Auto rotate image and retour base64

auto-rotate-image.ts

onRotateImage(file, checkError = true) {
		const promise = new Promise((resolve, reject) => {
			const reader = new FileReader();

			reader.onload = (e) => {
				this.getOrientation(file, (orientation) => {
					if (orientation > 0) {
						const image = new Image();
						image.src = e.target['result'];
						image.onload = () => {
							// only jpeg
							const canvas = document.createElement('canvas'),
								context = canvas.getContext('2d');
							switch (orientation) {
								case 8:
									canvas.width = image.height;
									canvas.height = image.width;
									context.save();
									context.translate(canvas.width / 2, canvas.height / 2);
									context.rotate(-90 * Math.PI / 180);
									context.drawImage(image, -image.width / 2, -image.height / 2);
									context.restore();
									break;
								case 3:
									canvas.width = image.width;
									canvas.height = image.height;
									context.save();
									context.translate(canvas.width / 2, canvas.height / 2);
									context.rotate(180 * Math.PI / 180);
									context.drawImage(image, -image.width / 2, -image.height / 2);
									context.restore();
									break;
								case 6:
									canvas.width = image.height;
									canvas.height = image.width;
									context.save();
									context.translate(canvas.width / 2, canvas.height / 2);
									context.rotate(90 * Math.PI / 180);
									context.drawImage(image, -image.width / 2, -image.height / 2);
									context.restore();
									break;
								default:
									canvas.width = image.width;
									canvas.height = image.height;
									context.drawImage(image, 0, 0);
									break;
							}
							resolve(canvas.toDataURL());
						};
					} else {
						resolve(e.target['result']);
					}
				});
			};

			const possibleImageType = ['image/jpeg', 'image/png', 'image/gif', 'image/svg+xml'];
			if (possibleImageType.indexOf(file.type) !== -1) {
				reader.readAsDataURL(file);
			} else if (checkError) {
				reject('Please select an image file');
			}
		});

		return promise;
	}

	getOrientation(file, callback) {
		const reader = new FileReader();
		reader.onload = function (e) {

			const view = new DataView(e.target['result']);
			if (view.getUint16(0, false) !== 0xFFD8) {
				return callback(-2);
			}
			const length = view.byteLength;
			let offset = 2;
			while (offset < length) {
				const marker = view.getUint16(offset, false);
				offset += 2;
				if (marker === 0xFFE1) {
					if (view.getUint32(offset += 2, false) !== 0x45786966) {
						return callback(-1);
					}
					const little = view.getUint16(offset += 6, false) === 0x4949;
					offset += view.getUint32(offset + 4, little);
					const tags = view.getUint16(offset, little);
					offset += 2;
					for (let i = 0; i < tags; i++) {
						if (view.getUint16(offset + (i * 12), little) === 0x0112) {
							return callback(view.getUint16(offset + (i * 12) + 8, little));
						}
					}
				} else if ((marker && 0xFF00) !== 0xFF00) {
					break;
				} else {
					offset += view.getUint16(offset, false);
				}
			}
			return callback(-1);
		};
		reader.readAsArrayBuffer(file.slice(0, 64 * 1024));
	}

// To use
this.onRotateImage(file)
    .then(base64 => {
      // ...
    })
    .catch(err => {
      // ...
    });