Files
gitea/web_src/js/markup/mermaid.ts
2026-02-11 03:22:33 +00:00

252 lines
11 KiB
TypeScript

import {isDarkTheme, parseDom} from '../utils.ts';
import {displayError} from './common.ts';
import {createElementFromAttrs, createElementFromHTML, queryElems} from '../utils/dom.ts';
import {html, htmlRaw} from '../utils/html.ts';
import {load as loadYaml} from 'js-yaml';
import type {MermaidConfig} from 'mermaid';
import {svg} from '../svg.ts';
const {mermaidMaxSourceCharacters} = window.config;
function getIframeCss(): string {
return `
html, body { height: 100%; }
body { margin: 0; padding: 0; overflow: hidden; }
#mermaid { display: block; margin: 0 auto; }
`;
}
function isSourceTooLarge(source: string) {
return mermaidMaxSourceCharacters >= 0 && source.length > mermaidMaxSourceCharacters;
}
function parseYamlInitConfig(source: string): MermaidConfig | null {
// ref: https://github.com/mermaid-js/mermaid/blob/develop/packages/mermaid/src/diagram-api/regexes.ts
const yamlFrontMatterRegex = /^---\s*[\n\r](.*?)[\n\r]---\s*[\n\r]+/s;
const frontmatter = (yamlFrontMatterRegex.exec(source) || [])[1];
if (!frontmatter) return null;
try {
return (loadYaml(frontmatter) as {config: MermaidConfig})?.config;
} catch {
console.error('invalid or unsupported mermaid init YAML config', frontmatter);
}
return null;
}
function parseJsonInitConfig(source: string): MermaidConfig | null {
// https://mermaid.js.org/config/directives.html#declaring-directives
// Do as dirty as mermaid does: https://github.com/mermaid-js/mermaid/blob/develop/packages/mermaid/src/utils.ts
// It can even accept invalid JSON string like:
// %%{initialize: { 'logLevel': 'fatal', "theme":'dark', 'startOnLoad': true } }%%
const jsonInitConfigRegex = /%%\{\s*(init|initialize)\s*:\s*(.*?)\}%%/s;
const jsonInitText = (jsonInitConfigRegex.exec(source) || [])[2];
if (!jsonInitText) return null;
try {
const processed = jsonInitText.trim().replace(/'/g, '"');
return JSON.parse(processed);
} catch {
console.error('invalid or unsupported mermaid init JSON config', jsonInitText);
}
return null;
}
function configValueIsElk(layoutOrRenderer: string | undefined) {
if (typeof layoutOrRenderer !== 'string') return false;
return layoutOrRenderer === 'elk' || layoutOrRenderer.startsWith('elk.');
}
function configContainsElk(config: MermaidConfig | null) {
if (!config) return false;
// Check the layout from the following properties:
// * config.layout
// * config.{any-diagram-config}.defaultRenderer
// Although only a few diagram types like "flowchart" support "defaultRenderer",
// as long as there is no side effect, here do a general check for all properties of "config", for ease of maintenance
return configValueIsElk(config.layout) || Object.values(config).some((diagCfg) => configValueIsElk(diagCfg?.defaultRenderer));
}
export function sourceNeedsElk(source: string) {
if (isSourceTooLarge(source)) return false;
const configYaml = parseYamlInitConfig(source), configJson = parseJsonInitConfig(source);
return configContainsElk(configYaml) || configContainsElk(configJson);
}
async function loadMermaid(needElkRender: boolean) {
const mermaidPromise = import(/* webpackChunkName: "mermaid" */'mermaid');
const elkPromise = needElkRender ? import(/* webpackChunkName: "mermaid-layout-elk" */'@mermaid-js/layout-elk') : null;
const results = await Promise.all([mermaidPromise, elkPromise]);
return {
mermaid: results[0].default,
elkLayouts: results[1]?.default,
};
}
function initMermaidViewController(viewController: HTMLElement, dragElement: SVGSVGElement) {
let inited = false, isDragging = false;
let currentScale = 1, initLeft = 0, lastLeft = 0, lastTop = 0, lastPageX = 0, lastPageY = 0;
const resetView = () => {
currentScale = 1;
lastLeft = initLeft;
lastTop = 0;
dragElement.style.left = `${lastLeft}px`;
dragElement.style.top = `${lastTop}px`;
dragElement.style.position = 'absolute';
dragElement.style.margin = '0';
};
const initAbsolutePosition = () => {
if (inited) return;
// if we need to drag or zoom, use absolute position and get the current "left" from the "margin: auto" layout.
inited = true;
const container = dragElement.parentElement!;
initLeft = container.getBoundingClientRect().width / 2 - dragElement.getBoundingClientRect().width / 2;
resetView();
};
for (const el of viewController.querySelectorAll('[data-control-action]')) {
el.addEventListener('click', () => {
initAbsolutePosition();
switch (el.getAttribute('data-control-action')) {
case 'zoom-in':
currentScale *= 1.2;
break;
case 'zoom-out':
currentScale /= 1.2;
break;
case 'reset':
resetView();
break;
}
dragElement.style.transform = `scale(${currentScale})`;
});
}
dragElement.addEventListener('mousedown', (e) => {
if (e.button !== 0 || e.altKey || e.ctrlKey || e.metaKey || e.shiftKey) return; // only left mouse button can drag
const target = e.target as Element;
// don't start the drag if the click is on an interactive element (e.g.: link, button) or text element
if (target.closest('div, p, a, span, button, input, text')) return;
initAbsolutePosition();
isDragging = true;
lastPageX = e.pageX;
lastPageY = e.pageY;
dragElement.style.cursor = 'grabbing';
});
dragElement.ownerDocument.addEventListener('mousemove', (e) => {
if (!isDragging) return;
lastLeft = e.pageX - lastPageX + lastLeft;
lastTop = e.pageY - lastPageY + lastTop;
dragElement.style.left = `${lastLeft}px`;
dragElement.style.top = `${lastTop}px`;
lastPageX = e.pageX;
lastPageY = e.pageY;
});
dragElement.ownerDocument.addEventListener('mouseup', () => {
if (!isDragging) return;
isDragging = false;
dragElement.style.removeProperty('cursor');
});
}
let elkLayoutsRegistered = false;
export async function initMarkupCodeMermaid(elMarkup: HTMLElement): Promise<void> {
// .markup code.language-mermaid
const mermaidBlocks: Array<{source: string, parentContainer: HTMLElement}> = [];
const attrMermaidRendered = 'data-markup-mermaid-rendered';
let needElkRender = false;
for (const elCodeBlock of queryElems(elMarkup, 'code.language-mermaid')) {
const parentContainer = elCodeBlock.closest('pre')!; // it must exist, if no, there must be a bug
if (parentContainer.hasAttribute(attrMermaidRendered)) continue;
parentContainer.setAttribute(attrMermaidRendered, 'true');
const source = elCodeBlock.textContent ?? '';
needElkRender = needElkRender || sourceNeedsElk(source);
mermaidBlocks.push({source, parentContainer});
}
if (!mermaidBlocks.length) return;
const {mermaid, elkLayouts} = await loadMermaid(needElkRender);
if (elkLayouts && !elkLayoutsRegistered) {
mermaid.registerLayoutLoaders(elkLayouts);
elkLayoutsRegistered = true;
}
mermaid.initialize({
startOnLoad: false,
theme: isDarkTheme() ? 'dark' : 'neutral', // TODO: maybe it should use "darkMode" to adopt more user-specified theme instead of just "dark" or "neutral"
securityLevel: 'strict',
suppressErrorRendering: true,
});
const iframeStyleText = getIframeCss();
const applyMermaidIframeHeight = (iframe: HTMLIFrameElement, height: number) => {
if (!height) return;
// use a min-height to make sure the buttons won't overlap.
iframe.style.height = `${Math.max(height, 85)}px`;
};
// mermaid is a globally shared instance, its document also says "Multiple calls to this function will be enqueued to run serially."
// so here we just simply render the mermaid blocks one by one, no need to do "Promise.all" concurrently
for (const block of mermaidBlocks) {
const {source, parentContainer} = block;
if (isSourceTooLarge(source)) {
displayError(parentContainer, new Error(`Mermaid source of ${source.length} characters exceeds the maximum allowed length of ${mermaidMaxSourceCharacters}.`));
continue;
}
try {
// render the mermaid diagram to svg text, and parse it to a DOM node
const {svg: svgText, bindFunctions} = await mermaid.render('mermaid', source, parentContainer);
const svgDoc = parseDom(svgText, 'image/svg+xml');
const svgNode = (svgDoc.documentElement as unknown) as SVGSVGElement;
const viewControllerHtml = html`
<div class="view-controller auto-hide-control flex-text-block">
<button type="button" class="ui tiny compact icon button" data-control-action="zoom-in">${htmlRaw(svg('octicon-zoom-in', 12))}</button>
<button type="button" class="ui tiny compact icon button" data-control-action="reset">${htmlRaw(svg('octicon-sync', 12))}</button>
<button type="button" class="ui tiny compact icon button" data-control-action="zoom-out">${htmlRaw(svg('octicon-zoom-out', 12))}</button>
</div>
`;
const viewController = createElementFromHTML(viewControllerHtml);
// create an iframe to sandbox the svg with styles, and set correct height by reading svg's viewBox height
const iframe = document.createElement('iframe');
iframe.classList.add('markup-content-iframe', 'is-loading');
// the styles are not ready, so don't really render anything before the "load" event, to avoid flicker of unstyled content
iframe.srcdoc = html`<html><head></head><body></body></html>`;
// although the "viewBox" is optional, mermaid's output should always have a correct viewBox with width and height
const iframeHeightFromViewBox = Math.ceil(svgNode.viewBox?.baseVal?.height ?? 0);
applyMermaidIframeHeight(iframe, iframeHeightFromViewBox);
// the iframe will be fully reloaded if its DOM context is changed (e.g.: moved in the DOM tree).
// to avoid unnecessary reloading, we should insert the iframe to its final position only once.
iframe.addEventListener('load', () => {
// same origin, so we can operate "iframe head/body" and all elements directly
const style = document.createElement('style');
style.textContent = iframeStyleText;
iframe.contentDocument!.head.append(style);
const iframeBody = iframe.contentDocument!.body;
iframeBody.append(svgNode);
bindFunctions?.(iframeBody); // follow "mermaid.render" doc, attach event handlers to the svg's container
// according to mermaid, the viewBox height should always exist, here just a fallback for unknown cases.
// and keep in mind: clientHeight can be 0 if the element is hidden (display: none).
if (!iframeHeightFromViewBox) applyMermaidIframeHeight(iframe, iframeBody.clientHeight);
iframe.classList.remove('is-loading');
initMermaidViewController(viewController, svgNode);
});
const container = createElementFromAttrs('div', {class: 'mermaid-block'}, iframe, viewController);
parentContainer.replaceWith(container);
} catch (err) {
displayError(parentContainer, err);
}
}
}