在 form上可以实现，在panel实现不了，为什么啊？
通过大家的帮助，我已经能够实现图形随着鼠标绘制。
但是问题又来了：
public partial class Form2 : Form
{
Point Form2_MouseMove;
public Form2()
{
InitializeComponent();
}
private void Form2_Paint(object sender, PaintEventArgs e)
{
Graphics dc = e.Graphics;
Pen blue = new Pen(Color.Blue, 3);
dc.DrawRectangle(blue, Form2_MouseMove.X, Form2_MouseMove.Y, 50, 50);
}
private void Form2_MouseMove_1(object sender, MouseEventArgs e)
{
Form2_MouseMove.X = e.X;
Form2_MouseMove.Y = e.Y;
this.Text = string.Format("鼠标位置：({0},{1})", Form2_MouseMove.X, Form2_MouseMove.Y);
this.Invalidate();
}
public partial class Form1 : Form
{
Point pt;
public Form1()
{
InitializeComponent();
}
private void panel1_Paint(object sender, PaintEventArgs e)
{
Graphics dc = e.Graphics;
Pen blue = new Pen(Color.Blue, 3);
dc.DrawRectangle(blue, pt.X, pt.Y, 50, 50);
}
private void panel1_MouseMove(object sender, MouseEventArgs e)
{
pt.X = e.X;
pt.Y = e.Y;
this.Text = string.Format("鼠标位置：({0},{1})", pt.X, pt.Y);
this.Invalidate();
}
}
public partial class Form1 : Form
{
Point pt;
public Form1()
{
InitializeComponent();
}
private void panel1_Paint(object sender, PaintEventArgs e)
{
Graphics dc = e.Graphics;
Pen blue = new Pen(Color.Blue, 3);
dc.DrawRectangle(blue, pt.X, pt.Y, 50, 50);
}
private void panel1_MouseMove(object sender, MouseEventArgs e)
{
pt.X = e.X;
pt.Y = e.Y;
this.Text = string.Format("鼠标位置：({0},{1})", pt.X, pt.Y);
panel1.Invalidate();
}
}
