Peeker uses Sky Software's EZShellExtensions, a set of libraries for everything related to Window shell extensions: contextual menus, file associations, icon overlays, etc...
That's why I've only made avaliable the installable version of the software. There's not, and there won't be, source code avaliable for Peeker; since this program uses a third party library which is neither open source nor free.
Using it is fairly simple: after installation and rebooting we'll have Peeker avaliable. As you can see, is fairly intuitive:
Besides the image preview, you have two more menu items: the first one states the image type and dimensions, and the second allows you to set that image as a expanded wallpaper.
By clicking on the image preview, or in the text just below it, you'll open a window with the full-scale image.
By clicking on the little banner just above the image preview, you'll open an About... form.
Peeker works with .BMP, .JPG, .GIF and .PNG files. You'll need to have preinstalled the .Net Framework 1.1.
You can download Peeker from here.
Any thoughts, doubts, requests, name-calling or whatever the program suggests you to do; please mail me.
