node-demotivator-native/crates/meow_image/src/demotivate.rs

use crate::text_width::get_text_width;
use image::{GenericImage, ImageBuffer, Rgb, RgbImage};
use imageproc::drawing::draw_text_mut;
use once_cell::sync::Lazy;
use rusttype::{Font, Scale};

const WHITE: Rgb<u8> = Rgb([255, 255, 255]);
const BLACK: Rgb<u8> = Rgb([0, 0, 0]);

static FONT_DATA: &[u8] = include_bytes!("../../../assets/XO_Thames_Nu.ttf");

static FONT: Lazy<Font<'static>> = Lazy::new(|| Font::try_from_bytes(FONT_DATA).unwrap());

#[derive(Clone, Copy)]
struct Border {
    pub top: u32,
    pub left: u32,
    pub bottom: u32,
    pub right: u32,
}

/// Makes a demotivator meme
pub fn demotivate(image: &RgbImage, top_text: &str, bottom_text: &str) -> RgbImage {
    let (width, height) = image.dimensions();

    // Calculate a border
    let border_size = (if width > height { width } else { height }) / 8;
    let border = Border {
        top: border_size,
        left: border_size,
        bottom: border_size * 2,
        right: border_size,
    };

    // Add a black border
    let mut image_with_border = add_border(image, BLACK, border);
    let (width, height) = image_with_border.dimensions();

    // Calculate the padding and the line width
    let padding = border_size / 10;
    let line_width = padding / 3;

    // Add a white box next to the image
    add_box(&mut image_with_border, WHITE, border, line_width, padding);

    // Calculate the scale and position of the top text
    {
        let scale = Scale::uniform(border_size as f32);

        let text_width = get_text_width(scale, &FONT, top_text);

        let x_text_position = (width - text_width) / 2; // center by width
        let y_text_position = height - (border.bottom - padding);

        // Draw the top text
        draw_text_mut(
            &mut image_with_border,
            WHITE,
            x_text_position as i32,
            y_text_position as i32,
            scale,
            &FONT,
            top_text,
        );
    }

    // Calculate the scale and position of the bottom text
    {
        let scale = Scale::uniform(border_size as f32 / 2f32);

        let text_width = get_text_width(scale, &FONT, bottom_text);

        let x_text_position = (width - text_width) / 2; // center by width
        let y_text_position = height - (border.bottom - padding) / 2;

        // Draw the bottom text
        draw_text_mut(
            &mut image_with_border,
            WHITE,
            x_text_position as i32,
            y_text_position as i32,
            scale,
            &FONT,
            bottom_text,
        );
    }

    image_with_border
}

fn add_border(
    image: &RgbImage,
    color: Rgb<u8>,
    Border {
        top,
        left,
        bottom,
        right,
    }: Border,
) -> RgbImage {
    // Get the dimensions of the image
    let (width, height) = image.dimensions();

    // Create a new image with a border
    #[rustfmt::skip]
    let mut out_image = ImageBuffer::from_fn(
        width + left + right,
        height + top + bottom,
        |_, _| color
    );

    // Copy the original image into the center of the new image
    out_image.copy_from(image, top, left).unwrap();

    out_image
}

fn add_box(
    image: &mut RgbImage,
    color: Rgb<u8>,
    Border {
        mut top,
        mut left,
        mut bottom,
        mut right,
    }: Border,
    line_width: u32,
    padding: u32,
) {
    top -= padding;
    left -= padding;
    bottom -= padding;
    right -= padding;

    // Get the dimensions of the image
    let (width, height) = image.dimensions();

    // Calculate the position and dimensions of the box
    let x1 = left;
    let y1 = top;

    let x2 = width - (right + 1);
    let y2 = height - (bottom + 1);

    // Iterate over the pixels of the line and set the pixel values to color
    for x in x1..=x2 {
        for i in 0..line_width {
            // top line
            // +i to go bottom
            image.put_pixel(x, y1 + i, color);

            // bottom line
            // -i to go top
            image.put_pixel(x, y2 - i, color);
        }
    }

    // Because we have already painted the corners
    for y in (y1 + line_width)..=(y2 - line_width) {
        for i in 0..line_width {
            // left line
            // +i to go right
            image.put_pixel(x1 + i, y, color);

            // right line
            // -i to go left
            image.put_pixel(x2 - i, y, color);
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use image::io::Reader as ImageReader;

    #[test]
    fn demotivate_test() {
        let image = ImageReader::open("./patterns/test.jpg")
            .unwrap()
            .decode()
            .unwrap()
            .into_rgb8();

        let demotivated_image = demotivate(&image, "He is crazy!", "RUN");

        demotivated_image.save("dem.jpg").unwrap();
    }
}