Evan Golub
Department of Computer Science
Human-Computer Interaction Lab
University of Maryland

The VirtualTransparency application allows the user of an XP-enabled computer to draw on top of a capture of the current live screen. This application was inspired by the preparation to use a TabletPC as a presentation tool in an HCI class. Very often it is useful to be able to draw attention to parts of an interface visually. The use of a laser pointer is often imprecise and can break the flow of discussion. A more natural interaction is to draw directly on the screen (as is often seen on PowerPoint presentations). This application enables that option on any presentation material by placing a virtual transparency on top of the current screen on which one can do freehand drawing.

An example of how one might use this in class follows:
    At the beginning of class, launch VirtualTransparency. There will be a one-time screen "flicker" (which is being investigated). Once launched, you will see the  logo in the lower right-hand corner of the screen and the cursor will appear as a pen (or eraser if you select that tool). Next, minimize VirtualTransparency and proceed with class as usual. When you have something on your screen that you would like to annotate for the class, bring VirtualTransparency to the foreground (Control-Alt-V). If as you are annotating, you would like to change the ink color, erase ink (either with an eraser or by erasing entire strokes) or temporarily hide the ink, you can right-click and bring up a context menu with access to these features. If when you are done with your annotations you may choose to save the current screen. This will save both the screen itself and the ink that you have drawn upon it. You can also erase the ink that you have drawn. At any time, you can minimize VirtualTransparency to resume interaction with your screen. At the end of class, bring VirtualTransparency back to the foreground (Control-Alt-V) and exit the application.

Figure 1 shows an example using the Virtual Transparency application to comment on the local department's home page:

Figure 1

This program requires the .NET Framework to be installed on the machine. You can download Beta Version 0.6.1 (~5.2 megs) of the application. This version works on a snapshot of the screen rather than working on the live screen due to problems with different machines acting differently with the transparency. The snapshot is automatically refreshed as the application is brought forward. It can also be manually refreshed by using (Control-R).

Future versions will have features that will be of use on a TabletPC in tablet mode:

  • a gesture for minimize
  • a gesture for save
  • a gesture for clear
  • a gesture for exit
  • hopefully the ability to draw on the live screen rather than a capture of it (I have a version of this that works on one laptop running Windows XP but that solution does not work on other hardware and another version that works on all platforms but is extremely slow and unusable.)

    This software is provided for free for use at educational institutions.
    If you are interested in using this software for commercial purposes contact the author, Evan Golub, at

    DISCLAIMER: This software is provided on an "as-is" basis, without warranty of any kind, express or implied, including but not limited to warranties that the software is free of defects, merchantable, fit for a particular purpose or non-infringing. User bears the entire risk as to the quality and performance of the software. Should the software prove defective in any respect, user assumes sole responsibility and liability for the entire cost of any service and repair in connection therewith. No use of this software is authorized except under this disclaimer.

    This page last modified on Saturday, 25-Dec-2004 00:07:34 EST.