Shapes data does not conform to LayerDataProtocol

🐛 Bug

Since Shapes is a Layer, its data should fulfill LayerDataProtocol. However, (some) internal ways of populating this don’t preserve the required properties

To Reproduce

Steps to reproduce the behavior:

Run the test:

def test_data_protocol():
    shp = Shapes()
    # Add 2-D ellipse
    data = np.ones((2, 2))
    data[:, 0] = [20, 20] # Center
    data[:, 1] = [10, 10] # Axes
    shp.add_ellipses(data)
    # Check for properties
    assert hasattr(shp.data, 'dtype')
    assert hasattr(shp.data, 'shape')

Expected behavior

I would expect that shp.data would have the shape and dtype properties.

Environment

• Please copy and paste the information at napari info option in help menubar here:

napari: 0.4.13
Platform: Linux-5.13.0-28-generic-x86_64-with-glibc2.31
System: Ubuntu 20.04.3 LTS
Python: 3.9.10 | packaged by conda-forge | (main, Feb 1 2022, 21:24:11) [GCC 9.4.0]
Qt: 5.12.9
PyQt5: 5.12.3
NumPy: 1.20.3
SciPy: 1.7.3
Dask: 2022.01.1
VisPy: 0.9.4

OpenGL:
- GL version: 4.6 (Compatibility Profile) Mesa 21.0.3
- MAX_TEXTURE_SIZE: 16384

Screens:
- screen 1: resolution 2560x1440, scale 1.0
- screen 2: resolution 1920x1080, scale 1.0

Plugins:
- Labeling: 0.1.dev9+g4bf5a30
- console: 0.0.4
- scikit-image: 0.4.13
- svg: 0.1.5

[gselzer]

What do you think of changing the current Shapes.data object then to Shapes.shapeData, and adding throwing an clear NotImplementedError in the Shapes.data getter and setter? That seems preferrable to getting an error saying that the data just doesn’t have these attributes.

While I can understand this - it would be a big breaking change to take away layer.data from shapes, everyone using the layer would have to change.

That’s a great point, yeah. For that reason, we probably shouldn’t do this.

[tlambert03]

cc @sofroniewn