Emacs got frozen when open pdf file

Question

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.

Update:

I just found this page:

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

https://twitter.com/ergoemacs/status/456088661059457024

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)

Answer 1

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.

Answer 2

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.