fixed crashes in camshiftdemo (ticket #875)

modules/video/src/camshift.cpp

@@ -90,6 +90,13 @@ cvMeanShift( const void* imgProb, CvRect windowIn,
         int dx, dy, nx, ny;
         double inv_m00;
         cur_rect = cv::Rect(cur_rect) & cv::Rect(0, 0, mat->cols, mat->rows);
+        if( cv::Rect(cur_rect) == cv::Rect() )
+        {
+            cur_rect.x = mat->cols/2;
+            cur_rect.y = mat->rows/2;
+        }
+        cur_rect.width = MAX(cur_rect.width, 1);
+        cur_rect.height = MAX(cur_rect.height, 1);
         
         cvGetSubRect( mat, &cur_win, cur_rect ); 
         cvMoments( &cur_win, &moments );

samples/cpp/camshiftdemo.cpp

@@ -22,6 +22,7 @@ void help()
         "\tc - stop the tracking\n"
         "\tb - switch to/from backprojection view\n"
         "\th - show/hide object histogram\n"
+        "\tp - pause video\n"
         "To initialize tracking, select the object with mouse\n" << endl;
 }
 
@@ -87,69 +88,85 @@ int main( int argc, char** argv )
 
     help();
 
-    namedWindow( "Histogram", 1 );
-    namedWindow( "CamShift Demo", 1 );
+    namedWindow( "Histogram", 0 );
+    namedWindow( "CamShift Demo", 0 );
     setMouseCallback( "CamShift Demo", onMouse, 0 );
     createTrackbar( "Vmin", "CamShift Demo", &vmin, 256, 0 );
     createTrackbar( "Vmax", "CamShift Demo", &vmax, 256, 0 );
     createTrackbar( "Smin", "CamShift Demo", &smin, 256, 0 );
 
-    Mat hsv, hue, mask, hist, histimg = Mat::zeros(200, 320, CV_8UC3), backproj;
+    Mat frame, hsv, hue, mask, hist, histimg = Mat::zeros(200, 320, CV_8UC3), backproj;
+    bool paused = false;
     
     for(;;)
     {
-        Mat frame;
-        cap >> frame;
-        if( frame.empty() )
-            break;
+        if( !paused )
+        {
+            cap >> frame;
+            if( frame.empty() )
+                break;
+        }
 
         frame.copyTo(image);
-        cvtColor(image, hsv, CV_BGR2HSV);
-
-        if( trackObject )
+        
+        if( !paused )
         {
-            int _vmin = vmin, _vmax = vmax;
+            cvtColor(image, hsv, CV_BGR2HSV);
 
-            inRange(hsv, Scalar(0, smin, MIN(_vmin,_vmax)),
-                    Scalar(180, 256, MAX(_vmin, _vmax)), mask);
-            int ch[] = {0, 0};
-            hue.create(hsv.size(), hsv.depth());
-            mixChannels(&hsv, 1, &hue, 1, ch, 1);
-
-            if( trackObject < 0 )
+            if( trackObject )
             {
-                Mat roi(hue, selection), maskroi(mask, selection);
-                calcHist(&roi, 1, 0, maskroi, hist, 1, &hsize, &phranges);
-                normalize(hist, hist, 0, 255, CV_MINMAX);
-                
-                trackWindow = selection;
-                trackObject = 1;
-
-                histimg = Scalar::all(0);
-                int binW = histimg.cols / hsize;
-                Mat buf(1, hsize, CV_8UC3);
-                for( int i = 0; i < hsize; i++ )
-                    buf.at<Vec3b>(i) = Vec3b(saturate_cast<uchar>(i*180./hsize), 255, 255);
-                cvtColor(buf, buf, CV_HSV2BGR);
-                    
-                for( int i = 0; i < hsize; i++ )
+                int _vmin = vmin, _vmax = vmax;
+
+                inRange(hsv, Scalar(0, smin, MIN(_vmin,_vmax)),
+                        Scalar(180, 256, MAX(_vmin, _vmax)), mask);
+                int ch[] = {0, 0};
+                hue.create(hsv.size(), hsv.depth());
+                mixChannels(&hsv, 1, &hue, 1, ch, 1);
+
+                if( trackObject < 0 )
                 {
-                    int val = saturate_cast<int>(hist.at<float>(i)*histimg.rows/255);
-                    rectangle( histimg, Point(i*binW,histimg.rows),
-                               Point((i+1)*binW,histimg.rows - val),
-                               Scalar(buf.at<Vec3b>(i)), -1, 8 );
+                    Mat roi(hue, selection), maskroi(mask, selection);
+                    calcHist(&roi, 1, 0, maskroi, hist, 1, &hsize, &phranges);
+                    normalize(hist, hist, 0, 255, CV_MINMAX);
+                    
+                    trackWindow = selection;
+                    trackObject = 1;
+
+                    histimg = Scalar::all(0);
+                    int binW = histimg.cols / hsize;
+                    Mat buf(1, hsize, CV_8UC3);
+                    for( int i = 0; i < hsize; i++ )
+                        buf.at<Vec3b>(i) = Vec3b(saturate_cast<uchar>(i*180./hsize), 255, 255);
+                    cvtColor(buf, buf, CV_HSV2BGR);
+                        
+                    for( int i = 0; i < hsize; i++ )
+                    {
+                        int val = saturate_cast<int>(hist.at<float>(i)*histimg.rows/255);
+                        rectangle( histimg, Point(i*binW,histimg.rows),
+                                   Point((i+1)*binW,histimg.rows - val),
+                                   Scalar(buf.at<Vec3b>(i)), -1, 8 );
+                    }
                 }
-            }
 
-            calcBackProject(&hue, 1, 0, hist, backproj, &phranges);
-            backproj &= mask;
-            RotatedRect trackBox = CamShift(backproj, trackWindow,
-                                TermCriteria( CV_TERMCRIT_EPS | CV_TERMCRIT_ITER, 10, 1 ));
+                calcBackProject(&hue, 1, 0, hist, backproj, &phranges);
+                backproj &= mask;
+                RotatedRect trackBox = CamShift(backproj, trackWindow,
+                                    TermCriteria( CV_TERMCRIT_EPS | CV_TERMCRIT_ITER, 10, 1 ));
+                if( trackWindow.area() <= 1 )
+                {
+                    int cols = backproj.cols, rows = backproj.rows, r = (MIN(cols, rows) + 5)/6;
+                    trackWindow = Rect(trackWindow.x - r, trackWindow.y - r,
+                                       trackWindow.x + r, trackWindow.y + r) &
+                                  Rect(0, 0, cols, rows);
+                }
 
-            if( backprojMode )
-                cvtColor( backproj, image, CV_GRAY2BGR );
-            ellipse( image, trackBox, Scalar(0,0,255), 3, CV_AA );
+                if( backprojMode )
+                    cvtColor( backproj, image, CV_GRAY2BGR );
+                ellipse( image, trackBox, Scalar(0,0,255), 3, CV_AA );
+            }
         }
+        else if( trackObject < 0 )
+            paused = false;
 
         if( selectObject && selection.width > 0 && selection.height > 0 )
         {
@@ -179,6 +196,9 @@ int main( int argc, char** argv )
             else
                 namedWindow( "Histogram", 1 );
             break;
+        case 'p':
+            paused = !paused;
+            break;
         default:
             ;
         }