CommonDialog.HelpRequest 事件

定義

命名空間:

System.Windows.Forms

組件:

System.Windows.Forms.dll

發生於使用者按一下通用對話方塊上的 [說明] 按鈕時。

public:
 event EventHandler ^ HelpRequest;

public event EventHandler? HelpRequest;

member this.HelpRequest : EventHandler 

Public Custom Event HelpRequest As EventHandler 

事件類型

EventHandler

範例

下列程式碼範例示範初始化 ColorDialog 物件設定 AnyColor 、 AllowFullOpen 屬性。 物件 ColorDialog 不允許使用者設定自訂色彩，但允許顯示一組完整的基本色彩。 藉由將 SolidColorOnly 屬性設定為 false，它允許在具有 256 個或更少色彩的系統上顯示其他色彩組合的色彩。 此範例也會示範如何設定 ShowHelp 屬性和處理 HelpRequest 對話方塊的事件。 若要執行此範例，請將下列程式碼貼到表單中，並在表單的建構函式或 Load 方法中呼叫 InitializeColorDialog 方法。 這個範例會要求 Click 按鈕的 事件連接到範例中定義的事件處理常式。

// 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

備註

如需處理事件的資訊，請參閱 處理和引發事件。

另請參閱

• OnHelpRequest(EventArgs)