Remove high gui requirement from most modules

[vade]

System information (version)

• OpenCV => 3.1
• Operating System / Platform => Mac OS X 10.12.1
• Compiler => Xcode 8.1

Detailed description

Attempting to integrate OpenCV Contrib into an application under development, and wanting the Saliency API. However, my app in aims to be slim, removes unnecessary dependencies from OpenCV like highgui and thus img_codecs, video_io and things my app provides.

However, compilation for most of the contrib modules requires highgui, which cascades a huge chain of dependencies and thus, in some cases, bloat depending on what you actually need.

Module opencv_saliency disabled because opencv_highgui dependency can't be resolved!

/Users/vade/Downloads/opencv-3.1.0/modules/videoio/src/cap_qtkit.mm:46:9: fatal error: 'QTKit/QTKit.h' file not found

Is highgui (which requires video_io, which requires Quicktime, which is deprecated) actually required for specific features, or is this a dependency chain nuance that could be "disentangled"

Thank you for all the work on this, OpenCV is amazing.

[vade]

Yea, editing the cmakelists file, re-configuring still compiles (on Mac OS X with cmake) Saliency fine without highgui.

I suspect there are a lot of unnecessary dependencies - so far:

Saliency - remove highgui WRAP python

• will update this and make a PR with updated CMake files

[alalek]

highgui is used for debugging which is disabled by default (search for SALIENCY_DEBUG).
So you should use "OPTIONAL" in this case (example).
"WRAP python" should be leaved as is.

[vade]

Thanks for the info!