Cranpose Foundation

Fundamental building blocks and system services for Cranpose UI.

When to Use

This crate provides the essential primitives that cranpose-ui is built upon. It contains:

• The Modifier System: The core logic for Modifier chains and node delegation.
• Basic Layouts: Box, Row, Column (the layout algorithms themselves).
• Input APIs: PointerInput, FocusManager.

Library authors building their own widget sets or design systems might depend on cranpose-foundation to avoid pulling in the opinionated widgets of cranpose-ui.

Key Concepts

• Modifier Node: A stateful object attached to a layout node that can participate in layout, drawing, and input handling. This is more efficient than the stateless Modifier chain object, which is just a factory configuration.
• Semantics: Accessibility and testing information attached to the UI tree.
• Focus System: Manages keyboard navigation and focus request propagation.

Example: Custom Modifier

Creating a custom modifier involves defining a ModifierNode and a fluent builder method.

use cranpose::prelude::*;

// 1. Define the Node
struct MyModifierNode;

impl ModifierNode for MyModifierNode {}

// 2. Define the Element (Factory)
struct MyModifierElement;

impl ModifierElement<MyModifierNode> for MyModifierElement {
    fn create(&self) -> MyModifierNode {
        MyModifierNode
    }
    
    fn update(&self, _node: &mut MyModifierNode) {
        // Update node properties if needed
    }
}

// 3. Extension method for fluent API
trait MyModifierExt {
    fn my_custom_modifier(self) -> Modifier;
}

impl MyModifierExt for Modifier {
    fn my_custom_modifier(self) -> Modifier {
        self.then(MyModifierElement)
    }
}