[Error] PDF cover cannot be shown

[seuplus]

Platform: Debian GNU/Linux 8.10 (jessie)

1、[error] PDF cover cannot be shown correctly. See the Picture1 below.
2、[enhancement] Can you add a go-back-to-cover button on epub browser. See the Picture2 below.

Thank you!

Picture1

Picture2

[pgaskin]

For the pdf cover, currently there is no way to extract it (there are no libraries written in go) short of writing a whole pdf rendering library (which would take a lot of work) or calling an external command (which will greatly decrease the indexing speed, and will not work on all systems). If I find a PDF library written in go, I will add covers.

For your second issue, it actually belongs in http://github.com/geek1011/ePubViewer/issues . You can view the cover by pressing the info button in the top left, or you can go to it in the table of contents. As for clicking the book title, may I ask why this would be useful?

[seuplus]

Thank you!

[LiMinggang]

Hi, @geek1011, is it possible to use the basic pdf reader implementation like https://github.com/rsc/pdf which lacks of rendering part, or https://github.com/yob/pdfreader which can convert pdf to svg.
Or, is it possible to use front-end pdf reader to do this?
It's very helpful for the pdf books.

[pgaskin]

Maybe. I need to look into this more.

[LiMinggang]

Please make high priority to issue #47 which is a big performance improvement for huge books like mine. I don't think the projects I listed are mature enough for use.
And I think I will try a workaround for the thumbnail issue of PDF, ie, use ghost script to generate thumbnails for BookBrowser. Anyway, the books should not update too often.

[pgaskin]

Yep. I was thinking of something like that. I'll probably make it call imagemagick if it is present.

As for #47, I'm working on it when I have time. I've figured out how to do an efficient checksum of the epub without reading the whole thing, and now, I just need to figure out how I'm going to store metadata in a forwards compatible way.

[LiMinggang]

Thanks for your hard work!
FYI
http://duncanlock.net/blog/2013/11/18/how-to-create-thumbnails-for-pdfs-with-imagemagick-on-linux/
https://stackoverflow.com/questions/26383405/ghostscript-command-create-thumbnail-images-from-pdf-file

[LiMinggang]

Another candidate in go
https://github.com/hhrutter/pdfcpu

[pgaskin]

@LiMinggang That looks almost perfect! I'll see how it works later this week.

[LiMinggang]

There is another JS version which supports PDF thumbnail. No idea if it's OK for us.
https://github.com/oguzhaninan/Buka

[pgaskin]

No, that won't work. It uses PDF.js to render it. Last time I tried, I couldn't get it running in otto (a js runtime for go).