//＂窗体加载＂事件处理方法
private void Form1_Load(object sender, EventArgs e)
{
SetStyle(ControlStyles.OptimizedDoubleBuffer | ControlStyles.AllPaintingInWmPaint | ControlStyles.UserPaint, true);
this.UpdateStyles();
Bitmap bmp = new Bitmap(pbImg.Width, pbImg.Height);
Graphics g = Graphics.FromImage(bmp);
g.FillRectangle(new SolidBrush(pbImg.BackColor), new Rectangle(0, 0, pbImg.Width, pbImg.Height));
g.Dispose();
dt = new DrawTools(this.pbImg.CreateGraphics(), Color.Red, bmp);//实例化工具类
DefaultPicSize = pbImg.Size;
}