I'm designing an editing program (Mac/Windows) that has a slightly unusual scheme for zooming and controlling the mouse cursor: a normal mode in which the cursor works normally, and a special mode in which the mouse cursor remains in the centre of the window and moving the mouse moves everything else, allowing you to move indefinitely for miles, and the mouse scroll wheel in this mode allows to zoom in and out by increments of 1.41x with the centred cursor as the focus. If this is confusing this video shows the special mode in action. This is managed with the following:
- A short middle mouse button click switches between those two modes
- A long middle mouse button click resets the view to the default zoom, focus, and normal cursor mode
- The scroll wheel zooms in and out, but only in the special mode
Obviously none of this works on a laptop without a mouse, which is a big problem, so I need to find key combinations on the keyboard that allow all this smoothly. By smoothly I mean you should be able to zoom in/out and switch modes all while your other hand is operating the trackpad, you want to be able to zoom at the same time as moving around. So using the arrow keys as part of the key combos probably wouldn't be convenient for users who prefer to operate the trackpad with their right hand (probably most of them), and obviously the usual combos for text editing are taken. I'm pretty free to use exotic kinds of combos (e.g. not using Ctrl or Cmd), although it's probably best if it doesn't get too weird.
If you were a user of a program with such modes of operation, what would you prefer as key combos when a typical mouse isn't available?
Edit: I just need an answer to the actual question, opinions on what is already done just make me have to explain why my approach is advantageous. I know it might be hard to appreciate when you never got to use this approach, but I can tell you that for certain things it's much better than anything else, this much cannot be overstated.