Add error messages for camera problems

src/cv.cpp

@@ -9,6 +9,7 @@
 #include <cv.hpp>
 #include <eye.hpp>
 #include <modelpart.hpp>
+#include <error.hpp>
 
 cv::Ptr<cv::face::Facemark> facemark;
 cv::CascadeClassifier haarFaceDetector;
@@ -38,12 +39,16 @@ void initCV() {
 	facemark = cv::face::FacemarkLBF::create();
 	facemark->loadModel (resolvePath("cvdata/lbfmodel.yaml"));
 
+	bool cameraOpened = false;	// true if *any* camera could be opened
+	bool cameraAccepted = false;	// true if we have accepted a camera
+
 	// cycle through all available cameras until we find one we can open
 	std::cout << "Looking for an open camera..." << std::endl;
 	for (int i = 0; i < 127; i++) {
 		vid = cv::VideoCapture (i);
 		if (vid.isOpened()) {
 			std::cout << "Camera " << i << " opened" << std::endl;
+			cameraOpened = true;
 
 			// check if camera is giving solid colored frames
 			cv::Mat testFrame;
@@ -53,10 +58,24 @@ void initCV() {
 				std::cout << "Camera " << i << " feed blank!" << std::endl;
 			} else {
 				std::cout << "Using camera " << i << std::endl;
+				cameraAccepted = true;
 				break;
 			}
 		}
 	}
+
+	// show errors if no camera found
+	if (!cameraAccepted) {
+		if (cameraOpened) {
+			showError("A camera was found, but the feed is blank. Check if your camera is "
+					"functioning properly and try again.",
+					"Camera error", true);
+		} else {
+			showError("No cameras were found. Check if your camera is plugged in and "
+					"detected by your computer.",
+					"No camera found", true);
+		}
+	}
 }
 
 void dnnFaceDetect(cv::Mat inFrame, std::vector<cv::Rect>* faces) {