C#画图

C#画图

在.NET下面画图需要用到System.Drawing命名空间，这个命名空间基本上是对GDI+(Graphic Devices Inteface plus)的封装。我们来看看怎么使用.NET画图。

 

1，先创建一个画布(Graphics)

GDI+是对显示器/打印机的图形输出设备的包装，通过GDI+我可以使用抽象语言输出图形，而不考虑硬件的驱动等细节。要画图先要有画布（其实是个输出设备），在.NET中我们用Graphics来表示这个画布。MSDN对Graphics类的解释是：Encapsulates a GDI+ drawing surface.

我们一般有两种方法创建画布(Graphics):

1,使用Graphics的静态方法，从Image，窗口来创建Graphics。

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//create graphics over window var frmGraphics = new frmGraphics(); Graphics g = Graphics.FromHwnd(frmGraphics.Handle);   //create graphics over image var img = Image.FromFile(@"C:\Users\a.png"); Graphics g2 = Graphics.FromImage(img);

 //create graphics over window

var frmGraphics = new frmGraphics();

Graphics g = Graphics.FromHwnd(frmGraphics.Handle);

 

//create graphics over image

var img = Image.FromFile(@"C:\Users\a.png");

Graphics g2 = Graphics.FromImage(img);

2,使用.NET控件的CreateGraphics方法
Graphics g = pictureBox1.CreateGraphics();

1	Graphics g = pictureBox1.CreateGraphics();

 

2，画出图形

我们可以用两种方式表示一个图形，用笔(Pen)勾画出形状。我们还可以用刷子(Brush)填充出这个形状，由些绘画API有分为两类，一类是勾画，这类API特点是都以Draw开头：

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g.DrawArc(redPen, rect, 125, 40);                 //弧 g.DrawBezier(redPen, p1, p2, p3, p5);             //Bezier曲线 g.DrawClosedCurve(redPen, points);                //闭合曲线 g.DrawCurve(redPen, points);                      //曲线 g.DrawEllipse(redPen, rect);                      //椭圆，当长宽比为1:1时即为圆 g.DrawLine(redPen, p1, p4);                       //线段 g.DrawLines(redPen, points);                      //点连成的线段 g.DrawPath(redPen, new GraphicsPath());           //由直线和曲线连成的路径 g.DrawPie(redPen, rect, 90, 45);                  //饼状图 g.DrawPolygon(redPen, points);                    //多边形 g.DrawRectangle(redPen, rect);                    //方形 g.DrawString("Cicle", new Font("Arial", 15), brush, p4);

 g.DrawArc(redPen, rect, 125, 40);                 //弧

g.DrawBezier(redPen, p1, p2, p3, p5);             //Bezier曲线

g.DrawClosedCurve(redPen, points);                //闭合曲线

g.DrawCurve(redPen, points);                      //曲线

g.DrawEllipse(redPen, rect);                      //椭圆，当长宽比为1:1时即为圆

g.DrawLine(redPen, p1, p4);                       //线段

g.DrawLines(redPen, points);                      //点连成的线段

g.DrawPath(redPen, new GraphicsPath());           //由直线和曲线连成的路径

g.DrawPie(redPen, rect, 90, 45);                  //饼状图

g.DrawPolygon(redPen, points);                    //多边形

g.DrawRectangle(redPen, rect);                    //方形

g.DrawString("Cicle", new Font("Arial", 15), brush, p4);

填充的API都是以Fill开头，基本用法跟上面类似，唯中的区别就是以Brush来代替Pen
g.FillClosedCurve(brush, points);

g.FillEllipse(brush, rect);

g.FillRegion(brush, new Region(rect));

g.FillPie(brush, rect, 90, 100);

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g.FillClosedCurve(brush, points); g.FillEllipse(brush, rect); g.FillRegion(brush, new Region(rect)); g.FillPie(brush, rect, 90, 100);

 

3，处理图像

Graphics有两类方法用来处理图像：
g.DrawIcon(icon, rect);

g.DrawImage(image, p1);

g.DrawImageUnscaledAndClipped(image, p2);

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g.DrawIcon(icon, rect); g.DrawImage(image, p1); g.DrawImageUnscaledAndClipped(image, p2);

DrawIcon, DrawImage将图标或图像显示在输出设备(Graphics)上。

 

4，截屏

Graphics类还提供了一个截图的方法CopyFromScreen，我们可以利用这个方法来截取屏幕：
g.CopyFromScreen(new Point(0, 0), new Point(100, 100), sz);

1	g.CopyFromScreen(new Point(0, 0), new Point(100, 100), sz);

 

5，其它

1，抗锯齿
g.SmoothingMode = SmoothingMode.AntiAlias;

1	g.SmoothingMode = SmoothingMode.AntiAlias;

 

2,画布的大小
g.VisibleClipBounds.Width;

g.VisibleClipBounds.Height;

1 2	g.VisibleClipBounds.Width; g.VisibleClipBounds.Height;

 

2，画布的变换(Transform)
var img = Image.FromFile(@"C:\Users\message.png");

g.RotateTransform(45);

g.ScaleTransform(0.5F, 0.5F);

g.DrawImage(img, p1);

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var img = Image.FromFile(@"C:\Users\message.png"); g.RotateTransform(45); g.ScaleTransform(0.5F, 0.5F); g.DrawImage(img, p1);