fix: store dimensions in JSON state as array not object since order matters #803

seankmartin · 2025-07-07T11:07:41Z

Since JSON objects are unordered in the spec, this could cause issues in processing of neuroglancer states by external tools for objects stored in the state where the name order matters. For example, in something that saves states or processes states.

The primary case where this has come up is in the global viewer dimensions where the order of the names determines the default order of the viewer, so the order matters. I know the precomputed annotation info metadata has a similar pattern too though.

To help with this, this PR is proposing to change the dimensions to be stored in an array, not an object. Here, the dimensions are handled in a split path. One "legacy" path, for pure dictionary style objects, and a new path, which handles arrays. New states are saved as arrays in the JSON state. This happens pretty automatically in the viewer, but from Python there is an extra kind of conversion call which happens on init of a new state.

Old state dims:

"dimensions": {
    "x": [
      4e-9,
      "m"
    ],
    "y": [
      4e-9,
      "m"
    ],
    "z": [
      4e-8,
      "m"
    ]
  }

New dims:

"dimensions": [
    {
      "name": "x",
      "scale": [
        4e-9,
        "m"
      ]
    },
    {
      "name": "y",
      "scale": [
        4e-9,
        "m"
      ]
    },
    {
      "name": "z",
      "scale": [
        4e-8,
        "m"
      ]
    }
  ],

Since JSON dicts don't guarantee any kind of key order in the spec, this could cause issues in downstream processing of neuroglancer states Here, the dimensions are handled in a split path. One legacy path, for dicts, and a new path, as arrays. New states are saved as arrays

seankmartin added 7 commits July 1, 2025 19:22

fix: correct check on input and scales

dbe05f9

fix: remove accidental change to valid check on new space

583b780

fix(python): co-ordinate space supports new state layout

c9acefc

feat: patch old states processed by Python to new state repr

443f048

feat: reintroduce an error on unexpected types

139ee3f

fix(python, test): correct failed test from dims

9748c4b

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