Foundation crate for rusty-mermaid: primitives, Scene, Theme, geometry, and text measurement.

This crate defines the universal intermediate representation that all diagram types produce and all rendering backends consume. The central type is [Scene], a collection of [Primitive] drawing elements (rects, circles, paths, text, etc.) that is completely backend-agnostic.

Key types

• [Scene] / [Primitive] -- the contract between layout and rendering
• [Theme] / [Style] / [TextStyle] -- visual configuration
• [Color] / [Point] / [BBox] -- geometric primitives
• [Shape] -- node shape catalog (rect, diamond, circle, etc.)
• [Direction] -- layout flow direction (TB, BT, LR, RL)

Key traits

• [Renderer] -- backends implement this to consume a [Scene]
• [TextMeasure] -- text dimension measurement for layout

Examples

use rusty_mermaid_core::{
    Scene, Primitive, Style, Color, Point, BBox, TextStyle, TextAnchor,
};

let mut scene = Scene::new(200.0, 100.0);

// Add a filled rectangle
scene.push(Primitive::Rect {
    bbox: BBox::new(100.0, 50.0, 120.0, 40.0),
    rx: 4.0,
    ry: 4.0,
    style: Style {
        fill: Some(Color::rgb(236, 236, 255)),
        stroke: Some(Color::rgb(147, 112, 219)),
        stroke_width: Some(2.0),
        ..Style::default()
    },
});

// Add a text label
scene.push(Primitive::Text {
    position: Point::new(100.0, 50.0),
    content: "Hello".into(),
    anchor: TextAnchor::Middle,
    style: TextStyle::default(),
});

assert_eq!(scene.len(), 2);