Feature: render EMF+ metafile images

[caio-pizzol]

What's happening

Documents containing EMF+ (Enhanced Metafile Plus) images show a placeholder SVG with "Unable to render EMF+ image" instead of the actual image. Standard EMF conversion to SVG works, but EMF+ uses GDI+ drawing records that the converter explicitly skips.

This is a follow-on to (). The classic EMF/WMF work landed, but EMF+ is still not truly rendered.

Codebase verification

The current import/render path does support classic EMF/WMF conversion.

• packages/super-editor/src/core/super-converter/v3/handlers/wp/helpers/encode-image-node-helpers.js converts metafiles during import via convertMetafileToSvg(...).
• packages/super-editor/src/tests/extensions/image.test.js documents that EMF/WMF are rendered like normal images after conversion.
• packages/super-editor/src/tests/import-export/emf-wmf-conversion.test.js asserts EMF/WMF are converted to svg/bmp/png for display while preserving original files for DOCX round-trip export.

But EMF+ is explicitly detected and downgraded to a placeholder today.

• packages/super-editor/src/core/super-converter/v3/handlers/wp/helpers/metafile-converter.js scans EMR_COMMENT records for the EMF+ signature 0x2B464D45.
• In that same file, convertEmfToSvg(...) returns a placeholder SVG labeled "Unable to render EMF+ image" instead of rendering the image when EMF+ is detected.

Why it's happening

The current EMF renderer path is built around the extracted rtf.js EMF/WMF converter and standard EMF records. EMF+ payloads use GDI+ drawing commands, so the current path deliberately avoids attempting full conversion and renders a placeholder instead.

Suggested fix

1. Check for an embedded bitmap fallback in EMF+ files and render that when present.
2. Extend or replace the current converter with EMF+ / GDI+ record support.
3. Add a WASM or server-side conversion path for EMF+ to a browser-safe format.

Acceptance criteria

• EMF+ images render actual document content instead of the placeholder SVG.
• Existing classic EMF/WMF rendering behavior is preserved.
• DOCX round-trip export continues to preserve the original metafile asset.
• Add targeted test coverage for at least one EMF+ sample document.

Reproduction

File: m3 proposal.docx
Page 1: Cover page shows "Unable to render EMF+ image" instead of branded cover design.

m3 proposal.docx

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Ref: SD-2503

[linear]

IT-1012