Abstraction methods of PdfViewerController.goTo

[xaqtr]

Discussed in #71

^{Originally posted by xaqtr January 26, 2022}
Hi,

first of all thanks for this library @espresso3389, it's really saving us for a work related project right now due to its flexiblity and features.

As I was trying to integrate this plugin into my App, I was kind of lost on how to programmatically scale into the PDF with the PdfViewerController (I wanted to implement a double tap zoom in /out functionality).

I digged into the plugin code and realized that you have the control about everything by using the PdfViewerController.goTo method. and passing a suited Matrix4 value. So my question is whether it would be possible to have methods that abstract the usage of this Matrix4. I think this would benefit many developers as in my opinion it requires some additional knowledge hurdle.

So my proposal would be some additional methods for PdfViewerController, e.g.:

// In this case, scale would be the destination scale 
// (so calling this method more than once with the same parameter will not change the scaling / position)
Future<void> scaleTo({ required double scale, Duration duration })

// Pan to a relative point of the specified page
// x and y would be relative values of the page, where the destination origin will be
// e.g.: pageNumber = 1, x = 0.5, y = 0.5 will put the origin into the center of the first page
Future<void> panTo({ required int pageNumber, required double x, required double y, Duration duration })

I dont' have the best understand about the usage of Matrix4 yet, so I'm not sure whether it's even possible to have such methods, but I would like to hear some opinions on that.
In the meantime I will try to implement the above mentioned methods.

[espresso3389]

1.0.22 that contains the dhanges is released!