fix(wsi): correct point annotation placement on SM/WSI viewports at n…

[katyayni1999000]

Context

Fixes WSIViewport annotation placement on HiDPI (Retina/high-DPI) displays.

WSIViewport sizes its canvas in CSS pixels and its internal transform (getTransform()) already operates in CSS-pixel space. The canvasToIndex method was pre-multiplying canvasPos by devicePixelRatio before transforming, and indexToCanvas was post-dividing by devicePixelRatio after transforming. On displays where devicePixelRatio > 1, this caused annotations to be placed at incorrect positions because the DPR scaling was applied twice.

Changes & Results

• canvasToIndex: Removed canvasPos.map((it) => it * devicePixelRatio) — pass canvasPos directly to transformPoint.
• indexToCanvas: Removed .map((it) => it / devicePixelRatio) — return transformPoint result directly.

Before: Annotations on WSI images are offset/misaligned on HiDPI screens (devicePixelRatio > 1).
After: Annotations render at the correct positions on all displays. No behavior change on standard displays where devicePixelRatio === 1.

Testing

1. Open a WSI image in a viewer using WSIViewport.
2. On a HiDPI/Retina display (or set browser zoom to simulate devicePixelRatio > 1), place an annotation (e.g. length or area tool).
3. Verify the annotation anchor points land exactly where you clicked, rather than being scaled away from the origin.

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: Windows 11"
• "Node version: 24.14.0"
• "Browser: Chrome (HiDPI display, devicePixelRatio = 2)"

Summary by CodeRabbit

• Bug Fixes
  • Improved coordinate conversion between canvas space and image index space for viewport interactions.
  • Fixed point/position mapping so interactions translate consistently on high-density displays.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: a7c64b13-7072-4f10-9ec8-3add90ed027b

📥 Commits

Reviewing files that changed from the base of the PR and between 3cc9ce9 and 3897eb1.

📒 Files selected for processing (1)

• packages/core/src/RenderingEngine/WSIViewport.ts

🚧 Files skipped from review as they are similar to previous changes (1)

• packages/core/src/RenderingEngine/WSIViewport.ts

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📝 Walkthrough

Walkthrough

WSIViewport no longer applies devicePixelRatio scaling in either direction when converting between canvas and index coordinates. Raw canvas positions now flow directly through the inverse transform, and transformed index positions are returned directly.

Changes

WSIViewport Coordinate Conversion

Layer / File(s)	Summary
Remove devicePixelRatio from canvas↔index transforms packages/core/src/RenderingEngine/WSIViewport.ts	canvasToIndex drops the devicePixelRatio pre-scaling on input, and indexToCanvas drops the devicePixelRatio post-division on output.

Estimated code review effort: 1 (Trivial) | ~2 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title uses the required semantic-release style and matches the PR’s main fix for WSIViewport annotation placement.
Description check	✅ Passed	The description includes context, changes, testing steps, and a completed checklist, so it mostly satisfies the template.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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