图像旋转

 一个坐标点围绕任意中心点旋转--C#实现
分类： C#/ASP.net 重用代码之C# 2011-07-19 20:23 1668人阅读 评论(0) 收藏 举报
            假设对图片上任意点(x,y)，绕一个坐标点(rx0,ry0)逆时针旋转RotaryAngle角度后的新的坐标设为(x', y')，有公式：
    x'= (x - rx0)*cos(RotaryAngle) + (y - ry0)*sin(RotaryAngle) + rx0 ;
    y'=-(x - rx0)*sin(RotaryAngle) + (y - ry0)*cos(RotaryAngle) + ry0 ;
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/// <summary>  
        /// 对一个坐标点按照一个中心进行旋转  
        /// </summary>  
        /// <param name="center">中心点</param>  
        /// <param name="p1">要旋转的点</param>  
        /// <param name="angle">旋转角度，笛卡尔直角坐标</param>  
        /// <returns></returns>  
        private  Point PointRotate(Point center, Point p1, double angle)  
        {  
            Point tmp = new Point();  
            double angleHude = angle * Math.PI / 180;/*角度变成弧度*/  
            double x1 = (p1.X - center.X) * Math.Cos(angleHude) + (p1.Y - center.Y ) * Math.Sin(angleHude) + center .X;  
            double y1 = -(p1.X - center.X) * Math.Sin(angleHude) + (p1.Y - center.Y) * Math.Cos(angleHude) + center.Y;  
            tmp.X = (int)x1;  
            tmp.Y = (int)y1;  
            return tmp;  
        }  

1 、旋转

e.Graphics.RotateTransform(30.0F, MatrixOrder.Prepend);

2、平移

 e.Graphics.TranslateTransform(100.0F, 0.0F);

3、缩放

 e.Graphics.ScaleTransform(3.0F, 1.0F, MatrixOrder.Append);
4、点坐标变换

            e.Graphics.TranslateTransform(40, 30);
            e.Graphics.TransformPoints(CoordinateSpace.Page, CoordinateSpace.World, points);
            e.Graphics.ResetTransform();


     // Create array of two points.
            Point[] points = { new Point(0, 0), new Point(100, 50) };

            // Draw line connecting two untransformed points.
            e.Graphics.DrawLine(new Pen(Color.Blue, 3), points[0], points[1]);

            // Set world transformation of Graphics object to translate.
            e.Graphics.TranslateTransform(40, 30);

            // Transform points in array from world to page coordinates.
            e.Graphics.TransformPoints(CoordinateSpace.Page, CoordinateSpace.World, points);

            // Reset world transformation.
            e.Graphics.ResetTransform();

            // Draw line that connects transformed points.
            e.Graphics.DrawLine(new Pen(Color.Red, 3), points[0], points[1]);
 

5、选择参数：将此变换参数放在已有的变换矩阵之后还是之前。MatrixOrder.Append//MatrixOrder.Prepend  

//----------------旋转和平移的顺序不一样，得到的结果页不一样。

6、辅助功能

 GraphicsState transState = e.Graphics.Save();//保存当前绘图板状态

e.Graphics.ResetTransform();//重置

e.Graphics.Restore(transState);//置为此状态