HTML5 Canvas App

My company develops the following app: [login to view URL] (audio is in portuguese, but you can get everything from the video without listening to it). The programmer who developed it left us due to other personal projects in his life, and there are several bugs left behind. We would like to make it again from scratch. This is your task. If you are hired, after you finish you'll be hired multiple times again for maintance and eventual minor changes. We expect you to be available for these extra projects in the future. There is a few very important details that the video left behind: 1 - The final image produced by the canvas must be converted to a jpg in high resolution. the image must be downloadable by the user and you are expected to send it to the server. 2 - The images position, width, height and all sorts of informations needed to remake the diagramation must be seriarizable to a json or xml so that it can be loaded later from the server. You are of course expected to provide load methods to load a json in the same format that your application produces so that the user can resume his/her work later. 3 - You'll have access to a rest api method from our server to fetch the images urls that are loaded on the navigation bar. 4 - You'll have access to our programmers to talk about client-server integration. All of them speak English fluently.