Image edits

use image_ops.qweruse image_crop, image_rotate from image_ops      // Quillo 0.6: only these

image = { version = "0.25", default-features = false, features = ["png", "jpeg", "webp", "gif"] }

// A photo editor's actions on an upload from a phone, stored sideways with an EXIF orientation.////   quillo run image_ops.qwe      then open http://localhost:8080/editsuse "image_ops.qwer"let PHOTO = "image_ops_sample.jpg"route GET /edits = {    upright: image_auto_orient(PHOTO, "data/edits/upright.jpg")?,    square: image_crop(PHOTO, "data/edits/square.jpg", 50, 0, 300, 300)?,    turned: image_rotate(PHOTO, "data/edits/turned.png", 90)?,    mirror: image_flip(PHOTO, "data/edits/mirror.webp", "horizontal")?,    grey: image_grayscale(PHOTO, "data/edits/grey.jpg")?,    blurred: image_blur(PHOTO, "data/edits/blurred.jpg", 6.0)?,    outside: is_err(image_crop(PHOTO, "data/edits/none.jpg", 900, 900, 10, 10)),}route GET /edits/:name {    let names = ["upright.jpg", "square.jpg", "turned.png", "mirror.webp", "grey.jpg", "blurred.jpg"]    if !contains(names, name) { reply 404 "No such edit" }    file(`data/edits/${name}`)}

//! Everyday picture edits: crop, rotate, flip, grayscale, blur and turning phone photos upright by their EXIF orientation, saved as JPEG, PNG, WebP or GIF.//! version: 1.0.0//!//! [dependencies]//! image = { version = "0.25", default-features = false, features = ["png", "jpeg", "webp", "gif"] }use image::{DynamicImage, ImageDecoder};use serde_json::{json, Value};fn reader(path: &str) -> Result<image::ImageReader<std::io::BufReader<std::fs::File>>, String> {    let mut r = image::ImageReader::open(path).map_err(|e| format!("{}: {}", path, e))?.with_guessed_format().map_err(|e| format!("{}: {}", path, e))?;    // A small file claiming to be enormous is refused before anything is allocated.    let mut l = image::Limits::default();    l.max_image_width = Some(12_000);    l.max_image_height = Some(12_000);    l.max_alloc = Some(512 * 1024 * 1024);    r.limits(l);    Ok(r)}// The picture turned upright by its EXIF orientation, as phones expect.fn open(path: &str) -> Result<DynamicImage, String> {    let mut dec = reader(path)?.into_decoder().map_err(|e| format!("{}: {}", path, e))?;    let o = dec.orientation().unwrap_or(image::metadata::Orientation::NoTransforms);    let mut img = DynamicImage::from_decoder(dec).map_err(|e| format!("{}: {}", path, e))?;    img.apply_orientation(o);    Ok(img)}// Saved in the format its extension names: .jpg (quality 88), .png, .webp (lossless) or .gif; folders are made.fn save(img: &DynamicImage, path: &str) -> Result<(), String> {    if let Some(dir) = std::path::Path::new(path).parent().filter(|d| !d.as_os_str().is_empty()) {        std::fs::create_dir_all(dir).map_err(|e| format!("{}: {}", dir.display(), e))?;    }    let ext = path.rsplit_once('.').map(|(_, e)| e.to_lowercase()).unwrap_or_default();    let err = |e: image::ImageError| format!("{}: {}", path, e);    match ext.as_str() {        "jpg" | "jpeg" => {            let f = std::fs::File::create(path).map_err(|e| format!("{}: {}", path, e))?;            image::codecs::jpeg::JpegEncoder::new_with_quality(std::io::BufWriter::new(f), 88).encode_image(&img.to_rgb8()).map_err(err)        }        "png" => img.save_with_format(path, image::ImageFormat::Png).map_err(err),        "webp" => DynamicImage::ImageRgba8(img.to_rgba8()).save_with_format(path, image::ImageFormat::WebP).map_err(err),        "gif" => DynamicImage::ImageRgba8(img.to_rgba8()).save_with_format(path, image::ImageFormat::Gif).map_err(err),        _ => Err(format!("{}: save as .jpg, .png, .webp or .gif", path)),    }}fn done(img: &DynamicImage, to: &str) -> Result<Value, String> {    save(img, to)?;    Ok(json!({ "width": img.width(), "height": img.height() }))}/// The part of the picture `w` by `h` pixels from its top-left corner `x`, `y` (in the upright picture), saved at `to` (.jpg, .png, .webp or .gif; folders made)./// A box reaching past the edges is cut to them; one wholly outside is an error. `{ width, height }` of the result, as for each function here.pub fn image_crop(from: &str, to: &str, x: i64, y: i64, w: i64, h: i64) -> Result<Value, String> {    let img = open(from)?;    let (iw, ih) = (img.width() as i64, img.height() as i64);    let (x0, y0) = (x.max(0), y.max(0));    let (x1, y1) = ((x + w).min(iw), (y + h).min(ih));    if w <= 0 || h <= 0 || x1 <= x0 || y1 <= y0 {        return Err(format!("the box {}×{} at ({}, {}) is outside the {}×{} picture", w, h, x, y, iw, ih));    }    done(&img.crop_imm(x0 as u32, y0 as u32, (x1 - x0) as u32, (y1 - y0) as u32), to)}/// The picture turned clockwise by `degrees`: 90, 180 or 270 (-90 is 270).pub fn image_rotate(from: &str, to: &str, degrees: i64) -> Result<Value, String> {    let img = open(from)?;    let out = match degrees.rem_euclid(360) {        0 => img,        90 => img.rotate90(),        180 => img.rotate180(),        270 => img.rotate270(),        d => return Err(format!("turn by 90, 180 or 270 degrees, not {}", d)),    };    done(&out, to)}/// The picture mirrored: `direction` "horizontal" (left and right swap) or "vertical" (top and bottom).pub fn image_flip(from: &str, to: &str, direction: &str) -> Result<Value, String> {    let img = open(from)?;    let out = match direction.to_lowercase().as_str() {        "horizontal" | "h" => img.fliph(),        "vertical" | "v" => img.flipv(),        d => return Err(format!("flip \"horizontal\" or \"vertical\", not `{}`", d)),    };    done(&out, to)}/// The picture in shades of grey (transparency kept).pub fn image_grayscale(from: &str, to: &str) -> Result<Value, String> {    let img = open(from)?;    let out = if img.color().has_alpha() { DynamicImage::ImageLumaA8(img.to_luma_alpha8()) } else { DynamicImage::ImageLuma8(img.to_luma8()) };    done(&out, to)}/// The picture blurred, `sigma` the strength in pixels (2 soft, 10 strong; up to 100): to hide faces or plates, or for a background.pub fn image_blur(from: &str, to: &str, sigma: f64) -> Result<Value, String> {    let img = open(from)?;    done(&img.blur(sigma.clamp(0.1, 100.0) as f32), to)}/// The picture turned upright by its EXIF orientation and saved: `{ width, height, orientation }`, `orientation` the one it had (1 when it was upright already)./// Every function here does this first, so a phone photo is cropped and turned as it is seen.pub fn image_auto_orient(from: &str, to: &str) -> Result<Value, String> {    let mut dec = reader(from)?.into_decoder().map_err(|e| format!("{}: {}", from, e))?;    let o = dec.orientation().unwrap_or(image::metadata::Orientation::NoTransforms);    let code = match o {        image::metadata::Orientation::NoTransforms => 1,        image::metadata::Orientation::FlipHorizontal => 2,        image::metadata::Orientation::Rotate180 => 3,        image::metadata::Orientation::FlipVertical => 4,        image::metadata::Orientation::Rotate90FlipH => 5,        image::metadata::Orientation::Rotate90 => 6,        image::metadata::Orientation::Rotate270FlipH => 7,        image::metadata::Orientation::Rotate270 => 8,    };    let mut img = DynamicImage::from_decoder(dec).map_err(|e| format!("{}: {}", from, e))?;    img.apply_orientation(o);    save(&img, to)?;    Ok(json!({ "width": img.width(), "height": img.height(), "orientation": code }))}