deckcraft/docs/file-format-parity.md

File-format parity with PowerPoint

Last reviewed: 2026-10-14 · Last updated: 2026-10-18 · Change: minor (native chart payloads stored in bounded ZIP members; previous: major, community PR wave 2026-10-14: seven owned PPTX corpus files, embedded fonts, EMF/WMF clip regions, threaded comments (#70), chart trendlines and workbooks (#335), SmartArt written as a diagram, tags and custom XML kept, picture export DPI; duplicated rows and headers folded; previous: trivial, lines in scaled groups, #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); an owned corpus of decks we author round-trips tables, charts, animations, media, sections, masters and layouts, comments, links and actions, custom shows, rotated groups, inherited placeholders, text effects and body layout, theme effects, fills, bevels, connectors, 3-D models and animation bounce end. Not measured against PowerPoint renders or decks from outside this repo	crates/pptx/tests/it/corpus.rs, corpus_kinds.rs, corpus_elements.rs, corpus_style.rs, corpus_themes.rs, corpus_charts.rs, corpus_media.rs, roundtrip.rs, sample.rs, malformed.rs, sniff.rs; 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	Handed over by the system (command line, file association) it starts the slide show, as in PowerPoint; File › Open opens it for editing. The macOS Finder event arrives with #432	crates/ui-egui/src/opening.rs tests
.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
PDF	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 outline; .md as Markdown (headings are slides, list items bullets) (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. PNG can leave the slide background out (transparentBackground, Export… “Transparent background”, deckcraft-cli render --transparent), so only the slide's content is opaque (#784)	render, engine, UI and CLI 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	yes (file.export format gif, Export…, deckcraft-cli, MCP export)	One frame per slide from the slide renderer; size small/medium/large/extra large or 16–3840 px wide, 0.1–600 s per slide, loop forever or play once, slide range, hidden slides skipped; a 256-colour palette per frame (exact, or NeuQuant above 256 colours). Transitions and build animations are not animated	crates/engine/src/gif_export.rs tests (decoded frames, size, delay, loop, hidden slides, hostile params), MCP, CLI and export dialog tests
MP4 / MOV video of the deck	export	n/a	no	Needs timeline render + H.264 encode	none
Print	yes	n/a	no	PR #66 (browser) open	none

Pictures and media inside decks

Native files retain a nonempty chart kept sidecar: relationships, part names, content types and nativeEntry references live in presentation.json; exact binary payloads live in distinct chart-parts/<index> ZIP members. This keeps workbooks and drawings through a native save before exporting back to PPTX without expanding workbook bytes into JSON numbers. Chart parts and media share the 4 GiB inflated-byte and 100,000-item budgets; each member is read through the existing 2 GiB entry limit. Missing chart members are reported by load_checked and left empty. A present chart member that fails decoding, CRC or its entry limit refuses the file immediately, so later corrupt members cannot reuse the remaining inflation budget. Invalid, reused or ambiguous references are refused. A synthetic 3 MiB payload test checks the ZIP layout and bounded reads, alongside shared-budget and all-owner round trips.

Older native files without a sidecar still load. Earlier inline chart byte arrays are read under the existing manifest-size limit, then charged to the shared budget; saving migrates them to ZIP members. Builds predating chart-sidecar support ignore it and lose it on resave. The intermediate build that required inline bytes cannot read the new referenced representation.

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). Rectangle clip regions (INTERSECTCLIPRECT, EXCLUDECLIPRECT, EXTSELECTCLIPRGN) limit later drawing. EMF+ only pictures play every EMF+ drawing record (brushes incl. gradients and textures, pens, paths, curves, images, strings, transforms, clipping; see crates/metafile/src/emfplus.rs for the few exceptions). 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
Embedded fonts	yes	yes	p:embeddedFontLst read and written. TrueType, OpenType and Embedded OpenType faces are used to draw; MicroType Express subsets are kept and written back, not drawn
3-D models (.glb)	yes	kept	The model part round-trips (p:contentPart, including an mc:AlternateContent choice and its fallback picture). Not drawn as a mesh and not inserted from the ribbon

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	Header, footer, date and slide-number text on the notes master is kept. Edited in View ▸ Notes Master. Notes keep their run and paragraph formatting (bold, italic, underline, size, levels, indents, bullets), shown and kept when edited in the notes pane and Notes Page (crates/pptx/tests/it/notes.rs). PDF notes pages print them as plain text; levels and bullets inherited from a custom notes master aren't shown
Handout master	yes	yes	Header, footer, date and slide-number text is kept. Edited in View ▸ Handout Master
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
Text: runs, paragraphs, bullets, numbering, levels, autofit, columns, vertical, RTL, script fonts, fields, hyperlinks	yes	yes	Round-trip tests incl. justLow, date fields and paragraph defRPr (the defaults a placeholder's runs inherit, including a link). A click or hover action keeps its sound, endSnd, and a custom show's "Show and return". Gradient and outline on a run, autofit, columns, vertical and RTL text, tab stops and line spacing round-trip (corpus_style.rs)
Effects: shadow, glow, soft edges, reflection	yes	yes	On a run, inner shadow, reflection and soft edges are kept along with the outer shadow and glow
3-D: scene3d, sp3d	kept	kept	A bevel preset with no sp3d of its own is written back on shapes and theme effect styles. Bevels, cameras, face lighting and extrusion sides draw approximately
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	Merges and both diagonal borders round-trip
Charts (c:chartSpace)	yes	yes	Original XML kept in Chart.raw. Trendlines (type, order or period, forecast, intercept, equation and R²) are read, written and drawn. A combo chart's secondary value axis is read and is not written back when the chart is rebuilt. An unchanged chart also keeps its embedded workbook and the other parts its relationships point at, under fresh keptN names so they never replace a part DeckCraft writes (#335); editing the chart drops that workbook instead of writing a stale one
Charts (cx: chartex: waterfall, funnel, treemap, sunburst, histogram, Pareto, box)	yes	yes	Unchanged parts kept, with their embedded workbook (#335); edited and new ones written from the model with a plain-chart fallback. Treemap and sunburst hierarchy levels kept; region maps kept, drawn as tiles (no map geometry)
SmartArt (dgm)	the drawing part as a group (text laid out on its dsp:txXfrm rectangle), and the outline from the data model (Text Pane)	as a diagram: data model from the outline; layout, quick style and colour parts (the file's own kept until the layout is switched); the group as the cached drawing	DeckCraft's layout definitions are simple; a diagram without a cached drawing isn't drawn. SmartArt kept only as XML, without its relationship parts, still loses the drawing and data parts (#203)
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; repeat, triggers and bounce end kept; rewind lost (#77)
Comments: legacy	yes	yes
Comments: modern threaded (p188)	yes	yes	Written next to the flattened legacy part; replies and resolved state round-trip (threads_and_resolved_round_trip)
Unknown slide-level elements (graphicFrame OLE, extensions, mc:AlternateContent)	kept	kept	Rendered as a labelled placeholder with the preview picture when present
Embedded fonts	yes	yes	MicroType Express subsets kept, not drawn
Tags (p:custDataLst) on the presentation, slides and shapes	yes	yes	Add-ins such as think-cell keep their identity; tags_survive_round_trip
Custom XML data, sensitivity label (docMetadata/LabelInfo.xml), custom document properties	kept verbatim	yes	SharePoint metadata and the label survive a save; custom_xml_label_and_custom_properties_survive_save
VBA	no	no
Encryption (password to open)	no	no

What would move the PPTX number

1. A larger owned corpus (corporate templates, SmartArt, chartex charts, EMF, embedded fonts, every transition and animation) in a corpus repo. crates/pptx/tests/it/corpus.rs and corpus_kinds.rs already check open → save → reopen (parts and text) for decks we author: tables, charts, animations, media, sections and masters/layouts among them. Still needed: render checks and a PowerPoint reference render for each (owner runs PowerPoint).
2. The round-trip losses above (#70, #74, #77).
3. SVG rendering. EMF+ records inside EMF/WMF are still not drawn.

Revision history

Date	Change	Summary
2026-10-18	minor	Native chart payloads use referenced ZIP members and share media byte/item limits; old inline sidecars remain readable. Synthetic tests cover multi-megabyte layout, all shape owners, shared budgets, missing/corrupt members and invalid references. Scores and milestone scope unchanged
2026-10-15	trivial	Native .deckcraft files serialize a nonempty chart kept sidecar (relationships, part names, content types and bytes). Older files without it still load; empty sidecars are omitted. Headless PPTX → edit → native save/reopen → PPTX checks keep the workbook and drawing bytes; editing chart data still drops the stale workbook
2026-10-15	trivial	PPTX interactive timing sequences keep later On Click steps and paragraph click builds (trigger_steps.rs); mixed starts and independent buttons survive import/edit/save/reopen
2026-10-15	minor	A .pptx slide that can't be read is reported instead of dropped in silence: file.open and file.openBytes return lostSlides, the app shows a message and opens a repaired copy (Save asks for a new name), and deckcraft-cli warns on stderr (#203)
2026-10-16	minor	PNG slide export with a transparent background (#784)
2026-10-16	trivial	A .ppsx opened from the command line or the file association starts the slide show (#862)
2026-10-14	minor	Community PR wave folded: one row each for .pptx (seven owned corpus files), outline, 3-D models, embedded fonts, text, effects, 3-D (extrusion sides draw now), SmartArt (written as a diagram) and VBA (tags and custom XML are kept)
2026-10-12	minor	SmartArt import lays each shape's text out on its dsp:txXfrm text rectangle instead of the shape box
2026-10-13	minor	EMF/WMF rectangle clip regions limit later drawing; EMF+ records remain
2026-10-13	minor	Embedded fonts read and written; TrueType, OpenType and Embedded OpenType faces drawn
2026-10-13	minor	Owned corpus round-trip (parts and text). Notes-master header, footer, date and slide-number text is written back
2026-10-13	minor	Owned corpus for comments, links and actions, custom shows, rotated groups and inherited placeholders. Paragraph defRPr and action sounds (including custom-show return) survive a save
2026-10-13	minor	Owned corpus for text effects, body layout, theme effects, fills, bevels and connectors. A run's inner shadow, reflection and soft edge, and a bevel preset with no kept 3-D XML, survive a save
2026-10-14	minor	3-D models (.glb) round-trip, including an alternate-content fallback picture; animation bounce end is read and written (corpus_media.rs)
2026-10-14	minor	Chart trendlines are drawn (linear, exponential, logarithmic, polynomial, power, moving average, forecast, equation and R²)
2026-10-14	minor	Chart trendlines round-trip (corpus_charts.rs); merges, diagonal borders, columns, autofit, vertical text and WordArt warp are in that slice
2026-10-13	minor	Add-in tags on the presentation, slides and shapes read and written
2026-10-13	minor	Custom XML parts, the sensitivity label and custom properties kept on save
2026-10-13	minor	Owned corpus round-trip for tables, charts, animations, media, sections and masters. Handout-master header, footer, date and slide-number text is written back
2026-10-14	minor	PNG and JPEG slide export record their resolution (scale × 72 dpi; the default 2× picture is 144 dpi)
2026-10-13	trivial	Unchanged charts keep the embedded workbook (ppt/embeddings/) and chart relationships (#335)
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)
2026-10-11	minor	Speaker notes: formatting shown in the notes pane and Notes Page and kept when they are edited
2026-10-11	minor	Animated GIF of the deck: export yes (#171)
2026-10-10	major	Created from PowerPoint 16.113.4's CFBundleDocumentTypes, crates/pptx reader/writer and tests, and the open round-trip issues
2026-10-13	minor	Comments: the writer emits the modern threaded part (p188) next to the flattened legacy one; the reader prefers the modern part and scales its EMU positions (#70)