用C# 实现 已知旋转矩形左上角点点和宽高以及角度，计算旋转矩形4点坐标 4点坐标为顺时针顺序

可以使用以下代码实现：

public static Point[] GetRotatedRectanglePoints(Point leftTop, double width, double height, double angle)
{
    Point[] points = new Point[4];
    double centerX = leftTop.X + width / 2;
    double centerY = leftTop.Y + height / 2;
    double radian = angle * Math.PI / 180;
    double sin = Math.Sin(radian);
    double cos = Math.Cos(radian);
    double dx1 = -width / 2;
    double dy1 = -height / 2;
    double dx2 = width / 2;
    double dy2 = -height / 2;
    double dx3 = width / 2;
    double dy3 = height / 2;
    double dx4 = -width / 2;
    double dy4 = height / 2;
    double x1 = centerX + cos * dx1 - sin * dy1;
    double y1 = centerY + sin * dx1 + cos * dy1;
    double x2 = centerX + cos * dx2 - sin * dy2;
    double y2 = centerY + sin * dx2 + cos * dy2;
    double x3 = centerX + cos * dx3 - sin * dy3;
    double y3 = centerY + sin * dx3 + cos * dy3;
    double x4 = centerX + cos * dx4 - sin * dy4;
    double y4 = centerY + sin * dx4 + cos * dy4;
    points[0] = new Point(x1, y1);
    points[1] = new Point(x2, y2);
    points[2] = new Point(x3, y3);
    points[3] = new Point(x4, y4);
    return points;
}

其中，`leftTop` 表示旋转矩形的左上角点，`width` 和 `height` 分别表示矩形的宽度和高度，`angle` 表示矩形的旋转角度（单位为度）。函数返回一个 `Point` 类型的数组，表示旋转矩形的四个顶点坐标，按顺时针顺序排列。