HelpEventHandler デリゲートとは何？わかりやすく解説 Weblio辞書

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.NET Framework クラスライブラリリファレンス

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HelpEventHandler デリゲート

Control の HelpRequested イベントを処理するメソッドを表します。

名前空間: System.Windows.Forms
アセンブリ: System.Windows.Forms (system.windows.forms.dll 内)
構文

Visual Basic (宣言)

Public Delegate Sub HelpEventHandler
 ( _
    sender As Object, _
    hlpevent As HelpEventArgs _
)

Visual Basic (使用法)

Dim instance As New HelpEventHandler(AddressOf
 HandlerMethod)

public delegate void HelpEventHandler (
    Object sender,
    HelpEventArgs hlpevent
)

C++

public delegate void HelpEventHandler (
    Object^ sender, 
    HelpEventArgs^ hlpevent
)

/** @delegate */
public delegate void HelpEventHandler (
    Object sender, 
    HelpEventArgs hlpevent
)

JScript

JScript では、デリゲートは使用できますが、新規に宣言することはできません。

パラメータ

sender: イベントのソース。

hlpevent: イベントデータを格納している HelpEventArgs。

解説

HelpEventHandler デリゲートを作成する場合は、イベントを処理するメソッドを識別してください。イベントをイベントハンドラに関連付けるには、デリゲートのインスタンスをイベントに追加します。デリゲートを削除しない限り、そのイベントが発生すると常にイベントハンドラが呼び出されます。デリゲートを使用したイベント処理の詳細については、「イベントとデリゲート」を参照してください。

使用例

HelpRequested イベントを処理して、4 つのアドレスフィールドを持つフォームにカスタムヘルプの内容を表示する例を次に示します。HelpRequested イベントは、アドレスフィールドにフォーカスがあるときに F1 キーを押すか、状況依存のヘルプのボタンを使用してヘルプカーソルをアドレスフィールド上に合わせてクリックすると、生成されます。Handled プロパティは、HelpRequested イベントが処理されることを示す true に設定されます。この例では、ヘルプテキストを Control.Tag プロパティに格納する方法についても示します。

Visual Basic

Imports System
Imports System.Drawing
Imports System.Windows.Forms

Public Class Form1
    Inherits System.Windows.Forms.Form
    Private WithEvents addressTextBox As
 System.Windows.Forms.TextBox
    Private WithEvents label2 As
 System.Windows.Forms.Label
    Private WithEvents cityTextBox As
 System.Windows.Forms.TextBox
    Private WithEvents label3 As
 System.Windows.Forms.Label
    Private WithEvents stateTextBox As
 System.Windows.Forms.TextBox
    Private WithEvents zipTextBox As
 System.Windows.Forms.TextBox
    Private WithEvents helpLabel As
 System.Windows.Forms.Label

    <STAThread()> _
    Shared Sub Main()
        Application.Run(New Form1)
    End Sub 'Main

    Public Sub New()
        Me.addressTextBox = New System.Windows.Forms.TextBox
        Me.helpLabel = New System.Windows.Forms.Label
        Me.label2 = New System.Windows.Forms.Label
        Me.cityTextBox = New System.Windows.Forms.TextBox
        Me.label3 = New System.Windows.Forms.Label
        Me.stateTextBox = New System.Windows.Forms.TextBox
        Me.zipTextBox = New System.Windows.Forms.TextBox

        ' Help Label
        Me.helpLabel.BorderStyle = System.Windows.Forms.BorderStyle.Fixed3D
        Me.helpLabel.Location = New System.Drawing.Point(8,
 80)
        Me.helpLabel.Size = New System.Drawing.Size(272,
 72)
        Me.helpLabel.Text = "Click on any control
 to give it focus, and then " & _
            "press F1 to display help for that" +
 " control.  Alternately, you can " & _
            "click the help button at the top of the dialog and
 then click on a control."

        ' Address Label
        Me.label2.Location = New System.Drawing.Point(16,
 8)
        Me.label2.Size = New System.Drawing.Size(100,
 16)
        Me.label2.Text = "Address:"

        ' Comma Label
        Me.label3.Location = New System.Drawing.Point(136,
 56)
        Me.label3.Size = New System.Drawing.Size(16,
 16)
        Me.label3.Text = ","

        ' Address TextBox
        Me.addressTextBox.Location = New System.Drawing.Point(16,
 24)
        Me.addressTextBox.Size = New System.Drawing.Size(264,
 20)
        Me.addressTextBox.TabIndex = 0
        Me.addressTextBox.Tag = "Enter the
 stree address in this text box."
        Me.addressTextBox.Text = ""

        ' City TextBox
        Me.cityTextBox.Location = New System.Drawing.Point(16,
 48)
        Me.cityTextBox.Size = New System.Drawing.Size(120,
 20)
        Me.cityTextBox.TabIndex = 3
        Me.cityTextBox.Tag = "Enter the city
 here."
        Me.cityTextBox.Text = ""

        ' State TextBox
        Me.stateTextBox.Location = New System.Drawing.Point(152,
 48)
        Me.stateTextBox.MaxLength = 2
        Me.stateTextBox.Size = New System.Drawing.Size(32,
 20)
        Me.stateTextBox.TabIndex = 5
        Me.stateTextBox.Tag = "Enter the state
 in this text box."
        Me.stateTextBox.Text = ""

        ' Zip TextBox
        Me.zipTextBox.Location = New System.Drawing.Point(192,
 48)
        Me.zipTextBox.Size = New System.Drawing.Size(88,
 20)
        Me.zipTextBox.TabIndex = 6
        Me.zipTextBox.Tag = "Enter the zip
 code here."
        Me.zipTextBox.Text = ""

        ' Set up how the form should be displayed and add the controls
 to the form.
        Me.ClientSize = New System.Drawing.Size(292,
 160)
        Me.Controls.AddRange(New System.Windows.Forms.Control()
 {Me.zipTextBox, _
                                Me.stateTextBox, Me.label3,
 Me.cityTextBox, _
                                Me.label2, Me.helpLabel,
 Me.addressTextBox})
        Me.FormBorderStyle = System.Windows.Forms.FormBorderStyle.FixedDialog
        Me.HelpButton = True
        Me.MaximizeBox = False
        Me.MinimizeBox = False
        Me.Text = "Help Event Demonstration"
    End Sub 'New

    Private Sub textBox_HelpRequested(ByVal
 sender As Object, ByVal
 hlpevent As System.Windows.Forms.HelpEventArgs) Handles addressTextBox.HelpRequested, cityTextBox.HelpRequested, stateTextBox.HelpRequested,
 zipTextBox.HelpRequested
        ' This event is raised when the F1 key is pressed or the
        ' Help cursor is clicked on any of the address fields.
        ' The Help text for the field is in the control's
        ' Tag property. It is retrieved and displayed in the label.

        Dim requestingControl As Control =
 CType(sender, Control)
        helpLabel.Text = CStr(requestingControl.Tag)
        hlpevent.Handled = True

    End Sub 'textBox_HelpRequested
End Class 'Form1

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.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 on any control to give
 it focus, and then " +
            "press F1 to display help for that control. 
 Alternately, you can " +
            "click the help button at the top of the dialog and then click on
 a control.";

        // 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 = ",";

        // 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.Tag = "Enter the street address
 in this text box.";
        this.addressTextBox.Text = "";
        this.addressTextBox.HelpRequested += new
 System.Windows.Forms.HelpEventHandler(this.textBox_HelpRequested);

        // 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.Tag = "Enter the city here.";
        this.cityTextBox.Text = "";
        this.cityTextBox.HelpRequested += new
 System.Windows.Forms.HelpEventHandler(this.textBox_HelpRequested);

        // 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.Tag = "Enter the state in
 this text box.";
        this.stateTextBox.Text = "";
        this.stateTextBox.HelpRequested += new
 System.Windows.Forms.HelpEventHandler(this.textBox_HelpRequested);

        // Zip TextBox
        this.zipTextBox.Location = new System.Drawing.Point(192,
 48);
        this.zipTextBox.Name = "zipTextBox";
        this.zipTextBox.Size = new System.Drawing.Size(88,
 20);
        this.zipTextBox.TabIndex = 6;
        this.zipTextBox.Tag = "Enter the zip code here.";
        this.zipTextBox.Text = "";
        this.zipTextBox.HelpRequested += new
 System.Windows.Forms.HelpEventHandler(this.textBox_HelpRequested);

        // Set up how the form should be displayed and add the controls
 to the form.
        this.ClientSize = new System.Drawing.Size(292,
 160);
        this.Controls.AddRange(new System.Windows.Forms.Control[]
 { this.zipTextBox, 
                                this.stateTextBox, this.label3,
 this.cityTextBox,  
                                this.label2, this.helpLabel,
 this.addressTextBox});

        this.FormBorderStyle = System.Windows.Forms.FormBorderStyle.FixedDialog;
        this.HelpButton = true;
        this.MaximizeBox = false;
        this.MinimizeBox = false;
        this.Text = "Help Event Demonstration";    
    }

    private void textBox_HelpRequested(object
 sender, System.Windows.Forms.HelpEventArgs hlpevent)
    {
        // This event is raised when the F1 key is pressed or the
        // Help cursor is clicked on any of the address fields.
        // The Help text for the field is in the control's
        // Tag property. It is retrieved and displayed in the label.

        Control requestingControl = (Control)sender;
        helpLabel.Text = (string)requestingControl.Tag;
        hlpevent.Handled = true;
    }
}

C++

#using <System.dll>
#using <System.Windows.Forms.dll>
#using <System.Drawing.dll>

using namespace System;
using namespace System::Drawing;
using namespace System::Windows::Forms;
public ref class Form1: public
 System::Windows::Forms::Form
{
private:
   System::Windows::Forms::TextBox^ addressTextBox;
   System::Windows::Forms::Label ^ label2;
   System::Windows::Forms::TextBox^ cityTextBox;
   System::Windows::Forms::Label ^ label3;
   System::Windows::Forms::TextBox^ stateTextBox;
   System::Windows::Forms::TextBox^ zipTextBox;
   System::Windows::Forms::Label ^ helpLabel;

public:
   Form1()
   {
      this->addressTextBox = gcnew System::Windows::Forms::TextBox;
      this->helpLabel = gcnew System::Windows::Forms::Label;
      this->label2 = gcnew System::Windows::Forms::Label;
      this->cityTextBox = gcnew System::Windows::Forms::TextBox;
      this->label3 = gcnew System::Windows::Forms::Label;
      this->stateTextBox = gcnew System::Windows::Forms::TextBox;
      this->zipTextBox = gcnew System::Windows::Forms::TextBox;
      
      // Help Label
      this->helpLabel->BorderStyle = System::Windows::Forms::BorderStyle::Fixed3D;
      this->helpLabel->Location = System::Drawing::Point(
 8, 80 );
      this->helpLabel->Size = System::Drawing::Size( 272,
 72 );
      this->helpLabel->Text = "Click on any control
 to give it focus, and then press F1 to display help for that
 control.  Alternately, you can click the help button at the top of the dialog and then click on a control.";
      
      // Address Label
      this->label2->Location = System::Drawing::Point( 16,
 8 );
      this->label2->Size = System::Drawing::Size( 100, 16
 );
      this->label2->Text = "Address:";
      
      // Comma Label
      this->label3->Location = System::Drawing::Point( 136,
 56 );
      this->label3->Size = System::Drawing::Size( 16, 16
 );
      this->label3->Text = ", ";
      
      // Address TextBox
      this->addressTextBox->Location = System::Drawing::Point(
 16, 24 );
      this->addressTextBox->Size = System::Drawing::Size(
 264, 20 );
      this->addressTextBox->TabIndex = 0;
      this->addressTextBox->Tag = "Enter the street
 address in this text box.";
      this->addressTextBox->Text = "";
      this->addressTextBox->HelpRequested += gcnew System::Windows::Forms::HelpEventHandler(
 this, &Form1::textBox_HelpRequested );
      
      // City TextBox
      this->cityTextBox->Location = System::Drawing::Point(
 16, 48 );
      this->cityTextBox->Size = System::Drawing::Size( 120,
 20 );
      this->cityTextBox->TabIndex = 3;
      this->cityTextBox->Tag = "Enter the city here.";
      this->cityTextBox->Text = "";
      this->cityTextBox->HelpRequested += gcnew System::Windows::Forms::HelpEventHandler(
 this, &Form1::textBox_HelpRequested );
      
      // State TextBox
      this->stateTextBox->Location = System::Drawing::Point(
 152, 48 );
      this->stateTextBox->MaxLength = 2;
      this->stateTextBox->Size = System::Drawing::Size(
 32, 20 );
      this->stateTextBox->TabIndex = 5;
      this->stateTextBox->Tag = "Enter the state in
 this text box.";
      this->stateTextBox->Text = "";
      this->stateTextBox->HelpRequested += gcnew System::Windows::Forms::HelpEventHandler(
 this, &Form1::textBox_HelpRequested );
      
      // Zip TextBox
      this->zipTextBox->Location = System::Drawing::Point(
 192, 48 );
      this->zipTextBox->Name = "zipTextBox";
      this->zipTextBox->Size = System::Drawing::Size( 88,
 20 );
      this->zipTextBox->TabIndex = 6;
      this->zipTextBox->Tag = "Enter the zip code here.";
      this->zipTextBox->Text = "";
      this->zipTextBox->HelpRequested += gcnew System::Windows::Forms::HelpEventHandler(
 this, &Form1::textBox_HelpRequested );
      
      // Set up how the form should be displayed and add the controls
 to the form.
      this->ClientSize = System::Drawing::Size( 292, 160 );
      array<System::Windows::Forms::Control^>^temp0 = {this->zipTextBox
,this->stateTextBox,this->label3,this->cityTextBox
,this->label2,this->helpLabel,this->addressTextBox};
      this->Controls->AddRange( temp0 );
      this->FormBorderStyle = System::Windows::Forms::FormBorderStyle::FixedDialog;
      this->HelpButton = true;
      this->MaximizeBox = false;
      this->MinimizeBox = false;
      this->Text = "Help Event Demonstration";
   }


private:
   void textBox_HelpRequested( Object^ sender, System::Windows::Forms::HelpEventArgs^
 hlpevent )
   {
      
      // This event is raised when the F1 key is pressed or the
      // Help cursor is clicked on any of the address fields.
      // The Help text for the field is in the control's
      // Tag property. It is retrieved and displayed in the label.
      Control^ requestingControl = dynamic_cast<Control^>(sender);
      helpLabel->Text = dynamic_cast<String^>(requestingControl->Tag);
      hlpevent->Handled = true;
   }

};


[STAThread]
int main()
{
   Application::Run( gcnew Form1 );
}

import System.*;
import System.Drawing.*;
import System.Windows.Forms.*;

public class Form1 extends 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.Label helpLabel;

    /** @attribute STAThread()
     */
    public static void main(String[]
 args)
    {
        Application.Run(new Form1());
    } //main

    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.set_BorderStyle(
            System.Windows.Forms.BorderStyle.Fixed3D);
        this.helpLabel.set_Location(new System.Drawing.Point(8,
 80));
        this.helpLabel.set_Size(new System.Drawing.Size(272,
 72));
        this.helpLabel.set_Text("Click on any control to
 give it focus, " 
            + "and then press F1 to display help for that
 control.  " 
            + "Alternately, you can click the help button at the top of "
 
            + "the dialog and then click on a control.");
        // Address Label
        this.label2.set_Location(new System.Drawing.Point(16,
 8));
        this.label2.set_Size(new System.Drawing.Size(100,
 16));
        this.label2.set_Text("Address:");
        // Comma Label
        this.label3.set_Location(new System.Drawing.Point(136,
 56));
        this.label3.set_Size(new System.Drawing.Size(16,
 16));
        this.label3.set_Text(",");
        // Address TextBox
        this.addressTextBox.set_Location(new
 System.Drawing.Point(16, 24));
        this.addressTextBox.set_Size(new System.Drawing.Size(264,
 20));
        this.addressTextBox.set_TabIndex(0);
        this.addressTextBox.set_Tag("Enter the street address
 " 
            + "in this text box.");
        this.addressTextBox.set_Text("");
        this.addressTextBox.add_HelpRequested(
            new System.Windows.Forms.HelpEventHandler(
            this.TextBox_HelpRequested));
        // City TextBox
        this.cityTextBox.set_Location(new System.Drawing.Point(16,
 48));
        this.cityTextBox.set_Size(new System.Drawing.Size(120,
 20));
        this.cityTextBox.set_TabIndex(3);
        this.cityTextBox.set_Tag("Enter the city here.");
        this.cityTextBox.set_Text("");
        this.cityTextBox.add_HelpRequested(
            new System.Windows.Forms.HelpEventHandler(
            this.TextBox_HelpRequested));
        // State TextBox
        this.stateTextBox.set_Location(new
 System.Drawing.Point(152, 48));
        this.stateTextBox.set_MaxLength(2);
        this.stateTextBox.set_Size(new System.Drawing.Size(32,
 20));
        this.stateTextBox.set_TabIndex(5);
        this.stateTextBox.set_Tag("Enter the state in
 this text box.");
        this.stateTextBox.set_Text("");
        this.stateTextBox.add_HelpRequested(
            new System.Windows.Forms.HelpEventHandler(
            this.TextBox_HelpRequested));
        // Zip TextBox
        this.zipTextBox.set_Location(new System.Drawing.Point(192,
 48));
        this.zipTextBox.set_Name("zipTextBox");
        this.zipTextBox.set_Size(new System.Drawing.Size(88,
 20));
        this.zipTextBox.set_TabIndex(6);
        this.zipTextBox.set_Tag("Enter the zip code here.");
        this.zipTextBox.set_Text("");
        this.zipTextBox.add_HelpRequested(
            new System.Windows.Forms.HelpEventHandler(
            this.TextBox_HelpRequested));
        // Set up how the form should be displayed and add the controls
 
        // to the form.
        this.set_ClientSize(new System.Drawing.Size(292,
 160));
        this.get_Controls().AddRange(new System.Windows.Forms.Control[]
 { 
            this.zipTextBox, this.stateTextBox,
 this.label3, this.cityTextBox, 
            this.label2, this.helpLabel, this.addressTextBox
 });

        this.set_FormBorderStyle(
            System.Windows.Forms.FormBorderStyle.FixedDialog);
        this.set_HelpButton(true);
        this.set_MaximizeBox(false);
        this.set_MinimizeBox(false);
        this.set_Text("Help Event Demonstration");
    } //Form1

    private void TextBox_HelpRequested(Object
 sender, 
        System.Windows.Forms.HelpEventArgs hlpEvent)
    {
        // This event is raised when the F1 key is pressed or the
        // Help cursor is clicked on any of the address fields.
        // The Help text for the field is in the control's
        // Tag property. It is retrieved and displayed in the label.
        Control requestingControl = (Control)sender;
        helpLabel.set_Text((String)requestingControl.get_Tag());
        hlpEvent.set_Handled(true);
    } //TextBox_HelpRequested
} //Form1

プラットフォーム

Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

開発プラットフォームの中には、.NET Framework によってサポートされていないバージョンがあります。サポートされているバージョンについては、「システム要件」を参照してください。

バージョン情報

.NET Framework
サポート対象 : 2.0、1.1、1.0
.NET Compact Framework
サポート対象 : 2.0

参照

関連項目
System.Windows.Forms 名前空間
Control.HelpRequested イベント
HelpEventArgs クラス

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HelpEventHandler デリゲートとは？ わかりやすく解説

HelpEventHandler デリゲート

「HelpEventHandler デリゲート」の関連用語

HelpEventHandler デリゲートとは？わかりやすく解説