在C＃Windows窗体中访问其他类

Question

I haven't done a whole lot of C# programming. I am very good at C/C++ though. I cannot figure out the proper way to access Class members from other classes within the project. For example, I have a class addChannel() which is a pop up box that allows the user to enter information for a Channel class. I have a treeView that will hold these channels. The treeView is in a ListView class which is the main form with the tree in it. I have a button on the addChannel pop-up window that, when clicked, should add a new Channel() and add this channel as a new Node to the tree. However I cannot access the tree at all and do not know how. Here is some relevant code.

namespace RSSReader
{
    public partial class addChannel : Form
    {
        public addChannel()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            // Save the info to an XML doc

            // I want to access the channelTree treeView here
            this.Close();
        }
    }
}

And here is the ListView partial class for the designer

namespace RSSReader
{
    partial class ListView
    {
        /// <summary>
        /// Required designer variable.
        /// </summary>
        private System.ComponentModel.IContainer components = null;

        /// <summary>
        /// Clean up any resources being used.
        /// </summary>
        /// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>
        protected override void Dispose(bool disposing)
        {
            if (disposing && (components != null))
            {
                components.Dispose();
            }
            base.Dispose(disposing);
        }

        #region Windows Form Designer generated code

        /// <summary>
        /// Required method for Designer support - do not modify
        /// the contents of this method with the code editor.


           // ALL THE INITIALIZATION IS HERE... I excluded it

        public System.Windows.Forms.TreeView channelTree;
        private System.Windows.Forms.WebBrowser webBrowser;
        private System.Windows.Forms.Button addBtn;
        private System.Windows.Forms.Button setBtn;
        private System.Windows.Forms.Button remBtn;
        private System.Windows.Forms.RadioButton titleFilter;
        private System.Windows.Forms.RadioButton dateFilter;
    }
}

Answer 1

This is not the normal set-up for Windows Forms.

Normally, you would just drag the TreeView onto the form, drag the buttons onto the form, and the resulting code would give you no trouble accessing anything:

namespace RssReader
{
    public partial class addChannel : Form
    {
        public addChannel()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            treeView1.ItemHeight = 6;
        }
    }
}

Here is the code-behind:

namespace RssReader
{
    partial class addChannel
    {
        /// <summary>
        /// Required designer variable.
        /// </summary>
        private System.ComponentModel.IContainer components = null;

        /// <summary>
        /// Clean up any resources being used.
        /// </summary>
        /// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>
        protected override void Dispose(bool disposing)
        {
            if (disposing && (components != null))
            {
                components.Dispose();
            }
            base.Dispose(disposing);
        }

                                                                                                                                                                    #region Windows Form Designer generated code

    /// <summary>
    /// Required method for Designer support - do not modify
    /// the contents of this method with the code editor.
    /// </summary>
    private void InitializeComponent()
    {
        this.treeView1 = new System.Windows.Forms.TreeView();
        this.button1 = new System.Windows.Forms.Button();
        this.SuspendLayout();
        // 
        // treeView1
        // 
        this.treeView1.Location = new System.Drawing.Point(12, 12);
        this.treeView1.Name = "treeView1";
        this.treeView1.Size = new System.Drawing.Size(121, 97);
        this.treeView1.TabIndex = 0;
        // 
        // button1
        // 
        this.button1.Location = new System.Drawing.Point(13, 116);
        this.button1.Name = "button1";
        this.button1.Size = new System.Drawing.Size(75, 23);
        this.button1.TabIndex = 1;
        this.button1.Text = "button1";
        this.button1.UseVisualStyleBackColor = true;
        this.button1.Click += new System.EventHandler(this.button1_Click);
        // 
        // addChannel
        // 
        this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
        this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
        this.ClientSize = new System.Drawing.Size(284, 262);
        this.Controls.Add(this.button1);
        this.Controls.Add(this.treeView1);
        this.Name = "addChannel";
        this.Text = "Form1";
        this.ResumeLayout(false);

    }

    #endregion

        private System.Windows.Forms.TreeView treeView1;
        private System.Windows.Forms.Button button1;
    }
}

Windows Forms is a lot easier if you follow the patterns which the Visual Studio designer implements for you. If you do it this way, you will find what you're trying to do very easy.

Answer 2

When you create the addChannel class , and before running it (using Show() etc..) , you need to hook it up with the listView form you want to get to. 2 options: 1. Pass the listview as a parameter to addChnel before running it. than you can call methods from addCahnnel to listView. 2. Create an event in you addChannel class and register the listView for this event (event can be: channel added/removed etc...)

Option 2 is better , but you will need to learn how to work with events and delegates. see: http://msdn.microsoft.com/en-us/library/aa645739(v=vs.71).aspx

Answer 3

Pass the TreeView in the constructor

public partial class addChannel : Form
{                     
    private TreeView _treeView; // TreeView on other Form.

    public addChannel(TreeView treeView)
    {
        InitializeComponent();
        _treeView = treeView;
    }

    private void button1_Click(object sender, EventArgs e)
    {
        // Save the info to an XML doc

        // Access _treeView here
        Console.WriteLine(_treeView.Name);

        this.Close();
    }
}

---

A completely different approach is to add a public property exposing the selected channel. You would not access the TreeView from the addChannel form at all, but do this work on the main form alone

public partial class addChannel : Form
{                     
    public addChannel()
    {
        InitializeComponent();
    }

    public Channel SelectedChannel { get; private set; }

    private void button1_Click(object sender, EventArgs e)
    {
        // Save the info to an XML doc

        SelectedChannel = theChannel;
        this.Close();
    }
}

In the main form you would do something like this:

var fdlg = new addChannel();
if (fdlg.ShowDialog(this) == DialogResult.OK) {
    this.treeView.Add(fdlg.SelectedChannel); // Or something similar
}

Make sure to set the DialogResult property of button1 to 'OK'. You cann also set the AcceptButton property of the dialog form to button1 ; this enables the user to close the form with the ENTER-key.