C#做的画板 问题请教！！
想用C#做个画板的小程序 不知道为什么不能画出画来 是我的鼠标事件没写对么 没有报错 但是鼠标不能画画
下面是form.cs 请各位帮忙看看 感激不尽


using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.IO;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;


namespace WindowsFormsApplication2
{
public partial class Form1 : Form
{
private Shape current;
private bool isDown;
private Bitmap bmp, bmp1;
private List <Shape >shapes=new List<Shape> ();
private ShapeType type = ShapeType.Line;
private bool isTrail;
private FileInfo currentFile;
private static string openFileName = "";
private static int lineWidth = 1;

public Form1()
{
InitializeComponent();
bmp = new Bitmap(pictureBox1 .Width ,pictureBox1 .Height );
bmp1 = new Bitmap(pictureBox1 .Width ,pictureBox1 .Height );
current = new MyLine();
this.button12.BackColor = Color.Black;
}

private void Form1_Paint(object sender, PaintEventArgs e)
{
Graphics grfx = e.Graphics;
grfx.DrawImage(bmp ,0,0);
}










private void button1_Click(object sender, EventArgs e)
{
isTrail = true;
type = ShapeType.Line;
}

private void button2_Click(object sender, EventArgs e)
{
isTrail = false ;
type = ShapeType.Line;

}

private void button3_Click(object sender, EventArgs e)
{
isTrail = false;
type = ShapeType.Rect ;
}

private void button5_Click(object sender, EventArgs e)
{
isTrail = false;
type = ShapeType.Ellipse ;
}

private void button4_Click(object sender, EventArgs e)
{
isTrail = false;
type = ShapeType.FilledRect ;
}

private void button6_Click(object sender, EventArgs e)
{
isTrail = false;
type = ShapeType.FilledEllipse ;
}

private void button7_Click(object sender, EventArgs e)
{
isTrail = false;
type = ShapeType.CircleRect;
}

private void button13_Click(object sender, EventArgs e)
{
this.button12.BackColor = this.button13.BackColor;
}

private void button14_Click(object sender, EventArgs e)
{
this.button12.BackColor = this.button14.BackColor;
}

private void button15_Click(object sender, EventArgs e)
{
this.button12.BackColor = this.button15.BackColor;
}

private void button16_Click(object sender, EventArgs e)
{
this.button12.BackColor = this.button16.BackColor;
}

private void button17_Click(object sender, EventArgs e)
{
this.button12.BackColor = this.button17.BackColor;

}

private void button18_Click(object sender, EventArgs e)
{
this.button12.BackColor = this.button18.BackColor;
}

private void button19_Click(object sender, EventArgs e)
{
if (colorDialog1.ShowDialog() == DialogResult.OK)
{
this.button12.BackColor = colorDialog1.Color;
}
}

private void button9_Click(object sender, EventArgs e)
{
lineWidth = 1;
}

private void button10_Click(object sender, EventArgs e)
{
lineWidth = 2;
}

private void button11_Click(object sender, EventArgs e)
{
lineWidth = 3;
}














private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
{
if (e.Button == MouseButtons.Left)
{
isDown = true;
current = ShapeFactory.CreateShape(type);
current.First = e.Location;

}
}
private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
{
if (isDown )
{
if (!isTrail)
{
DrawShape(e.Location);
}
else
{
DrawTrail(e.Location);
}
Graphics grfx = pictureBox1.CreateGraphics();
if (shapes.Count != 0)
{
grfx.DrawImage(bmp, 0, 0);
}
grfx.Dispose();
}


}
private void DrawTrail(Point point)
{
Graphics grfx = pictureBox1.CreateGraphics();
current.Last = point;
current.ForeColor = this.button12.BackColor;
current.PenWidth = lineWidth;
current.Draw(grfx );


Graphics img = Graphics.FromImage(bmp);
current.Draw(img) ;

shapes.Add(current);


current = ShapeFactory.CreateShape(type );
current.First = point;

grfx.Dispose();
img.Dispose();
}
private void DrawShape(Point point)
{
Graphics grfx = pictureBox1.CreateGraphics();
if (!current.Last.Equals(Point.Empty))
{
current.ForeColor = pictureBox1.BackColor;
current.PenWidth = lineWidth;
current.Draw(grfx);
}

current.Last = point;
current.ForeColor = this.button12.BackColor;
current.PenWidth = lineWidth;
current.Draw(grfx );

grfx.Dispose();

}
private void pictureBox1_MouseUp(object sender, MouseEventArgs e)
{
isDown = false;
if (!current.Last.Equals(Point.Empty))
{

Graphics img = Graphics.FromImage(bmp);
current.Draw(img);
shapes.Add(current);
}
current = null;

}

private void button8_Click(object sender, EventArgs e)
{
Graphics g = pictureBox1.CreateGraphics();
g.Clear(pictureBox1 .BackColor );
g.Dispose();

bmp = new Bitmap(pictureBox1 .Width ,pictureBox1 .Height );
}

private void Form1_Load(object sender, EventArgs e)
{

}

private void openFileDialog1_FileOk(object sender, CancelEventArgs e)
{

}

private void pictureBox1_Click(object sender, EventArgs e)
{

}

private void 文件保存ToolStripMenuItem_Click(object sender, EventArgs e)
{
if (File.Exists(openFileName))
{
currentFile = new FileInfo(openFileName);
bmp.Save(currentFile.FullName);
}
else
{
if (saveFileDialog1.ShowDialog() == DialogResult.OK)
{
currentFile = new FileInfo(saveFileDialog1 .FileName );
bmp.Save(currentFile.FullName);
}
}
}





}
}



[解决办法]
http://www.cnblogs.com/zhjzwl/archive/2009/02/27/1399505.html

to:代码够长的
[解决办法]
，，，，代码看着好乱，空件怎么不改名，我刚学C#，做过一个画板，你的代码，可以优化一下的，同类的按钮调用一个单击事件，在根据同类不同的按钮有不同的实现，不要每个按钮单击都对应一个事件
[解决办法]
你不应该用CreateGraphics，而应该在Paint事件中绘图
[解决办法]
直接使用OnPaint中的e.Graphics,其他绘图函数传入这个参数，鼠标动作中要调用Invaliedate，去进行重绘