Added pointPolygonTest_demo code for tutorials

samples/cpp/tutorial_code/ShapeDescriptors/pointPolygonTest_demo.cpp

+/**
+ * @function pointPolygonTest_demo.cpp
+ * @brief Demo code to use the pointPolygonTest function...fairly easy
+ * @author OpenCV team
+ */
+
+#include "opencv2/highgui/highgui.hpp"
+#include "opencv2/imgproc/imgproc.hpp"
+#include <iostream>
+#include <stdio.h>
+#include <stdlib.h>
+
+using namespace cv;
+using namespace std;
+
+/**
+ * @function main
+ */
+int main( int argc, char** argv )
+{
+  /// Create an image
+  const int r = 100;
+  Mat src = Mat::zeros( Size( 4*r, 4*r ), CV_8UC1 );
+
+  /// Create a sequence of points to make a contour:
+  vector<Point2f> vert(6);
+
+  vert[0] = Point( 1.5*r, 1.34*r );
+  vert[1] = Point( 1*r, 2*r );
+  vert[2] = Point( 1.5*r, 2.866*r );
+  vert[3] = Point( 2.5*r, 2.866*r );
+  vert[4] = Point( 3*r, 2*r );
+  vert[5] = Point( 2.5*r, 1.34*r );
+
+  /// Draw it in src
+  for( int j = 0; j < 6; j++ )
+     { line( src, vert[j],  vert[(j+1)%6], Scalar( 255 ), 3, 8 ); } 
+
+  /// Get the contours
+  vector<vector<Point> > contours; vector<Vec4i> hierarchy;
+  Mat src_copy = src.clone();
+
+  findContours( src_copy, contours, hierarchy, RETR_TREE, CHAIN_APPROX_SIMPLE);  
+
+  /// Calculate the distances to the contour
+  Mat raw_dist( src.size(), CV_32FC1 );
+
+  for( int j = 0; j < src.rows; j++ )
+     { for( int i = 0; i < src.cols; i++ )
+          { raw_dist.at<float>(j,i) = pointPolygonTest( contours[0], Point2f(i,j), true ); }
+     }
+
+  double minVal; double maxVal;
+  minMaxLoc( raw_dist, &minVal, &maxVal, 0, 0, Mat() );
+  minVal = abs(minVal); maxVal = abs(maxVal);
+  
+  /// Depicting the  distances graphically
+  Mat drawing = Mat::zeros( src.size(), CV_8UC3 );
+
+  for( int j = 0; j < src.rows; j++ )
+     { for( int i = 0; i < src.cols; i++ )
+          { 
+            if( raw_dist.at<float>(j,i) < 0 )
+              { drawing.at<Vec3b>(j,i)[0] = 255 - (int) abs(raw_dist.at<float>(j,i))*255/minVal; }
+            else if( raw_dist.at<float>(j,i) > 0 )
+              { drawing.at<Vec3b>(j,i)[2] = 255 - (int) raw_dist.at<float>(j,i)*255/maxVal; }    
+            else
+              { drawing.at<Vec3b>(j,i)[0] = 255; drawing.at<Vec3b>(j,i)[1] = 255; drawing.at<Vec3b>(j,i)[2] = 255; }     
+          }
+     }
+
+  /// Create Window and show your results
+  char* source_window = "Source";
+  namedWindow( source_window, CV_WINDOW_AUTOSIZE );
+  imshow( source_window, src );
+  namedWindow( "Distance", CV_WINDOW_AUTOSIZE );
+  imshow( "Distance", drawing );
+
+  waitKey(0);
+  return(0);
+}
+
+