Print Web page on 4 inch printer from mobile

I am developing a mobile web application. On the form when the user press Print button I need to print the page on a 4 inch printer.
My question is how can I connect to the printer from the mobile web browser(may be using bluetooth, USB).
My application will be running on all type of smart phones(Andriod , IOS, Windows, BB etc).

Unfortunately android and ios lack the concept of a printer driver so there is no native and widely supported way to print from mobile devices.

However there are a couple of other options to consider:

1. Rely on the user to have an app installed for their preferred printer (this probably is not a satisfactory solution as these apps often integrate poorly with mobile web browsers)
2. Target the (fairly common) printers which support email printing, that is allow the users to enter the email address for their printer and then send an email to that address containing whatever it is that you wish to print (for anything other than plaintext you will need to send a multipart email with html content)