Lightwing can periodically retrieve dynamic information from the internet via RSS channel feeds and display that information with Text or Ticker commands. The RSS command is required first to establish the internet connection and define a periodic update interval. RSS channels are always global, so RSS commands must be listed at the top of the script file, then the RSS channels are available to all pages in the script file.
A unique RSS channel name and URL for the RSS source are required parameters. Every RSS channel must have a unique name, which can be any mix of alpha and numeric characters and some symbols including underscore and hyphen. These RSS channel names are used to specify the source of RSS information to be displayed with either Text or Ticker commands via their RSS command options. By default, RSS channels do not update periodically and are limited to 100 items per channel. Use the command options below to change this.
Example of a Page that Displays RSS channel Information rss: NPR update: 1:00:00 url: http://www.npr.org/rss/rss.php?id=1001 page: PageName time 1, 10 text: OpenSansRegular_50 length: 70 lines: 6 rss: NPR type: RssItemDescription ticker: OpenSansRegular_50 rate: 10 loop: on rss: NPR type: RssItemTitle
Several variable names are available to display RSS channel and item information using the variable option with Text and/or Ticker commands. Each RSS channel will typically have multiple items that are displayed in a circular, round-robin manner. Lightwing automatically tracks the last displayed item for each channel and steps the RssItem variables to display the next item from the circular queue for that channel. This RSS stepping occurs whenever a page expires that uses an RSS channel or when a ticker loops that uses an RSS channel.
RSS Text and Ticker Variable Names
Name Example Resolved Text RssChannelTitle News: NPR RssChannelDescription Latest Headlines RssChannelLink http://www.npr.org/rss/rss.php?id=1001 RssChannelCopyright Copyright 2015 NPR RssChannelItems 100 RssItemTitle Star Trek Returns RssItemDescription Space, the final frontier. These are ... RssItemLink http://www.npr.org/star_trek_story/...
Some RSS feeds also provide thumbnail images to accompany the textual information. Lightwing can optionally display these images with either a box or object command when they are in either JPEG or PNG format. Since thumbnail images are usually small, the box or object commands can be configured to scale the images up, however scaling beyond a factor of 2.0 will produce poor quality, especially for JPEG. It is also important to preserve the aspect ratio of the images even though the ratios are typically different for each website. The best way to achieve this is to use the box command with dimensions 0.0, 0.0. This causes the aspect ratios of the original images to be preserved. Rather than using the scale option of the box command, use the scale option of the rss command, since it automatically adjusts for the display size; full-screen or windowed.
Lightwing automatically filters and removes advertising images and links from RSS content that would otherwise accompany the item description text.
Limit Option
Defines the maximum number of items that an RSS channel will maintain. An RSS source can potentially provide more items than desired. By default, Lightwing limits RSS channels to 100 items per channel, but this option allows any number to be set up to the maximum of 1000 items per channel.
Update Option
Defines a time interval to update an RSS channel from the internet. This can be specified as either a floating-point value in seconds or integer (sexagesimal) clock time. This interval is zero by default, which means to never update the channel.
There is a noticeable delay in animated text tickers and thumbnail images when they display information from an RSS channel while it is being updated from the internet. The update process also resets the active RSS item to the first item in the updated channel, which will occasionally have new information. These issues occur even if there is no actual change in the content of the channel. Therefore, it is recommended to define an update time interval of at least one hour or more to minimize these issues.
Example Time Specifications
Time Duration Float Clock One Half Second 0.5 n/a One Second 1.0 1 One Minute 60 1:00 One and One Half Minutes 90 1:30 One Hour 3600 1:00:00 One and One Half Hours 5400 1:30:00 One Day 86400 24:00:00
Thumbnail Option
Enables or disables retrieval of thumbnail images that accompany the textual information from some RSS websites. This parameter can be specified as off or on. It is off by default. Thumbnail images must be in either JPEG or PNG format as other formats are ignored. These images can be displayed with either box or object commands. These commands will only display valid images. When images are missing or in unsupported formats, the box or object is not drawn.
To diagnose problems with thumbnail images, run Lightwing with the maximum debug level set on the command line. This causes the temporary files for thumbnail images to be retained in the images folder so that they can be checked for accuracy.
Scale Option
Defines a single scaling factor for retrieved thumbnail images for this RSS channel. This can be used to stretch or reduce the image sizes while preserving their aspect ratios. The default scaling factor is 1.0 in full-screen mode, which disables scaling, or 0.5 when in windowed mode on Windows.