It is possible to implement an infinite zoom in HTML canvas, this is the source code of a proof of concept that I implemented and here you can test it live.
It is actually quite tricky to implement, and most probably you'll need to use big decimals.
The approach I followed uses the same coordinate space as d3-zoom. Basically, you have three coordinates, x, y and k. K is the zoom. If k is 2 it means that you have doubled everything.
Now, if you want to do infinite zoom, it is very easy to reach k = 64
, but that is already outside of float64 precision and you'll have a lot of artifacts, where translating in the image is not smooth, or you don't zoom in where you want.
One way to avoid those artifacts is to use coordinates that have infinite length, for example BigIntegers. To make my implementation easy and compatible with d3-zoom, I used big decimals instead, but I had to implement my own library of BigDecimals, basically infinite precission on the integer part and 32bits of precision on the decimal part. Of course, you also need to adapt the zooming library to support BigDecimals. Moreover, in the case of d3-zoom, a lot of calculations where done in the initial coordinate space (k=1)
but division of floats will always have an error and it is also perceivable once you are deep enough. To avoid that you need to do all computations locally.
It might sound like a lot of hassle to insist on using the d3-zoom library, but zooming UX is actually tricky, specially if you combine that at different k
, you'll need to consider scrolling, zooming on the phone, double tapping...
In case you want to use SVG transformations, then you'll need to fake it. You'll introduce nodes when they are barely visible, allow to scale them. However, most probably you'll also need to fake it when they are too big to avoid artifacts there.