demos/cpp/common: add const to mat refs

Author: Wovchena

demos/common/cpp/monitors/include/monitors/presenter.h

@@ -27,8 +27,8 @@ class Presenter {
         cv::Size graphSize = {150, 60},
         std::size_t historySize = 20);
     void addRemoveMonitor(MonitorType monitor);
-    void handleKey(int key); // handles c, d, m, h keys
-    void drawGraphs(cv::Mat& frame);
+    void handleKey(int key); // handles C, D, M, H keys
+    void drawGraphs(const cv::Mat& frame);
     std::vector<std::string> reportMeans() const;
 
     const int yPos;

demos/common/cpp/monitors/src/presenter.cpp

@@ -111,7 +111,7 @@ void Presenter::handleKey(int key) {
     }
 }
 
-void Presenter::drawGraphs(cv::Mat& frame) {
+void Presenter::drawGraphs(const cv::Mat& frame) {
     const std::chrono::steady_clock::time_point curTimeStamp = std::chrono::steady_clock::now();
     if (curTimeStamp - prevTimeStamp >= std::chrono::milliseconds{1000}) {
         prevTimeStamp = curTimeStamp;

demos/common/cpp/utils/include/utils/grid_mat.hpp

@@ -74,7 +74,7 @@ class GridMat {
     }
 
     void update(const cv::Mat& frame, const size_t sourceID) {
-        cv::Mat cell = outimg(cv::Rect(points[sourceID], cellSize));
+        const cv::Mat& cell = outimg(cv::Rect(points[sourceID], cellSize));
 
         if ((cellSize.width == frame.cols) && (cellSize.height == frame.rows)) {
             frame.copyTo(cell);

demos/common/cpp/utils/include/utils/performance_metrics.hpp

@@ -37,7 +37,7 @@ class PerformanceMetrics {
 
     PerformanceMetrics(Duration timeWindow = std::chrono::seconds(1));
     void update(TimePoint lastRequestStartTime,
-                cv::Mat& frame,
+                const cv::Mat& frame,
                 cv::Point position = {15, 30},
                 int fontFace = cv::FONT_HERSHEY_COMPLEX,
                 double fontScale = 0.75,
@@ -51,7 +51,7 @@ class PerformanceMetrics {
     /// @param fontScale font scale
     /// @param color font color
     /// @param thickness font thickness
-    void paintMetrics(cv::Mat& frame,
+    void paintMetrics(const cv::Mat& frame,
         cv::Point position = { 15, 30 },
         int fontFace = cv::FONT_HERSHEY_COMPLEX,
         double fontScale = 0.75,

demos/common/cpp/utils/src/performance_metrics.cpp

@@ -13,7 +13,7 @@ PerformanceMetrics::PerformanceMetrics(Duration timeWindow)
 {}
 
 void PerformanceMetrics::update(TimePoint lastRequestStartTime,
-    cv::Mat& frame,
+    const cv::Mat& frame,
     cv::Point position,
     int fontFace,
     double fontScale,
@@ -45,7 +45,7 @@ void PerformanceMetrics::update(TimePoint lastRequestStartTime) {
     }
 }
 
-void PerformanceMetrics::paintMetrics(cv::Mat & frame, cv::Point position, int fontFace,
+void PerformanceMetrics::paintMetrics(const cv::Mat& frame, cv::Point position, int fontFace,
     double fontScale, cv::Scalar color, int thickness, MetricTypes metricType) const {
     // Draw performance stats over frame
     Metrics metrics = getLast();