ca17d4f639
Parse all `<img>` tags, during doc-gen, and insert the width and height of the sourceed image, if neither are already specified. Warnings are reported if the `<img>` tag has no `src` attribute or the image cannot be loaded. The work is done in the `addImageDimensions` post-processor, which must be configured with a `basePath` so that it knows where to find the images. Closes #15888
41 lines
1.4 KiB
JavaScript
41 lines
1.4 KiB
JavaScript
const visit = require('unist-util-visit');
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const is = require('hast-util-is-element');
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const source = require('unist-util-source');
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/**
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* Add the width and height of the image to the `img` tag if they are
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* not already provided. This helps prevent jank when the page is
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* rendered before the image has downloaded.
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*
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* If there is no `src` attribute on an image, or it is not possible
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* to load the image file indicated by the `src` then a warning is emitted.
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*/
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module.exports = function addImageDimensions(getImageDimensions) {
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return function addImageDimensionsImpl() {
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return (ast, file) => {
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visit(ast, node => {
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if (is(node, 'img')) {
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const props = node.properties;
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const src = props.src;
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if (!src) {
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file.message('Missing src in image tag `' + source(node, file) + '`');
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} else if (props.width === undefined && props.height === undefined) {
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try {
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const dimensions = getImageDimensions(addImageDimensionsImpl.basePath, src);
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props.width = '' + dimensions.width;
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props.height = '' + dimensions.height;
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} catch(e) {
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if (e.code === 'ENOENT') {
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file.message('Unable to load src in image tag `' + source(node, file) + '`');
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} else {
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file.fail(e.message);
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}
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}
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}
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}
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});
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};
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};
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};
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