fop-types

Foundational types for the FOP (Formatting Objects Processor) Rust implementation. This crate has no internal dependencies and is used by all other FOP crates as the shared type foundation for lengths, colors, geometry, font metrics, and error handling.

Installation

Add fop-types to your Cargo.toml:

[dependencies]
fop-types = "0.1.1"

Types

Length

Dimensional measurements stored as integer millipoints (1/1000 of a typographic point) for precision without floating-point errors.

use fop_types::Length;

fn example() -> Result<(), Box<dyn std::error::Error>> {
    let a = Length::from_pt(72.0);    // 72 points
    let b = Length::from_inch(1.0);   // 1 inch = 72 points
    assert_eq!(a, b);

    let c = Length::from_mm(210.0);   // A4 width
    let d = Length::from_cm(21.0);    // Same thing
    assert_eq!(c, d);

    // Arithmetic
    let sum = a + b;
    let half = a / 2;

    // Convert back to physical units
    println!("sum = {} pt", sum.to_pt());
    println!("half = {} mm", half.to_mm());
    Ok(())
}

Color

RGBA color values with named color constants and hex parsing.

use fop_types::Color;

fn example() -> Result<(), Box<dyn std::error::Error>> {
    let red = Color::RED;
    let custom = Color::from_hex("#FF8800")?;
    let transparent = Color::new(255, 0, 0, 128);

    assert_eq!(red.r(), 255);
    assert_eq!(custom.g(), 0x88);
    assert_eq!(transparent.a(), 128);
    Ok(())
}

Point, Size, Rect

2D geometry types using Length for coordinates.

use fop_types::{Length, Point, Size, Rect};

fn example() -> Result<(), Box<dyn std::error::Error>> {
    let origin = Point::new(Length::from_pt(10.0), Length::from_pt(20.0));
    let size = Size::new(Length::from_pt(100.0), Length::from_pt(50.0));
    let rect = Rect::from_point_size(origin, size);

    assert!(rect.contains(Point::new(
        Length::from_pt(50.0),
        Length::from_pt(30.0),
    )));
    Ok(())
}

FontMetrics / FontRegistry

Font measurement data for layout calculations. Provides character widths, ascent, descent, and line height for built-in fonts (Helvetica, Times-Roman).

use fop_types::FontRegistry;

fn example() -> Result<(), Box<dyn std::error::Error>> {
    let registry = FontRegistry::with_defaults();
    let helvetica = registry
        .get("Helvetica")
        .ok_or("font not found")?;
    let width = helvetica.string_width("Hello", 12.0);

    println!("\"Hello\" in 12pt Helvetica = {} pt", width.to_pt());
    Ok(())
}

FopError / Result

Base error type used across all FOP crates, built on thiserror.

use fop_types::{FopError, FopResult};

fn parse_something(input: &str) -> FopResult<i32> {
    input.parse::<i32>().map_err(|e| {
        FopError::Parse(format!("invalid integer: {e}"))
    })
}

Modules

Tests

25 unit tests covering:

• Length unit conversions (pt, mm, cm, inch) and arithmetic
• Color hex parsing, named colors, edge cases
• Geometry containment, intersection, size calculations
• Font metrics string width computation
• Error type Display/Debug

Dependencies

Related Crates

License

Licensed under the Apache License, Version 2.0. See LICENSE for details.

Author

Copyright 2024-2026 COOLJAPAN OU (Team Kitasan)

Repository: https://github.com/cool-japan/fop