[WIP] feat/decimated loading

[mbellehumeur]

Context

Changes & Results

Testing

Checklist

PR

• [] My Pull Request title is descriptive, accurate and follows the
  semantic-release format and guidelines.

Code

• [] My code has been well-documented (function documentation, inline comments,
  etc.)

Public Documentation Updates

• [] The documentation page has been updated as necessary for any public API
  additions or removals.

Tested Environment

• [] OS:
• [] Node version:
• [] Browser:

Greptile Summary

This WIP PR introduces decimated volume loading for 3D rendering in OHIF: volumes exceeding a configurable voxel threshold are automatically downsampled via a new decimatedVolumeLoader, a GPU benchmark runs at startup to calibrate sample-distance defaults, and a new SmartScrollbar tracks per-slice load/viewed state with a visual progress fill.

• Auto-decimation pipeline: applyAutoDecimationIfNecessary estimates voxel count from display-set metadata and selects an IJK decimation tuple; CornerstoneCacheService constructs a decimatedVolumeLoader:…:I_J_K volume ID and passes it to Cornerstone's volume cache; an AutoDecimationOverlay badge notifies the user when a volume has been reduced.
• GPU benchmark (gpuPerformanceTest): measures triangle throughput, texture upload, and buffer operations via a temporary off-screen WebGL canvas; stores a generalPerformanceScore in localStorage to set rotateSampleDistanceFactor and sampleDistanceMultiplier once per browser session; Cypress/CPU-rendering paths skip the live test.
• SmartScrollbar + ViewportSliceProgressScrollbar: replaces the legacy scrollbar by default; renders loaded-bytes and viewed-bytes fills via useByteArray batched updates; introduces ViewedDataService to persist per-imageId viewed state across viewports.

Confidence Score: 3/5

Not ready to merge — the PR is explicitly marked [WIP] and several unresolved issues from prior review rounds remain in the code.

Multiple issues flagged in earlier review rounds are still present: numImageFrames is overwritten for decimated volumes in volumeLoadedHandler, decimated volume cache entries are not purged during display-set invalidation, and the GPU result assigns level 'failed' outside the declared union type. New findings in this round are lower-impact but add to the overall debt.

init.tsx (volumeLoadedHandler still corrupts numImageFrames), CornerstoneCacheService.ts (stale decimated volumes survive invalidation, no-op delete calls), gpuPerformanceTest.ts (type-union mismatch on level, debug window assignment).

Important Files Changed

Filename	Overview
extensions/cornerstone/src/utils/decimation/applyAutoDecimationIfNecessary.ts	New utility for auto-decimation of large volumes; fallback loop produces anisotropic K-only decimation for very large datasets; otherwise logic is sound for typical cases.
extensions/cornerstone/src/services/CornerstoneCacheService/CornerstoneCacheService.ts	Volume loading extended with decimated-loader support; volumeImageIds.delete calls inside the invalidation loop use volume IDs instead of display set UIDs (no-ops); decimated volumes still not purged on invalidation (flagged in prior review).
extensions/cornerstone/src/utils/gpuPerformanceTest.ts	New GPU benchmark utility; stores full result on window.gpuPerformanceResult in both paths (debug leak); 'failed' level not in the GPUPerformanceResult.level union (flagged in prior review).
extensions/cornerstone/src/init.tsx	Registers decimated volume loader, runs GPU benchmark on init, adds volumeLoadedHandler; handler still corrupts numImageFrames for decimated volumes (flagged in prior review).
platform/ui-next/src/components/SmartScrollbar/SmartScrollbar.tsx	New compound scrollbar component with ResizeObserver, drag, keyboard nav, and expandable indicator; well-structured with clear context separation and runtime child validation.
extensions/cornerstone/src/Viewport/Overlays/ViewportSliceProgressScrollbar/hooks.ts	New hooks for load/viewed progress tracking; useViewedSliceBytes correctly guards viewedDataService as nullable at runtime despite non-optional type annotation; event cleanup is properly handled.
extensions/cornerstone/src/utils/decimation/constants.ts	Exports decimation constants; AUTO_DECIMATION_VIEWPORT_TYPES includes 'volume' which is not a valid Cornerstone3D ViewportType and will never match.
extensions/cornerstone/src/commandsModule.ts	Adds volume cropping, decimation reload, and quality commands; fixes setVolumeRenderingQulaity typo; reloadVolumeWithDecimation handles camera/preset restoration and concurrent viewport updates.

Comments Outside Diff (1)

1. extensions/cornerstone/src/services/CornerstoneCacheService/CornerstoneCacheService.ts, line 110-145 (link)

   Decimated volumes are never purged from cache during invalidation

   invalidateVolume iterates candidateVolumeIds (baseVolumeId, …:volume3d, …:orthographic) but decimated volumes are stored under the key decimatedVolumeLoader:${baseVolumeIdWithSuffix}:${i}_${j}_${k}. When a display set is invalidated (e.g. after a series reload), the stale decimated volume remains in cs3DCache and will be served on the next viewport render instead of the freshly-loaded data. A scan of cs3DCache._volumeCache for keys that start with decimatedVolumeLoader: and contain the display set UID needs to be added to the purge loop.

   Prompt To Fix With AI

   This is a comment left during a code review.
   Path: extensions/cornerstone/src/services/CornerstoneCacheService/CornerstoneCacheService.ts
   Line: 110-145
   
   Comment:
   **Decimated volumes are never purged from cache during invalidation**
   
   `invalidateVolume` iterates `candidateVolumeIds` (`baseVolumeId`, `…:volume3d`, `…:orthographic`) but decimated volumes are stored under the key `decimatedVolumeLoader:${baseVolumeIdWithSuffix}:${i}_${j}_${k}`. When a display set is invalidated (e.g. after a series reload), the stale decimated volume remains in `cs3DCache` and will be served on the next viewport render instead of the freshly-loaded data. A scan of `cs3DCache._volumeCache` for keys that start with `decimatedVolumeLoader:` and contain the display set UID needs to be added to the purge loop.
   
   How can I resolve this? If you propose a fix, please make it concise.

Prompt To Fix All With AI

Fix the following 4 code review issues. Work through them one at a time, proposing concise fixes.

---

### Issue 1 of 4
extensions/cornerstone/src/utils/decimation/applyAutoDecimationIfNecessary.ts:229-246
**Fallback decimation loop only increments K axis**

When no pre-built candidate achieves the `requiredFactor` (i.e., the volume exceeds `8 × threshold`), the fallback loop keeps I and J fixed at `2` and increments K indefinitely. For a 900×512×512 volume at a 10M-voxel threshold the required factor is ≈ 47 → `[2, 2, 12]`, yielding a volume 6× more coarse in the slice direction than in-plane, making 3D renders look severely anisotropic. The fix would be to balance increments across all three axes in the fallback loop (e.g., cycle through incrementing i, j, and k in turn).

### Issue 2 of 4
extensions/cornerstone/src/utils/decimation/constants.ts:3
`'volume'` is not a valid Cornerstone3D `ViewportType` value — the enum only defines `'volume3d'`, `'orthographic'`, `'stack'`, etc. This entry will never be matched by `resolveViewportType` and is dead code that creates a false impression that plain `'volume'`-typed viewports are auto-decimated.

```suggestion
export const AUTO_DECIMATION_VIEWPORT_TYPES = new Set(['volume3d']);
```

### Issue 3 of 4
extensions/cornerstone/src/utils/gpuPerformanceTest.ts:603-606
**Debug result leaked onto `window` in production**

`window.gpuPerformanceResult` is set in both the success and failure paths of `gpuPerformanceTest`. The full `GPUPerformanceResult` object (including renderer info, texture sizes, and heap metrics) is permanently accessible from the browser console or any injected script. If this is a development-only aid, it should be guarded by a dev/debug flag or removed from production builds.

### Issue 4 of 4
extensions/cornerstone/src/services/CornerstoneCacheService/CornerstoneCacheService.ts:115-125
**`volumeImageIds.delete` calls inside the loop are no-ops**

`this.volumeImageIds` is keyed by `displaySet.displaySetInstanceUID` (see `this.volumeImageIds.set(displaySet.displaySetInstanceUID, volumeImageIds)` in `_getVolumeViewportData`). The loop deletes by `candidateVolumeId` (a fully-qualified volume ID like `cornerstoneStreamingImageVolume:DSUID:volume3d`), which will never match a display-set-UID key. Only the final `this.volumeImageIds.delete(invalidatedDisplaySetInstanceUID)` after the loop is effective. The per-candidate deletes inside the loop should be removed to avoid confusion.

_{Reviews (4): Last reviewed commit: "Add files to merge CornerstoneOverlays." | Re-trigger Greptile}

[claude]

Claude Code Review

This pull request is from a fork — automated review is disabled. A repository maintainer can comment @claude review to run a one-time review.

[netlify]

❌ Deploy Preview for ohif-dev failed. Why did it fail? →

Name	Link
🔨 Latest commit	dcedf30
🔍 Latest deploy log	https://app.netlify.com/projects/ohif-dev/deploys/6a103ac87478dd000874a46d