Irreal

Emacs-Elements has a nice demonstration on using Emacs’ DocView to read PDF files. One of the nice things about DocView—as opposed to PDF Tools—is that it can read PS, DVI, Djvu, and ODF files as well as PDF files. The downside, of course, is the way it works. When you open a document with DocView, it uses an external tool to render it as one or more PNG files. That can take a few seconds for a long document but more importantly—for me, at least—is that the PNGs are cached. That makes it speedy to reopen the document but it clutters up your file system unless you manually delete the cache.

The video shows how to configure DocView and integrate it with Bookmarks+ to make it easy to locate and open documents. It turns out that you can use any of three external programs to render PDFs into PNGs and the video has some advice on which to use.

Most of the rest of the video demonstrates how to navigate through a document and do things like extracting a rectangular region. DocView is surprisingly featureful and you can see some of that in the video.

If you can’t get PDF Tools working or don’t want to bother trying, DocView is a builtin solution that works well. Its main deficiency, as compared to PDF Tools, is that you can’t annotate the PDF.

Something that every Emacser knows is that learning Emacs is a lifelong journey. Even after years of use, we’re always discovering something new. Marcin ‘mbork’ Borkowski is always discovering new things and, happily, sharing them with the rest of us.

His latest discovery actually is something new. So new it hasn’t been officially released yet. Borkowski, being more courageous than I, doesn’t bother with releases; he simply compiles Master every once in while. The discovery is that the interactive declaration can now take extra arguments that specify which modes the function is valid for.

Functions with such a declaration appear in the describe-mode listing for any of the specified modes and it’s easy to arrange for the function not to be considered for completion when not in one of the specified modes.

Head on over to Borkowski’s post for the full story. He says that it should be in 27.2 but as far as I can tell, it isn’t. It looks as if it will be a helpful addition to the Emacs toolset.

Being an old time Unix head, I had a hard time warming up to the GNU Info system. I preferred the man pages when they were available and found the info utility hard to use. That’s probably because I was using Vi at the time and the key bindings were unfamiliar. The ironical twist that you had to read the Info manual to learn how to use info didn’t help.

That changed when I started using Emacs and Info became a natural and extraordinarily useful feature. Now I get annoyed when some tool I’m using doesn’t have an Info node. At this point, I’ve been using it for almost a decade and half and am pretty familiar with its ins and outs but Marcin Borkowski (mbork) taught me something new.

It turns out that if you use I instead of i to access the index, Emacs will build a virtual node that that has an entry for every term in the index that matches what you’re searching for. You can see this in action by bringing up the Elisp node and then searching (with I) for car.

That’s pretty useful and mbork has a bit more so be sure to take a look at his post.