CommonDialog.HelpRequest 事件

定义

当用户单击通用对话框中的“帮助”按钮时发生。Occurs when the user clicks the Help button on a common dialog box.

public:
 event EventHandler ^ HelpRequest;
public event EventHandler HelpRequest;
member this.HelpRequest : EventHandler 
Public Custom Event HelpRequest As EventHandler 

示例

下面的代码示例演示如何初始化 ColorDialog 设置 AnyColorAllowFullOpen 属性的对象。The following code example demonstrates initializing a ColorDialog object setting the AnyColor, AllowFullOpen properties. ColorDialog 对象不允许用户设置自定义颜色,但允许显示一组完整的基本颜色。The ColorDialog object does not allow the user to set a custom color, but it allows the full set of basic colors to be displayed. 通过将 "SolidColorOnly" 属性设置为 "false",可以在颜色为256或更低的系统上显示与其他颜色组合的颜色。By setting the SolidColorOnly property to false, it allows the display of colors that are combinations of other colors on systems with 256 or less colors. 该示例还演示如何设置 ShowHelp 属性以及如何处理对话框的 HelpRequest 事件。The example also shows setting the ShowHelp property and handling a HelpRequest event for a dialog box. 若要运行该示例,请将以下代码粘贴到窗体中,然后在窗体的构造函数或 Load 方法中调用 InitializeColorDialog 方法。To run the example, paste the following code in a form and call the InitializeColorDialog method in the form's constructor or Load method. 此示例要求按钮的 Click 事件连接到示例中定义的事件处理程序。This example requires that the Click event of the button is connected to the event handler defined in the example.

// This method initializes ColorDialog1 to allow any colors, 
// and combination colors on systems with 256 colors or less, 
// but will not allow the user to set custom colors.  The
// dialog will contain the help button.
void InitializeColorDialog()
{
   this->ColorDialog1 = gcnew System::Windows::Forms::ColorDialog;
   this->ColorDialog1->AllowFullOpen = false;
   this->ColorDialog1->AnyColor = true;
   this->ColorDialog1->SolidColorOnly = false;
   this->ColorDialog1->ShowHelp = true;
   
   // Associate the event-handling method with
   // the HelpRequest event.
   this->ColorDialog1->HelpRequest +=
      gcnew System::EventHandler( this, &Form1::ColorDialog1_HelpRequest );
}

// This method opens the dialog and checks the DialogResult value. 
// If the result is OK, the text box's background color will be changed 
// to the user-selected color.
void Button1_Click( System::Object^ sender, System::EventArgs^ e )
{
   ::DialogResult result = ColorDialog1->ShowDialog();
   if ( result == ::DialogResult::OK )
   {
      TextBox1->BackColor = ColorDialog1->Color;
   }
}

// This method is called when the HelpRequest event is raised, 
//which occurs when the user clicks the Help button on the ColorDialog object.
void ColorDialog1_HelpRequest( Object^ sender, System::EventArgs^ e )
{
   MessageBox::Show( "Please select a color by clicking it. " +
      "This will change the BackColor property of the TextBox." );
}
// This method initializes ColorDialog1 to allow any colors, 
// and combination colors on systems with 256 colors or less, 
// but will not allow the user to set custom colors.  The
// dialog will contain the help button.
private void InitializeColorDialog()
{
    this.ColorDialog1 = new System.Windows.Forms.ColorDialog();
    this.ColorDialog1.AllowFullOpen = false;
    this.ColorDialog1.AnyColor = true;
    this.ColorDialog1.SolidColorOnly = false;
    this.ColorDialog1.ShowHelp = true;
    
    // Associate the event-handling method with
    // the HelpRequest event.
    this.ColorDialog1.HelpRequest 
        += new System.EventHandler(ColorDialog1_HelpRequest);
}

// This method opens the dialog and checks the DialogResult value. 
// If the result is OK, the text box's background color will be changed 
// to the user-selected color.
private void Button1_Click(System.Object sender, System.EventArgs e)
{
    DialogResult result = ColorDialog1.ShowDialog();
    if (result.Equals(DialogResult.OK))
    {
        TextBox1.BackColor = ColorDialog1.Color;
    }
}

// This method is called when the HelpRequest event is raised, 
//which occurs when the user clicks the Help button on the ColorDialog object.
private void ColorDialog1_HelpRequest(object sender, System.EventArgs e)
{

    MessageBox.Show("Please select a color by clicking it. "
       + "This will change the BackColor property of the TextBox.");
}
   
   ' This method initializes ColorDialog1 to allow any colors, 
   ' and combination colors on systems with 256 colors or less, 
   ' but will not allow the user to set custom colors.  The
   ' dialog will contain the help button.
   Private Sub InitializeColorDialog()
       Me.ColorDialog1 = New System.Windows.Forms.ColorDialog
       Me.ColorDialog1.AllowFullOpen = False
       Me.ColorDialog1.AnyColor = True
       Me.ColorDialog1.SolidColorOnly = False
       Me.ColorDialog1.ShowHelp = True
   End Sub
 

   ' This method opens the dialog and checks the DialogResult value. 
   ' If the result is OK, the text box's background color will be changed 
   ' to the user-selected color.
   Private Sub Button1_Click(ByVal sender As System.Object,  _
       ByVal e As System.EventArgs) Handles Button1.Click
       Dim result As DialogResult = ColorDialog1.ShowDialog()
       If (result.Equals(DialogResult.OK)) Then
           TextBox1.BackColor = ColorDialog1.Color
       End If
   End Sub

 
   ' This method is called when the HelpRequest event is raised, 
   'which occurs when the user clicks the Help button on the ColorDialog object.
   Private Sub ColorDialog1_HelpRequest(ByVal sender As Object, _ 
       ByVal e As System.EventArgs) Handles ColorDialog1.HelpRequest

       MessageBox.Show("Please select a color by clicking it." _
       & "This will change the BackColor property of the TextBox.")
   End Sub

注解

有关处理事件的信息,请参阅处理和引发事件For information about handling events, see Handling and Raising Events.

适用于

另请参阅