PPTX export does not preserve HTML font sizing and causes text wrapping/clipping

[open-design-crew]

Summary

The exported PPTX does not preserve the font size and text layout from the original HTML deck. As a result, text wraps differently, overflows, or is partially clipped in the generated presentation.

Current behavior

When exporting a multi-slide HTML deck to PPTX and opening the result in WPS Office, the font size appears inconsistent with the source HTML. Text that fits on one line in the HTML may wrap onto multiple lines in the PPTX, and some copy is not fully visible within the original text area.

Observed examples include the slide heading content wrapping differently and extending beyond the expected layout boundaries.

Expected behavior

The PPTX export should preserve the source HTML typography and layout as closely as possible, including font size, line breaks, text box dimensions, and full text visibility. Exported slides should not introduce unexpected wrapping or clip copy that is visible in the original HTML.

Steps to reproduce

1. Open a multi-slide HTML deck in the local Open Design Electron app.
2. Export the deck as PPTX.
3. Open the generated index.pptx in WPS Office.
4. Compare the exported slides with the original HTML preview, especially slides containing large headings and Chinese text.
5. Check font size, line wrapping, text-box overflow, and whether all copy is visible.

Notes

• The issue was observed during local Electron validation of PR fix(desktop): reveal every deck-stage slide in multi-page PPT/PDF export #5645.
• The corresponding PDF export preserves the slide appearance more faithfully.
• The screenshots below compare the source HTML layout with the exported PPTX layout.

Evidence

Source HTML preview

Exported PPTX in WPS Office

Why this matters

PPTX is a user-facing export format. Typography and text overflow differences can make exported presentations materially different from the authored design and can hide or truncate important content.

[lefarcen]

Thanks for splitting this out — the repro details and the HTML-vs-PPTX screenshots make the failure mode very clear.

PR #5645 is fixing the separate “later slides go blank” export path, but this one looks like a fidelity bug in the editable PPTX route itself. The current export code hands the live slide DOM to the vendored dom-to-pptx engine in apps/desktop/src/main/deck-capture.ts, and right now we only do a narrow stabilization pass for backgrounds plus a very specific large single-line text case before generating the .pptx. My current read is that general HTML text metrics are still drifting in the PPTX/WPS rendering path, which would line up with the font-size change, extra wrapping, and clipping you captured here even though PDF stays faithful.

Keeping this open as a bug. The next useful step on our side is to reduce this into a focused regression case around Chinese headings / line-height / text-box width so we can pin whether the mismatch is coming from font embedding, line-height translation, or WPS-specific reflow.

[lefarcen]

PR #5852 is now open against this. It targets the editable PPTX path in apps/desktop/src/main/deck-capture.ts and specifically avoids forcing white-space: nowrap when a heading is visually split across multiple rendered lines, which matches the wrapped-title regression captured here. Keeping this issue open until the fix lands and the export behavior is verified on the merged build.

[github-actions]

This issue has been inactive for 30 days and is being marked as stale. If it is still relevant, please leave a comment or push an update — otherwise it will be closed in 7 days.

This is only a queue-management step, not a rejection of the report. Closed issues can be reopened when work resumes.

[lefarcen]

Quick sync: PR #5852 is still the active fix path for this issue.

The latest head there is carrying the follow-up work from review — preserving explicit PPTX line breaks for CSS-wrapped headings and adding the long no-newline CJK regression coverage — so this is still active work rather than a stale report. I’ve removed the stale label and we’ll keep this issue open until that PR lands and the merged build is verified.