//画笔参数
        Pen pen = new Pen(Color.Black, 1);
        Color color = Color.Black;
        float width;
        //直线参数
        Point startpoint;
        Point currentpoint;
        bool mousedown = false;
        //画图
        GraphicsPath gPath = new GraphicsPath();
        Graphics gs;
        Bitmap bitmap;
        private void Form1_Load(object sender, EventArgs e)
        {
            bitmap = new Bitmap(SystemInformation.PrimaryMonitorMaximizedWindowSize.Width,SystemInformation.PrimaryMonitorMaximizedWindowSize.Height);
            gs = Graphics.FromImage(bitmap);
            gs.Clear(Color.White);
            gs.Dispose();
        }  
        private void trackBar1_ValueChanged(object sender, EventArgs e)
        {
            width = trackBar1.Value;
        }
        private void colorPickerButton1_SelectedColorChanged(object sender, EventArgs e)
        {
            color = colorPickerButton1.SelectedColor;
        }
        private void panel1_MouseDown(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                mousedown = true;
                pen = new Pen(color, width);
                startpoint = new Point(e.X, e.Y);
            }
        }
        private void panel1_MouseMove(object sender, MouseEventArgs e)
        {
            if (mousedown && e.Button == MouseButtons.Left)
            {
                currentpoint = new Point(e.X, e.Y);
                Graphics gs = panel1.CreateGraphics();
                gs.DrawImage(bitmap, 0, 0);
                gs.DrawLine(pen, startpoint, currentpoint);
                gs.Dispose();
            }
        }
        private void panel1_MouseUp(object sender, MouseEventArgs e)
        {
            if (mousedown)
            {
                gPath.AddLine(startpoint, currentpoint);
                Graphics gs = Graphics.FromImage(bitmap);
                gs.DrawPath(pen, gPath);
            }
        }
        private void panel1_Paint(object sender, PaintEventArgs e)
        {
            e.Graphics.DrawImage(bitmap, 0, 0);
        }

画到第三条先，自动连接第一条和第二条直线的；画第四条直线自动连接第二条和第一条直线的！～
希望大侠帮帮忙，看看出了什么问题！

[[italic] 本帖最后由 68948436 于 2007-12-3 18:40 编辑 [/italic]]