forked from treehouse/mastodon
Fix uploaded image orientation in some browsers (#13493)
Some browsers (at least recent Chrome versions) automatically take
image metadata into account when drawing images into a canvas.
There seem to be no way to prevent that behavior, and the only
way to detect it seems to compare with a known image.
See: https://github.com/w3c/csswg-drafts/issues/4666
Solution adapted from: 1e4df70782
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commit
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@ -2,6 +2,45 @@ import EXIF from 'exif-js';
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const MAX_IMAGE_PIXELS = 1638400; // 1280x1280px
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const _browser_quirks = {};
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// Some browsers will automatically draw images respecting their EXIF orientation
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// while others won't, and the safest way to detect that is to examine how it
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// is done on a known image.
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// See https://github.com/w3c/csswg-drafts/issues/4666
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// and https://github.com/blueimp/JavaScript-Load-Image/commit/1e4df707821a0afcc11ea0720ee403b8759f3881
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const dropOrientationIfNeeded = (orientation) => new Promise(resolve => {
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switch (_browser_quirks['image-orientation-automatic']) {
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case true:
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resolve(1);
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break;
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case false:
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resolve(orientation);
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break;
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default:
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// black 2x1 JPEG, with the following meta information set:
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// - EXIF Orientation: 6 (Rotated 90° CCW)
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const testImageURL =
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'data:image/jpeg;base64,/9j/4QAiRXhpZgAATU0AKgAAAAgAAQESAAMAAAABAAYAAAA' +
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'AAAD/2wCEAAEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBA' +
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'QEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQE' +
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'BAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAf/AABEIAAEAAgMBEQACEQEDEQH/x' +
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'ABKAAEAAAAAAAAAAAAAAAAAAAALEAEAAAAAAAAAAAAAAAAAAAAAAQEAAAAAAAAAAAAAAAA' +
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'AAAAAEQEAAAAAAAAAAAAAAAAAAAAA/9oADAMBAAIRAxEAPwA/8H//2Q==';
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const img = new Image();
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img.onload = () => {
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const automatic = (img.width === 1 && img.height === 2);
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_browser_quirks['image-orientation-automatic'] = automatic;
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resolve(automatic ? 1 : orientation);
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};
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img.onerror = () => {
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_browser_quirks['image-orientation-automatic'] = false;
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resolve(orientation);
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};
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img.src = testImageURL;
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}
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});
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const getImageUrl = inputFile => new Promise((resolve, reject) => {
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if (window.URL && URL.createObjectURL) {
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try {
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@ -38,7 +77,11 @@ const getOrientation = (img, type = 'image/png') => new Promise(resolve => {
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EXIF.getData(img, () => {
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const orientation = EXIF.getTag(img, 'Orientation');
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resolve(orientation);
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if (orientation !== 1) {
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dropOrientationIfNeeded(orientation).then(resolve).catch(() => resolve(orientation));
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} else {
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resolve(orientation);
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}
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});
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});
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