Smith Chart (scattersmith) pan & zoom functionality

[radiosystemtoolbox]

This is a feature request for smith chart plotting. Smith chart plotting for impedance traces in RF electronic circuits is great in plotly. Here it is an example plot produced with such functionality:

Nevertheless, it lacks the basic pan & zoom capability that other plots have. In the case of smith chart:

Where, for other scatter plots, we have the tooling for pan & zoom:

I assume adding these same tools to this smithchart plotting might be reasonable.

[alexcjohnson]

Certainly reasonable, though it may take a long time to get on our roadmap unless someone is willing to sponsor the work. Zoom and pan will also take some designing, so if you can recommend behavior you've seen in a different program and found nice (or even what NOT to do), that would be very helpful. For example:

• Do we want to keep the plot area circular or when you zoom in would it expand to fill the rectangular domain? I guess based on analogy to polar and ternary probably we'd keep circular, is that reasonable? What then would the zoom interaction look like? Perhaps you click-drag and the start and end of the drag form the diameter of a circle, which becomes the new view? This I guess is the closest analog of cartesian, where the start and end of the drag are the corners of a rectangle that becomes the new view.
• How do you specify the view when zoomed/panned? xcenter, ycenter, and radius? realaxis.center, imaginaryaxis.center, and radius? Something else? Presumably mostly this would be determined by the GUI so you wouldn't need to calculate them yourself, but not always so we should find a way to describe the view that's meaningful to the chart creator.
• In the current implementation, tickvals are hardcoded for both coordinates. If you gain the ability to pan and zoom you'll probably also want automatic ticks of some sort, such that to get back the current default behavior you'd say something like nticks=5 and we'd automatically choose these ticks for full range view, but as you zoom in we'd choose different values, and it's not exactly obvious how to do this. In general I guess we wouldn't even be able to put the real labels across the center and the imaginary labels around the edge, depending on exactly where you've zoomed into.

[SeansHuang]

@alexcjohnson Hello ， May I ask if Smith chart supports admittance traces? Like this：