WindowControls

The minimize / maximize / close button cluster on the trailing edge of a TitleBar. Rendered only when PlatformTitleBarHost::renders_custom_controls is true (Windows + Wayland; never on macOS).

These are deliberately NOT built on top of the regular Button widget: Button carries a 72 dp minimum width, themed padding, focus ring and border, none of which are appropriate for a flush-fitting Win11-style window control. Instead, each control is a small composing widget ControlButton built from primitives (FixedSize + ZStack + RectWidget + Center + TextWidget) so we inherit centering, theming and reactive hover for free.

For M2 the maximize/restore swap is not implemented — the maximize button always shows the □ glyph. M3+ will add a Signal<bool>-driven glyph swap once the host can update it from WindowEvent::Resized.

API reference

📖 Full rustdoc API for this module

pub struct WindowControlsLayout

Layout snapshot that WindowControls exports to its parent TitleBar so the after_paint aggregator can read the per-button WidgetIds. Populated during WindowControls::build.

The maximize slot is the Switcher that wraps the two glyph buttons (□ / ❐), not either child directly: the inactive Switcher child is dormant and has Rect::ZERO bounds, but the Switcher container itself is always laid out by the parent HStack and has valid bounds. A synthetic tap dispatched at the Switcher's bounds-center routes through hit-testing to whichever child is currently visible.

pub struct WindowControlsLayout { /* fields */ }

pub type ControlAction

Action invoked when a ControlButton is tapped.

pub type ControlAction = Rc<dyn Fn(&mut EventContext)>;

pub struct ControlButton

A compact, flush-fitting window-control button.

Composes existing primitives — a FixedSize cell wrapping a ZStack of (hover background, centred glyph). Hover state is tracked in a Signal<bool> that drives a derived Signal<SurfaceRole> background, so a hover change repaints with no relayout. Both the glyph color (fg) and the hover surface are stored as roles (ColorProp / SurfaceRole) that resolve against the current theme at paint time — so the cluster retints live across ctx.set_theme(...) without a rebuild.

pub struct ControlButton { /* fields */ }

Methods

pub fn new(glyph: &'static str, width: f32, height: f32, fg: impl Into<ColorProp>) -> Self

Create a control button with the given Unicode glyph, fixed cell dimensions, and foreground color role. The hover background defaults to transparent until overridden via hover_background.

pub fn hover_background(mut self, role: SurfaceRole) -> Self

Set the surface role painted over the title bar background while the pointer is inside the button cell. The default is SurfaceRole::Transparent (flat).

pub fn on_tap(mut self, action: impl Fn(&mut EventContext) + 'static) -> Self

Register the callback invoked when the user taps this button.

pub struct WindowControls

The minimize / maximize / close cluster, laid out as an HStack of ControlButtons. Each cell forwards taps to the supplied host.

pub struct WindowControls { /* fields */ }

Methods

pub fn new( host: Rc<dyn PlatformTitleBarHost>, show_restore: Signal<bool>, close_action: Option<CloseAction>, ) -> Self

Build the minimize / maximize / close cluster for the given platform host.

show_restore drives the maximize ↔ restore swap: true renders the Restore affordance (a11y name and action), false the Maximize one. It is deliberately not called is_maximized: a window is also restorable — and must not offer "maximize" — while it is WindowPlacement::Fullscreen, which WindowPlacement::is_maximized reports as false. See crate::title_bar::TitleBar's own derivation.

close_action overrides the default ctx.close_window() behaviour (e.g. to show a "save before closing?" dialog).