HelpEventHandler 委托
定义
重要
一些信息与预发行产品相关，相应产品在发行之前可能会进行重大修改。 对于此处提供的信息，Microsoft 不作任何明示或暗示的担保。
表示将用来处理 HelpRequested 的 Control 事件的方法。
public delegate void HelpEventHandler(System::Object ^ sender, HelpEventArgs ^ hlpevent);public delegate void HelpEventHandler(object sender, HelpEventArgs hlpevent);public delegate void HelpEventHandler(object? sender, HelpEventArgs hlpevent);type HelpEventHandler = delegate of obj * HelpEventArgs -> unitPublic Delegate Sub HelpEventHandler(sender As Object, hlpevent As HelpEventArgs)参数
- sender
- Object
事件源。
- hlpevent
- HelpEventArgs
包含事件数据的 HelpEventArgs。
示例
以下示例演示如何处理 事件以 HelpRequested 在包含四个地址字段的窗体上显示自定义帮助内容。 通过 HelpRequested 按 F1 键将焦点放在地址字段中，或者通过使用上下文相关的“帮助”按钮并单击地址字段中的“帮助”光标，引发事件。 属性 Handled 设置为 true 以指示 HelpRequested 已处理事件。 该示例还演示如何在 属性中 Control.Tag 存储帮助文本。
#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 );
}
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;
}
}
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
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
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
End Class
注解
创建 HelpEventHandler 委托时，需要标识将处理该事件的方法。 若要将事件与事件处理程序关联，请将该委托的一个实例添加到事件中。 除非移除了该委托，否则每当发生该事件时就会调用事件处理程序。 有关使用委托处理事件的详细信息，请参阅 处理和引发事件。
扩展方法
| GetMethodInfo(Delegate) |
获取指示指定委托表示的方法的对象。 |
