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HelpProvider Class

Provides pop-up or online Help for controls.

Namespace:  System.Windows.Forms
Assembly:  System.Windows.Forms (in System.Windows.Forms.dll)
public class HelpProvider : Component, 
	IExtenderProvider

Each instance of HelpProvider maintains a collection of references to controls associated with it. To associate a Help file with the HelpProvider, set the HelpNamespace property. You specify the type of Help provided by calling the SetHelpNavigator method and providing a HelpNavigator value for the specified control. You provide the keyword or topic for the Help by calling the SetHelpKeyword method. To open Help to a specific topic, the keyword should be passed in the form topicName.htm.

To associate a specific Help string with a control, use the SetHelpString method. The string that you associate with a control using this method is displayed in a pop-up window when the user presses the F1 key while the control has focus.

If the HelpNamespace property has not been set, you must use the SetHelpString method to provide the Help text. If you have set both HelpNamespace and the Help string, Help based on the HelpNamespace will take precedence.

HelpProvider calls methods on the Help class to provide Help functionality.

The following code example demonstrates using the HelpProvider class to display context-sensitive Help on a form containing four address fields. The example uses the SetHelpString method to set the Help ToolTip text. When you use the context-sensitive Help button and click the Help cursor on an address field, the Help ToolTip appears with the specified text. When you press the F1 key with the focus in an address field, the mspaint.chm Help file is displayed because the HelpNamespace property has been set to mspaint.chm. The SetShowHelp method is called for each address control to identify that it has Help content available.

using System;
using System.Drawing;
using System.Windows.Forms;

public class Form1 : System.Windows.Forms.Form
{
	private System.Windows.Forms.TextBox addressTextBox;
	private System.Windows.Forms.Label label2;
	private System.Windows.Forms.TextBox cityTextBox;
	private System.Windows.Forms.Label label3;
	private System.Windows.Forms.TextBox stateTextBox;
	private System.Windows.Forms.TextBox zipTextBox;
	private System.Windows.Forms.HelpProvider helpProvider1;
	private System.Windows.Forms.Label helpLabel;

    [STAThread]
    static void Main() 
    {
        Application.Run(new Form1());
    }

	public Form1()
	{
        this.addressTextBox = new System.Windows.Forms.TextBox();
        this.helpLabel = new System.Windows.Forms.Label();
        this.label2 = new System.Windows.Forms.Label();
        this.cityTextBox = new System.Windows.Forms.TextBox();
        this.label3 = new System.Windows.Forms.Label();
        this.stateTextBox = new System.Windows.Forms.TextBox();
        this.zipTextBox = new System.Windows.Forms.TextBox();

        // Help Label 
        this.helpLabel.BorderStyle = System.Windows.Forms.BorderStyle.Fixed3D;
        this.helpLabel.Location = new System.Drawing.Point(8, 80);
        this.helpLabel.Size = new System.Drawing.Size(272, 72);
        this.helpLabel.Text = "Click the Help button in the title bar, then click a control " + 
            "to see a Help tooltip for the control.  Click on a control and press F1 to invoke " +
            "the Help system with a sample Help file.";

        // Address Label 
        this.label2.Location = new System.Drawing.Point(16, 8);
        this.label2.Size = new System.Drawing.Size(100, 16);
        this.label2.Text = "Address:";

        // Comma Label 
        this.label3.Location = new System.Drawing.Point(136, 56);
        this.label3.Size = new System.Drawing.Size(16, 16);
        this.label3.Text = ",";

        // Create the HelpProvider. 
        this.helpProvider1 = new System.Windows.Forms.HelpProvider();

        // Tell the HelpProvider what controls to provide help for, and 
        // what the help string is. 
        this.helpProvider1.SetShowHelp(this.addressTextBox, true);
        this.helpProvider1.SetHelpString(this.addressTextBox, "Enter the street address in this text box.");

        this.helpProvider1.SetShowHelp(this.cityTextBox, true);
        this.helpProvider1.SetHelpString(this.cityTextBox, "Enter the city here.");

        this.helpProvider1.SetShowHelp(this.stateTextBox, true);
        this.helpProvider1.SetHelpString(this.stateTextBox, "Enter the state in this text box.");

        this.helpProvider1.SetShowHelp(this.zipTextBox, true);
        this.helpProvider1.SetHelpString(this.zipTextBox, "Enter the zip code here.");

        // Set what the Help file will be for the HelpProvider. 
        this.helpProvider1.HelpNamespace = "mspaint.chm";

        // Sets properties for the different address fields. 

        // Address TextBox 
        this.addressTextBox.Location = new System.Drawing.Point(16, 24);
        this.addressTextBox.Size = new System.Drawing.Size(264, 20);
        this.addressTextBox.TabIndex = 0;
        this.addressTextBox.Text = "";

        // City TextBox 
        this.cityTextBox.Location = new System.Drawing.Point(16, 48);
        this.cityTextBox.Size = new System.Drawing.Size(120, 20);
        this.cityTextBox.TabIndex = 3;
        this.cityTextBox.Text = "";

        // State TextBox 
        this.stateTextBox.Location = new System.Drawing.Point(152, 48);
        this.stateTextBox.MaxLength = 2;
        this.stateTextBox.Size = new System.Drawing.Size(32, 20);
        this.stateTextBox.TabIndex = 5;
        this.stateTextBox.Text = "";

        // Zip TextBox 
        this.zipTextBox.Location = new System.Drawing.Point(192, 48);
        this.zipTextBox.Size = new System.Drawing.Size(88, 20);
        this.zipTextBox.TabIndex = 6;
        this.zipTextBox.Text = "";

        // Add the controls to the form. 
        this.Controls.AddRange(new System.Windows.Forms.Control[] {
                                    this.zipTextBox, this.stateTextBox,
                                    this.label3, this.cityTextBox,
                                    this.label2, this.helpLabel,
                                    this.addressTextBox});

        // Set the form to look like a dialog, and show the HelpButton.     
        this.FormBorderStyle = System.Windows.Forms.FormBorderStyle.FixedDialog;
        this.HelpButton = true;
        this.MaximizeBox = false;
        this.MinimizeBox = false;
        this.ClientSize = new System.Drawing.Size(292, 160);
        this.Text = "Help Provider Demonstration";

    }
}
Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0
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