[Feature] Added enablePanAlways to allow the user pan any view without restrictions.

[diegoveloper]

I added an option to allow us to pan the widget without any restriction.

class MyHomePage extends StatelessWidget {
  const MyHomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Center(
      child: ClipRect(
        child: Container(
          height: 300,
          color: Colors.white,
          child: PhotoView.customChild(
            backgroundDecoration: const BoxDecoration(color: Colors.transparent),
            enableRotation: true,
            minScale: _minScale,
            maxScale: _maxScale,
            enablePanAlways: true,
            child: FlutterLogo(),
          ),
        ),
      ),
    );
  }
}

Before
https://user-images.githubusercontent.com/4898256/120548459-fc0bdf00-c3b7-11eb-8fb7-ee7612cc0e48.mov

After
https://user-images.githubusercontent.com/4898256/120548469-ff06cf80-c3b7-11eb-999a-37c7d90b4504.mov

[jjkavalam]

Thank you ! Could it be possible to make a release with this feature ?

I am looking to implement an UI that allows users to select a part of the image as their profile picture. This feature combined with existing functionality in https://pub.dev/documentation/photo_view/latest/photo_view/PhotoView-class.html#controllers will get the job done 🎉

[TheJulianJES]

So this also reverted #420?

[Jackjun724]

oh my god, #420 fix master api bugs, It's reverted here, I think it's error.