Changelog

All notable changes to Fresco are documented here. The format is based on Keep a Changelog and the project adheres to Semantic Versioning.

0.1.1 — 2026-05-12

Small additive release for layered libraries. No breaking changes.

handle.appendNavButton(svg, title, onClick) — extensions append a button to the same .fresco-nav flexbox column that holds the built-in zoom-in / zoom-out / reset / fullscreen. Returns an unsubscribe function that removes the button on cleanup. Used by Etcher to add a pencil button that toggles annotation mode.
animation and update-viewport events bridged on the viewer handle (handle.on("animation", fn)). The existing zoom / pan events only fire on the intent of an input; the new ones fire on every spring-interpolated frame so overlays glide with the image instead of jumping at endpoints.

<Fresco.viewer> now sets phx-update="ignore" on its host div. Without it, LiveView morphdom patches walk the viewer's children on every render and wipe OSD's runtime-added canvas + extension overlays. The hook still receives updated callbacks for attribute changes (e.g. data-src swaps continue to work) — phx-update protects children only.
Nav column reordered top-to-bottom: fullscreen → zoom-in → zoom-out → reset. Extensions appending via handle.appendNavButton land at the bottom of the column.

Initial release. Polished pan-zoom image viewer for Phoenix apps, with a deliberate extension surface for layered libraries.

<Fresco.viewer id src class> LiveView function component
Pan: click-drag, touch-drag, keyboard arrows
Zoom: mouse wheel, pinch, double-click, dedicated buttons, + / - keys
Fit-to-view initial state regardless of image / container aspect ratio
Heroicons nav overlay at top-left: zoom-in, zoom-out, reset, fullscreen
Viewport clamped so the image can't be panned off-screen (visibilityRatio: 1.0, constrainDuringPan: true)
Smooth animations tuned for snappy responsiveness (animationTime: 0.3, springStiffness: 10)
Browser fullscreen mode

window.Fresco.viewerFor(domId) — synchronous lookup of a live viewer handle
window.Fresco.onViewerReady(domId, callback) — async-safe lookup that fires the callback as soon as the viewer is ready (handles mount-order races when an extension hook mounts before its host viewer)
window.Fresco.registerSourceProvider(predicate, factory) — registers a predicate-matched URL transformer; first registered provider that matches wins, falling back to a default plain-image provider
Viewer handle exposes: imageToScreen / screenToImage, getViewportBounds, fitBounds, setSource, swapSourcePreservingBounds, and on(event, handler) for zoom / pan / open / resize events

OpenSeadragon ~> 4.1 lazy-loaded from jsDelivr on first mount
One bundled JS file (priv/static/fresco.js); no npm dep, no build step in consumer apps
Heroicons SVGs inlined; no PNG sprite dance against a CDN