[shotwell/shotwell-0.30: 1/2] Fix compatibility with OpenCV 4

[Jens Georg <jensgeorg src gnome org>]

commit a8fc1328bcc4296045fece633330814fbfb40bcc
Author: Jens Georg <mail jensge org>
Date:   Sun Mar 15 11:19:18 2020 +0100

    Fix compatibility with OpenCV 4
    
    Second try, much simpler version
    
    (cherry picked from commit f54094594016359bbafd0be44a53ea28c8968593)

 facedetect/meson.build             | 5 ++++-
 facedetect/shotwell-facedetect.cpp | 6 +++---
 2 files changed, 7 insertions(+), 4 deletions(-)
---
diff --git a/facedetect/meson.build b/facedetect/meson.build
index 6724abcb..bd5f3c3b 100644
--- a/facedetect/meson.build
+++ b/facedetect/meson.build
@@ -1,6 +1,9 @@
 subproject = ('facedetect')
 add_languages('cpp')
-facedetect_dep = dependency('opencv', version : ['>= 2.3.0'], required : true)
+facedetect_dep = dependency('opencv4', version : ['>= 4.0.0'], required : false)
+if not facedetect_dep.found()
+    facedetect_dep = dependency('opencv', version : ['>= 3.4.0'], required : true)
+endif
 executable('shotwell-facedetect',
            'shotwell-facedetect.cpp',
            dependencies : facedetect_dep,
diff --git a/facedetect/shotwell-facedetect.cpp b/facedetect/shotwell-facedetect.cpp
index 1b093797..1c105806 100644
--- a/facedetect/shotwell-facedetect.cpp
+++ b/facedetect/shotwell-facedetect.cpp
@@ -34,7 +34,7 @@ void help() {
 void detectFaces(Mat &img, CascadeClassifier &cascade, double scale) {
 
        Mat gray;
-       cvtColor(img, gray, CV_BGR2GRAY);
+       cvtColor(img, gray, cv::COLOR_BGR2GRAY);
 
        Mat smallImg(cvRound(img.rows / scale), cvRound(img.cols / scale), CV_8UC1);
        Size smallImgSize = smallImg.size();
@@ -43,7 +43,7 @@ void detectFaces(Mat &img, CascadeClassifier &cascade, double scale) {
        equalizeHist(smallImg, smallImg);
 
        vector<Rect> faces;
-       cascade.detectMultiScale(smallImg, faces, 1.1, 2, CV_HAAR_SCALE_IMAGE, Size(30, 30));
+       cascade.detectMultiScale(smallImg, faces, 1.1, 2, cv::CASCADE_SCALE_IMAGE, Size(30, 30));
 
        int i = 0;
        for (vector<Rect>::const_iterator r = faces.begin(); r != faces.end(); r++, i++) {
@@ -117,7 +117,7 @@ int main(int argc, const char** argv) {
 
        }
 
-       Mat image = imread(inputName, 1);
+       Mat image = cv::imread(inputName, 1);
 
        if (image.empty()) {