Add xkcd document

showbits-thermal-printer/src/documents/xkcd/data.json

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+{
+  "number": 3064,
+  "title": "Lungfish",
+  "alt": "I know having so many base pairs makes rebasing complicated, but you're in Bilateria, so shouldn't you at LEAST be better at using git head?",
+  "feed": false
+}

showbits-thermal-printer/src/documents/xkcd/lib

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+../lib

showbits-thermal-printer/src/documents/xkcd/main.typ

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+#import "lib/main.typ" as lib;
+#show: it => lib.init(it)
+
+#let data = json("data.json")
+
+#align(center)[
+  xkcd #data.number
+  #v(-12pt)
+  #text(size: 32pt, data.title)
+]
+
+// If the image is an odd number of pixels wide, we need to add an extra row of
+// pixels (in this case, on the right) to ensure that the image pixels fall on
+// screen pixels.
+#context {
+  let img = image("image.png")
+  let width = measure(img).width
+  let additional = 2pt * calc.fract(width.pt() / 2)
+  align(center, stack(dir: ltr, img, h(additional)))
+}
+
+#align(center, data.alt)
+
+#if data.feed {
+  lib.feed
+}

showbits-thermal-printer/src/documents/xkcd/mod.rs

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+use std::io::Cursor;
+
+use anyhow::Context;
+use axum::{
+    Form,
+    extract::State,
+    response::{IntoResponse, Response},
+};
+use image::ImageFormat;
+use serde::{Deserialize, Serialize};
+
+use crate::server::{Server, somehow};
+
+#[derive(Deserialize)]
+struct ComicInfo {
+    num: u32,
+    title: String,
+    alt: String,
+    img: String,
+}
+
+#[derive(Serialize)]
+struct Data {
+    number: u32,
+    title: String,
+    alt: String,
+    feed: bool,
+}
+
+#[derive(Deserialize)]
+pub struct FormData {
+    pub number: Option<u32>,
+    pub feed: Option<bool>,
+}
+
+pub async fn post(server: State<Server>, Form(form): Form<FormData>) -> somehow::Result<Response> {
+    let client = reqwest::Client::builder()
+        .user_agent(crate::USER_AGENT)
+        .build()?;
+
+    let url = match form.number {
+        None => "https://xkcd.com/info.0.json".to_string(),
+        Some(number) => format!("https://xkcd.com/{number}/info.0.json"),
+    };
+
+    let info = client.get(url).send().await?.json::<ComicInfo>().await?;
+
+    let image_data = client.get(&info.img).send().await?.bytes().await?;
+    let image = image::load_from_memory(&image_data)?.into_rgba8();
+
+    let max_width = Some(384);
+    let max_height = Some(1024);
+    let image = super::image::dither(image, max_width, max_height, false, "stucki")
+        .map_err(somehow::Error)?;
+
+    let data = Data {
+        number: info.num,
+        title: info.title,
+        alt: info.alt,
+        feed: form.feed.unwrap_or(true),
+    };
+
+    let mut bytes: Vec<u8> = Vec::new();
+    image
+        .write_to(&mut Cursor::new(&mut bytes), ImageFormat::Png)
+        .context("failed to encode image as png")
+        .map_err(somehow::Error)?;
+
+    let typst = super::typst_with_lib()
+        .with_json("/data.json", &data)
+        .with_file("/image.png", bytes)
+        .with_main_file(include_str!("main.typ"));
+
+    server.print_typst(typst).await?;
+    Ok(().into_response())
+}