In `viewer.js` we have code that ensures that the document is re-rendered on zooming and rotation. However, for `components` based viewers this might not work correctly, since there's currently no code which handles that.
Note that there is a good chance that this "just works" in many `components` viewers already, thanks to the `watchScroll` function.
The explanation is that zooming or rotation, most of the time, causes the viewer to change its (scrollable) size, thus triggering `PDFViewer_update` through `PDFViewer_scrollUpdate`.
However, in general there's no guarantee that this will actually work (since zooming and rotation doesn't necessarily change the size of the viewer for all documents), and requiring every viewer `components` implementer to provide methods for this doesn't seem like a great idea.
d940078d95