关于paint的应用

Question

当第一次运行form时，我从数据库里读取画线的记录，然后在picturebox里的paint进行重画时，为什么只是闪了一下就没了？

Answer 1

你如何在paint中做的，至于其他地方是否操作了picturebox。

Answer 2

sorry，瞎说了
AutoRedraw是VB6的picturebox的属性，.NET里没有了

Answer 3

下面是我的代码，被这个问题搞了好久了，看了很多资料，自己都解决不了，惭愧
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Drawing.Drawing2D;
using System.Data.OleDb;namespace NSVstandard
{
    public partial class frmDraw : Form
    {
        Rectangle SelectRect = new Rectangle();
        Point ps = new Point();
        Point pe = new Point();
        OleDbConnection MyConn;        string strType = "Line";        public frmDraw()
        {
            InitializeComponent();
        }        private void frmDraw_Load(object sender, EventArgs e)
        {        }
        private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
        {
            SelectRect.Width = 0;
            SelectRect.Height = 0;
            SelectRect.X = e.X;
            SelectRect.Y = e.Y;            ps.X = e.X;
            ps.Y = e.Y;
            pe = ps;
        }        private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                switch (strType)
                {
                    case "Line":
                        ControlPaint.DrawReversibleLine(this.pictureBox1.PointToScreen(ps), this.pictureBox1.PointToScreen(pe), Color.Black);
                        pe = new Point(e.X, e.Y);
                        ControlPaint.DrawReversibleLine(this.pictureBox1.PointToScreen(ps), this.pictureBox1.PointToScreen(pe), Color.Black);
                        break;
                    case "Rect":
                        ControlPaint.DrawReversibleFrame(this.pictureBox1.RectangleToScreen(SelectRect), Color.Black, FrameStyle.Dashed);
                        SelectRect.Width = e.X - SelectRect.X;
                        SelectRect.Height = e.Y - SelectRect.Y;
                        ControlPaint.DrawReversibleFrame(this.pictureBox1.RectangleToScreen(SelectRect), Color.Black, FrameStyle.Dashed);
                        break;
                    case "Ellipse":
                        ControlPaint.DrawReversibleFrame(this.pictureBox1.RectangleToScreen(SelectRect), Color.Black, FrameStyle.Dashed);
                        SelectRect.Width = e.X - SelectRect.X;
                        SelectRect.Height = e.Y - SelectRect.Y;
                        ControlPaint.DrawReversibleFrame(this.pictureBox1.RectangleToScreen(SelectRect), Color.Black, FrameStyle.Dashed);
                        break;                }
            }
        }        private void pictureBox1_MouseUp(object sender, MouseEventArgs e)
        {
            Graphics g = this.pictureBox1.CreateGraphics();
            Pen p = new Pen(Color.Red, 1);
            SolidBrush brushBlue = new SolidBrush(Color.Blue);
            switch (strType)
            {
                case "Line":
                    ControlPaint.DrawReversibleLine(this.pictureBox1.PointToScreen(ps), this.pictureBox1.PointToScreen(pe), Color.Black);
                    g.DrawLine(p, ps, pe);
                    break;
                case "Rect":
                    ControlPaint.DrawReversibleFrame(this.pictureBox1.RectangleToScreen(SelectRect), Color.Black, FrameStyle.Dashed);
                    g.DrawRectangle(p, SelectRect);
                    break;
                case "Ellipse":
                    ControlPaint.DrawReversibleFrame(this.pictureBox1.RectangleToScreen(SelectRect), Color.Black, FrameStyle.Dashed);
                    g.DrawEllipse(p, SelectRect);
                    g.FillEllipse(brushBlue, SelectRect);
                    break;
            }
            g.Dispose();
        }        private void button1_Click(object sender, EventArgs e)
        {
            strType = "Line";
        }        private void button2_Click(object sender, EventArgs e)
        {
            strType = "Rect";
        }        private void pictureBox1_Paint(object sender, PaintEventArgs e)
        {
            string[] sArray;
            Graphics g = this.pictureBox1.CreateGraphics();
            //try
            //{
            //create a connection string to the access database
            MyConn = new OleDbConnection(@"Provider=Microsoft.Jet.OLEDB.4.0;User Id=;Password=;Data Source=" + Program.ObserveDB);
            MyConn.Open();
            //dAdapter = new OleDbDataAdapter("SELECT * FROM observe ORDER BY ID", MyConn);
            //dSet = new DataSet();
            //dAdapter.Fill(dSet, table);
            OleDbCommand MyCommand = new OleDbCommand("SELECT * FROM observe WHERE CODE = 4", MyConn);
            OleDbDataReader MyDataReader = MyCommand.ExecuteReader(CommandBehavior.CloseConnection);
            string strNum;
            while (MyDataReader.Read())
            {
                for (int i = 1; i < 50; i++)
                {
                    if (i < 10)
                    {
                        strNum = "0" + i.ToString();
                    }
                    else
                    {
                        strNum = i.ToString();
                    }                    if (MyDataReader["PROC" + strNum].ToString() != "")
                    {
                        sArray = MyDataReader["PROC" + strNum].ToString().Split(',');
                        if (sArray[1].ToString() == "0")
                            g.DrawLine(new Pen(Color.Red), Int16.Parse(sArray[2]), Int16.Parse(sArray[3]), Int16.Parse(sArray[4]), Int16.Parse(sArray[5]));
                    }
                }
            }
            MyConn.Close();
            //}
            //catch (Exception ex)
            //{
            //    MessageBox.Show("Error : " + ex.Message);
            //    //connectection failed
            //}
        }        private void button3_Click(object sender, EventArgs e)
        {
            strType = "Ellipse";
        }
    }
}

Answer 4

CHANGE
Graphics g = this.pictureBox1.CreateGraphics();withGraphics g = e.Graphics;

Answer 5

关注一下。上次面试。有个CIO问过Paint的一些东西====CSDN 小助手 V2.5 2005年11月05日发布====
CSDN小助手是一款脱离浏览器也可以访问Csdn论坛的软件
界面：http://blog.csdn.net/Qqwwee_Com/archive/2005/11/05/523395.aspx
下载：http://szlawbook.com/csdnv2