perspective_viewer/utils/
custom_element.rs

1// ┏━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┓
2// ┃ ██████ ██████ ██████       █      █      █      █      █ █▄  ▀███ █       ┃
3// ┃ ▄▄▄▄▄█ █▄▄▄▄▄ ▄▄▄▄▄█  ▀▀▀▀▀█▀▀▀▀▀ █ ▀▀▀▀▀█ ████████▌▐███ ███▄  ▀█ █ ▀▀▀▀▀ ┃
4// ┃ █▀▀▀▀▀ █▀▀▀▀▀ █▀██▀▀ ▄▄▄▄▄ █ ▄▄▄▄▄█ ▄▄▄▄▄█ ████████▌▐███ █████▄   █ ▄▄▄▄▄ ┃
5// ┃ █      ██████ █  ▀█▄       █ ██████      █      ███▌▐███ ███████▄ █       ┃
6// ┣━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┫
7// ┃ Copyright (c) 2017, the Perspective Authors.                              ┃
8// ┃ ╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌ ┃
9// ┃ This file is part of the Perspective library, distributed under the terms ┃
10// ┃ of the [Apache License 2.0](https://www.apache.org/licenses/LICENSE-2.0). ┃
11// ┗━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┛
12
13//! Utilities for building JavaScript Custom Elements with Rust.
14
15use wasm_bindgen::prelude::*;
16
17#[wasm_bindgen(inline_js = r#"
18    export function bootstrap(psp, name, clsname, statics) {
19        const cls = psp[clsname];
20        const proto = cls.prototype;
21        class x extends HTMLElement {
22            constructor() {
23                super();
24                this._instance = new cls(this);
25            }
26        }
27
28        const names = Object.getOwnPropertyNames(proto);
29        for (const key of names) {
30            if ('get' in Object.getOwnPropertyDescriptor(proto, key)) {
31                Object.defineProperty(x.prototype, key, {
32                    get: function() {
33                        return this._instance[key];
34                    }
35                });
36            } else {
37                Object.defineProperty(x.prototype, key, {
38                    value: function(...args) {
39                        return this._instance[key].call(this._instance, ...args);
40                    }
41                });
42            }
43        }
44
45        for (const key of statics) {
46            Object.defineProperty(x, key, {
47                value: function(...args) {
48                    return psp[key].call(psp, ...args);
49                }
50            });
51        }
52
53        Object.defineProperty(x, '__wasm_module__', {
54            get() {
55                return psp;
56            },
57        });
58
59        customElements.define(name, x);
60    }
61"#)]
62extern "C" {
63    #[wasm_bindgen(js_name = "bootstrap")]
64    fn js_bootstrap(psp: &JsValue, name: &str, cls: &str, statics: js_sys::Array) -> JsValue;
65}
66
67/// A trait which allows the [`define_web_component`] method to create a
68/// Custom Element (which must by definition inherit from `HTMLElement`) from
69/// a `[wasm_bindgen]` annotated Rust struct (for which this trait is
70/// implemented).
71pub trait CustomElementMetadata {
72    /// The name of the element to register.
73    const CUSTOM_ELEMENT_NAME: &'static str;
74
75    /// [optional] The names of the methods which should be static on the
76    /// element.
77    const STATICS: &'static [&'static str] = [].as_slice();
78
79    /// [optional] The name of the Rust struct.
80    const TYPE_NAME: &'static str = std::any::type_name::<Self>();
81
82    /// [optional] A custom implementation of struct name to class name.
83    #[must_use]
84    fn struct_name() -> &'static str {
85        match &Self::TYPE_NAME.rfind(':') {
86            Some(pos) => &Self::TYPE_NAME[pos + 1..],
87            None => Self::TYPE_NAME,
88        }
89    }
90}
91
92/// Register the Custom Element globally.
93pub fn define_web_component<T: CustomElementMetadata>(module: &JsValue) {
94    js_bootstrap(
95        module,
96        T::CUSTOM_ELEMENT_NAME,
97        T::struct_name(),
98        T::STATICS.iter().cloned().map(JsValue::from).collect(),
99    );
100}
perspective_viewer/utils/custom_element.rs

perspective_viewer/utils/
custom_element.rs
