rotate_imgae_via_exif_orientation.js

switch (EXIF.orientation) {
  case 2: ctx.transform(-1, 0, 0, 1, width, 0); break;
  case 3: ctx.transform(-1, 0, 0, -1, width, height ); break;
  case 4: ctx.transform(1, 0, 0, -1, 0, height ); break;
  case 5: ctx.transform(0, 1, 1, 0, 0, 0); break;
  case 6: ctx.transform(0, 1, -1, 0, height , 0); break;
  case 7: ctx.transform(0, -1, -1, 0, height , width); break;
  case 8: ctx.transform(0, -1, 1, 0, 0, width); break;
  default: ctx.transform(1, 0, 0, 1, 0, 0);
}