Fission 0.12.0: Interactive canvas and complete Web input

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August 23, 2026

Fission 0.12.0 adds a retained, backend-neutral camera and a declarative infinite canvas without creating a second rendering or state system. It also completes the input work those widgets require: multiple pointer identities, pinch and magnification, cancellation, detailed scrolling, browser editing shortcuts, context menus, and reliable WebGPU presentation at real application sizes.

This is a minor release because it adds major public capabilities and changes the public pointer and scoped-action contracts.

One camera for ordinary retained widgets

InteractiveViewer pans and uniformly scales one normal Fission widget subtree. The camera may be runtime-owned or controlled by application state, and its behavior is expressed with backend-neutral policies for boundaries, clipping, axes, minimum and maximum scale, wheel behavior, and inertia.

let viewer: Widget = InteractiveViewer {
    id: Some(WidgetId::explicit("floor-plan")),
    child: Image::asset("floor-plan.png").into(),
    min_scale: 0.25,
    max_scale: 8.0,
    zoom_policy: ViewportZoomPolicy::WheelWithModifier,
    ..Default::default()
}
.into();

Mouse, touch, stylus, modifier-wheel, macOS magnification, and browser pinch feed the same core controller. A draggable child wins an ordinary one-pointer drag, while a second contact promotes the nearest viewer to a captured two-pointer pan and zoom without a camera jump when one contact is released.

Callbacks preserve their bound action payload. Reducers read the live camera, focal points, pan delta, scale factor, input family, modifiers, and lifecycle from ctx.input.viewport_interaction().

InfiniteCanvas stays declarative

InfiniteCanvas builds on InteractiveViewer instead of introducing an imperative scene authority. Applications continue to own committed nodes, edges, selection, and optional controlled camera state.

The initial widget includes:

•

stable node and edge identities with negative and positive world coordinates;

•

straight and cubic edges, retained labels, grids, and stable z-order;

•

single, toggle, and marquee selection;

•

node movement, eight constant-screen-size resize handles, and symmetric grid snapping;

•

precise transformed hit testing and transformed accessibility bounds; and

•

visible-world batching for grid and edge paths.

The new interactive-canvas example demonstrates both widgets with responsive desktop and compact layouts. The public widgets are available through the normal desktop, android, ios, mobile, and web features. Static site, SSR, and Terminal-only builds intentionally do not expose them.

Complete pointer facts across shells

Fission no longer collapses every touch contact into one synthetic mouse pointer. PointerEvent now retains PointerId and PointerKind, explicit cancellation, line-versus-pixel scroll mode, scroll lifecycle, and multiplicative magnification. Native and Web test control use the same detailed events, which makes multi-contact behavior deterministic to test.

This is a source change for code that directly constructs or exhaustively matches PointerEvent.

Web behaves like a Fission application

Web applications now receive platform-correct secondary clicks and Fission-owned keyboard editing, selection, copy, cut, paste, and context menus. Browser defaults remain suppressed by default. An application can selectively delegate keyboard, pointer, touch, wheel, context-menu, or clipboard behavior with a composed BrowserDefaults value:

WebApp::<AppState, _>::new(App)
    .with_browser_defaults(
        BrowserDefaults::CONTEXT_MENU | BrowserDefaults::WHEEL,
    );

The release also fixes the blank or transparent WebGPU output seen at larger window sizes. Fission validates WebGPU work before presentation, configures the browser canvas surface correctly, sizes the forked Vello buffers from the real frame workload, and mirrors framework diagnostics into the browser console.

Authoring-tree and scoped-action contracts

Widget::kind() and Widget::visit() provide read-only, depth-first access to the authoring tree for integrations that need to discover widget structure. Scoped handlers now return an explicit ScopedActionResolution: handle the action locally, or forward an envelope once through normal dispatch. Fission rejects ambiguous multiple forwards and prevents a forwarded action from recursively re-entering the handler that forwarded it.

Migration

Update the framework and CLI:

fission = { version = "0.12.0", default-features = false, features = ["desktop"] }

cargo install cargo-fission --version 0.12.0 --locked

Then make these source updates where applicable:

Add pointer_id and kind to direct Down, Move, and Up constructors.

Handle PointerEvent::Cancel and PointerEvent::Magnify, and add scroll delta_mode and phase.

Return ScopedActionResolution::Handled from existing scoped handlers, or Forward(envelope) when dispatch should continue.

Use ctx.input.viewport_interaction() and ctx.input.canvas_interaction() for runtime event facts while keeping stable application context in the bound action.

Browser autocorrect, autofill, and soft-keyboard replacement/deletion still need full hidden-textarea value and selection synchronization. Hardware keyboard shortcuts, clipboard operations, context menus, and composition commits are implemented; the remaining work is tracked in issue #168.

Older post

Fission 0.11.1: Web LiveTest

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