From 3fe18392eff71f9f0a2d973d2378c4f7960dda80 Mon Sep 17 00:00:00 2001 From: saskatchewancatch Date: Thu, 20 Apr 2017 00:14:18 -0600 Subject: [PATCH] Updated comments for cv::ellipse and cv::ellipse2Poly to clarify some behaviour that has confused some users. Amend: Delete trailing whitespace to make doc tests happy --- modules/imgproc/include/opencv2/imgproc.hpp | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/modules/imgproc/include/opencv2/imgproc.hpp b/modules/imgproc/include/opencv2/imgproc.hpp index 4bab109107..bd03e3ce6d 100644 --- a/modules/imgproc/include/opencv2/imgproc.hpp +++ b/modules/imgproc/include/opencv2/imgproc.hpp @@ -4220,13 +4220,14 @@ CV_EXPORTS_W void circle(InputOutputArray img, Point center, int radius, /** @brief Draws a simple or thick elliptic arc or fills an ellipse sector. -The function cv::ellipse with less parameters draws an ellipse outline, a filled ellipse, an elliptic +The function cv::ellipse with more parameters draws an ellipse outline, a filled ellipse, an elliptic arc, or a filled ellipse sector. The drawing code uses general parametric form. A piecewise-linear curve is used to approximate the elliptic arc boundary. If you need more control of the ellipse rendering, you can retrieve the curve using cv::ellipse2Poly and then render it with polylines or fill it with cv::fillPoly. If you use the first variant of the function and want to draw the whole ellipse, not an arc, pass `startAngle=0` and -`endAngle=360`. The figure below explains the meaning of the parameters to draw the blue arc. +`endAngle=360`. If `startAngle` is greater than `endAngle`, they are swapped. The figure below explains +the meaning of the parameters to draw the blue arc. ![Parameters of Elliptic Arc](pics/ellipse.svg) @@ -4468,7 +4469,7 @@ CV_EXPORTS_W bool clipLine(Rect imgRect, CV_OUT CV_IN_OUT Point& pt1, CV_OUT CV_ /** @brief Approximates an elliptic arc with a polyline. The function ellipse2Poly computes the vertices of a polyline that approximates the specified -elliptic arc. It is used by cv::ellipse. +elliptic arc. It is used by cv::ellipse. If `arcStart` is greater than `arcEnd`, they are swapped. @param center Center of the arc. @param axes Half of the size of the ellipse main axes. See the ellipse for details.