This issue seems to have been addressed before in numerous round-about ways, but nothing for this specific problem. Here's what I need to do:
I have a folder of 100 JPG files that I need to randomly set as the Windows XP's desktop wallpaper. The change is done through an automated batch file I created - and it's to be used on several systems. I have the code for the random choosing of the JPG - it's the implementation of the wallpaper that I'm having trouble with. Through a "reg" command in the batch file I can use this registry key:
[HKEY_CURRENT_USER\Control Panel\Desktop] "Wallpaper"
for telling Windows to use the randomly-chosen picture file. Works great, but it only accepts BMP files, and of course my files are all JPGs. In fact, when the registry setting is adjusted through use of Control Panel->Display->Desktop, Windows XP itself converts the JPG to a BMP before adding it to this registry setting. I need to mimic what Windows does, and implement it through use of a batch file, or a set of commands/programs called from the batch file. It has to be automated and work in any XP system I use it.
(1) Either I need an command-line method to convert my JPG to BMP like Windows does
(2) I need another method for displaying my JPGs as wallpaper directly
My project will go on a CD, be poped it in to a computer, and it will change the wallpaper with near-total automation (besides starting the batch file).
I don't want to convert all my JPGs to BMPs (that would be a waste of space).
I don't want to enable Active Desktop as has been suggested elsewhere (waste of resources in my opinion).
I can't install any programs to accomplish this. The environment needs to be untouched. (vbscript, batch, or stand-alone programs ok).
I prefer free programs. :-)