Recalculate original state when resize() was called

[kevinlaw91]

Proposed fix for #185

[kevinlaw91]

Might need to refactor the fix because most of the code in this fix was borrowed from ShadowViewport.prototype.processCTM()

We cannot reuse processCTM() in the fix because we don't want to call setCTM() at the end. Calling it will reset zoom and pan every time when viewport resizes.

[bumbu]

Thank you for the work.
Will take a closer look at some point.
Agree that we can refactor the code and have less duplication

[kevinlaw91]

This line is only used by ShadowViewport.prototype.init(). So i moved it out and place it after calling processCTM() in init().

[kevinlaw91]

This will allow reuse of processCTM() in SvgPanZoom.prototype.resize()

[kevinlaw91]

@bumbu, I have refactored the code. You can test to see if it is ready for merge. This is a fix of behavior so could be a breaking change.

[bumbu]

Thanks @kevinlaw91
If it is a breaking change then it may be better to postpone it until next major release.
I'm really busy now and just can't find enough time for a bigger release, but I'll try as soon as possible.

[kevinlaw91]

Squashed everything and rebase to master

[kevinlaw91]

Thanks for your time. FYI this is just a simple bug fix for an odd behavior. I believe the old behavior wasn't suppose to be a feature, so it may not be a breaking change either. Anyway, feel free to test it out when you have time. Hope to see this get merged before next major release. ✌️

[bumbu]

I tested it with different SVGs, also I paid attention to SVGs with viewBox attribute. All worked fine.
The changes make sense, and I agree that old behaviour shouldn't be a feature. Still some project may depend on that so I'll release it as a new minor version.

Thanks for the effort!