Trait Widget

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pub trait Widget:
    Brick
    + Send
    + Sync {
Show 13 methods    // Required methods
    fn type_id(&self) -> TypeId;
    fn measure(&self, constraints: Constraints) -> Size;
    fn layout(&mut self, bounds: Rect) -> LayoutResult;
    fn paint(&self, canvas: &mut dyn Canvas);
    fn event(&mut self, event: &Event) -> Option<Box<dyn Any + Send>>;
    fn children(&self) -> &[Box<dyn Widget>];
    fn children_mut(&mut self) -> &mut [Box<dyn Widget>];

    // Provided methods
    fn is_interactive(&self) -> bool { ... }
    fn is_focusable(&self) -> bool { ... }
    fn accessible_name(&self) -> Option<&str> { ... }
    fn accessible_role(&self) -> AccessibleRole { ... }
    fn test_id(&self) -> Option<&str> { ... }
    fn bounds(&self) -> Rect { ... }
}

Expand description

Core widget trait that all UI elements implement.

§Brick Architecture (PROBAR-SPEC-009)

Widget REQUIRES the Brick trait, enforcing the “tests define interface” philosophy:

Every Widget has assertions that define its contract
Every Widget has a performance budget
Rendering is blocked if assertions fail (Popperian falsification)

§Lifecycle

verify: Check Brick assertions (mandatory)
measure: Compute intrinsic size given constraints
layout: Position self and children within allocated bounds
paint: Generate draw commands (only if can_render() returns true)

Required Methods§

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fn type_id(&self) -> TypeId

Get the type identifier for this widget type.

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fn measure(&self, constraints: Constraints) -> Size

Compute intrinsic size constraints.

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fn layout(&mut self, bounds: Rect) -> LayoutResult

Position children within allocated bounds.

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fn paint(&self, canvas: &mut dyn Canvas)

Generate draw commands for rendering.

§Panics

Panics if called when can_render() returns false (Brick verification failed).

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fn event(&mut self, event: &Event) -> Option<Box<dyn Any + Send>>

Handle input events.

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fn children(&self) -> &[Box<dyn Widget>]

Get child widgets for tree traversal.

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fn children_mut(&mut self) -> &mut [Box<dyn Widget>]

Get mutable child widgets.

Provided Methods§

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fn is_interactive(&self) -> bool

Check if this widget is interactive (can receive focus/events).

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fn is_focusable(&self) -> bool

Check if this widget can receive keyboard focus.

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fn accessible_name(&self) -> Option<&str>

Get the accessible name for screen readers.

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fn accessible_role(&self) -> AccessibleRole

Get the accessible role.

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fn test_id(&self) -> Option<&str>

Get the test ID for this widget (if any).

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fn bounds(&self) -> Rect

Get the current bounds of this widget.

Dyn Compatibility§

This trait is dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementations on Foreign Types§

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fn layout(&mut self, bounds: Rect) -> LayoutResult

Lay the video out in bounds.

The bounds are stored as given, so verify can judge them (like Grid and Waveform). They are sanitised where they are used (NaN and infinities become 0, components are clamped to +-1e15, a negative size becomes 0), so every rect and glyph vertex paint emits is finite and the returned size is finite and not negative.

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