- import EXIF from 'exif-js';
-
- const MAX_IMAGE_PIXELS = 2073600; // 1920x1080px
-
- 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;
- }
- });
-
- // Some browsers don't allow reading from a canvas and instead return all-white
- // or randomized data. Use a pre-defined image to check if reading the canvas
- // works.
- const checkCanvasReliability = () => new Promise((resolve, reject) => {
- switch(_browser_quirks['canvas-read-unreliable']) {
- case true:
- reject('Canvas reading unreliable');
- break;
- case false:
- resolve();
- break;
- default:
- // 2×2 GIF with white, red, green and blue pixels
- const testImageURL =
- 'data:image/gif;base64,R0lGODdhAgACAKEDAAAA//8AAAD/AP///ywAAAAAAgACAAACA1wEBQA7';
- const refData =
- [255, 255, 255, 255, 255, 0, 0, 255, 0, 255, 0, 255, 0, 0, 255, 255];
- const img = new Image();
- img.onload = () => {
- const canvas = document.createElement('canvas');
- const context = canvas.getContext('2d');
- context.drawImage(img, 0, 0, 2, 2);
- const imageData = context.getImageData(0, 0, 2, 2);
- if (imageData.data.every((x, i) => refData[i] === x)) {
- _browser_quirks['canvas-read-unreliable'] = false;
- resolve();
- } else {
- _browser_quirks['canvas-read-unreliable'] = true;
- reject('Canvas reading unreliable');
- }
- };
- img.onerror = () => {
- _browser_quirks['canvas-read-unreliable'] = true;
- reject('Failed to load test image');
- };
- img.src = testImageURL;
- }
- });
-
- const getImageUrl = inputFile => new Promise((resolve, reject) => {
- if (window.URL && URL.createObjectURL) {
- try {
- resolve(URL.createObjectURL(inputFile));
- } catch (error) {
- reject(error);
- }
- return;
- }
-
- const reader = new FileReader();
- reader.onerror = (...args) => reject(...args);
- reader.onload = ({ target }) => resolve(target.result);
-
- reader.readAsDataURL(inputFile);
- });
-
- const loadImage = inputFile => new Promise((resolve, reject) => {
- getImageUrl(inputFile).then(url => {
- const img = new Image();
-
- img.onerror = (...args) => reject(...args);
- img.onload = () => resolve(img);
-
- img.src = url;
- }).catch(reject);
- });
-
- const getOrientation = (img, type = 'image/png') => new Promise(resolve => {
- if (type !== 'image/jpeg') {
- resolve(1);
- return;
- }
-
- EXIF.getData(img, () => {
- const orientation = EXIF.getTag(img, 'Orientation');
- if (orientation !== 1) {
- dropOrientationIfNeeded(orientation).then(resolve).catch(() => resolve(orientation));
- } else {
- resolve(orientation);
- }
- });
- });
-
- const processImage = (img, { width, height, orientation, type = 'image/png' }) => new Promise(resolve => {
- const canvas = document.createElement('canvas');
-
- if (4 < orientation && orientation < 9) {
- canvas.width = height;
- canvas.height = width;
- } else {
- canvas.width = width;
- canvas.height = height;
- }
-
- const context = canvas.getContext('2d');
-
- switch (orientation) {
- case 2: context.transform(-1, 0, 0, 1, width, 0); break;
- case 3: context.transform(-1, 0, 0, -1, width, height); break;
- case 4: context.transform(1, 0, 0, -1, 0, height); break;
- case 5: context.transform(0, 1, 1, 0, 0, 0); break;
- case 6: context.transform(0, 1, -1, 0, height, 0); break;
- case 7: context.transform(0, -1, -1, 0, height, width); break;
- case 8: context.transform(0, -1, 1, 0, 0, width); break;
- }
-
- context.drawImage(img, 0, 0, width, height);
-
- canvas.toBlob(resolve, type);
- });
-
- const resizeImage = (img, type = 'image/png') => new Promise((resolve, reject) => {
- const { width, height } = img;
-
- const newWidth = Math.round(Math.sqrt(MAX_IMAGE_PIXELS * (width / height)));
- const newHeight = Math.round(Math.sqrt(MAX_IMAGE_PIXELS * (height / width)));
-
- checkCanvasReliability()
- .then(getOrientation(img, type))
- .then(orientation => processImage(img, {
- width: newWidth,
- height: newHeight,
- orientation,
- type,
- }))
- .then(resolve)
- .catch(reject);
- });
-
- export default inputFile => new Promise((resolve) => {
- if (!inputFile.type.match(/image.*/) || inputFile.type === 'image/gif') {
- resolve(inputFile);
- return;
- }
-
- loadImage(inputFile).then(img => {
- if (img.width * img.height < MAX_IMAGE_PIXELS) {
- resolve(inputFile);
- return;
- }
-
- resizeImage(img, inputFile.type)
- .then(resolve)
- .catch(() => resolve(inputFile));
- }).catch(() => resolve(inputFile));
- });
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