amamic1803 / tinydraw-rs

A small 2D drawing library in Rust

tinydraw-rs

tinydraw is a small library for 2D drawing in Rust

---

It's a simple crate used for drawing basic, anti-aliased shapes onto images, written in pure Rust. Support for reading and exporting images as PNG or bytes is included (dependencies).

Documentation

Crate

Available Shapes

• line
• rectangle
• circle
• ellipse

Example

use tinydraw::ImageRGB8;

fn main() { 
    let background_color: [u8; 3] = [255, 155, 0];
    let mut image: ImageRGB8 = ImageRGB8::new(640, 360, background_color);
  
    image.draw_line(0, 0, 639, 359, [255, 255, 255], 1, 1.0);
    image.draw_line(0, 359, 639, 0, [255, 255, 255], 1, 1.0);
    image.draw_rectangle(0, 0, 639, 359, [255, 255, 255], 3, 1.0);
    image.draw_ellipse(319, 179, 300, 150, [0, 0, 0], 0, 0.5);
    image.draw_circle(149, 179, 30, [255, 255, 255], 0, 1.0);
    image.draw_circle(149, 179, 20, [0, 0, 0], 0, 1.0);
    image.draw_circle(489, 179, 30, [255, 255, 255], 0, 1.0);
    image.draw_circle(489, 179, 20, [0, 0, 0], 0, 1.0);
    image.draw_ellipse(319, 90, 80, 30, [255, 255, 255], 0, 1.0);
    image.draw_ellipse(319, 90, 60, 20, [0, 0, 0], 0, 1.0);
  
    image.to_png("image.png").unwrap();
}

This code generates the following image:

Limitations

• thickness above 1 doesn't work for:
  • line
  • circle
  • ellipse
• coordinates exceeding the image bounds don't work for:
  • rectangle
  • circle
  • ellipse
• only RGB images with bit depth of 8 are currently supported

Dependencies

bytemuck (reading, exporting bytes)

png (reading, exporting PNG)

Development

I intend to fix the limitations and perhaps add more shapes in the future. It depends on my free time and whether there will be any interest for this crate. If you encounter a bug or have any suggestions, feel free to open an issue. If you want to contribute, feel free to open a pull request.

References

Wikipedia - Xiaolin Wu's line algorithm

GeeksforGeeks - Anti-aliased Line | Xiaolin Wu’s algorithm

Stephan Brumme - Drawing Antialiased Circles and Ellipses

David Moksha - Fast, Antialiased Circles and Ellipses from Xiaolin Wu’s concepts

tinydraw-rs's Issues

Small bug when drawing horizontal lines

Trying out the tinydraw crate for some simple drawing task… There I noticed that when drawing completely horizontal lines only half of the line is visible. Here is a little code example visualizing this behaviour.

fn main() {                                                                                                                                                                                                                                                                     
    let width: u32 = 1920;
    let height: u32 = 1080;
    // let h_center = width / 2;
    let v_center = height / 2;
    let background: [u8; 3] = [64, 64, 128];
    let mut image = tinydraw::ImageRGB8::new(width as usize, height as usize, background);

    let bug_color: [u8; 3] = [255, 0, 0];
    image.draw_line(
        0,
        v_center as usize,
        width as usize,
        v_center as usize,
        bug_color,
        1,
        0.5,
    );

    let okay_color: [u8; 3] = [0, 255, 0];
    image.draw_line(
        0,
        v_center as usize - 50,
        width as usize,
        v_center as usize - 51, // FIXME: should also be -50
        okay_color,
        1,
        0.5,
    );

    image.to_png("output.png").unwrap();
}

And here is how it looks like.

The horizontal red line stops somewhere in the middle. The green line is just for reference and "fakes" a horizontal line (sets 1px off between y1 and y2).

Panics due to overflow in usize subtraction

thread 'main' panicked at /home/nils/.cargo/registry/src/index.crates.io-6f17d22bba15001f/tinydraw-0.1.1/src/image.rs:325:47:
attempt to subtract with overflow

I didn't print/debug the exact x1/y1/x2/y2 values yet. Very likely those are huge due to an incorrect conversion from signed to unsigned on the input side…

Update: Yep, the values became huge as assumed! To simplify debugging a little I use smaller values in i16 range (approximately +/-[0..32000]). It seems that the algorithm panics when y2 < y1 && x2 > x1.

(36,81) -> (28,43)   Okay
(28,43) -> (80,75)   Okay
(80,75) -> (88,49)   Panic!