Emacs Open PDF

just try it
emacs nome.pdf

it's also possible to edit one buffer and see pdf in another.

Commands to zoom in and zoom out
The zoom commands + (doc-view-enlarge) and - (doc-view-shrink) need to reconvert the document at the new size. The current page is converted first.

For efficiency, DocView caches the images produced by gs. The name of this directory is given by the variable doc-view-cache-directory. You can clear the cache directory by typing M-x doc-view-clear-cache.

To force a reconversion of the currently viewed document, type r or g (revert-buffer). To kill the converter process associated with the current buffer, type K (doc-view-kill-proc). The command k (doc-view-kill-proc-and-buffer) kills the converter process and the DocView buffer.