yoga 0.5.0

Rust bindings for Facebook's Yoga, a Flexbox layout engine
Documentation 
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extern crate yoga;

use std::{cell::RefCell, rc::Rc};
use yoga::{get_node_ref_context, Context, Direction, MeasureMode, Node, NodeRef, Size, Undefined};

#[test]
fn test_context_0() {
    let root = Node::new();
    assert!(root.get_context().is_none());
    assert!(root.get_context_mut().is_none());
}

#[test]
fn test_context_1() {
    let mut root = Node::new();
    root.set_context(Some(Context::new("test".to_string())));

    let context = root.get_context().unwrap();
    assert!(context.downcast_ref::<bool>().is_none());
    assert!(context.downcast_ref::<&str>().is_none());
    assert_eq!(context.downcast_ref::<String>().unwrap(), "test");
}

#[test]
fn test_context_2_safe_check() {
    #[derive(Debug, PartialEq)]
    struct Bogus {}

    extern "C" fn measure(
        node_ref: NodeRef,
        _: f32,
        _: MeasureMode,
        _: f32,
        _: MeasureMode,
    ) -> Size {
        let context = get_node_ref_context(&node_ref).unwrap().downcast_ref::<Bogus>();

        assert_eq!(context, None);

        Size { width: 1.0, height: 1.0 }
    }

    let mut root = Node::new();
    let context = Context::new("test".to_string());
    root.set_context(Some(context));
    root.set_measure_func(Some(measure));

    root.calculate_layout(Undefined, Undefined, Direction::LTR);

    let root_layout = root.get_layout();

    assert_eq!(0.0, root_layout.left());
    assert_eq!(0.0, root_layout.top());
    assert_eq!(1.0, root_layout.width());
    assert_eq!(1.0, root_layout.height());
}

#[test]
fn test_context_2() {
    extern "C" fn measure(
        node_ref: NodeRef,
        _: f32,
        _: MeasureMode,
        _: f32,
        _: MeasureMode,
    ) -> Size {
        let context = get_node_ref_context(&node_ref).unwrap().downcast_ref::<String>().unwrap();

        Size { width: context.len() as f32, height: if context == "test" { 1.0 } else { 0.0 } }
    }

    let mut root = Node::new();
    let context = Context::new("test".to_string());
    root.set_context(Some(context));
    root.set_measure_func(Some(measure));

    root.calculate_layout(Undefined, Undefined, Direction::LTR);

    let root_layout = root.get_layout();

    assert_eq!(0.0, root_layout.left());
    assert_eq!(0.0, root_layout.top());
    assert_eq!(4.0, root_layout.width());
    assert_eq!(1.0, root_layout.height());
}

#[test]
fn test_context_3() {
    struct LocalSimpleFont {
        letter_width: f32,
        letter_height: f32,
    }

    struct LocalCustomData {
        text: String,
        font: Rc<RefCell<LocalSimpleFont>>,
    }

    extern "C" fn measure(
        node_ref: NodeRef,
        _: f32,
        _: MeasureMode,
        _: f32,
        _: MeasureMode,
    ) -> Size {
        let context =
            get_node_ref_context(&node_ref).unwrap().downcast_ref::<LocalCustomData>().unwrap();

        let text = &context.text;
        let font = context.font.borrow();

        Size { width: text.len() as f32 * font.letter_width, height: font.letter_height }
    }

    let shared_font =
        Rc::new(RefCell::new(LocalSimpleFont { letter_width: 2.0, letter_height: 10.0 }));

    let data = Context::new(LocalCustomData { text: "hello world".to_string(), font: shared_font });

    let mut root = Node::new();
    root.set_context(Some(data));
    root.set_measure_func(Some(measure));

    root.calculate_layout(Undefined, Undefined, Direction::LTR);

    let root_layout = root.get_layout();

    assert_eq!(0.0, root_layout.left());
    assert_eq!(0.0, root_layout.top());
    assert_eq!(22.0, root_layout.width());
    assert_eq!(10.0, root_layout.height());
}

struct ExternalSimpleFont {
    letter_width: f32,
    letter_height: f32,
}

struct ExternalCustomData {
    text: String,
    font: Rc<RefCell<ExternalSimpleFont>>,
}

#[test]
fn test_context_4() {
    let shared_font =
        Rc::new(RefCell::new(ExternalSimpleFont { letter_width: 2.0, letter_height: 10.0 }));

    let data =
        Context::new(ExternalCustomData { text: "hello world".to_string(), font: shared_font });

    let mut root = Node::new();
    root.set_context(Some(data));
    root.set_measure_func(Some(external_measure));

    root.calculate_layout(Undefined, Undefined, Direction::LTR);

    let root_layout = root.get_layout();

    assert_eq!(0.0, root_layout.left());
    assert_eq!(0.0, root_layout.top());
    assert_eq!(22.0, root_layout.width());
    assert_eq!(10.0, root_layout.height());
}

extern "C" fn external_measure(
    node_ref: NodeRef,
    _: f32,
    _: MeasureMode,
    _: f32,
    _: MeasureMode,
) -> Size {
    let context =
        get_node_ref_context(&node_ref).unwrap().downcast_ref::<ExternalCustomData>().unwrap();

    let text = &context.text;
    let font = context.font.borrow();

    Size { width: text.len() as f32 * font.letter_width, height: font.letter_height }
}