52 lines
1.8 KiB
JavaScript
52 lines
1.8 KiB
JavaScript
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// @flow
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import katexReplaceWithTex from './katex2tex';
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// Return <div class="katex"> element containing node, or null if not found.
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function closestKatex(node: Node): ?Element {
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// If node is a Text Node, for example, go up to containing Element,
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// where we can apply the `closest` method.
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const element: ?Element =
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(node instanceof Element ? node : node.parentElement);
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return element && element.closest('.katex');
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}
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// Global copy handler to modify behavior on/within .katex elements.
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document.addEventListener('copy', function(event: ClipboardEvent) {
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const selection = window.getSelection();
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if (selection.isCollapsed || !event.clipboardData) {
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return; // default action OK if selection is empty or unchangeable
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}
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const clipboardData = event.clipboardData;
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const range = selection.getRangeAt(0);
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// When start point is within a formula, expand to entire formula.
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const startKatex = closestKatex(range.startContainer);
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if (startKatex) {
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range.setStartBefore(startKatex);
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}
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// Similarly, when end point is within a formula, expand to entire formula.
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const endKatex = closestKatex(range.endContainer);
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if (endKatex) {
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range.setEndAfter(endKatex);
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}
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const fragment = range.cloneContents();
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if (!fragment.querySelector('.katex-mathml')) {
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return; // default action OK if no .katex-mathml elements
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}
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const htmlContents = Array.prototype.map.call(fragment.childNodes,
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(el) => (el instanceof Text ? el.textContent : el.outerHTML)
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).join('');
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// Preserve usual HTML copy/paste behavior.
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clipboardData.setData('text/html', htmlContents);
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// Rewrite plain-text version.
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clipboardData.setData('text/plain',
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katexReplaceWithTex(fragment).textContent);
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// Prevent normal copy handling.
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event.preventDefault();
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});
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