裁剪

规则形状的裁剪区域 Graphics g = e.Graphics;             g.FillRectangle(Brushes.White, this.ClientRectangle);             //Define the rectangle that we'll use to define our clipping region             Rectangle rect = new Rectangle(10, 10, 80, 50);             //Draw the clipping region             g.DrawRectangle(Pens.Black, rect);             //now apply the clipping region             g.SetClip(rect);             //now draw something onto the drawing surface             //with the clipping region applied             g.FillEllipse(Brushes.Blue, 20, 20, 100, 100); 不规则形状的裁剪区域 Graphics g = e.Graphics;             g.FillRectangle(Brushes.White, this.ClientRectangle);             //create a region object and make sure it's empty             Region reg = new Region();             reg.MakeEmpty();             //create an irregular Region..             //..add a circle to the region             GraphicsPath gp = new GraphicsPath();             gp.AddEllipse(10, 10, 50, 50);             reg.Union(gp);             //..add a triangle to the region             gp.Reset();             gp.AddLine(40, 40, 70, 10);             gp.AddLine(70, 10, 100, 40);             gp.CloseFigure();             reg.Union(gp);             //..add a rectangle to the region             reg.Union(new Rectangle(40, 50, 60, 60));             //set the clipping region             g.SetClip(reg, CombineMode.Replace);             //paint the client rectangle green,             //only the clipped region will be affected             g.FillRectangle(Brushes.Green, this.ClientRectangle);             gp.Dispose();             reg.Dispose(); 这里通过使用一些Union类型创建了一个相当复杂的Region对象，然后把此区域分配给裁剪区域（使用SetClip方法）。最后，我们把整个客户区域矩形涂上绿色。 注：开头调用Region对象的MakeEmpty方法是必要的，因为我们使用的重载的Region构造函数生成了一个Region对象，表示完整的无限大的绘图表面。但我们想做的是首先创建一个空的Region对象，然后向其中添加内容。所以，我们使用MakeEmpty来创建空的Region、 在裁剪区域使用文本 我们可以创建一个GraphicsPath对象，使用它的AddString方法，让他具有字符串中字符轮廓的形状，从而创建一个特殊的效果。然后，可以使用GraphicsPath作为裁剪区域的轮廓，最后用我们选择的任意笔画或图像来绘制裁剪的绘图表面。 Graphics g = e.Graphics;             g.FillRectangle(Brushes.White, this.ClientRectangle);             GraphicsPath gp = new GraphicsPath();             gp.AddString("Swirly", new FontFamily("Times New Roman"),                 (int)(FontStyle.Bold | FontStyle.Italic),                 144, new Point(5, 5), StringFormat.GenericTypographic);             //set clipping region             g.SetClip(gp);             //paint the client rectangle using an image.             //only the clipped region will be affected             g.DrawImage(new Bitmap("a.jpg"), this.ClientRectangle);             gp.Dispose();

CombineMode枚举用来表示指定区域如何与现有裁剪区域结合，枚举中一共有6个值：CombineMode.Replace,CombineMode.Complement,CombineMode.Exclude,CombineMode.Intersect,CombineMode.Union,CombineMode.Xor，当传递一个Region对象给SetClip方法时，还必须同时传递一个取自CombineMode枚举的值。