如何在winforms c＃中将值传递给用户控件

我有一个winforms应用程序，我以编程方式创建用户控件并将值传递给它。 当我运行程序时，用户控件中的所有变量都为null。 我不知道我做错了什么。 当我查找类似的程序时，看起来我有相同的代码，但它不起作用。 也许这里有人可以提供帮助。

这是主要的表单代码：

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.Data.SqlClient; using System.Diagnostics; using System.Net; namespace AddPanel { public partial class Form1 : Form { public Form1() { InitializeComponent(); DisplayImage(); } private void DisplayImage() { FileStream fs = new FileStream("ntst.jpg", FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.ReadWrite); cameraTable = (from x in db.CamTable1s select x).ToList(); test nt = new test(); nt.Location = new System.Drawing.Point(33, 20); nt.Name = "test1"; nt.usrID = "username"; nt.IPadd = "ipaddress"; nt.pswd = "password"; nt.ws = fs; nt.Size = new System.Drawing.Size(408, 266); this.Controls.Add(nt); } } } 

用户控制代码：

 using System; using System.Collections.Generic; using System.ComponentModel; using System.Drawing; using System.Drawing.Imaging; using System.Data; using System.Linq; using System.Text; using System.Windows.Forms; using System.Diagnostics; using System.IO; using System.Net; using AForge; using AForge.Video; using AForge.Controls; using AForge.Video.DirectShow; namespace AddPanel { public partial class test : UserControl { public string IPadd { get; set; } public string usrID { get; set; } public string pswd { get; set; } public string filename { get; set; } public FileStream ws { get; set; } public test() { JPEGStream jpegSource1 = new JPEGStream("http://" + IPadd + "/jpg/image.jpg?resolution=320x240"); jpegSource1.Login = usrID; jpegSource1.Password = pswd; jpegSource1.NewFrame += new NewFrameEventHandler(jpegSource1_NewFrame); //source1.VideoSourceError += new VideoSourceErrorEventHandler(source1_VideoSourceError); jpegSource1.VideoSourceError += new VideoSourceErrorEventHandler(jpegSource1_VideoSourceError); Player1.VideoSource = jpegSource1; InitializeComponent(); } void jpegSource1_NewFrame(object sender, NewFrameEventArgs eventArgs) { Bitmap image = new Bitmap(eventArgs.Frame, 320, 240); image.Save(ws, System.Drawing.Imaging.ImageFormat.Bmp); } void jpegSource1_VideoSourceError(object sender, VideoSourceErrorEventArgs eventArgs) { //Error handler Debug.WriteLine(eventArgs.Description); Bitmap ErPic = new Bitmap(320, 240); using (var g = Graphics.FromImage(ErPic)) { using (var arialFontLarge = new Font("Arial", 15)) { g.DrawString("Camera Offline", arialFontLarge, Brushes.White, 75, 100); } } ErPic.Save(ws, ImageFormat.Bmp); } private void StartBut_Click(object sender, EventArgs e) { Player1.VideoSource.Start(); } private void StopBut_Click(object sender, EventArgs e) { Player1.VideoSource.Stop(); ws.Close(); } } } 

Answer 1

当您启动UserControl时，您的UserControls构造函数会运行，您将在事后设置您的值。 我个人要么创建一个可以在初始设置中传递的构造函数，要么在填充值后创建一个执行的方法来初始化它。

像这样的东西：

 public partial class test : UserControl { public string IPadd { get; set; } public string usrID { get; set; } public string pswd { get; set; } public string filename { get; set; } public FileStream ws { get; set; } public test() { InitializeComponent(); } public test(string Ip, string Id, string Pass, string file, FileStream stream ) { InitializeComponent(); IPadd = Ip; usrID = Id; pswd = Pass; filename = file; ws = stream; JPEGStream jpegSource1 = new JPEGStream("http://" + IPadd + "/jpg/image.jpg?resolution=320x240"); jpegSource1.Login = usrID; jpegSource1.Password = pswd; jpegSource1.NewFrame += new NewFrameEventHandler(jpegSource1_NewFrame); source1.VideoSourceError += new VideoSourceErrorEventHandler(source1_VideoSourceError); pegSource1.VideoSourceError += new VideoSourceErrorEventHandler(jpegSource1_VideoSourceError); Player1.VideoSource = jpegSource1; } } 

Answer 2

问题是我对在表单之间使用变量的理解是错误的。

我应该放

 public string IPadd { get; set; } public string usrID { get; set; } public string pswd { get; set; } public string filename { get; set; } public FileStream ws { get; set; } 

在Form1中，然后在测试中访问它们。 像这样：Form1

 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.Data.SqlClient; using System.Diagnostics; using System.Net; using AForge.Video; using AForge.Controls; using AForge.Video.DirectShow; namespace AddPanel { public partial class Form1 : Form { private string iPadd; public string IPadd { get { return iPadd;} set { iPadd = value; } } private string usrID; public string UsrID { get { return usrID; } set { usrID = value; } } private string Pswd; public string pswd { get{return Pswd;} set { Pswd = value; } } private string Filename; public string filename { get { return Filename; } set { Filename = value; } } public Form1() { InitializeComponent(); DisplayImage(); } private void DisplayImage() { FileStream fs = new FileStream(filename, FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.ReadWrite); UsrID = "webservice"; IPadd = "10.108.212.100"; pswd = "E4emw@tch!ngU"; WS = fs; test nt = new test(); nt.Location = new System.Drawing.Point(33, h); nt.Name = "test1"; nt.Size = new System.Drawing.Size(408, 266); this.Controls.Add(nt); } } } 

然后我可以在测试中访问这些变量，如下所示：

 using System; using System.Collections.Generic; using System.ComponentModel; using System.Drawing; using System.Drawing.Imaging; using System.Data; using System.Linq; using System.Text; using System.Windows.Forms; using System.Diagnostics; using System.IO; using System.Net; using AForge; using AForge.Video; using AForge.Controls; using AForge.Video.DirectShow; namespace AddPanel { public partial class test : UserControl { public test() { Form1 f1 = new Form1(); JPEGStream jpegSource1 = new JPEGStream("http://" + f1.IPadd + "/jpg/image.jpg?resolution=320x240"); jpegSource1.Login = f1.UsrID; jpegSource1.Password = f1.pswd; jpegSource1.NewFrame += new NewFrameEventHandler(jpegSource1_NewFrame); //source1.VideoSourceError += new VideoSourceErrorEventHandler(source1_VideoSourceError); jpegSource1.VideoSourceError += new VideoSourceErrorEventHandler(jpegSource1_VideoSourceError); Player1.VideoSource = jpegSource1; InitializeComponent(); } void jpegSource1_NewFrame(object sender, NewFrameEventArgs eventArgs) { Bitmap image = new Bitmap(eventArgs.Frame, 320, 240); image.Save(ws, System.Drawing.Imaging.ImageFormat.Bmp); } void jpegSource1_VideoSourceError(object sender, VideoSourceErrorEventArgs eventArgs) { //Error handler Debug.WriteLine(eventArgs.Description); Bitmap ErPic = new Bitmap(320, 240); using (var g = Graphics.FromImage(ErPic)) { using (var arialFontLarge = new Font("Arial", 15)) { g.DrawString("Camera Offline", arialFontLarge, Brushes.White, 75, 100); } } ErPic.Save(ws, ImageFormat.Bmp); } private void StartBut_Click(object sender, EventArgs e) { Player1.VideoSource.Start(); } private void StopBut_Click(object sender, EventArgs e) { Player1.VideoSource.Stop(); ws.Close(); } } }