag windows between monitors on the desktop.
Monitor
A physical display device such as a CRT or LCD.
Primary Monitor
In an extended desktop system, the primary monitor is the monitor that contains the origin (0,0). If the desktop is not extended, then the primary monitor is the one that is considered "default" by the graphics system.
Screen
On UNIX systems, the word Screen describes one of a display's drawing surfaces. A single X server can control more than one Screen, but is generally operated or controlled by a single user with a single keyboard and pointing device.
Secondary Monitor
In an extended desktop system, a secondary monitor is any monitor that is not the primary monitor. If the desktop is not extended, then a secondary monitor is the one that is not considered "default" by the graphics system.
Virtual Desktop
A desktop configured so that it is larger than the monitor used to display it. The user can "pan" the desktop around to cause the desired parts of it to be visible on the monitor.
X Server
A program that runs on the machine to which the graphics adapter is attached. It owns the graphics adapter and is responsible for drawing on it.
X Client
A program that connects to an X server, sending commands to the X server to draw on the display device. The X client is typically the application and may or may not be executing on the same machine as the X server.
X Multi-Screen
The "core" method for an X server to handle more than one monitor. Each monitor is assigned a Screen; the user can move the pointing device from one monitor to another, but cannot drag windows between monitors. Each Screen is addressed by the final digit in the X Display name (e.g., the 1 in ajax:0.1).
XINERAMA
An X11 extension that allows a single X11 screen to be displayed across multiple monitors. This allows an application to open windows on any monitor using the same Display/Screen connection. This is an example of an extended desktop implementation for UNIX systems and is essentially a way to emulate the extended desktop that Windows presents to the user.
