The current Dart SDK version is 2.1.0-dev.0.0.flutter-be6309690f.

Because zoomable_image 1.2.0 requires SDK version >=1.19.0 <2.0.0 and no versions of zoomable_image match >1.2.0 <2.0.0, zoomable_image ^1.2.0 is forbidden. So, because flutter_test_1 depends on zoomable_image ^1.2.0, version solving failed. pub get failed (1)

In the method _child(), it seems like the CustomPaint() that is instantiated requires a valid "child" object in order for the gesture detector to function correctly if used in a Scaffold.

I added an empty container as a child, and then things started working as expected, so I believe this may be related to this mentioned in the docs on CustomPaint:

Custom painters normally size themselves to their child. If they do not have a child, they attempt to size themselves to the size, which defaults to Size.zero.

in order to reference this package I think the name in pubspec has to be the same as in the url. URL: flutter_zoomable_image PUBSPEC: zoomable_image

zoomable_image:
    git:
      url: https://github.com/perlatus/flutter_zoomable_image.git

Error on get Packages:

C:\sdks\flutter\bin\flutter.bat --no-color packages get Running "flutter packages get" in lookatmybaby_flutter... Error on line 1, column 7: "name" field doesn't match expected name "flutter_zoomable_image". name: zoomable_image ^^^^^^^^^^^^^^

Whenever I zoomed in there was an annoying jitter - this was caused by using the old zoom to calculate the new offset. Now zooming in completely smooth in my project.

ZoomView has render problem when I use it inside PagerView with NetworkImage provider. When open screen with pager or scrolling pager from one image to another during one second instead next image you can error screen, after one second everything okey before you start scrolling again.

The user is able to zoom out until the image disappears. This fixed it for me:

I changed:

  void _handleScaleUpdate(Size size, ScaleUpdateDetails d) {
    double newZoom = _previousZoom * d.scale;
    bool tooZoomedIn = _image.width * _scale / newZoom <= size.width ||
        _image.height * _scale / newZoom <= size.height;
    
    if (tooZoomedIn) {
      return;
    }

to:

  void _handleScaleUpdate(Size size, ScaleUpdateDetails d) {
    double newZoom = _previousZoom * d.scale;
    bool tooZoomedIn = _image.width * _scale / newZoom <= size.width ||
        _image.height * _scale / newZoom <= size.height;
      
    // Too Zoomed Out
    if (newZoom < 0.9)
        newZoom = 0.9;
      
    if (tooZoomedIn) {
        return;
    }

where 0.9 is the "give" or "leeway" so that the image can zoom out a little.

Image Scrolls out of Viewport. I fixed this in the Horizontal direction, but not the vertical. In the same function, I changed:

// Ensure that item under the focal point stays in the same place despite zooming
    final Offset normalizedOffset =
        (_startingFocalPoint - _previousOffset) / _previousZoom;
    Offset newOffset = d.focalPoint / _scale - normalizedOffset * _zoom;
    
    setState(() {
      _zoom = newZoom;
      _offset = newOffset;
    });
  }

to this:

// Ensure that item under the focal point stays in the same place despite zooming
    final Offset normalizedOffset =
        (_startingFocalPoint - _previousOffset) / _previousZoom;
    Offset newOffset = d.focalPoint / _scale - normalizedOffset * _zoom;
    
    // Out of Bounds X]
    double give = 20.0;
    if (newOffset.dx > give/_scale) 
        newOffset = newOffset.scale(0.0, 1.0).translate(give/_scale, 0.0);  
    else if (newOffset.dx*_scale + size.width*_zoom < size.width - give)
        newOffset = newOffset.scale(0.0, 1.0).translate((size.width - size.width*_zoom - give)/_scale, 0.0);
      
    setState(() {
      _zoom = newZoom;
      _offset = newOffset;
    });
  }

Here the variable "give" is the padding around the picture when it moves to its extreme right or left. Feel free to incorporate this into your code. No attribution or anything necessary. Sorry I couldn't do any fancy animations, but maybe you can figure it out.

It's possible to continue panning the image way off the canvas. Some users have reported crashes, and it's also possible to lose track of where the image is.

We need a stopgap solution to prevent overscrolling until #2 can be implemented.

The center of the screen should not change when the screen is rotated. The image should never be clipped when rotating from portrait to landscape (zoom out) but rotating from landscape to portrait can clip (zoom in) to keep rotation idempotent.

In order to not have a black screen delay when loading network images, being able to provide a lower-res image and swapping it out for a full-res one would be ideal.

Boundaries should be elastic.

• When you zoom in too far, it should let you—but then shrink back to the smallest zoom size.
• When you zoom out too far, it should let you—but then grow to fill the screen.
• When you pan past the boundaries, it should let you—but then pan until the viewport boundaries are back.
• ...

Probably depends on #1.

Should have a delay so that it only animates when not between pinch-zooms.