Radio Eyes Help

Active Labels

The ability to label the screen is not limited to static (unchanging) text.  You may create active labels which take their source of information from files or the internet. These labels can be text or pictures.  When an active label is used, Radio Eyes will:

The content of the active label can be either a picture or text.  The most obvious usage would be to gather this content from a dynamic source such as the internet.  For example, several solar images are updated at regular intervals on the internet at various sites. You could retrieve the most recent solar image captured at Xray wavelengths, for example.  This image would forced to fit in a box region, the size of which you specify in the script. You would use the labels anchor type and X, Y properties to determine where the image would be displayed on the screen. 

Text content could come from file or an internet page.  In the case of an internet page the entire page is downloaded into Radio Eyes. The program then uses special commands that locate the desired text on the page by specifying the text that comes before and after the desired content text.  This will become clearer after reviewing the commands of the scripting language for Active Labels.  An example is also given to walk you through the steps for developing such a script.  After the text content has been extracted from the file or internet page it is displayed as any ordinary label would be displayed on the sky map. 

When would you want to use text from from a file on your PC?  Lets say you know how to program in QBASIC and you wanted to keep updated on the physical temperature of your LNA (low noise amplifier). You could write a little program that reads a temperature sensor on the LNA and outputs the temperature once per minute to a file on your computer.  You could display this content in Radio Eyes using an Active Label. 

Note: Active Labels are not currently displayed in the Dome View.

To create an active label you add the label to the sky map in the same manner used for ordinary labels. However, for the active label you must specify a script file using the Script button on the Add Label panel.  Script files use the extension "RLS" (Radio Eyes Label Script) and should always be located in the subdirectory Radio Eyes\ Label Scripts.  You should also specify the Script Interval in seconds on the Add Label panel.  This parameter sets the amount of time between executions of the script.  If the content for the Active Label is only updated on the source (file or internet page) every hour, it would make no sense to run the script every 10 seconds or less as this would simply consume computer resources with no great benefit in changing content. 

Active Labels will often bear no relationship to a specific Right Ascension / Declination (RADEC) point on the sky map as would say a label for radio source Cass A. Thus make sure you select an appropriate Anchor Type for your label.  You may be more inclined to place the label on the map based upon its position on the screen, for example, in the lower left corner.

Writing Active Label Scripts

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