Pan / Zoom test with Processing

I needed a convenient way to zoom in (to see the details) and out (to see the overall layout) in a PGraphics. The result reminds me a bit of the interface of online street maps: click and drag to pan, use the scroll wheel to zoom in and out. It's not very obvious in the video, but the 6 tiles are not static images, but animated (it's drawing lines continuously on them). The tiles are 400x400 pixels in size, and their content is 1500x1500 pixels.