EdgeDrawing: Add output of segment index for line detection

Author: ToFam

modules/ximgproc/include/opencv2/ximgproc/edge_drawing.hpp

@@ -72,9 +72,10 @@ class CV_EXPORTS_W EdgeDrawing : public Algorithm
     /** @brief Detects lines.
 
     @param lines  output Vec<4f> contains start point and end point of detected lines.
+    @param segments  output vector containing the edge segment index for each line, see getSegments()
     @note you should call detectEdges() method before call this.
     */
-    CV_WRAP virtual void detectLines(OutputArray lines) = 0;
+    CV_WRAP virtual void detectLines(OutputArray lines, OutputArray segments = cv::noArray()) = 0;
 
     /** @brief Detects circles and ellipses.
 

modules/ximgproc/src/edge_drawing.cpp

@@ -109,7 +109,7 @@ class EdgeDrawingImpl : public EdgeDrawing
     void getGradientImage(OutputArray dst) CV_OVERRIDE;
 
     vector<vector<Point> > getSegments() CV_OVERRIDE;
-    void detectLines(OutputArray lines) CV_OVERRIDE;
+    void detectLines(OutputArray lines, OutputArray segments = cv::noArray()) CV_OVERRIDE;
     void detectEllipses(OutputArray ellipses) CV_OVERRIDE;
 
     virtual void read(const FileNode& fn) CV_OVERRIDE;
@@ -1263,7 +1263,7 @@ int EdgeDrawingImpl::RetrieveChainNos(Chain* chains, int root, int chainNos[])
     return count;
 }
 
-void EdgeDrawingImpl::detectLines(OutputArray _lines)
+void EdgeDrawingImpl::detectLines(OutputArray _lines, OutputArray _lineSegments)
 {
     std::vector<Vec4f> linePoints;
     if (segmentPoints.size() < 1)
@@ -1312,12 +1312,19 @@ void EdgeDrawingImpl::detectLines(OutputArray _lines)
     for (int i = 1; i <= size - linesNo; i++)
         lines.pop_back();
 
+    std::vector<int> lineSegmentIndices;
     for (int i = 0; i < linesNo; i++)
     {
         Vec4f line((float)lines[i].sx, (float)lines[i].sy, (float)lines[i].ex, (float)lines[i].ey);
         linePoints.push_back(line);
+        lineSegmentIndices.push_back(lines[i].segmentNo);
     }
     Mat(linePoints).copyTo(_lines);
+    if (_lineSegments.needed())
+    {
+        Mat(lineSegmentIndices).copyTo(_lineSegments);
+    }
+
     delete[] x;
     delete[] y;
 }