blinc_portal_ui

Immediate-mode widgets for canvas closures. Renders interactive widgets and free-form paint inside a [blinc_canvas_kit::CanvasKit] element: node bodies in [blinc_node_editor], tool palettes, in-canvas mini UIs.

let outcome = portal
    .begin(ctx, &kit, body_rect)
    .style(&PortalStyle::from_active_theme())
    .host(&host_bridge)
    .run(|ui| {
        ui.label("Threshold");
        ui.slider(&threshold).range(0.0..1.0).show();
        let resp = ui.chart(&samples).area().pip(true).show();
        if resp.pip_clicked {
            open_chart_popover(ui.host().rect_to_screen(resp.rect));
        }
    });

Documentation

• Widget reference — every widget with a usage example. Covers input widgets (label, button, switch, slider, numeric_input, text_input, color_picker, select) and the square-aspect display-portal family (chart, pie_chart, radar_chart, noise, texture, sdf_shape).
• Host integration — module map, the frame contract, click + keyboard hook installation, overlay anchoring, fit-content sizing via FrameOutcome::natural_width/height, PiP popovers, theme integration (per-frame PortalStyle::from_active_theme + per-portal overrides + ShadowToken resolution), signal lifecycle, custom widgets.

Imgui, not retained mode

Canvas closures re-run every frame. had_canvas_painted already cache-busts the canvas interior, so an imgui rhythm (re-emit every frame) drops in cleanly: no offscreen texture, no diffable tree, no second event router. Widget calls are draw + hit_rect; the kit provides both.

State

Two layers:

1. Widget-local (slider drag offset, hover ease, cursor) lives in PortalStorage, a HashMap<WidgetId, Box<dyn Any>>. WidgetId hashes the portal id + the id stack at the call site
   • an optional caller key, so re-emitting the same call sequence produces stable ids. Untouched entries drop at frame end.
2. Semantic (the values widgets edit) lives in Signal<T>. Every built-in value-bearing widget reads + auto-subscribes via the reactive tracker and writes on edit. Mutations from outside the portal (FSM, animation, retained-mode cn::input on the same signal) flip the portal dirty bit and the next composite repaints.

What works, what doesn't

Built-in widget catalog: label, label_signal, button (+ six variants), switch, slider, numeric_input, text_input, textarea, file_picker, color_picker, select_trigger / select / select_signal, chart (line / bar / area), pie_chart, radar_chart, wave_graph (oscilloscope / audio waveform), noise (Perlin / Worley / Voronoi), texture (ImageId + inline RGBA), sdf_shape (2D + 3D, eight variants). Layout primitives: horizontal, spacing, push_id, allocate_painter, request_animation. Custom widgets are one-liners over allocate_painter.

Gaps:

• No flexbox. Layout combinators are vertical / horizontal stack + indent.
• No Tab traversal between widgets — focus moves only on pointer click.
• Selection (drag-to-select), clipboard (Cmd+C / V / X), and IME composition for text_input.

Modules

See docs/integration.md for the per-module breakdown and host-side wiring patterns.