c#图片在PictureBox内任意角度旋转问题（360度）

（1）

public static Bitmap RotateImage(Image image, float angle)
{
if (image == null)
throw new ArgumentNullException("image");
float dx = image.Width / 2.0f;
float dy = image.Height / 2.0f;

Bitmap rotatedBmp = new Bitmap(image.Width, image.Height);
rotatedBmp.SetResolution(image.HorizontalResolution, image.VerticalResolution);
Graphics g = Graphics.FromImage(rotatedBmp);
g.TranslateTransform(dx, dy);
g.RotateTransform(angle);
g.TranslateTransform(-dx, -dy);
g.DrawImage(image, new PointF(0, 0));
return rotatedBmp;
}

void tm_Elapsed(object sender, EventArgs e)
{
if (isStart)
{
angle += 5;
if (angle >= 359) angle = 0;
RotateImage(pic1, Properties.Resources._1, angle);
}
}

private void RotateImage(PictureBox pb, Image img, float angle)
{
if (img == null || pb.Image == null)
return;
Image oldImage = pb.Image;
pb.Image = Utilities.RotateImage(img, angle);
if (oldImage != null)
{
oldImage.Dispose();
}
}

（2）

//任意角度旋转
private void RotateTransformButton_Click(object sender, EventArgs e)
{
try
{
Bitmap a = new Bitmap(pictureBox1.Image);//得到图片框中的图片
pictureBox1.Image = Rotate(a, Convert.ToInt32(textBox1.Text));
pictureBox1.SizeMode = PictureBoxSizeMode.AutoSize;
pictureBox1.Location = panel1.Location;
pictureBox1.Refresh();//最后刷新图片框
}
catch { }
}

#region 图片旋转函数
/// <summary>
/// 以逆时针为方向对图像进行旋转
/// </summary>
/// <param name="b">位图流</param>
/// <param name="angle">旋转角度[0,360](前台给的)</param>
/// <returns></returns>
public Bitmap Rotate(Bitmap b, int angle)
{
angle = angle % 360;

//弧度转换
double radian = angle * Math.PI / 180.0;
double cos = Math.Cos(radian);
double sin = Math.Sin(radian);

//原图的宽和高
int w = b.Width;
int h = b.Height;
int W = (int)(Math.Max(Math.Abs(w * cos - h * sin), Math.Abs(w * cos + h * sin)));
int H = (int)(Math.Max(Math.Abs(w * sin - h * cos), Math.Abs(w * sin + h * cos)));

//目标位图
Bitmap dsImage = new Bitmap(W, H);
Graphics g = Graphics.FromImage(dsImage);

g.InterpolationMode = InterpolationMode.Bilinear;

g.SmoothingMode = SmoothingMode.HighQuality;

//计算偏移量
Point Offset = new Point((W - w) / 2, (H - h) / 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 rect = new Rectangle(Offset.X, Offset.Y, w, h);
Point center = new Point(rect.X + rect.Width / 2, rect.Y + rect.Height / 2);
g.TranslateTransform(center.X, center.Y);
g.RotateTransform(360 - angle);

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

//重至绘图的所有变换
g.ResetTransform();

g.Save();
g.Dispose();
return dsImage;
}
#endregion 图片旋转函数