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Fix uploaded image orientation in some browsers (#13493)

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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
This commit is contained in:
ThibG 2020-04-18 15:37:03 +02:00 committed by GitHub
parent e12a5635da
commit a1ce9cbb67
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1 changed files with 44 additions and 1 deletions
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43
app/javascript/mastodon/utils/resize_image.js
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@ -2,6 +2,45 @@ import EXIF from 'exif-js';
const MAX_IMAGE_PIXELS = 1638400; // 1280x1280px
const _browser_quirks = {};
// Some browsers will automatically draw images respecting their EXIF orientation
// while others won't, and the safest way to detect that is to examine how it
// is done on a known image.
// See https://github.com/w3c/csswg-drafts/issues/4666
// and https://github.com/blueimp/JavaScript-Load-Image/commit/1e4df707821a0afcc11ea0720ee403b8759f3881
const dropOrientationIfNeeded = (orientation) => new Promise(resolve => {
switch (_browser_quirks['image-orientation-automatic']) {
case true:
resolve(1);
break;
case false:
resolve(orientation);
break;
default:
// black 2x1 JPEG, with the following meta information set:
// - EXIF Orientation: 6 (Rotated 90° CCW)
const testImageURL =
'data:image/jpeg;base64,/9j/4QAiRXhpZgAATU0AKgAAAAgAAQESAAMAAAABAAYAAAA' +
'AAAD/2wCEAAEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBA' +
'QEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQE' +
'BAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAf/AABEIAAEAAgMBEQACEQEDEQH/x' +
'ABKAAEAAAAAAAAAAAAAAAAAAAALEAEAAAAAAAAAAAAAAAAAAAAAAQEAAAAAAAAAAAAAAAA' +
'AAAAAEQEAAAAAAAAAAAAAAAAAAAAA/9oADAMBAAIRAxEAPwA/8H//2Q==';
const img = new Image();
img.onload = () => {
const automatic = (img.width === 1 && img.height === 2);
_browser_quirks['image-orientation-automatic'] = automatic;
resolve(automatic ? 1 : orientation);
};
img.onerror = () => {
_browser_quirks['image-orientation-automatic'] = false;
resolve(orientation);
};
img.src = testImageURL;
}
});
const getImageUrl = inputFile => new Promise((resolve, reject) => {
if (window.URL && URL.createObjectURL) {
try {
@ -38,7 +77,11 @@ const getOrientation = (img, type = 'image/png') => new Promise(resolve => {
EXIF.getData(img, () => {
const orientation = EXIF.getTag(img, 'Orientation');
if (orientation !== 1) {
dropOrientationIfNeeded(orientation).then(resolve).catch(() => resolve(orientation));
} else {
resolve(orientation);
}
});
});