Merge pull request #2970 from PhilLab:patch-3

modules/core/doc/drawing_functions.rst

@@ -371,6 +371,36 @@ Draws a line segment connecting two points.
 The function ``line`` draws the line segment between ``pt1`` and ``pt2`` points in the image. The line is clipped by the image boundaries. For non-antialiased lines with integer coordinates, the 8-connected or 4-connected Bresenham algorithm is used. Thick lines are drawn with rounding endings.
 Antialiased lines are drawn using Gaussian filtering. To specify the line color, you may use the macro ``CV_RGB(r, g, b)`` .
 
+arrowedLine
+----------------
+Draws a arrow segment pointing from the first point to the second one.
+
+.. ocv:function:: void arrowedLine(Mat& img, Point pt1, Point pt2, const Scalar& color,          int thickness=1, int lineType=8, int shift=0, double tipLength=0.1)
+
+    :param img: Image.
+
+    :param pt1: The point the arrow starts from.
+
+    :param pt2: The point the arrow points to.
+
+    :param color: Line color.
+
+    :param thickness: Line thickness.
+
+    :param lineType: Type of the line:
+
+            * **8** (or omitted) - 8-connected line.
+
+            * **4** - 4-connected line.
+
+            * **CV_AA** - antialiased line.
+
+    :param shift: Number of fractional bits in the point coordinates.
+
+    :param tipLength: The length of the arrow tip in relation to the arrow length
+
+The function ``arrowedLine`` draws an arrow between ``pt1`` and ``pt2`` points in the image. See also :ocv:func:`line`.
+
 
 LineIterator
 ------------

modules/core/include/opencv2/core/core.hpp

@@ -2590,6 +2590,10 @@ CV_EXPORTS_AS(randShuffle) void randShuffle_(InputOutputArray dst, double iterFa
 CV_EXPORTS_W void line(CV_IN_OUT Mat& img, Point pt1, Point pt2, const Scalar& color,
                      int thickness=1, int lineType=8, int shift=0);
 
+//! draws an arrow from pt1 to pt2 in the image
+CV_EXPORTS_W void arrowedLine(CV_IN_OUT Mat& img, Point pt1, Point pt2, const Scalar& color,
+                     int thickness=1, int line_type=8, int shift=0, double tipLength=0.1);
+
 //! draws the rectangle outline or a solid rectangle with the opposite corners pt1 and pt2 in the image
 CV_EXPORTS_W void rectangle(CV_IN_OUT Mat& img, Point pt1, Point pt2,
                           const Scalar& color, int thickness=1,

modules/core/src/drawing.cpp

@@ -1580,6 +1580,25 @@ void line( Mat& img, Point pt1, Point pt2, const Scalar& color,
     ThickLine( img, pt1, pt2, buf, thickness, line_type, 3, shift );
 }
 
+void arrowedLine(Mat& img, Point pt1, Point pt2, const Scalar& color,
+           int thickness, int line_type, int shift, double tipLength)
+{
+    const double tipSize = norm(pt1-pt2)*tipLength;// Factor to normalize the size of the tip depending on the length of the arrow
+
+    line(img, pt1, pt2, color, thickness, line_type, shift);
+
+    const double angle = atan2( (double) pt1.y - pt2.y, (double) pt1.x - pt2.x );
+
+    Point p(cvRound(pt2.x + tipSize * cos(angle + CV_PI / 4)),
+                cvRound(pt2.y + tipSize * sin(angle + CV_PI / 4)));
+    line(img, p, pt2, color, thickness, line_type, shift);
+
+    p.x = cvRound(pt2.x + tipSize * cos(angle - CV_PI / 4));
+    p.y = cvRound(pt2.y + tipSize * sin(angle - CV_PI / 4));
+    line(img, p, pt2, color, thickness, line_type, shift);
+
+}
+
 void rectangle( Mat& img, Point pt1, Point pt2,
                 const Scalar& color, int thickness,
                 int lineType, int shift )