Component Props

<PowerPointViewer> follows the Vue binding's contract with two Svelte 5 conventions: events are callback props (onload, not @load), and the content prop is named source.

Content and appearance

Prop	Type	Default	Description
source	Uint8Array | ArrayBuffer | null | undefined	-	Raw .pptx bytes. Assigning a new value loads the new presentation in place.
fonts	ViewerFontSource[]	-	Licensed font sources supplied by the host ({ family, src, format?, weight?, style? }).
theme	ViewerTheme	built-in	Partial palette / radius / raw CSS vars; see Theming.
locale	string	'en'	UI locale (BCP 47). Register non-English dictionaries via pptx-svelte-viewer/i18n.
class	string	-	Extra class on the root element.

Chrome and behaviour

Prop	Type	Default	Description
initialSlide	number	0	Slide shown after load (0-based, clamped).
showThumbnails	boolean	true	Show the thumbnail sidebar.
showToolbar	boolean	true	Show the navigation/zoom toolbar (and, when editable, the ribbon).
showNotes	boolean	true	Show the speaker-notes panel and its toolbar toggle. Pass onnotesupdate to make the panel editable; omit it for read-only notes.
hiddenActions	ToolbarActionId[]	-	Toolbar buttons and/or ribbon tabs to hide (see values below).
fileName	string	-	Display name shown in the desktop title bar.
smartArt3D	boolean	false	Opt in to the Three.js (WebGL) SmartArt renderer. Requires the optional three dependency; falls back to SVG when it is unavailable or the WebGL mount fails.
editable	boolean	false	Enable in-place editing: select, drag, resize/rotate handles, double-click text editing, keyboard shortcuts, undo/redo, save/download.

hiddenActions values

ToolbarActionId is a union of quick-access button ids and ribbon tab ids:

• Buttons: share, broadcast, export, undo, redo, record, notes, fullscreen, zoom, navigation
• Tabs: file, home, insert, draw, design, transitions, animations, slideShow, record, review, view, help

zoom and navigation each hide their whole control cluster. record is shared by the quick-access button and the ribbon tab, so hiding it removes both.

<!-- A read-only embed with the collaboration entry points removed -->
<PowerPointViewer source={bytes} hiddenActions={['share', 'broadcast']} />

File > Options pickers

These drive the built-in Appearance and Language pickers under File > Options. Without the on*Change callbacks the user's choice is persisted to localStorage automatically; supplying a callback hands persistence to the host.

Prop	Type	Default	Description
defaultThemeKey	string	stored, else 'default'	Initial Appearance selection: a key into availableThemes (or the built-in THEME_CATALOG).
availableThemes	readonly ThemeCatalogEntry[]	THEME_CATALOG	Theme choices offered by the Appearance picker.
onThemeChange	(themeKey: string) => void	-	Fired when the user picks a theme (Design tab or Options).
defaultLocale	string	stored, else locale	Initial Language selection (locale code).
availableLocales	readonly LocaleCatalogEntry[]	registered locales	Language choices offered by the Language picker; defaults to every locale registered via registerTranslations.
onLocaleChange	(locale: string) => void	-	Fired when the user picks a language from Options.
accountAuth	AccountAuthConfig	disabled	Optional hook point for a real sign-in flow in File > Account ({ enabled, onSignIn, signedInUser? }).

Precedence

Once the user picks a theme from the UI, that catalog key drives the effective theme for the rest of the session; the theme prop still wins whenever the resolved key is 'default'. Similarly, a user-picked language always wins over the locale prop for the session.

Autosave

See Getting Started > Autosave for the full flow.

Prop	Type	Default	Description
autosave	boolean	true	Recovery autosave to the shared IndexedDB store (requires filePath). A policy ceiling over the title-bar toggle; see below.
filePath	string	-	IndexedDB record key (typically the open file's name/path). Autosave is inert without one.
autosaveIntervalMs	number	File > Options cadence	Debounce window (ms). An explicit value outranks the user's AutoRecover setting.

Who decides: the autosave prop or the AutoSave toggle?

The rule is the same in all five bindings and lives in one shared decision function, resolveAutosaveActivation:

The autosave prop is a policy ceiling. The title-bar AutoSave toggle is the user's preference inside it.

autosave	What runs	The toggle
omitted	Autosave runs; the user's toggle decides, defaulting to on.	Works.
true	Same as omitted: the host permits it, the user decides.	Works.
false	Autosave is off, and no recovery prompt is offered on load.	Inert (it must not move).

A preference can never exceed a policy, which is why autosave: false also takes the switch away: a control that silently does nothing is worse than no control. canEdit/editable and a filePath key remain hard requirements either way.

The same rule governs the cadence: an explicit autosaveIntervalMs is a host policy honoured as given, and omitting it follows the user's File > Options > Save > "Save AutoRecover information every N minutes" (two minutes by default).

The default is true because crash recovery that is off by default is crash recovery nobody has.

Recovering a snapshot

When a deck finishes loading and a snapshot newer than 24 hours exists for the same key, the viewer raises a "Recover unsaved changes?" dialog offering Restore or Discard. Restore loads the snapshot's bytes; Discard deletes it. It is deliberately not raised for a snapshot this tab has already taken delivery of (for example when the host itself restored it through restoreSessionDeck).

Collaboration

See Collaboration for the config shape and transports.

Prop	Type	Default	Description
collaboration	CollaborationConfig	-	When set, connects to the room and syncs edits in real time. Clearing it tears the session down.
shareDefaults	{ roomId?: string; userName?: string; serverUrl?: string }	-	Prefilled values for the built-in Share dialog (Broadcast reuses serverUrl).

Event callbacks

Prop	Signature	Fired when
onload	(detail: ViewerLoadDetail) => void	A presentation finishes loading ({ slideCount, canvasSize }).
onerror	(message: string) => void	A load fails (message is human-readable).
onslidechange	(index: number) => void	The active slide changes (0-based).
onchange	() => void	After every committed editing mutation (move / resize / rotate / delete / duplicate / nudge / text / notes).
ondirtychange	(dirty: boolean) => void	The unsaved-edits flag flips.
oncontentchange	(content: Uint8Array) => void	The serialized document bytes change.
onmodechange	(mode: string) => void	The viewer mode changes ('preview' | 'edit' | 'present' | 'master').
onzoomchange	(zoom: number) => void	The zoom level changes (1 = 100%).
onselectionchange	(elementIds: string[]) => void	The element selection changes.
onslidecountchange	(count: number) => void	The total slide count changes.
onnotesupdate	(notes: string) => void	The user commits a speaker-notes edit (change / blur). Omit to render the notes panel read-only.
onopenfile	() => void	Host override for the File > Open action.
onautosave	(bytes: Uint8Array) => void	After each successful autosave snapshot.
onautosavetoggle	(enabled: boolean) => void	The desktop title bar toggles AutoSave.
onstartcollaboration	(config: CollaborationConfig) => void	The user starts a session from the Share/Broadcast dialog.
onstopcollaboration	() => void	The user stops the collaboration session.
onThemeChange	(themeKey: string) => void	The user picks a theme (note the camelCase name; it belongs to the Options-picker group above).
onLocaleChange	(locale: string) => void	The user picks a language (camelCase, Options-picker group).

Payload types

interface ViewerLoadDetail {
	/** Number of slides in the loaded presentation. */
	slideCount: number;
	/** Slide canvas size in pixels. */
	canvasSize: CanvasSize; // { width: number; height: number }
}

Type exports

import type {
	CanvasSize,
	CollaborationConfig,
	CollaborationRole,
	CollaborationTransport,
	PowerPointViewerApi,
	PowerPointViewerProps,
	ViewerLoadDetail,
	ViewerTheme,
	ViewerThemeColors,
	AutosaveStatus,
	AutosaveRecord,
} from 'pptx-svelte-viewer';

Theme presets and helpers (vermilionLightTheme, vermilionDarkTheme, defaultThemeColors, defaultRadius, themeToCssVars, defaultCssVars) are exported from the package root; i18n helpers (registerTranslations, translate, keyToLabel, translationsEn, and the TranslationKey type) live under pptx-svelte-viewer/i18n. See Theming and Localization.