83 lines
6.0 KiB
Markdown
83 lines
6.0 KiB
Markdown
# DeckCraft architecture
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> **Last reviewed:** 2026-10-13 · **Last updated:** 2026-10-13 · **Change:** minor (transition frames: perspective meshes, slide parts, headless compositor; previous: created from the code on main at d556ff9) · **Target:** Microsoft PowerPoint for Mac 16.113 (Microsoft 365)
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How DeckCraft is built today. The binding rules (layering, everything is a command, thin UI, never
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break wasm, never crash) are in [AGENTS.md](../AGENTS.md) §3–§5; this document describes what
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exists. 117k lines of Rust in 23 crates, 3 apps and `xtask`; 504 `#[test]` functions
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(`cargo xtask stats` counts them per crate).
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## Layers
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`cargo xtask layers` enforces that a crate depends only on lower layers (the table in
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`xtask/src/layers.rs`, which is authoritative; AGENTS.md §4 gives the simplified picture), and that
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nothing below L6 uses egui, eframe, winit or rfd.
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| Layer | Crates | What they do |
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|---|---|---|
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| L0 | `geom`, `color`; standalone `bitstream`, `matroska`, `ogg`, `opus` | EMU/pt units, transforms, ~180 preset shape generators re-derived from ECMA-376, adjust handles, hit testing; RGB/HSL and DrawingML colour transforms; MKV/WebM and Ogg demuxers, the Opus decoder |
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| L1 | `model`, `fonts`; `h264`, `hevc`, `vp9`, `av1`, `isobmff` | Presentation, masters, layouts, slides, shapes, text, themes, tables, charts, transitions, animations, placeholder inheritance (`resolve`); font database (craft-fonts + system) with metric-compatible substitutes for Office fonts (Carlito for Calibri, Caladea for Cambria, Liberation for Arial/Times); video decoders and the MP4/MOV demuxer |
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| L2 | `text`, `anim`, `format`, `media` | Shaping (HarfRust), UAX #9 bidi, UAX #14 line breaking, autofit, caret hit testing; per-shape animation state over time, the show state machine, transition frame layouts, Morph matching; `.deckcraft` (zip + JSON + media) and outline text; media probing, decoding, mixer and clock |
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| L3 | `render`, `pptx` | `vello_cpu` raster of slides, masters and layouts (fills, outlines, effects, pictures, tables, charts, Morph frames); PPTX import/export from ECMA-376 |
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| L4 | `pdf` | PDF export through krilla |
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| L5 | `engine` | Sessions, documents, selection, undo history on shared slide snapshots, the command registry (226 commands in `cmd/*`), pointer tools, keys, AutoRecover, the panic guard (`guard.rs`) |
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| L6 | `ui-egui`, `mcp` | The PowerPoint-style interface (ribbon with 10 tabs + contextual tabs, canvas, thumbnails, panes, 27 dialogs, show and presenter windows, the JSON control channel); the MCP server (JSON-RPC 2.0 over stdio), headless or connected to a running app |
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| apps | `deckcraft` (desktop: eframe/wgpu, cpal audio, logging), `deckcraft-cli` (run, render, convert, mcp, app), `deckcraft-web` (trunk; WebGPU with WebGL2 fallback), `xtask` | Exempt from layering |
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The media codecs and containers are clean-room pure Rust, 59k lines, shared in spirit with
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FilmCraft.
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## Data model
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A `Presentation` holds a theme set, slide masters with their layouts, slides, sections, custom
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shows, comments, media and document properties. Shapes are a tree (`ShapeKind`: preset or custom
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geometry, picture, table, chart, group, connector, ink, media, SmartArt-as-group, and `Opaque` for
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anything read from PPTX that DeckCraft doesn't model: its XML is kept and written back). Text
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bodies hold paragraphs of runs with DrawingML properties; formatting resolves slide → layout →
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master → theme at render time. Transitions live on slides; animations are the flat ordered list the
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Animation Pane shows, rebuilt into PowerPoint's timing tree on save.
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## Commands and frontends
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Every user-visible action is a `CommandSpec` (id, label, ribbon/menu place, shortcut, params doc,
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`enabled`, `run`) in `crates/engine/src/cmd/*`. The UI, `deckcraft-cli run`, the JSON control
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channel (`deckcraft --control PORT`, [control-protocol.md](control-protocol.md)) and MCP
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([mcp.md](mcp.md)) all dispatch through `Session::execute`, so they behave identically.
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Programmatic calls never open dialogs. Pointer gestures go through `Session::pointer`, keys through
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`Session::key`.
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## Rendering and the show
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The renderer draws a slide to an RGBA pixmap on the CPU; the UI uploads it as an egui texture.
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Transitions are layers of textured quads over the old and new slide images, or over their
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backgrounds and contents rendered apart (Dynamic Content), from `anim::transition_frame`: 3-D
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effects project cards through a perspective camera and `anim::layer_mesh` subdivides them so
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textures stay straight; soft edges are per-corner opacities. The show renders the slides once per
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transition and only composites cached textures each frame; `render::composite_transition` is the
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CPU twin used by `deckcraft-cli render-transition` and the tests. The show window and the presenter view are egui viewports; animation state per shape
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comes from `anim::timeline` each frame. PDF export renders each slide at print resolution and
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overlays an invisible real-text layer with embedded font subsets.
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## File I/O
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- **PPTX** (`crates/pptx`): lenient reader (unknown parts skipped, malformed parts logged and
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ignored, sizes and depths bounded, zip bombs capped), writer that PowerPoint opens without
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repair. Unknown elements round-trip through `Opaque` and `raw_ext` fields.
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- **Native** (`crates/format`): zip with `mimetype`, `presentation.json` and `media/<id>`; readers
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ignore unknown fields; `.slidecraft` files from before the rename still open.
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- Formats and their gaps: [file-format-parity.md](file-format-parity.md).
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## Quality gates
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`cargo xtask ci`: rustfmt check, clippy `-D warnings`, tests, layering, asset attribution
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(`cargo xtask assets`), wasm32 check. CI runs it on Ubuntu for every PR and push to `main`;
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macOS is built and tested by the release workflow only. Releases (pushes to `release`) build signed
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macOS, Windows, Linux, FreeBSD and web artifacts.
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## Revision history
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| Date | Change | Summary |
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|---|---|---|
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| 2026-10-13 | minor | Transitions: perspective meshes, background/content parts, CPU compositor |
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| 2026-10-10 | major | Created from the code on main (d556ff9) and AGENTS.md §4 |
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