libjpeg 6b vs libjpeg_turbo

[S.J. Becker]

I'm building a utility program which outputs group4 tif files for monochrome and jpeg files for color.

I ran into problems linking with a modern jpg library because 6b is linked in from the third_party folder.

Since jpeg_stdio_dest and jpeg_stdio_src are stripped out, I presume that it's being used by pdfium

to read pdf embedded jpg images from memory.

libjpeg_turbo is over twice as fast and proven on all platforms. Modifying my code to cope with the

limitations of 6b works but it's very slow.

Making pdfium use libjpeg_turbo and optionally the system library could really speed up the loading

of pdfs which contain jpeg images from chromium and chrome (and my app).

[S.J. Becker]

I just found:

#if !defined(_FX_JPEG_TURBO_)

at the top of one of the third_party/libjpeg files.

Where does this get defined? What else can I configure?

[Lei Zhang]

I don't know where the _FX_JPEG_TURBO_ checks came from. Maybe FoxIt was experimenting with using libjpeg_turbo. We definitely want to move to that so Chromium does not need to ship with both libraries.

[Lei Zhang]

https://code.google.com/p/chromium/issues/detail?id=541704 is relevant.

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[S.J. Becker]

On Thursday, October 15, 2015 at 7:08:23 PM UTC-7, Lei Zhang wrote:

https://code.google.com/p/chromium/issues/detail?id=541704 is relevant.

I made a post on that issue to further the discussion and found out:

1) as of november, chromium builds without thirdparty/libjpeg

2) my needs concerned pdfium standalone so I needed to create an issue in

        https://bugs.chromium.org/p/pdfium/issues/list

So I did.

I also checked out and configured the chromium source tree and then

searched around for libjpeg and found:

libjpeg_gyp_path in the gyp files

   and

use_system_libjpeg in the gn files

So we are probably close to getting the standalone to support

a different copy of libjpeg.

I don't know much about the build systems. Does the standalone

support .gn yet?

TIA

[Lei Zhang]

The standalone build uses GYP. It does not support GN yet. If you want
to do standalone PDFium build with libjpeg-turbo, you'll need to:

- Copy the libjpeg-turbo source to third_party/libjpeg_turbo.
- Change the libjpeg_gyp_path variable in build/standalone.gypi to
point to the right place.
- Add 'defines': ['USE_LIBJPEG_TURBO=1'] in the right GYP targets, so
all the places that check for USE_LIBJPEG_TURBO have it defined.
- Generate new build files with gyp_pdfium or gclient runhooks, cross
fingers, and rebuild.

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[Lei Zhang]

I see you filed
https://bugs.chromium.org/p/pdfium/issues/detail?id=389 - shall we
continue the conversation there?

[S.J. Becker]

For the benefit of anyone reading this, if you open this link, you can see

steps to get pdfium linked with the system libjpeg or libjpeg-turbo.

On average turbo is twice as fast as the old libjpeg. If anyone needs to

save the converted image as a jpeg, I can give you some code to accomplish

this.

[M ForSure]

Has there been any progress with this? 
Scott's idea to keep this thread updates is appreciated, Thanks for that. 

[Lei Zhang]

You are referencing a thread from 6 years ago. What exactly are you
asking about exactly?
https://bugs.chromium.org/p/pdfium/issues/detail?id=389 has been
marked as fixed a several years now.

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