how to open specific page on Google's docs viewer
I found a solution I'll post here just in case somebody is in the same situation.
Every page inside google's docs viewer iframe has an id like :0.page.X
, being X the number of the page. Calling the service like this
<iframe id="iframe1" src="http://docs.google.com/gview?url=http://yourpdf&embedded=true#:0.page.20">
won't work (maybe because the pages ids are not yet created when the page is rendered?)
So you just have to add an onload attribute to the iframe:
<iframe id="iframe1" src="http://docs.google.com/gview?url=http://yourpdf&embedded=true" onload="javascript:this.contentWindow.location.hash=':0.page.20';">
and voilà, the iframe will automatically scroll down after loading.
Note that page indices are zero-based. If you want to view the 20th page of a document in the viewer, you would need use the parameter :0.page.19
For me this solution didn't work with the current version of google viewer. Link to specific page on Google Document Viewer on iPad helped me out. Use &a=bi&pagenumber=xx as additonal URL parameter.
I found these two ones :
1) just an Screenshot(Image) of specific page (without navigation):
https://docs.google.com/viewer?url=http://infolab.stanford.edu/pub/papers/google.pdf&embedded=true&a=bi&pagenumber=12
2) a link to specific page of PDF in IFRAME (with navigation):
<script>
var docURL='https://docs.google.com/viewer?url=http://infolab.stanford.edu/pub/papers/google.pdf&embedded=true';
var startPAGE=7;
document.write('<iframe id="iframe1" onload="javascript:go_to_page('+ startPAGE +')" src="https://docs.google.com/viewer?url=http://infolab.stanford.edu/pub/papers/google.pdf&embedded=true"width="600" height="400" ></iframe>');
function go_to_page(varr) { document.getElementById("iframe1").setAttribute("src", docURL + '#:0.page.'+ (varr-1) );}
</script>
p.s. then you can have on your website <a href="javascript:go_to_page('3');">go to page 3</a>