Allow saving/downloading a page image.

[Philip Burns]

No description provided.

[Craig Berry]

There is some discussion of how to do this with OpenSeadragon at https://github.com/openseadragon/openseadragon/issues/477.

[Craig Berry]

I'll consider this resolved by the following, although it only allows you to get whatever is on-screen rather than the full image.

#!

commit a02e675fae30127c4b4a05e00b621e402f4355d8
Author: Craig A. Berry <[e-mail]>
Date:   Fri May 4 10:13:27 2018 -0500

    Add facsimile screenshot capability.

    Use the openseadragon-screenshot plug-in to allow people to take
    screenshots of portions of the facsimile image.  The main thing
    it provides over and above the native screenshot capability of the
    OS is that it can obtain higher resolutions than what's presented
    in the browser.

    Caveats:

    It can be extremely slow for higher resolutions.

    There is no way to specify the filename of the downloaded image. It
    would be nice, for example, to get A03240-003-a.png rather than just
    screenshot.png.

    There is no way to get the entire original image for the many cases
    where the image does not quite fit in OpenSeadragon's viewport; it can
    give you a higher resolution image of what's visible on-screen, but it
    can't give you more than what's visible on-screen.

    There is no way to control the style of the selection window except
    by completely replacing the div that implements it.

    Co-authored-by: Philip R. Burns <[e-mail]>