Argument exception - parameter is not valid ( LinkLabel on WinForm )

Question

Hi,

I wrote a Win Forms app to test how a LinkLabel class works. It appears to be fine until I click on the changed LinkLabel. The Form1.cs code is below:

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.Diagnostics;

namespace LinkLabelTest
{
// Editor: code not fully indented - laziness!
public partial class Form1 : Form
{

    public Form1()
    {  
            InitializeComponent();
    }

    private void btnLinkColor_Click(object sender, EventArgs e)
    {
        colorDialog1.ShowDialog();
        llblinkLabel1.LinkColor = colorDialog1.Color;
    }

    private void btnActiveLinkColor_Click(object sender, EventArgs e)
    {
        colorDialog1.ShowDialog();
        llblinkLabel1.ActiveLinkColor = colorDialog1.Color;
    }

    private void btnVisitedLinkColor_Click(object sender, EventArgs e)
    {
        colorDialog1.ShowDialog();
        llblinkLabel1.VisitedLinkColor = colorDialog1.Color;
    }

    private void llblinkLabel1_LinkClicked(object sender, LinkLabelLinkClickedEventArgs e)
    {

        try
        {

            if (!(e.Link.Description == null))
            {
                if (e.Button == MouseButtons.Right)
                {
                    PopulateLinkDetails(e.Link);
                }

                if (e.Button == MouseButtons.Left)
                {   
                    e.Link.Visited = true;
                    Debugger.Break();
                }
            }
        }
        catch (Exception exc)
        {
            Debugger.Break();
            MessageBox.Show(exc.Message.ToString());
        }   
    }

    private void PopulateLinkDetails(LinkLabel.Link link)
    {
        textDescription.Text = link.Description;
        textLinkData.Text = (string)link.LinkData;
        textName.Text = link.Name;
        checkBoxEnabled.Checked = link.Enabled;
        checkBoxVisited.Checked = link.Visited;
        nudLinkAreaStart.Value = link.Start;
        nudLinkAreaEnd.Value = link.Length;
    }


    private void Form1_Load(object sender, EventArgs e)
    {
            cmbLinkBehaviour.DataSource = Enum.GetValues(typeof(LinkBehavior));
    }

    private void cmbLinkBehaviour_SelectedIndexChanged(object sender, EventArgs e)
    {
        llblinkLabel1.LinkBehavior = (LinkBehavior)cmbLinkBehaviour.SelectedItem;
    }

    private void AddLink_Click(object sender, EventArgs e)
    {
            LinkLabel.Link link = new LinkLabel.Link();

            link.Description = textDescription.Text.ToString();
            link.LinkData = textLinkData.Text.ToString();
            link.Name = textName.Text.ToString();
            link.Enabled = checkBoxEnabled.Checked;
            link.Visited = checkBoxVisited.Checked;
            link.Start = (int)nudLinkAreaStart.Value;
            link.Length = (int)nudLinkAreaEnd.Value;

            llblinkLabel1.Links.Add(link);
    }

}
}

The stack trace is below :

at System.Drawing.Region.GetHrgn(Graphics g) at System.Windows.Forms.Control.Invalidate(Region region, Boolean invalidateChildren) at System.Windows.Forms.LinkLabel.InvalidateLink(Link link) at System.Windows.Forms.LinkLabel.OnGotFocus(EventArgs e) at System.Windows.Forms.Control.WmSetFocus(Message& m) at System.Windows.Forms.Control.WndProc(Message& m) at System.Windows.Forms.Label.WndProc(Message& m) at System.Windows.Forms.LinkLabel.WndProc(Message& msg) at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m) at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m) at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam) at System.Windows.Forms.UnsafeNativeMethods.SetFocus(HandleRef hWnd) at System.Windows.Forms.Control.FocusInternal() at System.Windows.Forms.LinkLabel.OnMouseDown(MouseEventArgs e) at System.Windows.Forms.Control.WmMouseDown(Message& m, MouseButtons button, Int32 clicks) at System.Windows.Forms.Control.WndProc(Message& m) at System.Windows.Forms.Label.WndProc(Message& m) at System.Windows.Forms.LinkLabel.WndProc(Message& msg) at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m) at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m) at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam) at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG& msg) at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(Int32 dwComponentID, Int32 reason, Int32 pvLoopData) at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context) at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context) at System.Windows.Forms.Application.Run(Form mainForm) at LinkLabelTest.Program.Main() in C:\Users\Tony\Documents\Visual Studio 2008\Projects\LinkLabelTest\LinkLabelTest\Program.cs:line 22

Below is the designer generated code:

using System.Diagnostics;

namespace LinkLabelTest
{
// Editor: code not fully indented - laziness again!
partial class Form1
{
    /// <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.llblinkLabel1 = new System.Windows.Forms.LinkLabel();
        this.colorDialog1 = new System.Windows.Forms.ColorDialog();
        this.btnLinkColor = new System.Windows.Forms.Button();
        this.btnActiveLinkColor = new System.Windows.Forms.Button();
        this.btnVisitedLinkColor = new System.Windows.Forms.Button();
        this.nudLinkAreaStart = new System.Windows.Forms.NumericUpDown();
        this.lbllabel1 = new System.Windows.Forms.Label();
        this.nudLinkAreaEnd = new System.Windows.Forms.NumericUpDown();
        this.lbllabel2 = new System.Windows.Forms.Label();
        this.cmbLinkBehaviour = new System.Windows.Forms.ComboBox();
        this.lbllabel3 = new System.Windows.Forms.Label();
        this.groupBox1 = new System.Windows.Forms.GroupBox();
        this.textDescription = new System.Windows.Forms.TextBox();
        this.label1 = new System.Windows.Forms.Label();
        this.textName = new System.Windows.Forms.TextBox();
        this.label2 = new System.Windows.Forms.Label();
        this.label3 = new System.Windows.Forms.Label();
        this.textLinkData = new System.Windows.Forms.TextBox();
        this.label4 = new System.Windows.Forms.Label();
        this.checkBoxEnabled = new System.Windows.Forms.CheckBox();
        this.AddLink = new System.Windows.Forms.Button();
        this.btnAmendLink = new System.Windows.Forms.Button();
        this.checkBoxVisited = new System.Windows.Forms.CheckBox();
        this.panel1 = new System.Windows.Forms.Panel();
        this.textBox1 = new System.Windows.Forms.TextBox();
        ((System.ComponentModel.ISupportInitialize)(this.nudLinkAreaStart)).BeginInit();
        ((System.ComponentModel.ISupportInitialize)(this.nudLinkAreaEnd)).BeginInit();
        this.groupBox1.SuspendLayout();
        this.panel1.SuspendLayout();
        this.SuspendLayout();
        // 
        // llblinkLabel1
        // 
        this.llblinkLabel1.AutoSize = true;
        this.llblinkLabel1.Location = new System.Drawing.Point(13, 27);
        this.llblinkLabel1.Name = "llblinkLabel1";
        this.llblinkLabel1.Size = new System.Drawing.Size(96, 13);
        this.llblinkLabel1.TabIndex = 0;
        this.llblinkLabel1.TabStop = true;
        this.llblinkLabel1.Text = "This is a link label !";
        this.llblinkLabel1.LinkClicked += new System.Windows.Forms.LinkLabelLinkClickedEventHandler(this.llblinkLabel1_LinkClicked);
        // 
        // btnLinkColor
        // 
        this.btnLinkColor.Location = new System.Drawing.Point(0, 19);
        this.btnLinkColor.Name = "btnLinkColor";
        this.btnLinkColor.Size = new System.Drawing.Size(93, 23);
        this.btnLinkColor.TabIndex = 2;
        this.btnLinkColor.Text = "LinkColor";
        this.btnLinkColor.UseVisualStyleBackColor = true;
        this.btnLinkColor.Click += new System.EventHandler(this.btnLinkColor_Click);
        // 
        // btnActiveLinkColor
        // 
        this.btnActiveLinkColor.Location = new System.Drawing.Point(0, 48);
        this.btnActiveLinkColor.Name = "btnActiveLinkColor";
        this.btnActiveLinkColor.Size = new System.Drawing.Size(93, 23);
        this.btnActiveLinkColor.TabIndex = 3;
        this.btnActiveLinkColor.Text = "ActiveLinkColor";
        this.btnActiveLinkColor.UseVisualStyleBackColor = true;
        this.btnActiveLinkColor.Click += new System.EventHandler(this.btnActiveLinkColor_Click);
        // 
        // btnVisitedLinkColor
        // 
        this.btnVisitedLinkColor.Location = new System.Drawing.Point(0, 77);
        this.btnVisitedLinkColor.Name = "btnVisitedLinkColor";
        this.btnVisitedLinkColor.Size = new System.Drawing.Size(93, 23);
        this.btnVisitedLinkColor.TabIndex = 4;
        this.btnVisitedLinkColor.Text = "VisitedLinkColor";
        this.btnVisitedLinkColor.UseVisualStyleBackColor = true;
        this.btnVisitedLinkColor.Click += new System.EventHandler(this.btnVisitedLinkColor_Click);
        // 
        // nudLinkAreaStart
        // 
        this.nudLinkAreaStart.Location = new System.Drawing.Point(152, 64);
        this.nudLinkAreaStart.Maximum = new decimal(new int[] {
        21,
        0,
        0,
        0});
        this.nudLinkAreaStart.Name = "nudLinkAreaStart";
        this.nudLinkAreaStart.Size = new System.Drawing.Size(66, 20);
        this.nudLinkAreaStart.TabIndex = 6;
        // 
        // lbllabel1
        // 
        this.lbllabel1.AutoSize = true;
        this.lbllabel1.Location = new System.Drawing.Point(224, 71);
        this.lbllabel1.Name = "lbllabel1";
        this.lbllabel1.Size = new System.Drawing.Size(74, 13);
        this.lbllabel1.TabIndex = 7;
        this.lbllabel1.Text = "Link area start";
        // 
        // nudLinkAreaEnd
        // 
        this.nudLinkAreaEnd.Location = new System.Drawing.Point(152, 99);
        this.nudLinkAreaEnd.Maximum = new decimal(new int[] {
        21,
        0,
        0,
        0});
        this.nudLinkAreaEnd.Name = "nudLinkAreaEnd";
        this.nudLinkAreaEnd.Size = new System.Drawing.Size(67, 20);
        this.nudLinkAreaEnd.TabIndex = 8;
        // 
        // lbllabel2
        // 
        this.lbllabel2.AutoSize = true;
        this.lbllabel2.Location = new System.Drawing.Point(224, 105);
        this.lbllabel2.Name = "lbllabel2";
        this.lbllabel2.Size = new System.Drawing.Size(83, 13);
        this.lbllabel2.TabIndex = 9;
        this.lbllabel2.Text = "Link area length";
        // 
        // cmbLinkBehaviour
        // 
        this.cmbLinkBehaviour.FormattingEnabled = true;
        this.cmbLinkBehaviour.Location = new System.Drawing.Point(0, 106);
        this.cmbLinkBehaviour.Name = "cmbLinkBehaviour";
        this.cmbLinkBehaviour.Size = new System.Drawing.Size(93, 21);
        this.cmbLinkBehaviour.TabIndex = 10;
        this.cmbLinkBehaviour.SelectedIndexChanged += new System.EventHandler(this.cmbLinkBehaviour_SelectedIndexChanged);
        // 
        // lbllabel3
        // 
        this.lbllabel3.AutoSize = true;
        this.lbllabel3.Location = new System.Drawing.Point(-3, 130);
        this.lbllabel3.Name = "lbllabel3";
        this.lbllabel3.Size = new System.Drawing.Size(78, 13);
        this.lbllabel3.TabIndex = 11;
        this.lbllabel3.Text = "Link Behaviour";
        // 
        // groupBox1
        // 
        this.groupBox1.Controls.Add(this.btnLinkColor);
        this.groupBox1.Controls.Add(this.btnActiveLinkColor);
        this.groupBox1.Controls.Add(this.lbllabel3);
        this.groupBox1.Controls.Add(this.btnVisitedLinkColor);
        this.groupBox1.Controls.Add(this.cmbLinkBehaviour);
        this.groupBox1.Location = new System.Drawing.Point(12, 57);
        this.groupBox1.Name = "groupBox1";
        this.groupBox1.Size = new System.Drawing.Size(124, 155);
        this.groupBox1.TabIndex = 13;
        this.groupBox1.TabStop = false;
        this.groupBox1.Text = "THE link label";
        // 
        // textDescription
        // 
        this.textDescription.Location = new System.Drawing.Point(152, 136);
        this.textDescription.Name = "textDescription";
        this.textDescription.Size = new System.Drawing.Size(100, 20);
        this.textDescription.TabIndex = 14;
        // 
        // label1
        // 
        this.label1.AutoSize = true;
        this.label1.Location = new System.Drawing.Point(259, 143);
        this.label1.Name = "label1";
        this.label1.Size = new System.Drawing.Size(60, 13);
        this.label1.TabIndex = 15;
        this.label1.Text = "Description";
        // 
        // textName
        // 
        this.textName.Location = new System.Drawing.Point(152, 163);
        this.textName.Name = "textName";
        this.textName.Size = new System.Drawing.Size(100, 20);
        this.textName.TabIndex = 16;
        // 
        // label2
        // 
        this.label2.AutoSize = true;
        this.label2.Location = new System.Drawing.Point(262, 170);
        this.label2.Name = "label2";
        this.label2.Size = new System.Drawing.Size(35, 13);
        this.label2.TabIndex = 17;
        this.label2.Text = "Name";
        // 
        // label3
        // 
        this.label3.AutoSize = true;
        this.label3.Location = new System.Drawing.Point(16, 11);
        this.label3.Name = "label3";
        this.label3.Size = new System.Drawing.Size(283, 13);
        this.label3.TabIndex = 18;
        this.label3.Text = "Right Click on a link to retrieve properties. Left Click to visit";
        // 
        // textLinkData
        // 
        this.textLinkData.Location = new System.Drawing.Point(152, 191);
        this.textLinkData.Name = "textLinkData";
        this.textLinkData.Size = new System.Drawing.Size(100, 20);
        this.textLinkData.TabIndex = 19;
        // 
        // label4
        // 
        this.label4.AutoSize = true;

        this.label4.Location = new System.Drawing.Point(262, 198);
        this.label4.Name = "label4";
        this.label4.Size = new System.Drawing.Size(53, 13);
        this.label4.TabIndex = 20;
        this.label4.Text = "Link Data";
        // 
        // checkBoxEnabled
        // 
        this.checkBoxEnabled.AutoSize = true;
        this.checkBoxEnabled.Location = new System.Drawing.Point(151, 218);
        this.checkBoxEnabled.Name = "checkBoxEnabled";
        this.checkBoxEnabled.Size = new System.Drawing.Size(65, 17);
        this.checkBoxEnabled.TabIndex = 21;
        this.checkBoxEnabled.Text = "Enabled";
        this.checkBoxEnabled.UseVisualStyleBackColor = true;
        // 
        // AddLink
        // 
        this.AddLink.Location = new System.Drawing.Point(385, 64);
        this.AddLink.Name = "AddLink";
        this.AddLink.Size = new System.Drawing.Size(75, 23);
        this.AddLink.TabIndex = 22;
        this.AddLink.Text = "Add Link";
        this.AddLink.UseVisualStyleBackColor = true;
        this.AddLink.Click += new System.EventHandler(this.AddLink_Click);
        // 
        // btnAmendLink
        // 
        this.btnAmendLink.Enabled = false;
        this.btnAmendLink.Location = new System.Drawing.Point(385, 99);
        this.btnAmendLink.Name = "btnAmendLink";
        this.btnAmendLink.Size = new System.Drawing.Size(75, 23);
        this.btnAmendLink.TabIndex = 23;
        this.btnAmendLink.Text = "AmendLink";
        this.btnAmendLink.UseVisualStyleBackColor = true;
        // 
        // checkBoxVisited
        // 
        this.checkBoxVisited.AutoSize = true;
        this.checkBoxVisited.Location = new System.Drawing.Point(151, 241);
        this.checkBoxVisited.Name = "checkBoxVisited";
        this.checkBoxVisited.Size = new System.Drawing.Size(57, 17);
        this.checkBoxVisited.TabIndex = 24;
        this.checkBoxVisited.Text = "Visited";
        this.checkBoxVisited.UseVisualStyleBackColor = true;
        // 
        // panel1
        // 
        this.panel1.Controls.Add(this.textBox1);
        this.panel1.Location = new System.Drawing.Point(474, 13);
        this.panel1.Name = "panel1";
        this.panel1.Size = new System.Drawing.Size(200, 239);
        this.panel1.TabIndex = 25;
        // 
        // textBox1
        // 
        this.textBox1.Dock = System.Windows.Forms.DockStyle.Fill;
        this.textBox1.Location = new System.Drawing.Point(0, 0);
        this.textBox1.Multiline = true;
        this.textBox1.Name = "textBox1";
        this.textBox1.Size = new System.Drawing.Size(200, 239);
        this.textBox1.TabIndex = 0;
        // 
        // Form1
        // 
        this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
        this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
        this.ClientSize = new System.Drawing.Size(704, 264);
        this.Controls.Add(this.panel1);
        this.Controls.Add(this.checkBoxVisited);
        this.Controls.Add(this.btnAmendLink);
        this.Controls.Add(this.AddLink);
        this.Controls.Add(this.checkBoxEnabled);
        this.Controls.Add(this.label4);
        this.Controls.Add(this.textLinkData);
        this.Controls.Add(this.label3);
        this.Controls.Add(this.label2);
        this.Controls.Add(this.textName);
        this.Controls.Add(this.label1);
        this.Controls.Add(this.textDescription);
        this.Controls.Add(this.groupBox1);
        this.Controls.Add(this.lbllabel2);
        this.Controls.Add(this.nudLinkAreaEnd);
        this.Controls.Add(this.lbllabel1);
        this.Controls.Add(this.nudLinkAreaStart);
        this.Controls.Add(this.llblinkLabel1);
        this.Name = "Form1";
        this.Text = "Form1";
        this.Load += new System.EventHandler(this.Form1_Load);
        ((System.ComponentModel.ISupportInitialize)(this.nudLinkAreaStart)).EndInit();
        ((System.ComponentModel.ISupportInitialize)(this.nudLinkAreaEnd)).EndInit();
        this.groupBox1.ResumeLayout(false);
        this.groupBox1.PerformLayout();
        this.panel1.ResumeLayout(false);
        this.panel1.PerformLayout();
        this.ResumeLayout(false);
        this.PerformLayout();

    }

    #endregion

    private System.Windows.Forms.LinkLabel llblinkLabel1;
    private System.Windows.Forms.ColorDialog colorDialog1;
    private System.Windows.Forms.Button btnLinkColor;
    private System.Windows.Forms.Button btnActiveLinkColor;
    private System.Windows.Forms.Button btnVisitedLinkColor;
    private System.Windows.Forms.NumericUpDown nudLinkAreaStart;
    private System.Windows.Forms.Label lbllabel1;
    private System.Windows.Forms.NumericUpDown nudLinkAreaEnd;
    private System.Windows.Forms.Label lbllabel2;
    private System.Windows.Forms.ComboBox cmbLinkBehaviour;
    private System.Windows.Forms.Label lbllabel3;
    private System.Windows.Forms.GroupBox groupBox1;
    private System.Windows.Forms.TextBox textDescription;
    private System.Windows.Forms.Label label1;
    private System.Windows.Forms.TextBox textName;
    private System.Windows.Forms.Label label2;
    private System.Windows.Forms.Label label3;
    private System.Windows.Forms.TextBox textLinkData;
    private System.Windows.Forms.Label label4;
    private System.Windows.Forms.CheckBox checkBoxEnabled;
    private System.Windows.Forms.Button AddLink;
    private System.Windows.Forms.Button btnAmendLink;
    private System.Windows.Forms.CheckBox checkBoxVisited;
    private System.Windows.Forms.Panel panel1;
    private System.Windows.Forms.TextBox textBox1;
}
}

Please can someone advise. Is the problem that there is no windows handle for the LinkLabel when its Paint event occurs.

Many thanks in advance

Tony

Answer 1

No doubt the answer is not that complicated, but I do not know how to resolve the issue. The designer generated code is not necessary but saves time for any person kind enough to test my code and resolve the problem. The stack trace is not an area I am familiar with and is pertinent as the exception could not be caught with try/catch at the method source since it is generated by events out of my control.

Please can you copy and paste the code and inform me what my mistake was and why ?

Many thanks,

Tony