From e90e9fcceed659355f5f27fccb30cac799fd250e Mon Sep 17 00:00:00 2001
From: ToFam <ToFam@gmx.de>
Date: Mon, 13 Dec 2021 18:48:45 +0100
Subject: [PATCH] EdgeDrawing: Add getter for line edge segments

---
 .../ximgproc/include/opencv2/ximgproc/edge_drawing.hpp |  6 ++++++
 modules/ximgproc/src/edge_drawing.cpp                  | 10 ++++++++++
 2 files changed, 16 insertions(+)

diff --git a/modules/ximgproc/include/opencv2/ximgproc/edge_drawing.hpp b/modules/ximgproc/include/opencv2/ximgproc/edge_drawing.hpp
index e33b23b08..1d198fe6f 100644
--- a/modules/ximgproc/include/opencv2/ximgproc/edge_drawing.hpp
+++ b/modules/ximgproc/include/opencv2/ximgproc/edge_drawing.hpp
@@ -67,8 +67,14 @@ public:
     CV_WRAP virtual void getEdgeImage(OutputArray dst) = 0;
     CV_WRAP virtual void getGradientImage(OutputArray dst) = 0;
 
+    /** @brief Returns std::vector<std::vector<Point>> of detected edge segments, see detectEdges()
+     */
     CV_WRAP virtual std::vector<std::vector<Point> > getSegments() = 0;
 
+    /** @brief Returns for each line found in detectLines() its edge segment index in getSegments()
+     */
+    CV_WRAP virtual std::vector<int> getSegmentIndicesOfLines() const = 0;
+
     /** @brief Detects lines.
 
     @param lines  output Vec<4f> contains start point and end point of detected lines.
diff --git a/modules/ximgproc/src/edge_drawing.cpp b/modules/ximgproc/src/edge_drawing.cpp
index 62166f98c..7cb6b2754 100644
--- a/modules/ximgproc/src/edge_drawing.cpp
+++ b/modules/ximgproc/src/edge_drawing.cpp
@@ -109,6 +109,7 @@ public:
     void getGradientImage(OutputArray dst) CV_OVERRIDE;
 
     vector<vector<Point> > getSegments() CV_OVERRIDE;
+    vector<int> getSegmentIndicesOfLines() const CV_OVERRIDE;
     void detectLines(OutputArray lines) CV_OVERRIDE;
     void detectEllipses(OutputArray ellipses) CV_OVERRIDE;
 
@@ -120,6 +121,7 @@ protected:
     int height;       // height of source image
     uchar *srcImg;
     vector<vector<Point> > segmentPoints;
+    vector<int> segmentIndicesOfLines;
     Mat smoothImage;
     uchar *edgeImg;   // pointer to edge image data
     uchar *smoothImg; // pointer to smoothed image data
@@ -440,6 +442,11 @@ std::vector<std::vector<Point> > EdgeDrawingImpl::getSegments()
     return segmentPoints;
 }
 
+std::vector<int> EdgeDrawingImpl::getSegmentIndicesOfLines() const
+{
+    return segmentIndicesOfLines;
+}
+
 void EdgeDrawingImpl::ComputeGradient()
 {
     for (int j = 0; j < width; j++)
@@ -1312,12 +1319,15 @@ void EdgeDrawingImpl::detectLines(OutputArray _lines)
     for (int i = 1; i <= size - linesNo; i++)
         lines.pop_back();
 
+    segmentIndicesOfLines.clear();
     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);
+        segmentIndicesOfLines.push_back(lines[i].segmentNo);
     }
     Mat(linePoints).copyTo(_lines);
+
     delete[] x;
     delete[] y;
 }