fix: fix opencv_contrib issue #2941

[Chester-zZz]

fix #2941

Pull Request Readiness Checklist

See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request

• I agree to contribute to the project under Apache 2 License.
• To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV
• The PR is proposed to the proper branch
• There is a reference to the original bug report and related work
• There is accuracy test, performance test and test data in opencv_extra repository, if applicable
  Patch to opencv_extra has the same branch name.
• The feature is well documented and sample code can be built with the project CMake

[Chester-zZz]

anything else i can do to continue the merging process? or i can just wait? @asmorkalov

[opencv-alalek]

It is still buggy. Bug is in API itself.

Good API should configure min/max at once through single call (using cv::Range).

Or setting min should set the min and adjust the MAX value (instead of min).

[Chester-zZz]

Got it. Since constantsHost_ will be upload to gpu in initialize, i can just compare them in initialize. and keep the setVarXXX method simple.

float real_varMin = ::fminf(constantsHost_.varMin_, constantsHost_.varMax_);
float real_varMax = ::fmaxf(constantsHost_.varMin_, constantsHost_.varMax_);
constantsHost_.varMin_ = real_varMin;
constantsHost_.varMax_ = real_varMax;