53 lines
2.7 KiB
HTML
53 lines
2.7 KiB
HTML
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<!DOCTYPE html>
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<script src="../include.js"></script>
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<script>
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// 1x1 valid PNGs (red and blue) used to observe re-evaluation of the picture's source set.
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const RED_PNG_DATA_URL = "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVR42mP8z8BQDwADhQGAWjR9awAAAABJRU5ErkJggg==";
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const BLUE_PNG_DATA_URL = "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVR4nGNgAAIAAAUAAen63NgAAAAASUVORK5CYII=";
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asyncTest(async done => {
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const picture = document.createElement("picture");
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const source = document.createElement("source");
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source.setAttribute("srcset", RED_PNG_DATA_URL);
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const img = document.createElement("img");
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picture.appendChild(source);
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picture.appendChild(img);
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document.body.appendChild(picture);
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// Wait for first load: img picks up the source's srcset.
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await new Promise(resolve => img.addEventListener("load", resolve, { once: true }));
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const firstSrc = img.currentSrc;
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// https://html.spec.whatwg.org/multipage/images.html#relevant-mutations
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// "The element's parent is a picture element and a source element that is a previous
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// sibling has its srcset, sizes, media, type, width or height attributes set, changed,
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// or removed."
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// Mutating the source's srcset must trigger update-the-image-data on the img.
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const secondLoaded = new Promise(resolve => img.addEventListener("load", resolve, { once: true }));
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source.setAttribute("srcset", BLUE_PNG_DATA_URL);
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await secondLoaded;
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const secondSrc = img.currentSrc;
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println(`first matches red: ${firstSrc === RED_PNG_DATA_URL}`);
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println(`second matches blue: ${secondSrc === BLUE_PNG_DATA_URL}`);
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println(`re-evaluated on srcset mutation: ${firstSrc !== secondSrc}`);
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// Inserting a new <source> as a previous sibling of the img must also trigger re-eval.
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const thirdLoaded = new Promise(resolve => img.addEventListener("load", resolve, { once: true }));
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const newSource = document.createElement("source");
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newSource.setAttribute("srcset", RED_PNG_DATA_URL);
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picture.insertBefore(newSource, source);
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await thirdLoaded;
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println(`re-evaluated on source insertion: ${img.currentSrc === RED_PNG_DATA_URL}`);
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// Removing that source must again trigger re-eval, falling back to the remaining source.
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const fourthLoaded = new Promise(resolve => img.addEventListener("load", resolve, { once: true }));
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picture.removeChild(newSource);
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await fourthLoaded;
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println(`re-evaluated on source removal: ${img.currentSrc === BLUE_PNG_DATA_URL}`);
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done();
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});
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</script>
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