用Drawing画图如何不会消失

方法一：将事件放在form_Load中,在窗体中画图

   1:          protected void MainForm_Load(object sender,EventArgs e)

   2:          {

   3:              InitialPoint();

   4:              Bitmap bm = new Bitmap(this.Width,this.Height);

   5:              Graphics grp = Graphics.FromImage(bm);

   6:              DrawCurves(grp,lpt);

   7:              pictureBox1.Image =bm;

   8:              //if use load event,then use bitmap,if not ,there is no need.

9:

  10:          }

方法二：利用picturebox画图，放在Load事件中。

   1:          protected void MainForm_Load(object sender,EventArgs e)

   2:          {

   3:              InitialPoint();

   4:              Bitmap bm = new Bitmap(pictureBox1.Width,pictureBox1.Height);

   5:              pictureBox1.Image =bm;

   6:              using(Graphics grp =Graphics.FromImage(pictureBox1.Image))

   7:              {

   8:                  DrawCurves(grp,lpt);

   9:              }

10:

  11:          }

方法三：将事件放在Paint事件中，这个只能放在form中，因为grp本例和e无关，但是参数是：PaintEventArgs e

   1:          private void Form1_Paint(object sender, PaintEventArgs e)

   2:          {

   3:              //if in this method,there is no need to use bitmap

   4:              InitialPoint();

   5:              Graphics grp =this.CreateGraphics();

   6:              DrawCurves(grp,lpt);

   7:          }

方法四：paint事件，在picturebox上，按照下边这个例子，用e这个参数，不仅可以放在form的paint上，也可以放在picturebox的paint上

   1:          private void pic_paint(object sender,PaintEventArgs e)

   2:          {

   3:               Graphics g = e.Graphics;

   4:               DrawCurves(g,lpt);

   5:          }

   1:          private void DrawCurves(Graphics grp, List<Point> pointList)

   2:          {

   3:              Point[] temps = new Point[pointList.Count];

   4:              pointList.CopyTo(temps);

   5:              grp.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias;

   6:              grp.DrawCurve(new Pen(Color.Red, 2), temps);

   7:             // grp.Dispose();如果用Paint事件绘图，这个似乎不可以

   8:          }

注明：lpt是一个List<Point>

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