Is there a way to use Google Search on an indexed (by google) PDF file to not only search within the PDF, but show snippets or previews of the search results? For example, one or two lines of text after the matching keyword(s)
The only thing you need to do is add the fallowing line as a parameter in your search query:
'filetype' parameter helps google to understand what kind of files you'r trying to search within, so you want to search in PDF files, so add the 'filetype' parameter with 'PDF' value.
As dangowans says, here is an example query about computer articles within the pdf files:
Basically, google shows up to two lines of the content as the snippets which depends on the query the user types. but if you want to get a little better preview of the pages, you can use plug-ins/extensions for your browser. for example, CoolPreviews and ezLinkPreview are two of the popular extensions for Google Chrome browser.