思科和华为交换机常用命令之对比学习

C Sharp or C#，微软公司的某一产品。准确的说其实还是一种编程语言。它与C、C++、Java这三种语言有相似之处。而跟Java相比较，在某些方法可以说是一模一样。今天简单了解了一下Csharp，写了一个画图板程序。可以画直线，椭圆，矩形，还可以选择颜色，重绘也实现了。

一些核心代码：
1、获取画布对象

// 获取画板的画布对象¨
private System.Drawing.Graphics g ;
g = this.panel1.CreateGraphics();

2、颜色
C Sharp 中有表示颜色的Color类，但改变颜色的话需要用到Pen类。
定义一个按钮来实现颜色选择

private static Color color = Color.Black;
private System.Drawing.Pen p = new System.Drawing.Pen(color);

//按下按钮时触发的事件

public  void  button4_Click(object sender, EventArgs e)
{
System.Windows.Forms.ColorDialog cd = new ColorDialog();
cd.ShowDialog();
color = cd.Color;
p = new Pen(color);
}

添加按钮事件监听器的代码为;

//改变画图板的颜色
this.button4.Click += new EventHandler(button4_Click);

3、鼠标监听器的添加方法

//鼠标的各种监听,此处添加到面板上。
this.panel1.MouseDown += new MouseEventHandler(Form1_MouseDown);
this.panel1.MouseUp += new MouseEventHandler(Form1_MouseUp);

再具体实现监听器的方法。

//鼠标松开
public void Form1_MouseUp(object sender, MouseEventArgs e)
{
x2 = e.X;
y2 = e.Y;
Shape shape = new Shape();

if (s.Equals("Line"))
{
g.DrawLine(p, x1, y1, x2, y2);
shape.x1 = x1;
shape.y1 = y1;
shape.x2 = x2;
shape.y2 = y2;
shape.item = "Line";
shape.c = this.p.Color;
this.list.Add(shape);

}
else if (s.Equals("Oval"))
{
g.DrawEllipse(p, x1, y1, Math.Abs(x2-x1), Math.Abs(y2-y1));
shape.x1 = x1;
shape.y1 = y1;
shape.x2 = x2;
shape.y2 = y2;
shape.item = "Oval";
shape.c = this.p.Color;
this.list.Add(shape);
}
else if (s.Equals("Rectangle"))
{
g.DrawRectangle(p, x1, y1, Math.Abs(x2 - x1), Math.Abs(y2 - y1));
shape.x1 = x1;
shape.y1 = y1;
shape.x2 = x2;
shape.y2 = y2;
shape.item = "Rectangle";
shape.c = this.p.Color;
this.list.Add(shape);
}
}

//鼠标按下
public void Form1_MouseDown(object sender, MouseEventArgs e)
{
x1 = e.X;
y1 = e.Y;
}

class Shape
{
public int x1, x2, y1, y2;
public String item;
public Color c;
}

4、最后就是重绘的方法
C sharp中有相应的重绘方法，为OnPaint (PaintEventArgs e)
重写方法时，方法前要添加override。

//重绘一下
protected override void OnPaint(PaintEventArgs e)
{
for (int i = 0; i < this.list.Count;i++ )
{
Shape shape = this.list[i];
if(shape.item.Equals("Line"))
{
Pen pen = new Pen(shape.c);
g.DrawLine(pen,shape.x1,shape.y1,shape.x2,shape.y2);
}
else if (shape.item.Equals("Oval"))
{
Pen pen = new Pen(shape.c);
g.DrawEllipse(pen, shape.x1, shape.y1, Math.Abs(shape.x2 - shape.x1), Math.Abs(shape.y2 - shape.y1));
}
else if (shape.item.Equals("Rectangle"))
{
Pen pen = new Pen(shape.c);
g.DrawRectangle(pen, shape.x1, shape.y1, Math.Abs(shape.x2 - shape.x1), Math.Abs(shape.y2 - shape.y1));
}
}
}

另外，C Sharp中的队列，List可以使用泛型，但ArrayList貌似不行，这个还有待研究。