Basic sketch app implementing existing javascript + social sharing

I need a customizable, mobile-friendly HTML page that implements the sketch functionality of [login to view URL] but with a pre-set background image as canvas. In addition to the regular SAVE (export) function, two SHARE buttons should appear so that the user can share a link to the page with his sketch. When a friend clicks, it shows a button to start a new sketch from scratch at the bottom. Here's an example of how that functionality should work: [login to view URL] (please click one of the images, draw something, then share, then check the shared link). Additional notes: - Check the attached image for a mockup of the interface. - In the mockup, the hand drawn lines are part of the canvas and should be included in the exported image. - The canvas/background image can be any size, but let's say it's 600x600 pixels your build. - If possible, Ribbon should be the default brush. I would need this delivered and bug-free by January 19. Any questions, please shoot.