Clarify zoom API about astrowidgets HOT 4 CLOSED

Oh, it's about relative vs absolute zoom. That is get/set of zoom is all that is needed for the functionality, but something along the lines of this is useful:

def zoom(factor):
    self.zoom_level = self.zoom_level*factor

So it's really just trivial syntactic sugar. Now that I look at that, perhaps an alternative is to just tell users to do self.zoom_level *= factor, though? As long as zoom_level is a multiplicative factor rather than a non-linear thing like some other js image viewers I've seen, anyway.

from astrowidgets.

I implemented what I just said above in #15 ...

however, that made me realize a confusing element: ginga distinguishes between "zoom" and "scale". As I understand it, scale is 2d (x and y), while zoom is a fixed change. But zoom is also distinguished by the "rate" being settable. Presumably this is to facilitate user interaction to make the zoom be faster.

My instinct is that the API we're using here is a bit better for the purpose we have here because it's simpler, and is what I think more people have in mind when they think of "zooming" (of course I would since I wrote it 😉). But it's a lot closer to what ginga calls "scale", which might be added confusion. And maybe we do want a way to control the "zoom rate". I just think that should be handled as a widget property and not better of the Python-useful API. Do you have any thoughts on that @pllim ?

from astrowidgets.

Looks like #15 is merged. I'm okay with current implementation. We can revisit extra functionality if users complain about not able to set zoom the other way. Should we close this?

from astrowidgets.

Closed by #15

from astrowidgets.