Build or edit javascript code to build a graphics measurement tool.

Hello there, I have a web application that is based in JAVA backend, and javascript/html front-end. The web application allows users to analyze images (images are actually electrocardiograms). I need a JavaScript library that allows users to: (sort of like an image caliper) 1. Draw measurement lines. 2. Drag and Drop drawn measurement lines to compare distances on an image. 3. Measure angles 4. Distances must be calibrated to the background grid that looks like this (see attached). Where one big box is 200ms wide and 1mV high. Alternatively, if it can't be done automatically, there should be a button that says "measure distances", which prompts the user to calibrate by drawing a box around the big box in the grid. 5. Have a zoom window to make precise measurements. There should be a small <div> that I can attach to the image that houses buttons for drawing/measurement controls I want it to be similar to this: [login to view URL] There is a GITHUB project on this: [login to view URL] However, the GITHub project doesn't have dragging, and doesn't have image self-calibration. He has given us permission to use and edit his code, you can use it as a starting point.