Full Code of fpapado/blurhash-rust-wasm for AI

Repository: fpapado/blurhash-rust-wasm
Branch: master
Commit: a81e33c46a10
Files: 23
Total size: 48.5 KB

Directory structure:
gitextract_tzlsaf77/

├── .gitignore
├── Cargo.toml
├── LICENSE.md
├── README.md
├── build-wasm.sh
├── demo/
│   ├── .babelrc
│   ├── .gitignore
│   ├── .travis.yml
│   ├── App.js
│   ├── LICENSE-APACHE
│   ├── LICENSE-MIT
│   ├── README.md
│   ├── bootstrap.js
│   ├── data.json
│   ├── index.html
│   ├── index.js
│   ├── package.json
│   └── webpack.config.js
├── netlify.toml
├── src/
│   ├── lib.rs
│   └── utils.rs
└── tests/
    ├── integration_test.rs
    └── web.rs

================================================
FILE CONTENTS
================================================

================================================
FILE: .gitignore
================================================
/target
**/*.rs.bk
Cargo.lock
bin/
pkg/
wasm-pack.log
.vscode/


================================================
FILE: Cargo.toml
================================================
[package]
name = "blurhash-wasm"
version = "0.2.0"
authors = ["fpapado <fgpapado@gmail.com>"]
edition = "2018"

description = "A Rust and WASM implementation of the blurhash algorithm"
repository = "https://github.com/fpapado/blurhash-rust-wasm"
license = "MIT"

[lib]
crate-type = ["cdylib", "rlib"]

[features]
default = ["console_error_panic_hook"]

[dependencies]
wasm-bindgen = "0.2"
js-sys = "0.3"
thiserror = "1"

# The `console_error_panic_hook` crate provides better debugging of panics by
# logging them with `console.error`. This is great for development, but requires
# all the `std::fmt` and `std::panicking` infrastructure, so isn't great for
# code size when deploying.
console_error_panic_hook = { version = "0.1.1", optional = true }

# `wee_alloc` is a tiny allocator for wasm that is only ~1K in code size
# compared to the default allocator's ~10K. It is slower than the default
# allocator, however.
#
# Unfortunately, `wee_alloc` requires nightly Rust when targeting wasm for now.
wee_alloc = { version = "0.4.2", optional = true }

[dev-dependencies]
wasm-bindgen-test = "0.2"
image = "0.22.0"

[profile.release]
# Tell `rustc` to optimize for small code size.
# When measuring, this didn't really change size much (it actually increased!).
# For that reason, we've left it out for now.
# opt-level = 's'
lto = true


================================================
FILE: LICENSE.md
================================================
MIT License

Copyright (c) 2019 Fotis Papadogeorgopoulos

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.


================================================
FILE: README.md
================================================
# blurhash-wasm

A Rust implementation of the [blurhash algorithm](https://github.com/woltapp/blurhash).

It is compiled to WebAssembly (WASM), and [available on npm as `blurhash-wasm`](https://npmjs.com/blurhash-wasm).

BlurHash is an algorithm written by [Dag Ågren](https://github.com/DagAgren) and folks at [Wolt (woltapp/blurhash)](https://github.com/woltapp/blurhash). BlurHash is "a compact representation of a placeholder for an image." It enables you to store that representation in your database. It can then be transferred together with the initial data, in order to decode and show it, before the main image request has finished (or even started).

[Online Demo](https://blurhash-wasm.netlify.com).

## Usage in JS

### Installation

You will need a package manager, either npm ([comes with node](https://nodejs.org/en/download/)) or [yarn](https://yarnpkg.com/lang/en/docs/install/).

You will also need a bundler, [webpack](https://webpack.js.org/) or [Rollup](https://rollupjs.org/guide/en/), configured for your project.

Then, in a terminal:

```shell
npm install blurhash-wasm
# Or, yarn add blurhash-wasm
```

The [demo app source](/demo) has a complete example of using `blurhash-wasm`.

### decode

```js
import * as blurhash from "blurhash-wasm";

// You can use this to construct canvas-compatible resources
try {
  const pixels = blurhash.decode("LKO2?U%2Tw=w]~RBVZRi};RPxuwH", 40, 30);
} catch (error) {
  console.log(error);
}
```

### encode

Implented, aim to be published in 0.3.0

## Usage in Rust

### Installation

You will need [Rust and Cargo](https://doc.rust-lang.org/cargo/getting-started/installation.html).

Add the version you want to `Cargo.toml`:

```
[dependencies]
blurhash-wasm = "0.1.0"
```

### decode

```rust
use blurhash_wasm;

// Result<Vec<u8>, blurhash::Error>
let res = blurhash::decode("LKO2?U%2Tw=w]~RBVZRi};RPxuwH", 40, 30);
```

### encode

Implented, aim to be published in 0.3.0

## About the setup

[**Based on the rust wasm-pack template**][template-docs]

This template is designed for compiling Rust libraries into WebAssembly and
publishing the resulting package to NPM.

Be sure to check out [other `wasm-pack` tutorials online][tutorials] for other
templates and usages of `wasm-pack`.

[tutorials]: https://rustwasm.github.io/docs/wasm-pack/tutorials/index.html
[template-docs]: https://rustwasm.github.io/docs/wasm-pack/tutorials/npm-browser-packages/index.html

## 🚴 Usage

### 🛠️ Build with `wasm-pack build`

```
wasm-pack build
```

### 🔬 Test in Headless Browsers with `wasm-pack test`

```
wasm-pack test --headless --firefox
```

### 🎁 Publish to NPM with `wasm-pack publish`

```
wasm-pack publish
```

## 🔋 Batteries Included

- [`wasm-bindgen`](https://github.com/rustwasm/wasm-bindgen) for communicating
  between WebAssembly and JavaScript.
- [`console_error_panic_hook`](https://github.com/rustwasm/console_error_panic_hook)
  for logging panic messages to the developer console.
- [`wee_alloc`](https://github.com/rustwasm/wee_alloc), an allocator optimized
  for small code size.


================================================
FILE: build-wasm.sh
================================================
#!/bin/bash

# The initial build
# Set wee_alloc as a smaller allocator.
# We do it here instead of Cargo.toml, to keep
# the default allocator in the native Rust library build.
wasm-pack build -- --features wee_alloc

echo "Initial size"

wc -c pkg/blurhash_wasm_bg.wasm

# Optimize wasm
# NOTE: Again, setting -Os did not decrease the size,
# so might as well optimise for speed.
# You might need to install wasm-opt from binaryen:
# https://github.com/WebAssembly/binaryen/releases
wasm-opt pkg/blurhash_wasm_bg.wasm -O3 -o pkg/blurhash_wasm_bg.wasm

echo "Size after wasm-opt"
wc -c pkg/blurhash_wasm_bg.wasm

echo "Size after gzip"
gzip -9 < pkg/blurhash_wasm_bg.wasm | wc -c


================================================
FILE: demo/.babelrc
================================================
{
  "plugins": [
    ["@babel/plugin-transform-react-jsx", { "pragma":"h" }]
  ]
}


================================================
FILE: demo/.gitignore
================================================
node_modules
dist


================================================
FILE: demo/.travis.yml
================================================
language: node_js
node_js: "10"

script:
  - ./node_modules/.bin/webpack


================================================
FILE: demo/App.js
================================================
import * as blurhash from 'blurhash-wasm';

// Using react/preact in this demo mostly for convenience and habit.
// You can of course render blurhashes however you want!
import {h, Component} from 'preact';
import {useState, useRef, useEffect} from 'preact/hooks';

export function App(props) {
  const {images} = props;
  return (
    <main className="pa3 vs4 mw8 center">
      <Pitch />
      <div className="vs3">
        <h2 id="demo">Demo</h2>
        {images.map(image => (
          <div className="mb5">
            <div className="mb3 mw6">
              <CustomImage image={image} key={image.id} />
            </div>
            <ImageCredit credit={image.credit} />
          </div>
        ))}
      </div>
    </main>
  );
}

function CustomImage(props) {
  const {src, alt, hash, ratio} = props.image;

  // Hardcoded width/height for the decode and canvas
  // We keep these low and let the UI scale them up
  const WIDTH = 32; // pixels
  const HEIGHT = 32; // pixels

  const canvasRef = useRef(null);

  // Cycle the opacity of the final image, for demo purposes
  // (You could also do this with CSS animation keyframes :) )
  const [opacity, setOpacity] = useState(-1);

  useInterval(() => {
    setOpacity(prevOpacity => prevOpacity * -1);
  }, 2000);

  // When the component mounts, set the image placeholder
  useEffect(
    () => {
      // Decode the hash into pixels
      try {
        const pixels = blurhash.decode(hash, WIDTH, HEIGHT);
        // Set the pixels to the canvas
        const asClamped = new Uint8ClampedArray(pixels);
        const imageData = new ImageData(asClamped, WIDTH, HEIGHT);

        const canvasEl = canvasRef.current;

        if (canvasEl) {
          const ctx = canvasEl.getContext('2d');
          ctx.putImageData(imageData, 0, 0);
        }
      } catch (error) {
        console.error(error);
      }
    },
    [hash]
  );

  // Layout notes:
  // canvas goes below the img
  // both canvas and img have a fixed aspect-ratio placeholder
  // to preserve the layout size before either has loaded.
  return (
    <div>
      <div className={`aspect-ratio aspect-ratio--${ratio}`}>
        <canvas
          ref={canvasRef}
          width={WIDTH}
          height={HEIGHT}
          className="aspect-ratio--object"
        />
        <img
          src={src}
          alt={alt}
          className="aspect-ratio--object transition-opacity"
          style={{opacity: opacity}}
        />
      </div>
    </div>
  );
}

function ImageCredit(props) {
  const {username, displayName} = props.credit;
  return (
    <p>
      Photo by <a href={`https://unsplash.com/@${username}`}>{displayName}</a>{' '}
      on <a href="https://unsplash.com">Unsplash</a>
    </p>
  );
}

function Pitch() {
  return (
    <div className="vs4">
      <div>
        <h1>Rust Wasm BlurHash</h1>
        <a href="#demo">Skip to Demo</a>
        <p>
          A Rust and WebAssembly implementation of the{' '}
          <a href="https://blurha.sh">BlurHash algorithm</a>.
        </p>
        <p>
          BlurHash is "a compact representation of a placeholder for an image."
          It enables you to store that representation in your database. It can
          then be transferred together with the initial data, in order to decode
          and show it, before the main image request has finished (or even
          started).
        </p>
        <p>
          You can seamlessly use it in the browser through JS imports and
          bundling.
        </p>
      </div>
      <pre>
        <code>{`npm install blurhash-wasm`}</code>
      </pre>
      <pre>
        <code>
          {`import * as blurhash from "blurhash-wasm";

// You can use this to construct canvas-compatible resources
try {
  const pixels = blurhash.decode("LKO2?U%2Tw=w]~RBVZRi};RPxuwH", 40, 30);
} catch (error) {
  console.log(error);
}`}
        </code>
      </pre>
      <div className="vs3">
        <h2>Credits</h2>
        <ul className="vs2">
          <li>
            The Blurhash algorithm was originally written by{' '}
            <a href="https://github.com/DagAgren">Dag Ågren</a>. Implementations
            are maintained by{' '}
            <a href="https://github.com/woltapp/blurhash#authors">
              folks at Wolt and outside
            </a>
            .
          </li>
          <li>
            blurhash-wasm is written by{' '}
            <a href="https://twitter.com/isfotis">
              Fotis Papado&shy;georgo&shy;poulos
            </a>
            .
          </li>
        </ul>
      </div>
      <div className="vs3">
        <h2>Sources and installation</h2>
        <ul className="vs2">
          <li>
            <a href="https://github.com/fpapado/blurhash-rust-wasm">
              Source on Github
            </a>
          </li>
          <li>
            <a href="https://npmjs.com/blurhash-wasm">Package on npm</a>
          </li>
          <li>
            <a href="https://crates.io/crates/blurhash-wasm">
              Package on crates.io
            </a>
          </li>
          <li>
            <a href="https://github.com/fpapado/blurhash-rust-wasm/tree/master/demo">
              Source for this demo
            </a>
          </li>
        </ul>
      </div>
    </div>
  );
}

/**
 * Internal custom hook to periodically call a function
 * @see https://overreacted.io/making-setinterval-declarative-with-react-hooks/
 */
function useInterval(callback, delay) {
  const savedCallback = useRef();

  // Remember the latest callback.
  useEffect(
    () => {
      savedCallback.current = callback;
    },
    [callback]
  );

  // Set up the interval.
  useEffect(
    () => {
      function tick() {
        savedCallback.current();
      }
      if (delay !== null) {
        let id = setInterval(tick, delay);
        return () => clearInterval(id);
      }
    },
    [delay]
  );
}


================================================
FILE: demo/LICENSE-APACHE
================================================
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================================================
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================================================
FILE: demo/README.md
================================================
<div align="center">

  <h1><code>create-wasm-app</code></h1>

  <strong>An <code>npm init</code> template for kick starting a project that uses NPM packages containing Rust-generated WebAssembly and bundles them with Webpack.</strong>

  <p>
    <a href="https://travis-ci.org/rustwasm/create-wasm-app"><img src="https://img.shields.io/travis/rustwasm/create-wasm-app.svg?style=flat-square" alt="Build Status" /></a>
  </p>

  <h3>
    <a href="#usage">Usage</a>
    <span> | </span>
    <a href="https://discordapp.com/channels/442252698964721669/443151097398296587">Chat</a>
  </h3>

  <sub>Built with 🦀🕸 by <a href="https://rustwasm.github.io/">The Rust and WebAssembly Working Group</a></sub>
</div>

## About

This template is designed for depending on NPM packages that contain
Rust-generated WebAssembly and using them to create a Website.

* Want to create an NPM package with Rust and WebAssembly? [Check out
  `wasm-pack-template`.](https://github.com/rustwasm/wasm-pack-template)
* Want to make a monorepo-style Website without publishing to NPM? Check out
  [`rust-webpack-template`](https://github.com/rustwasm/rust-webpack-template)
  and/or
  [`rust-parcel-template`](https://github.com/rustwasm/rust-parcel-template).

## 🚴 Usage

```
npm init wasm-app
```

## 🔋 Batteries Included

- `.gitignore`: ignores `node_modules`
- `LICENSE-APACHE` and `LICENSE-MIT`: most Rust projects are licensed this way, so these are included for you
- `README.md`: the file you are reading now!
- `index.html`: a bare bones html document that includes the webpack bundle
- `index.js`: example js file with a comment showing how to import and use a wasm pkg
- `package.json` and `package-lock.json`:
  - pulls in devDependencies for using webpack:
      - [`webpack`](https://www.npmjs.com/package/webpack)
      - [`webpack-cli`](https://www.npmjs.com/package/webpack-cli)
      - [`webpack-dev-server`](https://www.npmjs.com/package/webpack-dev-server)
  - defines a `start` script to run `webpack-dev-server`
- `webpack.config.js`: configuration file for bundling your js with webpack

## License

Licensed under either of

* Apache License, Version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0)
* MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)

at your option.

### Contribution

Unless you explicitly state otherwise, any contribution intentionally
submitted for inclusion in the work by you, as defined in the Apache-2.0
license, shall be dual licensed as above, without any additional terms or
conditions.


================================================
FILE: demo/bootstrap.js
================================================
// A dependency graph that contains any wasm must all be imported
// asynchronously. This `bootstrap.js` file does the single async import, so
// that no one else needs to worry about it again.
import("./index.js")
  .catch(e => console.error("Error importing `index.js`:", e));


================================================
FILE: demo/data.json
================================================
{
  "images": [
    {
      "id": 1,
      "src": "/images/1.jpg",
      "alt": "A mountain range in blue and pale purple colours.",
      "hash": "LUDT3yayV?ay%jWBa#a}9Xj[j@fP",
      "ratio": "4x6",
      "credit": { "username": "eth_gaaar", "displayName": "Edgar Hernández" }
    },
    {
      "id": 2,
      "src": "/images/2.jpg",
      "alt": "A panoramic view of white and blue roofs on a Greek island.",
      "hash": "L3JkcZ^+00~V00009G0000R:%$4T",
      "ratio": "4x6",
      "credit": {
        "username": "hellothisisbenjamin",
        "displayName": "Benjamin Behre"
      }
    },
    {
      "id": 3,
      "src": "/images/3.jpg",
      "alt": "A row of coloured buildings, on a curved stret.",
      "hash": "LFF$O@O,znM*~XNZ#+t8IUV@S5xu",
      "ratio": "6x4",
      "credit": {
        "username": "jonathanricci",
        "displayName": "Jonathan Ricci"
      }
    }
  ]
}


================================================
FILE: demo/index.html
================================================
<!DOCTYPE html>
<html lang="en-US" dir="ltr">
  <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <title>Rust Wasm Blurhash</title>

    <style>
      :root {
        --blue: #1261C9;
        --indigo: #1e12c9;
        --indigo-darker: #1a10b4;
      }
      *:focus {
        outline: 3px solid transparent;
        box-shadow: 0 0 0 3px var(--indigo);
      }
      body {
        hyphens: auto;
        -webkit-hyphens: auto;
        -moz-hyphens: auto;
        -ms-hyphens: auto;
      }
      h1, h2 {
        line-height: 1.25;
      }
      h2 {
        margin-top: 0;
        margin-bottom: 0;
      }
      p, li, h1, h2 {
        max-width: 36em;
      }
      pre {
        padding: 1rem;
        overflow-x: auto;
        -webkit-overflow-scroll: touch;
        border-radius: 4px;
        background-color: #eaeaef;
        font-size: 1rem;
      }
      a:link, a:visited {
        transition: color 0.12s ease;
        color: var(--indigo);
      }
      a:hover, a:focus, a:active {
        color: var(--indigo-darker);
      }
      a:focus {
        text-decoration: none;
      }
      canvas {
        display: block;
      }
      img {
        display: block;
        max-width: 100%;
      }
      .z-n1 {
        z-index: -1;
      }
      .transition-opacity {
        transition: opacity 1s ease-in-out;
      }
      .vs2 > * + * {
        margin-top: 0.5rem;
      }
      .vs3 > * + * {
        margin-top: 1rem;
      }
      .vs4 > * + * {
        margin-top: 2rem;
      }
    </style>
  </head>
  <body class="f4 lh-copy sans-serif bg-near-white near-black">
    <div id="root"></div>
    <script src="./bootstrap.js"></script>
  </body>
</html>


================================================
FILE: demo/index.js
================================================
import "tachyons"
import { App } from "./App";
import { render, h } from "preact";

// You can imagine a similar data structure coming from your backend.
// Note how the blurhash is included in the fields!
import data from "./data.json";

function main() {
  const root = document.getElementById("root");
  render(<App images={data.images} />, root);
}

main();


================================================
FILE: demo/package.json
================================================
{
  "name": "blurhash-wasm-demo",
  "version": "0.1.0",
  "description": "A demo app for blurhash-wasm",
  "main": "index.js",
  "bin": {
    "create-wasm-app": ".bin/create-wasm-app.js"
  },
  "scripts": {
    "build": "webpack --config webpack.config.js",
    "start": "webpack-dev-server"
  },
  "repository": {
    "type": "git",
    "url": "git+https://github.com/rustwasm/create-wasm-app.git"
  },
  "keywords": [
    "webassembly",
    "wasm",
    "rust",
    "blurhash"
  ],
  "author": "Fotis Papadogeorgopoulos <fgpapado@gmail.com>",
  "license": "(MIT OR Apache-2.0)",
  "homepage": "https://github.com/fpapado/blurhash-rust-wasm",
  "dependencies": {
    "blurhash-wasm": "^0.2.0",
    "preact": "^10.0.0-rc.0",
    "tachyons": "^4.11.1"
  },
  "devDependencies": {
    "@babel/core": "^7.5.5",
    "@babel/plugin-transform-react-jsx": "^7.3.0",
    "@babel/preset-env": "^7.5.5",
    "babel-loader": "^8.0.6",
    "copy-webpack-plugin": "^5.0.0",
    "css-loader": "^3.1.0",
    "hello-wasm-pack": "^0.1.0",
    "mini-css-extract-plugin": "^0.8.0",
    "webpack": "^4.29.3",
    "webpack-cli": "^3.1.0",
    "webpack-dev-server": "^3.1.5"
  }
}


================================================
FILE: demo/webpack.config.js
================================================
const CopyWebpackPlugin = require("copy-webpack-plugin");
const MiniCssExtractPlugin = require("mini-css-extract-plugin");
const path = require("path");

module.exports = {
  entry: "./bootstrap.js",
  output: {
    path: path.resolve(__dirname, "dist"),
    filename: "bootstrap.js"
  },
  mode: "development",
  plugins: [
    new CopyWebpackPlugin(["index.html", "public"]),
    new MiniCssExtractPlugin({
      // Options similar to the same options in webpackOptions.output
      // all options are optional
      filename: "[name].[contenthash].css",
      chunkFilename: "[id].css",
      ignoreOrder: false // Enable to remove warnings about conflicting order
    })
  ],
  module: {
    rules: [
      {
        test: /\.m?js$/,
        exclude: /(node_modules|bower_components)/,
        use: {
          loader: "babel-loader",
          options: {
            presets: ["@babel/preset-env"],
            plugins: [["@babel/plugin-transform-react-jsx", { pragma: "h" }]]
          }
        }
      },
      {
        test: /\.css$/,
        use: [
          {
            loader: MiniCssExtractPlugin.loader,
            options: {
              hmr: process.env.NODE_ENV === "development"
            }
          },
          "css-loader"
        ]
      }
    ]
  }
};


================================================
FILE: netlify.toml
================================================
# This file configures the headers and redirect rules for Netlify.
# Some are important for the page to work correctly, and other
# are for performance.
# Reference: https://www.netlify.com/docs/netlify-toml-reference/

# Global settings applied to the whole site.
#
# “base” is the directory to change to before starting build. If you set base:
#        that is where we will look for package.json/.nvmrc/etc, not repo root!
# “command” is your build command.
# “publish” is the directory to publish (relative to the root of your repo).

[build]
  base    = "demo"
  publish = "demo/dist"
  command = "npm run build"

# Redirects
# Anything else, we redirect to index.html
[[redirects]]
  from = "/*"
  to = "/index.html"
  status = 200

# Headers
[[headers]]
  # Anything under /static is hashed, so we can cache indefinitely
  for = "/static/*"

  [headers.values]
    cache-control = '''
    public,
    max-age=31536000,
    immutable'''

[[headers]]
  # Assets under images/ are mutable, but large-ish
  # We cache them for a short time, to avoid excessive data consumption
  for = "/images/*"

  [headers.values]
    cache-control =  '''
    public,
    max-age=600,
    must-revalidate'''


================================================
FILE: src/lib.rs
================================================
mod utils;

use std::cmp::Ordering;
use std::convert::TryFrom;
use std::f64::consts::PI;
use thiserror::*;
use wasm_bindgen::prelude::*;

// When the `wee_alloc` feature is enabled, use `wee_alloc` as the global
// allocator.
#[cfg(feature = "wee_alloc")]
#[global_allocator]
static ALLOC: wee_alloc::WeeAlloc = wee_alloc::WeeAlloc::INIT;

// TODO: Add adjustable 'punch'
// TODO: Avoid panicing infrasturcture (checked division, .get, no unwrap)

#[derive(Clone, Copy, Debug, PartialEq, Eq, Error)]
pub enum Error {
    #[error("the length of the hash is invalid")]
    LengthInvalid,
    #[error("the specified number of components does not match the actual length")]
    LengthMismatch,
}

#[derive(Clone, Copy, Debug, PartialEq, Eq, Error)]
pub enum EncodingError {
    #[error("cannot encode this number of components")]
    ComponentsNumberInvalid,
    #[error("the bytes per pixel does not match the pixel count")]
    BytesPerPixelMismatch,
}

// Decode

/// Decode for WASM target. If an error occurs, the function will throw a `JsError`.
#[wasm_bindgen(js_name = "decode")]
pub fn wasm_decode(blur_hash: &str, width: usize, height: usize) -> Result<Vec<u8>, JsValue> {
    decode(blur_hash, width, height).map_err(|err| js_sys::Error::new(&err.to_string()).into())
}

pub fn decode(blur_hash: &str, width: usize, height: usize) -> Result<Vec<u8>, Error> {
    if blur_hash.len() < 6 {
        return Err(Error::LengthInvalid);
    }

    // 1. Number of components
    // For a BlurHash with nx components along the X axis and ny components
    // along the Y axis, this is equal to (nx - 1) + (ny - 1) * 9.
    let size_flag = decode_base83_string(blur_hash.get(0..1).unwrap());

    let num_y = (size_flag / 9) + 1;
    let num_x = (size_flag % 9) + 1;

    // Validate that the number of digits is what we expect:
    // 1 (size flag) + 1 (maximum value) + 4 (average colour) + (num_x - num_y - 1) components * 2 digits each
    let expected_digits = 4 + 2 * num_x * num_y;

    if blur_hash.len() != expected_digits {
        return Err(Error::LengthMismatch);
    }

    // 2. Maximum AC component value, 1 digit.
    // All AC components are scaled by this value.
    // It represents a floating-point value of (max + 1) / 166.
    let quantised_maximum_value = decode_base83_string(blur_hash.get(1..2).unwrap());
    let maximum_value = ((quantised_maximum_value + 1) as f64) / 166f64;

    let mut colours: Vec<[f64; 3]> = Vec::with_capacity(num_x * num_y);

    for i in 0..(num_x * num_y) {
        if i == 0 {
            // 3. Average colour, 4 digits.
            let value = decode_base83_string(blur_hash.get(2..6).unwrap());
            colours.push(decode_dc(value));
        } else {
            // 4. AC components, 2 digits each, nx * ny - 1 components in total.
            let value = decode_base83_string(blur_hash.get((4 + i * 2)..(4 + i * 2 + 2)).unwrap());
            colours.push(decode_ac(value, maximum_value * 1.0));
        }
    }

    // Now, construct the image
    // NOTE: We include an alpha channel of 255 as well, because it is more convenient,
    // for various representations (browser canvas, for example).
    // This could probably be configured
    let bytes_per_row = width * 4;

    let mut pixels = vec![0; bytes_per_row * height];

    for y in 0..height {
        for x in 0..width {
            let mut r = 0f64;
            let mut g = 0f64;
            let mut b = 0f64;

            for j in 0..num_y {
                for i in 0..num_x {
                    let basis = f64::cos(PI * (x as f64) * (i as f64) / (width as f64))
                        * f64::cos(PI * (y as f64) * (j as f64) / (height as f64));
                    let colour = colours[i + j * num_x];
                    r += colour[0] * basis;
                    g += colour[1] * basis;
                    b += colour[2] * basis;
                }
            }

            let int_r = linear_to_srgb(r);
            let int_g = linear_to_srgb(g);
            let int_b = linear_to_srgb(b);

            pixels[4 * x + y * bytes_per_row] = int_r as u8;
            pixels[4 * x + 1 + y * bytes_per_row] = int_g as u8;
            pixels[4 * x + 2 + y * bytes_per_row] = int_b as u8;
            pixels[4 * x + 3 + y * bytes_per_row] = 255 as u8;
        }
    }

    Ok(pixels)
}

fn decode_dc(value: usize) -> [f64; 3] {
    let int_r = value >> 16;
    let int_g = (value >> 8) & 255;
    let int_b = value & 255;
    [
        srgb_to_linear(int_r),
        srgb_to_linear(int_g),
        srgb_to_linear(int_b),
    ]
}

fn decode_ac(value: usize, maximum_value: f64) -> [f64; 3] {
    let quant_r = f64::floor((value / (19 * 19)) as f64);
    let quant_g = f64::floor(((value / 19) as f64) % 19f64);
    let quant_b = (value as f64) % 19f64;
    [
        sign_pow((quant_r - 9f64) / 9f64, 2f64) * maximum_value,
        sign_pow((quant_g - 9f64) / 9f64, 2f64) * maximum_value,
        sign_pow((quant_b - 9f64) / 9f64, 2f64) * maximum_value,
    ]
}

fn sign_pow(value: f64, exp: f64) -> f64 {
    value.abs().powf(exp).copysign(value)
}

fn linear_to_srgb(value: f64) -> usize {
    let v = f64::max(0f64, f64::min(1f64, value));
    if v <= 0.003_130_8 {
        (v * 12.92 * 255f64 + 0.5) as usize
    } else {
        ((1.055 * f64::powf(v, 1f64 / 2.4) - 0.055) * 255f64 + 0.5) as usize
    }
}

fn srgb_to_linear(value: usize) -> f64 {
    let v = (value as f64) / 255f64;
    if v <= 0.04045 {
        v / 12.92
    } else {
        ((v + 0.055) / 1.055).powf(2.4)
    }
}

// Encode

// TODO: Think about argument order here...
// What is more common in Rust? Data or config first?
pub fn encode(
    pixels: Vec<u8>,
    cx: usize,
    cy: usize,
    width: usize,
    height: usize,
) -> Result<String, EncodingError> {
    // Should we assume RGBA for round-trips? Or does it not matter?
    let bytes_per_row = width * 4;
    let bytes_per_pixel = 4;

    // NOTE: We could clamp instead of Err.
    // The TS version does that. Not sure which one is better.
    // We also could (should?) be checking for the color space
    if cx < 1 || cx > 9 || cy < 1 || cy > 9 {
        return Err(EncodingError::ComponentsNumberInvalid);
    }

    if width * height * 4 != pixels.len() {
        return Err(EncodingError::BytesPerPixelMismatch);
    }

    let mut dc: [f64; 3] = [0., 0., 0.];
    let mut ac: Vec<[f64; 3]> = Vec::with_capacity(cy * cx - 1);

    for y in 0..cy {
        for x in 0..cx {
            let normalisation = if x == 0 && y == 0 { 1f64 } else { 2f64 };
            let factor = multiply_basis_function(
                &pixels,
                width,
                height,
                bytes_per_row,
                bytes_per_pixel,
                0,
                |a, b| {
                    (normalisation
                        * f64::cos((PI * x as f64 * a) / width as f64)
                        * f64::cos((PI * y as f64 * b) / height as f64))
                },
            );

            if x == 0 && y == 0 {
                // The first iteration is the dc
                dc = factor;
            } else {
                // All others are the ac
                ac.push(factor);
            }
        }
    }

    let mut hash = String::new();

    let size_flag = ((cx - 1) + (cy - 1) * 9) as usize;
    hash += &encode_base83_string(size_flag, 1);

    let maximum_value: f64;

    if !ac.is_empty() {
        // I'm sure there's a better way to write this; following the Swift atm :)
        let actual_maximum_value = ac
            .clone()
            .into_iter()
            .map(|[a, b, c]| f64::max(f64::max(f64::abs(a), f64::abs(b)), f64::abs(c)))
            .max_by(|a, b| a.partial_cmp(b).unwrap_or(Ordering::Equal))
            .unwrap();
        let quantised_maximum_value = usize::max(
            0,
            usize::min(82, f64::floor(actual_maximum_value * 166f64 - 0.5) as usize),
        );
        maximum_value = ((quantised_maximum_value + 1) as f64) / 166f64;
        hash += &encode_base83_string(quantised_maximum_value, 1);
    } else {
        maximum_value = 1f64;
        hash += &encode_base83_string(0, 1);
    }

    hash += &encode_base83_string(encode_dc(dc), 4);

    for factor in ac {
        hash += &encode_base83_string(encode_ac(factor, maximum_value), 2);
    }

    Ok(hash)
}

fn multiply_basis_function<F>(
    pixels: &[u8],
    width: usize,
    height: usize,
    bytes_per_row: usize,
    bytes_per_pixel: usize,
    pixel_offset: usize,
    basis_function: F,
) -> [f64; 3]
where
    F: Fn(f64, f64) -> f64,
{
    let mut r = 0f64;
    let mut g = 0f64;
    let mut b = 0f64;

    for x in 0..width {
        for y in 0..height {
            let basis = basis_function(x as f64, y as f64);
            r += basis
                * srgb_to_linear(
                    usize::try_from(pixels[bytes_per_pixel * x + pixel_offset + y * bytes_per_row])
                        .unwrap(),
                );
            g += basis
                * srgb_to_linear(
                    usize::try_from(
                        pixels[bytes_per_pixel * x + pixel_offset + 1 + y * bytes_per_row],
                    )
                    .unwrap(),
                );
            b += basis
                * srgb_to_linear(
                    usize::try_from(
                        pixels[bytes_per_pixel * x + pixel_offset + 2 + y * bytes_per_row],
                    )
                    .unwrap(),
                );
        }
    }

    let scale = 1f64 / ((width * height) as f64);

    [r * scale, g * scale, b * scale]
}

fn encode_dc(value: [f64; 3]) -> usize {
    let rounded_r = linear_to_srgb(value[0]);
    let rounded_g = linear_to_srgb(value[1]);
    let rounded_b = linear_to_srgb(value[2]);
    ((rounded_r << 16) + (rounded_g << 8) + rounded_b) as usize
}

fn encode_ac(value: [f64; 3], maximum_value: f64) -> usize {
    let quant_r = f64::floor(f64::max(
        0f64,
        f64::min(
            18f64,
            f64::floor(sign_pow(value[0] / maximum_value, 0.5) * 9f64 + 9.5),
        ),
    ));
    let quant_g = f64::floor(f64::max(
        0f64,
        f64::min(
            18f64,
            f64::floor(sign_pow(value[1] / maximum_value, 0.5) * 9f64 + 9.5),
        ),
    ));
    let quant_b = f64::floor(f64::max(
        0f64,
        f64::min(
            18f64,
            f64::floor(sign_pow(value[2] / maximum_value, 0.5) * 9f64 + 9.5),
        ),
    ));

    (quant_r * 19f64 * 19f64 + quant_g * 19f64 + quant_b) as usize
}

// Base83

// I considered using lazy_static! for this, but other implementations
// seem to hard-code these as well. Doing that for consistency.
static ENCODE_CHARACTERS: [char; 83] = [
    '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I',
    'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b',
    'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u',
    'v', 'w', 'x', 'y', 'z', '#', '$', '%', '*', '+', ',', '-', '.', ':', ';', '=', '?', '@', '[',
    ']', '^', '_', '{', '|', '}', '~',
];

fn decode_base83_string(string: &str) -> usize {
    string
        .chars()
        .filter_map(|character| ENCODE_CHARACTERS.iter().position(|&c| c == character))
        .fold(0, |value, digit| value * 83 + digit)
}

fn encode_base83_string(value: usize, length: u32) -> String {
    (1..=length)
        .map(|i| (value / usize::pow(83, length - i)) % 83)
        .map(|digit| ENCODE_CHARACTERS[digit])
        .collect()
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn it_decodes_size_flag() {
        assert_eq!(21, decode_base83_string("L"));
        assert_eq!(0, decode_base83_string("0"));
    }
    #[test]
    fn decodes_size_0_out_of_range() {
        let res = decode_base83_string("/");
        assert_eq!(
            0, res,
            "Did not expect to decode size for input out of range (expected 0), but got {}",
            res
        );
    }
}


================================================
FILE: src/utils.rs
================================================
pub fn set_panic_hook() {
    // When the `console_error_panic_hook` feature is enabled, we can call the
    // `set_panic_hook` function at least once during initialization, and then
    // we will get better error messages if our code ever panics.
    //
    // For more details see
    // https://github.com/rustwasm/console_error_panic_hook#readme
    #[cfg(feature = "console_error_panic_hook")]
    console_error_panic_hook::set_once();
}


================================================
FILE: tests/integration_test.rs
================================================
use blurhash_wasm::{decode, encode};
use image;
use std::convert::TryFrom;

#[test]
fn err_if_hash_length_less_than_6() {
    assert_eq!(
        Err(blurhash_wasm::Error::LengthInvalid),
        decode("L", 40, 30)
    );
}

#[test]
fn decodes_ok() {
    // From the online demo
    let res = decode("LUDT3yayV?ay%jWBa#a}9Xj[j@fP", 40, 30);

    // From a known encode/decode
    let expected = image::open("tests/data/decode-test-expected.png")
        .unwrap()
        .to_rgba();

    match res {
        Ok(img) => {
            // image::save_buffer("decode-test-out.png", &img, 40, 30, image::RGBA(8));
            assert_eq!(expected.to_vec(), img);
        }

        Err(_err) => assert!(false),
    }
}

#[test]
fn encodes_ok() {
    // From a known encode/decode
    let input = image::open("tests/data/encode-test-input.jpg")
        .unwrap()
        .to_rgba();
    let (width, height) = input.dimensions();

    // From the online demo
    // let expected = "LKO2?U%2Tw=w]~RBVZRi};RPxuwH";

    // From our encoding, not sure why they differ
    let expected = "LKO2?V%2Tw=^]~RBVZRi};RPxuwH";

    let res = encode(
        input.into_vec(),
        4,
        3,
        usize::try_from(width).unwrap(),
        usize::try_from(height).unwrap(),
    );

    match res {
        Ok(actual) => {
            assert_eq!(expected, actual);
        }

        Err(_err) => assert!(false),
    }
}

#[test]
fn encodes_ok_2() {
    // From a known encode/decode
    let input = image::open("tests/data/encode-test-input-2.jpg")
        .unwrap()
        .to_rgba();
    let (width, height) = input.dimensions();

    // From the online demo
    // let expected = "LGF5]+Yk^6#M@-5c,1J5@[or[Q6.";

    // From our encoding
    // Again, weird mismatch
    let expected = "LGFFaXYk^6#M@-5c,1Ex@@or[j6o";

    let res = encode(
        input.into_vec(),
        4,
        3,
        usize::try_from(width).unwrap(),
        usize::try_from(height).unwrap(),
    );

    match res {
        Ok(actual) => {
            assert_eq!(expected, actual);
        }

        Err(_err) => assert!(false),
    }
}

#[test]
fn round_trips_ok() {
    // From a known encode/decode
    let input = image::open("tests/data/encode-test-input.jpg")
        .unwrap()
        .to_rgba();
    let (width, height) = input.dimensions();

    // From the online demo
    // let expected = "LKO2?U%2Tw=w]~RBVZRi};RPxuwH";

    // From our encoding, not sure why they differ
    let expected_encode = "LKO2?V%2Tw=^]~RBVZRi};RPxuwH";

    let encode_res = encode(
        input.into_vec(),
        4,
        3,
        usize::try_from(width).unwrap(),
        usize::try_from(height).unwrap(),
    );

    match encode_res {
        Ok(actual_encode) => {
            assert_eq!(expected_encode, actual_encode);
            let expected_decode = image::open("tests/data/roundtrip-test-input-decode.png")
                .unwrap()
                .to_rgba();

            let decode_res = decode(&actual_encode, 32, 32);

            match decode_res {
                Ok(actual_decode) => {
                    assert_eq!(expected_decode.to_vec(), actual_decode);
                }

                Err(_err) => assert!(false),
            }
        }

        Err(_err) => assert!(false),
    }
}


================================================
FILE: tests/web.rs
================================================
//! Test suite for the Web and headless browsers.

#![cfg(target_arch = "wasm32")]

extern crate wasm_bindgen_test;
use wasm_bindgen_test::*;

wasm_bindgen_test_configure!(run_in_browser);

#[wasm_bindgen_test]
fn pass() {
    assert_eq!(1 + 1, 2);
}