bug#44338: 27.1; EWW can't download and view pdf

[Nicholas Harrison]

I'll make a couple more comments on the original problem I explained. It looks like you may have identified additional improvements in the process.

I believe the first problem for me is that both mailcap-mime-data and mailcap-user-mime-data are nil. This causes the `error in process filter: mailcap-view-mime: Symbol’s function definition is void: nil` and makes the pdf download and appear in Fundamental mode. This occurs whether I will be using doc-view-mode or pdf-view-mode. I'll use DocView for the rest of this example.

1. emacs -Q
2. M-x eww
3. https://www.gnu.org/software/emacs/manual/pdf/emacs-xtra.pdf

This results in the error message and the following:

This can be (partially) corrected by running the following code before the steps 2 and 3:
(add-to-list 'mailcap-user-mime-data
             '((type . "application/pdf")
               (viewer . doc-view-mode)))

This chooses a view mode for the pdf but that brings the second problem. This selects the default encoding of raw-text and the conversion fails:

Instead I choose doc-view-mode manually for the eww pdf buffer:

Then selecting binary for the encoding finally gets a viewable pdf:

I hope this is in some way helpful.

Nicholas

On Sat, Oct 31, 2020 at 7:43 AM Basil L. Contovounesios <contovob@tcd.ie> wrote:

Nicholas Harrison <nicholasharrison222@gmail.com> writes:

> Using the EWW browser, I can navigate around to webpages, but navigating
> to a pdf fails. It appears to download an unreadable pdf. Downloading
> and viewing the pdf manually in emacs (pdf-view-mode) works fine.
>
> I've tried these solutions to no avail:
> - Adding "application/pdf; emacsclient %s" to a ~/.mailcap file. This
>   makes the process hang indefinitely.
> - Running the following elisp code:
>   `(add-to-list 'mailcap-user-mime-data
>                  '((type . "application/pdf")
>                    (viewer . pdf-view-mode)))`
>   This doesn't seem to have an effect.

Seems to have been fixed on master:

1. emacs -Q
2. M-x eww RET https://www.gnu.org/software/emacs/manual/emacs.html RET
3. C-s extra pdf RET RET

This opens the "Specialized Emacs Features" manual in a *eww pdf* buffer
in doc-view-mode.

With PDF Tools and the mailcap-user-mime-data setting above installed,
it opens in pdf-view-mode instead.

I'm surprised the setting for mailcap-user-mime-data is needed though,
since pdf-view-mode appears before doc-view-mode in both
mailcap-mime-data and my version of auto-mode-alist.

Lars?

--
Basil