C# HelpProvider.GetHelpString方法代码示例

//引入命名空间
using System.Drawing;
using System.Windows.Forms;
using System;
using Microsoft.VisualBasic;

public class Form1:
    System.Windows.Forms.Form

{

    public Form1() : base()
    {        

        InitializeComponent();
        AddHandlers();
        InitializeFormHelp();
    }

    internal System.Windows.Forms.Label Label1;
    internal System.Windows.Forms.Label Label2;
    internal System.Windows.Forms.Label Label3;
    internal System.Windows.Forms.TextBox withdrawal;
    internal System.Windows.Forms.TextBox deposit;
    internal System.Windows.Forms.ErrorProvider ErrorProvider1;
    internal System.Windows.Forms.Label balance;
    internal System.Windows.Forms.HelpProvider HelpProvider1;
    
[System.Diagnostics.DebuggerStepThrough]
    private void InitializeComponent()
    {
        this.withdrawal = new System.Windows.Forms.TextBox();
        this.deposit = new System.Windows.Forms.TextBox();
        this.Label1 = new System.Windows.Forms.Label();
        this.Label2 = new System.Windows.Forms.Label();
        this.Label3 = new System.Windows.Forms.Label();
        this.ErrorProvider1 = new 		System.Windows.Forms.ErrorProvider();
        this.balance = new System.Windows.Forms.Label();
        this.HelpProvider1 = new 		System.Windows.Forms.HelpProvider();
        this.SuspendLayout();
        
        this.withdrawal.Location = new System.Drawing.Point(32, 200);
        this.withdrawal.Name = "withdrawal";
        this.withdrawal.Size = new System.Drawing.Size(88, 20);
        this.withdrawal.TabIndex = 0;
        this.withdrawal.Text = "";
        
        this.deposit.Location = new System.Drawing.Point(168, 200);
        this.deposit.Name = "deposit";
        this.deposit.TabIndex = 1;
        this.deposit.Text = "";
        
        this.Label1.Location = new System.Drawing.Point(56, 88);
        this.Label1.Name = "Label1";
        this.Label1.Size = new System.Drawing.Size(96, 24);
        this.Label1.TabIndex = 2;
        this.Label1.Text = "Account Balance:";
        
        this.Label2.Location = new System.Drawing.Point(168, 168);
        this.Label2.Name = "Label2";
        this.Label2.Size = new System.Drawing.Size(96, 24);
        this.Label2.TabIndex = 4;
        this.Label2.Text = "Deposit:";
        
        this.Label3.Location = new System.Drawing.Point(32, 168);
        this.Label3.Name = "Label3";
        this.Label3.Size = new System.Drawing.Size(96, 24);
        this.Label3.TabIndex = 5;
        this.Label3.Text = "Withdrawal:";
        
        this.ErrorProvider1.ContainerControl = this;
        
        this.balance.BorderStyle = System.Windows.Forms.BorderStyle.Fixed3D;
        this.balance.Location = new System.Drawing.Point(152, 88);
        this.balance.Name = "balance";
        this.balance.TabIndex = 6;
        this.balance.Text = "345.65";
        this.balance.TextAlign = System.Drawing.ContentAlignment.MiddleLeft;
        
        this.ClientSize = new System.Drawing.Size(292, 266);
        this.Controls.Add(this.balance);
        this.Controls.Add(this.Label3);
        this.Controls.Add(this.Label2);
        this.Controls.Add(this.Label1);
        this.Controls.Add(this.deposit);
        this.Controls.Add(this.withdrawal);
        this.Name = "Form1";
        this.Text = "Form1";
        this.ResumeLayout(false);
    }

    private void AddHandlers()
    {
        // Add the event-handler delegates to handled the KeyDown
        // events.
        deposit.KeyDown +=new KeyEventHandler(ProcessEntry);  
        withdrawal.KeyDown += new KeyEventHandler(ProcessEntry);

        // Add the event-handler delegates to handled the KeyPress 
        // events.
        deposit.KeyPress += new KeyPressEventHandler(CheckForDigits);
        withdrawal.KeyPress += 
            new KeyPressEventHandler(CheckForDigits);
    }

    private void InitializeFormHelp()
    {

        // Set the form's border to the FixedDialog style.
        this.FormBorderStyle = FormBorderStyle.FixedDialog;

        // Remove the Maximize and Minimize buttons from the form.
        this.MaximizeBox = false;
        this.MinimizeBox = false;

        // Add the Help button to the form.
        this.HelpButton = true;

        // Set the Help string for the deposit textBox.
        HelpProvider1.SetHelpString(deposit, 
            "Enter an amount in the format xxx.xx" +
            "and press Enter to deposit.");

        // Set the Help string for the withdrawal textBox.
        HelpProvider1.SetHelpString(withdrawal, 
            "Enter an amount in the format xxx.xx" +
            "and press Enter to withdraw.");
    }

    private void ProcessEntry(object sender, KeyEventArgs e)
    {

        // Cast the sender back to a TextBox.
        Control textBoxSender = (TextBox) sender;

        // Set the error description to an empty string ().
        ErrorProvider1.SetError(textBoxSender, "");

        // Declare the variable to hold the new balance.
        double newBalance = 0;

        // Wrap the code in a Try/Catch block to catch 
        // errors that can occur when converting the string 
        // to a double.

        try
        {
            if (e.KeyCode==Keys.Enter)

                // Switch on the text box that received
                // the KeyPress event. Convert the text to type double,
                // and compute the new balance.
            {
                switch(textBoxSender.Name)
                {
                    case "withdrawal":
                        newBalance = Double.Parse(balance.Text) 
                            - Double.Parse(withdrawal.Text);
                        withdrawal.Text = "";
                        break;
                    case "deposit":
                        newBalance = Double.Parse(balance.Text) 
                            + Double.Parse(deposit.Text);
                        deposit.Text = "";
                        break;
                }

                // Check the value of new balance and set the
                // Forecolor property accordingly.
                if (newBalance < 0)
                {
                    balance.ForeColor = Color.Red;
                }
                else
                {
                    balance.ForeColor = Color.Black;
                }

                // Set the text of the balance text box
                // to the newBalance value.
                balance.Text = newBalance.ToString();
            }
        }
        catch(FormatException)
        {

            // If a FormatException is thrown, set the
            // error string to the HelpString message for 
            // the control.
            ErrorProvider1.SetError(textBoxSender, 
                HelpProvider1.GetHelpString(textBoxSender));
        }
    }

    private void CheckForDigits(object sender, KeyPressEventArgs e)
    {

        // If the character is not a digit, period, or backspace then
        // ignore it by setting the KeyPressEventArgs.Handled
        // property to true.
        if (!(Char.IsDigit(e.KeyChar) || e.KeyChar == '.' || 
            e.KeyChar == (char)(Keys.Back)))
        {
            e.Handled = true;
        }
    }

    public static void Main()
    {
        Application.Run(new Form1());
    }
}