For webcam input, freeze and convert to img.
Using a link you can open whatsapp on mobile and have a predefined text to be sent to 1 or more contacts. If it is 1, it will open the conversation and the text will be already typed but it can be edited. In case of selecting multiple contacts, the message will be sent individualy without being able to edit.
<a href="whatsapp://send?text=https://cdn.shopify.com/s/files/1/0743/4993/products/Cyprus_Mesa_de_Ajedrez_de_Madera_-_Nogal_3.png" data-action="share/whatsapp/share">Share via Whatsapp</a>
https://udinra.com/blog/whatsapp-share-button-website
https://www.whatsapp.com/faq/en/iphone/23559013
To show a preview of the image http://stackoverflow.com/questions/19778620/provide-a-picture-for-whatsapp-link-sharing