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Nikita RakitinandCursor
d04df05249
A default export is 2 pixels per point. Without a resolution, Preview treats those pixels as 72 dpi and the picture opens at twice the slide's size. PNG pHYs and JPEG JFIF density now say scale times 72, so the default is 144 dpi. Screenshots stay untagged. Co-authored-by: Cursor <cursoragent@cursor.com>
8.3 KiB
8.3 KiB
File-format parity with PowerPoint
Last reviewed: 2026-10-14 · Last updated: 2026-10-14 · Change: minor (a PNG or JPEG slide export records its resolution, so the default 2× picture is 144 dpi; previous: groups with a small legacy child coordinate space draw outlines at their own width, #233) · Target: Microsoft PowerPoint for Mac 16.113 (Microsoft 365)
Every format PowerPoint reads or writes, DeckCraft's support, fidelity and how it is tested. Gaps are itemized in gaps.md. Dimension score: ~58% ready (estimated), 60–110 h to parity.
Weights inside this dimension: PPTX 70%, PDF export 10%, image export 5%, legacy binary formats 5%, everything else (templates, shows, macros, ODP, video, GIF, outline) 10%.
Documents
From /Applications/Microsoft PowerPoint.app/Contents/Info.plist CFBundleDocumentTypes (Editor =
PowerPoint opens and saves; Viewer = opens only).
| Format | PowerPoint | DeckCraft read | DeckCraft write | Fidelity / notes | Tested by |
|---|---|---|---|---|---|
.pptx presentation |
Editor | yes | yes | Broad (see below); never measured on real decks | crates/pptx/tests/roundtrip.rs, sample.rs, malformed.rs, sniff.rs (30 tests); opened in PowerPoint by hand 2026-10-06 |
.potx template |
Editor | yes (as a presentation) | no: written with the .pptx content type |
file.saveTemplate is Save As under another name |
none |
.ppsx slide show |
Editor | yes (as a presentation) | no: written as .pptx content |
Doesn't start in show mode | none |
.pptm / .potm / .ppsm macro-enabled |
Editor | no | no | Should open and keep vbaProject.bin without running it |
none |
.ppt / .pot / .pps 97–2003 binary |
Editor | no | no | Owner decision; import only would be enough | none |
.odp OpenDocument |
Editor | no | no | none | |
.thmx Office theme |
Viewer | no | no | Browse for themes is a P2 row | none |
.deckcraft native (zip + JSON) |
n/a | yes (also .slidecraft) |
yes | Lossless for the DeckCraft model, forward compatible | crates/format tests |
| export | no | yes | Slides, notes pages, handouts (1–9); real-text layer with embedded subsets, links, bookmarks. Slide artwork is a raster image at print resolution, not vector | crates/pdf tests |
|
Outline .rtf / .txt |
export (RTF), import (outline) | .txt/.md outline (slide.fromOutline) |
.txt outline |
No RTF | engine tests |
| PNG / JPEG slide images | export | n/a | yes (file.export, deckcraft-cli render) |
Matches the editor's renderer. PNG pHYs and JPEG JFIF density are scale × 72 dpi (default scale 2 is 144 dpi), so Preview shows the slide's real size |
render and engine tests |
| TIFF / BMP / GIF slide images | export | n/a | no | Easy (the image crate writes them) |
none |
| Animated GIF of the deck | export | n/a | no | none | |
| MP4 / MOV video of the deck | export | n/a | no | Needs timeline render + H.264 encode | none |
| yes | n/a | no | PR #66 (browser) open | none |
Pictures and media inside decks
| Kind | PowerPoint | DeckCraft | Notes |
|---|---|---|---|
| PNG, JPEG, GIF (animated), BMP, TIFF, WebP | yes | yes | image 0.25; animated GIFs play since #39 |
| SVG | yes (with PNG fallback) | no | The PNG fallback shows; SVG files can't be inserted |
| EMF / WMF | yes | partial | Drawn as vectors (paths, pens, pattern and hatch brushes, bitmaps, text in the document's fonts with the file's character advances); clip regions and EMF+ records are not drawn. Legacy OLE objects (VML preview) and ActiveX controls show their pictures |
| HEIC | yes (macOS) | no | |
| Audio: MP3, AAC/M4A, ALAC, WAV, AIFF, CAF, FLAC, Ogg Vorbis, Opus | yes (Ogg/Opus partly) | yes | Pure-Rust decoders in crates/media, crates/opus |
| WMA | yes (Windows) | embedded, not playable | |
| Video: H.264, HEVC in MP4/MOV | yes | yes | Pure-Rust, software decode |
| Video: VP9, AV1 in WebM/MKV | partly (OS codecs) | yes | Ahead of PowerPoint for Mac |
| WMV | yes (Windows) | embedded, not playable | |
| Online video (YouTube embeds) | yes | no | Cloud feature |
| Embedded OLE objects | yes | kept on round trip (opaque), not insertable or editable | ShapeKind::Opaque |
3-D models (.glb) |
yes | no | |
| Embedded fonts | yes | no | p:embeddedFontLst ignored |
PPTX coverage (PresentationML / DrawingML)
What crates/pptx reads and writes, from ECMA-376. "Kept" means the XML is preserved untouched for
the round trip even though DeckCraft doesn't model it.
| Part / feature | Read | Write | Notes |
|---|---|---|---|
| OPC package, content types, relationships | yes | yes | Content types found anywhere in the zip (#19); zip bombs capped; relationship cycles bounded |
| Presentation, slide size, sections (p14), custom shows | yes | yes | |
| Slide masters, layouts, placeholders and inheritance | yes | yes | |
| Themes: colour, font (Latin/EA/CS), effect schemes, background styles | yes | yes | Unknown theme parts kept |
| Notes slides and notes master | yes | yes | No notes-master editing view |
| Handout master | no | no | |
| Shapes: preset geometry (~180 presets), custom geometry, groups, connectors | yes | yes | Presets re-derived in crates/geom/src/preset.rs (and preset/extra.rs). Outlines, dashes, arrowheads and ink inside a group, and text, keep their size in points whatever the group's child-coordinate scale (#233). |
| Fills: solid, gradient, picture (stretch/tile/crop), pattern, group | yes | yes | |
| Lines: dash, compound, caps, joins, arrowheads | yes | yes | |
| Effects: shadow, glow, soft edges, reflection | yes | yes | |
3-D: scene3d, sp3d |
kept | kept | Not rendered |
| Text: runs, paragraphs, bullets, numbering, levels, autofit, columns, vertical, RTL, script fonts, fields, hyperlinks | yes | yes | Round-trip tests incl. justLow and date fields |
Text warp (prstTxWarp) |
yes | yes | All 40 presets rendered (crates/geom/src/warp.rs); adjust values (avLst) round-trip |
| Pictures with crop, recolour, duotone, alpha, luminance | yes | yes | |
| Tables with styles | yes | yes | |
Charts (c:chartSpace) |
yes | yes | Original XML kept in Chart.raw |
Charts (cx: chartex: waterfall, funnel, treemap, sunburst, histogram, box) |
no | no | |
SmartArt (dgm) |
drawing part only, as a group | as shapes | Diagram data model lost on save |
Equations (OMML, a14:m) |
no | no | PR #55 open |
Audio / video (p14:media, trim, fades, bookmarks) |
yes | partly | Playback options lost on save (#74) |
Ink (contentPart) |
yes | as a group of freeform lines | PowerPoint sees shapes, not ink |
| Transitions incl. p14/p15 (Vortex, Morph…) | all 48 | all 48 | every_transition_kind_round_trips |
| Animations: timing tree, build paragraphs, triggers, motion paths | yes (flattened to the Animation Pane list) | yes (rebuilt) | every_animation_effect_survives; rewind lost (#77) |
| Comments: legacy | yes | yes | |
Comments: modern threaded (p188) |
yes | no (written as legacy) | Replies and resolved state lost (#70) |
Unknown slide-level elements (graphicFrame OLE, extensions, mc:AlternateContent) |
kept | kept | Rendered as a labelled placeholder with the preview picture when present |
| Tags, custom XML, VBA | no / no / no | ||
| Embedded fonts | no | no | |
| Encryption (password to open) | no | no |
What would move the PPTX number
- An owned corpus of real-world-shaped decks (corporate templates, SmartArt, chartex charts, EMF, embedded fonts, every transition and animation) in a corpus repo, with import → render → export → re-import checks in CI and a PowerPoint reference render for each (owner runs PowerPoint).
- The round-trip losses above (#70, #74, #77).
- SVG rendering, and clip regions inside EMF/WMF.
Revision history
| Date | Change | Summary |
|---|---|---|
| 2026-10-14 | minor | PNG and JPEG slide export record their resolution (scale × 72 dpi; the default 2× picture is 144 dpi) |
| 2026-10-12 | minor | EMF/WMF text and pattern brushes drawn; OLE (VML) and ActiveX previews read |
| 2026-10-12 | minor | Text warps rendered; their adjust values read and written |
| 2026-10-12 | trivial | Groups with a small legacy child coordinate space draw outlines, dashes, arrowheads and ink at their own width (#233) |
| 2026-10-10 | major | Created from PowerPoint 16.113.4's CFBundleDocumentTypes, crates/pptx reader/writer and tests, and the open round-trip issues |