如何确定一个点是否在椭圆内？ [英] How to determine if a point is within an ellipse?

问题描述

我遇到了麻烦，发现经典的Contains方法，如果它位于矩形，椭圆或其他对象内部的某个点上，它将返回。这些对象位于画布中。

我试过VisualTreeHelper.FindElementsInHostCoordinates，但找不到路。

有人帮助我吗？

此致敬礼！

解决方案

*（如果您觉得它有用，请投票！）

http://my.safaribooksonline.com/book/programming/csharp/9780672331985/graphics-with-windows-forms- and-gdiplus / ch17lev1sec22

  public bool包含（Ellipse Ellipse，Point location）
 {
 Point center = new Point（
 Canvas.GetLeft（Ellipse）+（Ellipse.Width / 2），
 Canvas.GetTop（Ellipse）+（Ellipse.Height / 2））; 
 
 double _xRadius = Ellipse.Width / 2; 
 double _yRadius = Ellipse.Height / 2; 
 
 
 if（_xRadius< = 0.0 || _yRadius< = 0.0）
 return false; 
 / *这是圆形方程的更一般形式
 * 
 * X ^ 2 / a ^ 2 + Y ^ 2 / b ^ 2 <= 1 
 * / 
 
点归一化=新点（location.X  -  center.X，
 location.Y  -  center.Y）; $（b）
 $ b return（（double）（normalized.X * normalized.X）
 /（_xRadius * _xRadius））+（（double）（normalized.Y * normalized.Y）/（_yRadius * _yRadius））
 <= 1.0; 
} 
  

I'm having troubles finding the classic 'Contains' method wich returns if a point it's within a rectangle, ellipse or some else object. These objects are in a canvas.

I've tried VisualTreeHelper.FindElementsInHostCoordinates but I can't find the way.

does Anybody help me?

Thanks in advance!

解决方案

This works for me. *(If you find it usefull please vote it!)

http://my.safaribooksonline.com/book/programming/csharp/9780672331985/graphics-with-windows-forms-and-gdiplus/ch17lev1sec22

 public bool Contains(Ellipse Ellipse, Point location)
        {
            Point center = new Point(
                  Canvas.GetLeft(Ellipse) + (Ellipse.Width / 2),
                  Canvas.GetTop(Ellipse) + (Ellipse.Height / 2));

            double _xRadius = Ellipse.Width / 2;
            double _yRadius = Ellipse.Height / 2;


            if (_xRadius <= 0.0 || _yRadius <= 0.0)
                return false;
            /* This is a more general form of the circle equation
             *
             * X^2/a^2 + Y^2/b^2 <= 1
             */

            Point normalized = new Point(location.X - center.X,
                                         location.Y - center.Y);

            return ((double)(normalized.X * normalized.X)
                     / (_xRadius * _xRadius)) + ((double)(normalized.Y * normalized.Y) / (_yRadius * _yRadius))
                <= 1.0;
        }

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