Accessing JPEG EXIF rotation data in JavaScript on the client side

Question

I\'d like to rotate photos based on their original rotation, as set by the camera in JPEG EXIF image data. The trick is that all this should happen in the browser, using Jav

Answer 1

Improving / Adding more functionality to Ali's answer from earlier, I created a util method in Typescript that suited my needs for this issue. This version returns rotation in degrees that you might also need for your project.

ImageUtils.ts

/**
 * Based on StackOverflow answer: https://stackoverflow.com/a/32490603
 *
 * @param imageFile The image file to inspect
 * @param onRotationFound callback when the rotation is discovered. Will return 0 if if it fails, otherwise 0, 90, 180, or 270
 */
export function getOrientation(imageFile: File, onRotationFound: (rotationInDegrees: number) => void) {
  const reader = new FileReader();
  reader.onload = (event: ProgressEvent) => {
    if (!event.target) {
      return;
    }

    const innerFile = event.target as FileReader;
    const view = new DataView(innerFile.result as ArrayBuffer);

    if (view.getUint16(0, false) !== 0xffd8) {
      return onRotationFound(convertRotationToDegrees(-2));
    }

    const length = view.byteLength;
    let offset = 2;

    while (offset < length) {
      if (view.getUint16(offset + 2, false) <= 8) {
        return onRotationFound(convertRotationToDegrees(-1));
      }
      const marker = view.getUint16(offset, false);
      offset += 2;

      if (marker === 0xffe1) {
        if (view.getUint32((offset += 2), false) !== 0x45786966) {
          return onRotationFound(convertRotationToDegrees(-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 onRotationFound(convertRotationToDegrees(view.getUint16(offset + i * 12 + 8, little)));
          }
        }
        // tslint:disable-next-line:no-bitwise
      } else if ((marker & 0xff00) !== 0xff00) {
        break;
      } else {
        offset += view.getUint16(offset, false);
      }
    }
    return onRotationFound(convertRotationToDegrees(-1));
  };
  reader.readAsArrayBuffer(imageFile);
}

/**
 * Based off snippet here: https://github.com/mosch/react-avatar-editor/issues/123#issuecomment-354896008
 * @param rotation converts the int into a degrees rotation.
 */
function convertRotationToDegrees(rotation: number): number {
  let rotationInDegrees = 0;
  switch (rotation) {
    case 8:
      rotationInDegrees = 270;
      break;
    case 6:
      rotationInDegrees = 90;
      break;
    case 3:
      rotationInDegrees = 180;
      break;
    default:
      rotationInDegrees = 0;
  }
  return rotationInDegrees;
}

Usage:

import { getOrientation } from './ImageUtils';
...
onDrop = (pics: any) => {
  getOrientation(pics[0], rotationInDegrees => {
    this.setState({ image: pics[0], rotate: rotationInDegrees });
  });
};