图像处理-03-实现图像的旋转

实现图像的旋转

private void btnRotating_Click( object sender, EventArgs e )
        {
            pbNewPicture.Image = Rotating((Bitmap)pbImage.Image, Convert.ToInt32( cmbAngle.SelectedItem.ToString() ) );
        }
        public Bitmap Rotating(Bitmap bitmap,int angle)
        {
            angle = angle % 360;//弧度转换
            double radian = angle * Math.PI / 180;
            double cos = Math.Cos( radian );
            double sin = Math.Sin( radian );

            //原图像的宽和高
            int width=bitmap.Width;
            int height=bitmap.Height;
            int newWidth=(int)Math.Max(Math.Abs(width*cos-height*sin),Math.Abs(width*cos+height*sin));
            int newHeight=(int)(Math.Max(Math.Abs(width*sin-height*sin),Math.Abs(width*sin+height*cos)));

            //目标位图
            Bitmap newBitmap = new Bitmap(newWidth,newHeight);
            Graphics graphics = Graphics.FromImage( newBitmap );
            graphics.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.Bilinear;//指定缩放算法
            graphics.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;//指定抗锯齿呈现图形边缘，用于平滑直线、曲线等
            
            //计算偏移量
            Point offset = new Point((newWidth-width)/2,(newHeight-height)/2);

            //构造图像显示区域：让图像的中心与窗口的中心点一致
            Rectangle rectangle = new Rectangle(offset.X,offset.Y,width,height);
            Point center = new Point(rectangle.X+rectangle.Width/2,rectangle.Y+rectangle.Height/2);
            graphics.TranslateTransform( center.X, center.Y );
            graphics.RotateTransform( 360 - angle );

            //恢复图像在水平和垂直方向的平移
            graphics.TranslateTransform( -center.X, -center.Y );
            graphics.DrawImage( bitmap, rectangle );

            //重置绘图的所有变换
            graphics.ResetTransform();
            graphics.Save();
            return newBitmap;
        }

与真实的图像旋转相差一定的距离，继续努力中......