Bounding box has wrong extent for non-base level of multi-scale images

[andy-sweet]

🐛 Bug Report

When showing the bounding box for a multi-scale image at some resolution other than its highest (i.e. other than level 0), it is too large.

💡 Steps to Reproduce

One way to reproduce this issue is to show a multi-scale image in 3D since that always uses the lowest resolution image.

import napari
import numpy as np
from skimage.transform import pyramid_gaussian

image = np.random.rand(8, 8, 8)
ms_image = list(pyramid_gaussian(image, downscale=2, max_layer=3))
scale = 3 * (2,)

viewer = napari.Viewer(ndisplay=3)
layer = viewer.add_image(ms_image, scale=scale)
layer.bounding_box.visible = True

napari.run()

There are ways to write tests with non-public APIs to force similar behavior for 2D. Or you can force the multi-scale image slicing code to use a specific level to see the effect in 2D.

💡 Expected Behavior

I expect the bounding-box to always show the correct extent of the image, regardless of the scale being viewed.

🌎 Environment

napari: 0.4.17rc4.dev804+g1bcbbf885.d20240625 Platform: macOS-14.5-arm64-arm-64bit System: MacOS 14.5 Python: 3.10.14 | packaged by conda-forge | (main, Mar 20 2024, 12:51:49) [Clang 16.0.6 ] Qt: 5.15.11 PyQt5: 5.15.10 NumPy: 1.26.4 SciPy: 1.13.1 Dask: 2024.5.1 VisPy: 0.14.2 magicgui: 0.8.2 superqt: 0.6.6 in-n-out: 0.2.1 app-model: 0.2.7 npe2: 0.7.5

OpenGL:

• GL version: 2.1 Metal - 88.1
• MAX_TEXTURE_SIZE: 16384
• GL_MAX_3D_TEXTURE_SIZE: 2048

Screens:

• screen 1: resolution 2560x1440, scale 1.0
• screen 2: resolution 1512x982, scale 2.0

Optional:

• numba: 0.59.1
• triangle not installed

Settings path:

• /Users/asweet/Library/Application Support/napari/napari-dev_bed8b9b3d61b11a9560a577ec715d63283498f35/settings.yaml Plugins:
• napari: 0.4.17rc4.dev804+g1bcbbf885.d20240625 (81 contributions)
• napari-console: 0.0.9 (0 contributions)
• napari-ome-zarr: 0.5.2 (2 contributions)
• napari-svg: 0.1.10 (2 contributions)

💡 Additional Context

This issue comes from a similar fix: https://github.com/napari/napari/pull/6319#issuecomment-2192432547

I think this can be fixed by modifying the child transform so that it also factors in the scale component of tile2data, not just the offsets.