(The button containing the href attribute shown above becomes enabled as described in slideshowGuide.php.)

The query part of the URL should be ?dir=directoryname. but the code also accepts an older version in form ?cap=captionsfile&file=segmentname. (In the latter case the dir value is computed as dirname(cap)/file.) From the query, the code finds the appropriate captions file via pkscripts:findCoveringCapFile. The desired file: segment is the last directory name in the dir parameter. Picture lines in the file's segment are

[picturename.ext] caption

Most of the SlideShow.php code is to prepare for slideshowdefs.js on the client side. The key step is scanning the captions file. Each picture line adds an element to an array of Pic objects. The scan also looks for lines assigning values to pace, startn, random, and repeat. These are passed to slideshowdefs to initialize the parameters in the slidescontrol panel.

The Pic object, defined in slideshowdefs.js, has these fields:

The remainder of SlideShow.php is a singularly uninteresting viewable page.  It displays the "Loading" gif shown below and has three hidden buffers; one each for the previous, current, and next slide. At the top it links in slideshowdefs.js. The onload attribute for the body calls startShow in that script, which runs the show. The page's final action is to include the popup control panel, slidescontrol.php.