Switch Windows builds of mapnik to using jpeg-turbo rather then standard jpeg library.

[flippmoke]

@BergWerkGIS could you look into this?

[wilhelmberg]

It this what's used on other platforms, too?

As far as I've looked into it, it seems to require additional dependencies, we don't yet have:

• MSYS
• JDK 32bit
• JDK 64bit

At least I'm hitting a wall without those:

Even, when building with Visual Studio the build process has to be started from the MYSYS shell.
This seems difficult to be integrated in our current workflow.

See docs about buildscripts:
The Windows native builds (both Visual C++ and MinGW) must be conducted from
within an MSYS shell.

And which one of those do we need?
I suppose, just turbojpeg?

[springmeyer]

It this what's used on other platforms, too?

Yes, this is what is used on osx + linux: https://github.com/mapnik/mapnik-packaging/blob/master/osx/scripts/build_jpeg_turbo.sh

within an MSYS shell.

Bizarre. Right, we only need the libjpeg (I think the final binary should be named jpeg.dll) it produces. Can you find anyone else that has been able to build just the libjpeg? I wonder how Chromium does it: do they use jpeg-turbo or the original libjpeg?

[wilhelmberg]

I just made it work this very moment.
Turns out, I needed to create make files with CMake and install nasmhttp://nasm.us/.

These are the binaries I get:

[springmeyer]

@BergWerkGIS - are we officially using jpeg-turbo now or does this still need finished?

[wilhelmberg]

@springmeyer no, still using libjpeg. I'll look into it.

[wilhelmberg]

Done.
Lastest mapnik/master and node-mapnik/master compile successfully.
Leaving open and assigned to publish new packages.

[springmeyer]

🙏

[wilhelmberg]

AppVeyor for node-mapnik is green with new mapnik SDK.
https://ci.appveyor.com/project/Mapbox/node-mapnik/build/1.0.563

[springmeyer]

YAYYYYYY: I've removed the hacks disabling or reducing the comparison threshold for jpeg image fixtures. And after using a Win SDK with jpeg-turbo all tests are still passing: https://ci.appveyor.com/project/Mapbox/node-mapnik/build/1.0.575