drawing_texts.md

Drawing Texts

To draw a text on our image, we need an additional crate, ab_glyph.

cargo add ab_glyph

The dependencies in Cargo.toml should look like this:

[dependencies]
ab_glyph = "0.2.29"
imageproc = "0.25.0"

To use the crate, we need an otf font file. In the following example, we use FogSans.otf that can be downloaded from this website.

use ab_glyph::FontVec;
use imageproc::{drawing, image};

use std::fs;

fn main() {
    let mut buf = image::ImageBuffer::new(100, 100);
    
    let font_data = fs::read("FogSans.otf").unwrap();
    let font = FontVec::try_from_vec(font_data).unwrap();

    drawing::draw_text_mut(
        &mut buf,
        image::Rgb::from([128u8, 255u8, 64u8]),
        10,
        34,
        24.,
        &font,
        "Draw Text",
    );

    buf.save("text.png").unwrap();
}

We first read the font data from the file FogSans.otf. Then we transform the data to FontVec by FontVec::try_from_vec. Finally, we use draw_text_mut to draw a string Draw Text with font size 24 at location (10, 34).

text.png:

Additionally, we can use text_size to get the width and height of the drawn text.

let size = drawing::text_size(24., &font, "Draw Text");
println!("{:?}", size);

Output:

(80, 13)

To draw on a copied image, we can use draw_text.

➡️ Next: Translating

📘 Back: Table of contents