使用PointF作为中心c＃绘制圆

Question

I was searching for this but I couldnt find anything. The idea is I have a PointF like (52.66, 60.11) and I want to draw an empty circle with this PointF as its center. I was trying to do with DrawEllipse but it does not care about the center! it is just a rectangle...I think some kind of conversion formula should be used?

Answer 1

You can compute the coordinates of the rectangle from the center and radius:

float x = center.X - radius;
float y = center.Y - radius;
float width = 2 * radius;
float height = 2 * radius;
graphics.DrawEllipse(pen, x, y, width, height);

Answer 2

out of mind:

RectangleF circle2Rect(Point midPoint, float radius) {
   return new RectangleF(midPoint.X-radius,
                        midPoint.Y-radius,
                        radius*2,
                        radius*2); 
}

(This is not tested) Use it to convert the parameter of the circle to a rectangle for drawing.

Answer 3

如果您绘制具有相同高度和宽度的椭圆，则会得到一个圆，如果您需要知道绘制圆的正方形的上下左右坐标，则知道中间点（中心）是相当平庸的。