Core types and traits for Presentar UI framework.

This crate provides foundational types used throughout Presentar:

• Geometric primitives: [Point], [Size], [Rect]
• Color representation: [Color] with WCAG contrast calculations
• Layout constraints: [Constraints]
• Events and messages: [Event], [Message]
• Draw commands: [DrawCommand] for GPU rendering

Quick Start

use presentar_core::{Color, Size, Constraints, Rect};

// Create a size
let size = Size::new(100.0, 50.0);

// Create constraints
let constraints = Constraints::new(0.0, 200.0, 0.0, 100.0);
let bounded = constraints.constrain(size);

// Create a color
let red = Color::RED;
assert_eq!(red.r, 1.0);

Widget Trait

The core [Widget] trait defines the measure-layout-paint cycle:

use presentar_core::{Widget, Constraints, Size, Canvas};

struct MyWidget;

impl Widget for MyWidget {
    fn measure(&self, constraints: &Constraints) -> Size {
        constraints.constrain(Size::new(100.0, 50.0))
    }

    fn layout(&mut self, size: Size) { }

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