C# 显式转换运算符

Question

你好，我需要一些帮助:) 我有我的自定义 class 过滤器，我在其中定义了显式转换运算符以从 AForge.Point 转换为 System.Drawing.PointF AForge.Point 和 System.Drawing.PointF 都是来自库的结构。 blob.CenterOfGravity 是 AForge.Point 的类型。问题是智能感知告诉我“无法将 'AForge.Point' 转换为 'System.Drawing.PointF'。我不知道为什么无法完成此转换：/。感谢所有回复。

class Filters
{
        public static explicit operator System.Drawing.PointF(AForge.Point apoint)
        {
            return new PointF(apoint.X,apoint.Y);
        }
        public void DrawData(Blob blob, Bitmap bmp)
        {
            int width = blob.Rectangle.Width;
            int height = blob.Rectangle.Height;
            int area = blob.Area;
            PointF cog = (PointF)blob.CenterOfGravity;
        }
        ...
}

Answer 1

您不能使用 operator 执行此操作，因为它们必须由您正在转换的类型定义（即 AForge.Point 或 System.Drawing.PointF）。根据 documentation:

Either the type of the argument to be converted, or the type of the result of the conversion, but not both, must be the containing type.

一种替代方法是为 AForge.Point 定义扩展方法：

public static class PointExtensions
{
    public static PointF ToPointF(this AForge.Point source)
    {
        return new PointF(source.X, source.Y);
    }
}

并像这样使用：

PointF cog = blob.CenterOfGravity.ToPointF();

Answer 2

你可以试试这个

private static System.Drawing.PointF convertToPointF(AForge.Point apoint)
    {
        return new PointF(apoint.X,apoint.Y);
    }
    public void DrawData(Blob blob, Bitmap bmp)
    {
        int width = blob.Rectangle.Width;
        int height = blob.Rectangle.Height;
        int area = blob.Area;
        PointF cog = convertToPointF(blob.CenterOfGravity);
    }

C# 显式转换运算符

C# explicit conversion operators

c#

explicit-conversion