When I open pdf with emacs, it got frozen. And I installed pdf-tools, open pdf, it got frozen again.

What's the underlining process when emacs open a pdf? Is there a lot of converting work? What should I do to speed it up?

  • Emacs 24.4
  • Ubuntu 14.04 LTS
  • Intel 2.4GHz x 2
  • 4G RAM.


I just found this page:

"learnt a lesson. Never open a pdf in emacs. Never even do it accidentally."


It's a sad news to me! Isn't it a great idea to view pdf using Emacs?

Update 2

I thought it was because my pdf file is too large:

5.7M, 1313 pages

So I tried a small pdf file,

402K, 66 pages

it got frozen again.

Update 3

I open pdf file using C-c C-x from helm, and it opens the pdf file in an external viewer: zathura. Since there is no converting process, the file opens lighting fast. (As fast as mupdf. I guess zathura using mupdf as its back end.)

There are four points makes zathura outstanding:

  1. Lighting fast. (Both open and search)
  2. High quality display.
  3. Tab displays the chapter/section menu just like Adobe Reader.
  4. Good keyboard shortcuts support. (Actually, it uses vim-style keybinding, which make sense since there is no need to switch mode in pdf viewer.

Update 4

Screen shot for quality comparasion:

!Left: Zathura; Right: PDF in Emacs

I really got confused what Emacs uses for open PDF. (I've already removed pdf-tools)

  • Don't you want to tell us more about your Emacs config related to pdf files? – Nsukami _ Dec 24 '14 at 9:26
  • @Nsukami_ Thanks for asking. Actually I have nothing related to pdf file in my configuration. 1. I open pdf with default installation. 2. Installed pdf-tools, open pdf. – Nick Dec 24 '14 at 9:32
  • You can use Emacs as PDF reader fine. I now use Emacs to read PDF exclusively. I also use Ubuntu. But how large is your PDF file? – Tu Do Dec 24 '14 at 9:42
  • 4
    Clearly, it's time for emacs -Q again. – wasamasa Dec 24 '14 at 9:53
  • 2
    To install pdf-tools, you have to clone the repo, run ./autogen.sh and follow the standard procedure: ./configure && make && sudo make install. Then, it will produce a pdf-tools.tar.gz in the pdf-tools directory you cloned. Then, put (pdf-tools-install) somewhere in your init file. From now on, Emacs will use pdf-view-mdoe which gives better quality and better rendering speed. – Tu Do Dec 25 '14 at 15:26

You should disable linum-mode when opening a PDF file. Otherwise it will hang your Emacs. i.e. only add it to prog-mode for editing text:

(add-hook 'prog-mode-hook 'linum-on)

To install pdf-tools:

  • You have to clone the repository:

    git clone https://github.com/politza/pdf-tools.git

  • cd pdf-tools

  • Run make.

  • Then, it will produce a pdf-tools-${VERSION}.tar in the pdf-tools directory you cloned; in Emacs, M-x package-install-file RET pdf-tools-${VERSION}.tar RET

  • Then, put (pdf-tools-install) somewhere in your init file. From now on, Emacs will use pdf-view-mode which gives better quality and better rendering speed.

Here is a demo using pdf-tools. The PDF file is 28MB and it took a few seconds to open. Note that the quality of the images in the gif are a bit lower quality compared with the actual source, but as you can see the text is crystal clear. I did not record the whole screen to reduce the size of the gif, because it's already 13MB.

I use plain Isearch using C-s as in other buffers for searching. Don't press too fast, leave about 1 second delay between searches. You should use Isearch to search current page or nearby pages, basically something small. To search the whole document, use pdf-occur; the command is quite fast. You may want to keep the search results for later use (in the same session) by renaming the occur default *PDF-Occur* buffer to some other name to avoid it is overridden by future searches.

If you want the table of contents, in the PDF buffer press o to open it in outline-mode.

  • Hat tips to this great package (and answer). The difference is huge if you compare it with the default viewer. – KookieMonster Jun 5 '15 at 20:09
  • (add-hook 'prog-mode-hook 'linum-on) should be (add-hook 'prog-mode-hook 'linum-mode) on 24.5.1. – Yang Feb 19 '16 at 5:08

I’m using Emacs for reading documentation, scientific papers and books — all of that without issues.

My doc-view-mode uses mudraw (from mupdf) for rendering PDFs as you can see by checking doc-view-pdfdraw-program variable:

doc-view-pdfdraw-program is a variable defined in `doc-view.el'. Its value is "mudraw" Documentation: Name of MuPDF's program to convert PDF files to PNG. This variable was introduced, or its default value was changed, in version 24.4 of Emacs.

By default doc-view mode uses ghotscript’s gs for rendering which can be slow in comparison. You can read about switch from ghostscript’s gs to mupdf’s mudraw:

I've since been testing that patch and never looked back since the switch sped up the pdf->png conversion by a factor of two and brought anti-aliasing with it.

In your situation:

  1. install mupdf and open PDF in an emacs session without your configuration e.g.:

    env HOME=/tmp emacs -Q

    and check if doc-view-pdfdraw-program is set correctly to mudraw.

  2. report back if above improved your situation.

PS I have no experience with pdf-tools.

  • I have mupdf installed, and it's surprisingly fast. I run env HOME=/tmp emacs -Q, emacs sais "still converting…", and takes a while to convert. The speed is fine but the quality is poor. To my surprise, there's no variable named doc-view-pdfdraw-program. If Emacs can use mupdf, that would be really terrific! – Nick Dec 24 '14 at 22:45
  • Are you sure that you are using 24.4? doc-view-pdfdraw-program should be available in such case. Is mudraw available in your shell? – kmicu Dec 25 '14 at 0:25
  • Yes, I'm running Emacs 24.4. This is GNU Emacs 24.4.2 (x86_64-unknown-linux-gnu, GTK+ Version 3.10.8) mudraw is not availabe, so I installed. (the package mupdf-tools), thus I can run mudraw in shell. The converting speed is even more slow, and the pdf display quality is still poor. – Nick Dec 25 '14 at 1:32
  • "To my surprise, there's no variable named doc-view-pdfdraw-program." without knowing what is set in that variable we cannot be sure if you are really using mudraw in doc-view mode, maybe this is still gs. "pdf display quality is still poor" is a relative and subjective statement - can you update your question with some screenshots? For me Zathura (with mupdf backend) has exactly the same PDF rendering quality and speed as in Emacs. – kmicu Dec 25 '14 at 21:22
  • 1
    To get that variable, you have to load it: (require 'doc-view). I think mudraw is the default and the problem is that doc-view cannot fit the whole PDF page into the whole buffer. And I'm not sure about the quality. – Tu Do Dec 26 '14 at 8:30

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