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use anyhow::Error; use image::{DynamicImage, GenericImage, GenericImageView, Rgba}; use std::cmp::max; pub type Result<T> = std::result::Result<T, Error>; pub fn diff(before: &DynamicImage, after: &DynamicImage) -> Result<DynamicImage> { let (after_width, after_height) = after.dimensions(); let (before_width, before_height) = before.dimensions(); let width = max(after_width, before_width); let height = max(after_height, before_height); let mut result = DynamicImage::new_rgba8(width, height); for y in 0..height { for x in 0..width { let new_color: [u8; 4]; let pixel: Rgba<u8>; if x >= before_width || y >= before_height || x >= after_width || y >= after_height { new_color = [255, 0, 0, 255]; pixel = Rgba(new_color); } else { let before_pixel: Rgba<u8> = before.get_pixel(x, y); let after_pixel: Rgba<u8> = after.get_pixel(x, y); let alpha = before_pixel[3]; let is_diff = before_pixel[0] != after_pixel[0] || before_pixel[1] != after_pixel[1] || before_pixel[2] != after_pixel[2]; let mut new_red = after_pixel[0]; let mut new_green = after_pixel[1]; let mut new_blue = after_pixel[2]; if is_diff { new_red = 255; new_green = 0; new_blue = 0; } new_color = [new_red, new_green, new_blue, alpha]; pixel = Rgba(new_color); } result.put_pixel(x, y, pixel); } } Ok(result) } #[cfg(test)] mod tests { use super::*; #[test] fn test_diff() { let before = image::open("test/before.png"); let after = image::open("test/after.png").unwrap(); let dif = diff(&before.unwrap(), &after); assert_eq!(true, dif.is_ok()); } }