Cursor rule

1---
2description: Rust code style and conventions for skia-rs
3globs: ["**/*.rs"]
4alwaysApply: true
5---
6 
7# Code Style & Conventions
8 
9## Rust Edition & Version
10 
11- **Edition**: 2024
12- **MSRV**: 1.85
13- All code must compile on stable Rust
14 
15## Naming Conventions
16 
17- Follow Skia's naming where possible for API compatibility
18- Use `snake_case` for functions and variables
19- Use `PascalCase` for types and traits
20- Prefix internal/private items with underscore only when necessary
21- Crate names: `skia-rs-{module}` (hyphenated)
22- Module imports: `skia_rs_{module}` (underscored)
23 
24## Type Aliases
25 
26```rust
27// Core type alias - matches Skia's SkScalar
28pub type Scalar = f32;
29```
30 
31## Documentation
32 
33- All public items MUST have doc comments
34- Use `//!` for module-level documentation
35- Include examples in doc comments for complex APIs
36- Reference corresponding Skia types/functions in docs
37 
38```rust
39/// A 2D point with floating-point coordinates.
40///
41/// Corresponds to Skia's `SkPoint`.
42///
43/// # Examples
44/// ```
45/// use skia_rs_core::Point;
46/// let p = Point::new(10.0, 20.0);
47/// assert_eq!(p.length(), (500.0_f32).sqrt());
48/// ```
49#[derive(Debug, Clone, Copy, PartialEq, Default)]
50#[repr(C)]
51pub struct Point {
52    pub x: Scalar,
53    pub y: Scalar,
54}
55```
56 
57## Error Handling
58 
59- Use `thiserror` for error types
60- Prefer `Option<T>` over `Result<T, E>` for simple failure cases (matching Skia patterns)
61- Never panic in library code except for invariant violations
62- Use `debug_assert!` for development-time checks
63 
64## Memory & Performance
65 
66- Use `#[repr(C)]` for FFI-compatible structs
67- Derive `bytemuck::{Pod, Zeroable}` for types that need zero-copy operations
68- Use `SmallVec` for small, stack-allocated collections
69- Prefer `&self` over `&mut self` where possible
70- Avoid allocations in hot paths
71 
72```rust
73use bytemuck::{Pod, Zeroable};
74 
75#[derive(Debug, Clone, Copy, Pod, Zeroable)]
76#[repr(C)]
77pub struct Color(pub u32);
78```
79 
80## Inline Hints
81 
82- Use `#[inline]` for small, frequently-called methods
83- Use `#[inline(always)]` sparingly, only for critical hot paths
84- Let the compiler decide for complex functions
85 
86```rust
87impl Point {
88    #[inline]
89    pub const fn new(x: Scalar, y: Scalar) -> Self {
90        Self { x, y }
91    }
92 
93    #[inline]
94    pub fn length(&self) -> Scalar {
95        (self.x * self.x + self.y * self.y).sqrt()
96    }
97}
98```
99