Maximum minimum ratio support is required.

[intelryzen]

We are using your plug-in well and are using your plug-in to operate the actual service. It is evaluated as the best chart library in Plutter. However, there are some problems with the plug-in.

First, the zoom recognition of both fingers is not good, so it is difficult to zoom in and out.

Second, the maximum reduction radius is not specified. Currently, the scope of reduction seems to be small. I hope we can widen the radius of reduction to the maximum. Thank you.

[mafanwei]

The maximum and minimum scaling is an API that can be adjusted freely, but there may be some UI problems, which is determined by the underlying structure. I have considered whether to reconstruct this project, but I haven't started because I don't have enough time