Detect Changes in Annotations

In addition to controlling annotation changes via our create, update, and delete APIs, we also expose a number of events that can be used to intercept annotation changes that originate in the UI by clicks from the user or that are synced from the server.

Event	Use Case
`annotations.load`	Fires whenever annotations are loaded from the document.
`annotations.willChange`	Fires whenever a user action performed via the UI (e.g. drawing) on an annotation occurs.
`annotations.change`	Fires whenever the current annotations change due to a user action (e.g. clicking the UI) or via the API.
`annotations.create`	Fires whenever annotations are created.
`annotations.update`	Fires whenever annotations are updated.
`annotations.delete`	Fires whenever annotations are deleted.

instance.addEventListener("annotations.load", loadedAnnotations => {
  console.log(loadedAnnotations);
});
instance.addEventListener("annotations.willChange", event => {
  if (event.reason === PSPDFKit.AnnotationsWillChangeReason.DRAW_START) {
    console.log("The user is drawing...");
  }
});
instance.addEventListener("annotations.change", () => {
  console.log("Something in the annotations has changed.");
});
instance.addEventListener("annotations.create", createdAnnotations => {
  console.log(createdAnnotations);
});
instance.addEventListener("annotations.update", updatedAnnotations => {
  console.log(updatedAnnotations);
});
instance.addEventListener("annotations.delete", deletedAnnotations => {
  console.log(deletedAnnotations);
});