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 { 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 (!['image/jpeg', 'image/webp'].includes(type)) { 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); // The Tor Browser and maybe other browsers may prevent reading from canvas // and return an all-white image instead. Assume reading failed if the resized // image is perfectly white. const imageData = context.getImageData(0, 0, width, height); if (imageData.data.every(value => value === 255)) { throw 'Failed to read from canvas'; } 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))); getOrientation(img, type) .then(orientation => processImage(img, { width: newWidth, height: newHeight, orientation, type, })) .then(resolve) .catch(reject); }); export default inputFile => new Promise((resolve, reject) => { 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(reject); });