Module state 

Internal state for ColorPicker.

ColorComponents is constructed once in the picker’s build() and holds derived Signals for each RGB / HSV channel plus typed setters that recompose the bound Signal<Color> when a single channel changes. Centralizing the conversions here keeps every subwidget (HSV canvas, hue strip, alpha strip, RGB/HSV spinners, preview) reading from clean per-channel signals without duplicating the conversion logic.

Hue preservation across grays

When saturation drops to 0 or value drops to 0, the underlying sRGB representation has no hue (gray / black). A naive value.map(|c| c.to_hsv().0) would clamp the visible hue back to 0° — which makes the HSV canvas snap from “red” back to “red at the top-left” the moment the user drags down to white. We avoid this by caching the last non-degenerate hue in ColorComponents and returning it whenever the bound color’s saturation/value collapses.