uppy/packages/@uppy/image-editor/src/utils/limitCropboxMovementOnResize.js

function limitCropboxMovementOnResize (canvas, cropboxData, prevCropbox) {
  // For the left boundary
  if (cropboxData.left < canvas.left) {
    return ({
      left: canvas.left,
      width: (prevCropbox.left + prevCropbox.width) - canvas.left,
    })
  }

  // For the top boundary
  if (cropboxData.top < canvas.top) {
    return ({
      top: canvas.top,
      height: (prevCropbox.top + prevCropbox.height) - canvas.top,
    })
  }

  // For the right boundary
  if (cropboxData.left + cropboxData.width > canvas.left + canvas.width) {
    return ({
      left: prevCropbox.left,
      width: (canvas.left + canvas.width) - prevCropbox.left,
    })
  }

  // For the bottom boundary
  if (cropboxData.top + cropboxData.height > canvas.top + canvas.height) {
    return ({
      top: prevCropbox.top,
      height: (canvas.top + canvas.height) - prevCropbox.top,
    })
  }

  return null
}

export default limitCropboxMovementOnResize