How to generate thumbnail images of HTML pages

Question

I am trying to create thumbnail images for several HTML pages, so the user can have an idea of what the HTML looks like before they open the link. I have searched online but hav

Answer 1

http://phantomJs.org offers a free tool to capture HTML locally from a file (if you enable that via a command line parameter and use the file:// URI scheme) or from a website and render it to an image. That is a very well-established very popular tool It's also used by people who write automated tests. There's a wiki page that covers that tool, and similar ones.

It has a cropping option. You could run the output of that through other image manipulation tools to scale it.

As far as getting intelligent previews/thumbnails like Twitter and Facebook do, that I'm not sure of. I know there is an oEmbed protocol that is popular that Twitter and other sites provide, and ways to extract the metadata whereby you could possibly construct your own small HTML file and then render it to an image.

(Note about phantomJs: If you don't get the image quality you want in the rendered image, try raising the quality setting for the image parameter to 100, as well as increasing the page's zoom factor option. I've found zoom factor of 2 produces profoundly better quality than zoom factor 1 - see the API docs regarding zoom).