I’m just curious about this, as it’s probably too much trouble to be worth it for me. I’m wondering how it’s possible to have each file of a custom type have a different, descriptive icon in windows explorer. A classic example it Photoshop’s .psd files. Windows doesn’t natively have a clue what a psd is (I assume?), but somehow, when browsing in Windows, the file icon is a thumbnail of the psd itself.
How is this done? I’m curious both from a programming perspective and OS perspective. For example, when Windows sees .psd, what does it do to get the thumbnail? Does Adobe install some separate utility in a magic location that Windows uses to generate the thumbnail for the file?
This is done via Shell Extension Handlers , to see how its done , see Creating Icon Handlers .