Whiteboard for private maths tutor.

I have a website that I have written in php. It has membership (that is already working and fine) and secure pages for the whiteboard to go on. I want to add whiteboards to various pages. When those pages load I can already detect if it is a member of the site. If it is I will run the code that puts a whiteboard on their browser. All I need is code for a whiteboard that I can drop into my existing code... you just need to show that it works once and I can then use it all over my site! I don't care if it is java or html5 or what. But I must be able to drop what you write into my php code. It might be html-ready in which case I just need to echo it all... that is fine if that is the case. Ideally it would run on as many platforms as possible, preferably including mobile web on iphones and androids (for which I believe a new standard in html5 makes it possible). Please say which platforms/browsers your code should work on... if there is a good reason not to support certain platforms/browsers (code is simpler or the current standards are too unreliable or whatever) please tell me and I may go with you if you explain it well. Required features: (1) ability to draw using cursor (2) change pen color (3) chat area (4) ability to give each user a name that is then shown in the chat (I will know their name already from when they log in so I do not want options for changing the name). Optional features that will make it more likely I choose you: (1) ability to put a pdf file in the background so we are drawing over that (2) ability to save what has been done as an image (or some kind of file) for future reference. Finally: I am offering this as a job because the code I have just written myself is painfully slow and rubbish. I've managed to do loads of good quality coding myself for my website (I am a professional programmer myself doing contract work in windows development) but this is beyond my skill set and I can't be bothered to learn yet another programming language! If you think I need a better quality hosting package to speed it up can you help with that too. I have a Business Pro account with 1and1 and if I am starting to use Java push/pull (or whatever it is called) do I need to upgrade to a cloud server or something to make it a decent response time? Thanks...