eunoia 0.18.0

A library for creating area-proportional Euler and Venn diagrams
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80

//! Example demonstrating pole of inaccessibility for label placement.
//!
//! This example shows how to use the pole_of_inaccessibility method
//! to find optimal label positions for polygons.
//!
//! Run with: cargo run --example label_placement

use eunoia::geometry::primitives::Point;
use eunoia::geometry::shapes::Polygon;

fn main() {
    println!("=== Label Placement Example ===\n");

    // Example 1: Square - pole should be near center
    println!("1. Square:");
    let square = Polygon::new(vec![
        Point::new(0.0, 0.0),
        Point::new(10.0, 0.0),
        Point::new(10.0, 10.0),
        Point::new(0.0, 10.0),
    ]);
    let centroid = square.centroid();
    let pole = square.pole_of_inaccessibility(0.01);
    println!("   Centroid: ({:.2}, {:.2})", centroid.x(), centroid.y());
    println!("   Pole:     ({:.2}, {:.2})", pole.x(), pole.y());
    println!("   → Similar positions (symmetric shape)\n");

    // Example 2: L-shape - pole is better than centroid
    println!("2. L-shaped polygon:");
    let l_shape = Polygon::new(vec![
        Point::new(0.0, 0.0),
        Point::new(4.0, 0.0),
        Point::new(4.0, 1.0),
        Point::new(1.0, 1.0),
        Point::new(1.0, 4.0),
        Point::new(0.0, 4.0),
    ]);
    let centroid = l_shape.centroid();
    let pole = l_shape.pole_of_inaccessibility(0.1);
    println!("   Centroid: ({:.2}, {:.2})", centroid.x(), centroid.y());
    println!("   Pole:     ({:.2}, {:.2})", pole.x(), pole.y());
    println!("   → Pole is in the thick part (better for labels!)\n");

    // Example 3: Rectangle - pole should be at center
    println!("3. Rectangle:");
    let rect = Polygon::new(vec![
        Point::new(0.0, 0.0),
        Point::new(20.0, 0.0),
        Point::new(20.0, 5.0),
        Point::new(0.0, 5.0),
    ]);
    let centroid = rect.centroid();
    let pole = rect.pole_of_inaccessibility(0.1);
    println!("   Centroid: ({:.2}, {:.2})", centroid.x(), centroid.y());
    println!("   Pole:     ({:.2}, {:.2})", pole.x(), pole.y());
    println!("   → Similar positions (symmetric shape)\n");

    // Example 4: C-shaped polygon
    println!("4. C-shaped polygon:");
    let c_shape = Polygon::new(vec![
        Point::new(0.0, 0.0),
        Point::new(10.0, 0.0),
        Point::new(10.0, 2.0),
        Point::new(2.0, 2.0),
        Point::new(2.0, 8.0),
        Point::new(10.0, 8.0),
        Point::new(10.0, 10.0),
        Point::new(0.0, 10.0),
    ]);
    let centroid = c_shape.centroid();
    let pole = c_shape.pole_of_inaccessibility(0.1);
    println!("   Centroid: ({:.2}, {:.2})", centroid.x(), centroid.y());
    println!("   Pole:     ({:.2}, {:.2})", pole.x(), pole.y());
    println!("   → Pole avoids the opening (better for labels!)\n");

    println!("=== Summary ===");
    println!("For symmetric shapes: pole ≈ centroid");
    println!("For complex/concave shapes: pole > centroid (better visual center)");
    println!("\nUse pole_of_inaccessibility() for better label placement!");
}