DrawItemEventHandler Делегат

Определение

Представляет метод, обрабатывающий событие DrawItem элемента управления ComboBox, ListBox, MenuItem или TabControl.Represents the method that will handle the DrawItem event of a ComboBox, ListBox, MenuItem, or TabControl control.

public delegate void DrawItemEventHandler(System::Object ^ sender, DrawItemEventArgs ^ e);
public delegate void DrawItemEventHandler(object sender, DrawItemEventArgs e);
type DrawItemEventHandler = delegate of obj * DrawItemEventArgs -> unit
Public Delegate Sub DrawItemEventHandler(sender As Object, e As DrawItemEventArgs)

Параметры

sender
Object

Источник события.The source of the event.

e
DrawItemEventArgs

Объект DrawItemEventArgs, содержащий данные события.A DrawItemEventArgs that contains the event data.

Наследование
DrawItemEventHandler

Примеры

В следующем примере кода показано меню с элементом меню, рисуемым владельцем.The following code example demonstrates a menu with an owner-drawn menu item. В этом примере оператор AddHandler AddressOf и оператор используются для обозначения делегата, обрабатывающего MenuItem.DrawItem событие.This example uses the AddHandler statement and the AddressOf operator to designate a delegate to handle the MenuItem.DrawItem event. Чтобы выполнить пример, вставьте его в форму, в которой импортируются пространства имен System, System. Windows. Forms и System. Drawing.To run the example place paste it in a form that imports the System, System.Windows.Forms, and System.Drawing namespaces. Убедитесь, что все события связаны с их методами обработки событий.Ensure all events are associated with their event-handling methods.

internal:
   // Declare the MainMenu control.
   System::Windows::Forms::MainMenu^ MainMenu1;

   // Declare MenuItem2 as With-Events because it will be user drawn.
   System::Windows::Forms::MenuItem^ MenuItem2;

private:
   void InitializeMenu()
   {
      
      // Create MenuItem1, which will be drawn by the operating system.
      MenuItem^ MenuItem1 = gcnew MenuItem( "Regular Menu Item" );
      
      // Create MenuItem2.
      MenuItem2 = gcnew MenuItem( "Custom Menu Item" );
      
      // Set OwnerDraw property to true. This requires handling the
      // DrawItem event for this menu item.
      MenuItem2->OwnerDraw = true;
      
      //Add the event-handler delegate to handle the DrawItem event.
      MenuItem2->DrawItem += gcnew DrawItemEventHandler( this, &Form1::DrawCustomMenuItem );
      
      // Add the items to the menu.
      array<MenuItem^>^temp0 = {MenuItem1,MenuItem2};
      MainMenu1 = gcnew MainMenu( temp0 );
      
      // Add the menu to the form.
      this->Menu = this->MainMenu1;
   }

   // Draw the custom menu item.
   void DrawCustomMenuItem( Object^ sender, DrawItemEventArgs^ e )
   {
      // Cast the sender to MenuItem so you can access text property.
      MenuItem^ customItem = dynamic_cast<MenuItem^>(sender);
      
      // Create a Brush and a Font to draw the MenuItem.
      System::Drawing::Brush^ aBrush = System::Drawing::Brushes::DarkMagenta;
      System::Drawing::Font^ aFont = gcnew System::Drawing::Font( "Garamond",10,FontStyle::Italic,GraphicsUnit::Point );
      
      // Get the size of the text to use later to draw an ellipse
      // around the item.
      SizeF stringSize = e->Graphics->MeasureString( customItem->Text, aFont );
      
      // Draw the item and then draw the ellipse.
      e->Graphics->DrawString( customItem->Text, aFont, aBrush, (float)e->Bounds.X, (float)e->Bounds.Y );
      e->Graphics->DrawEllipse( gcnew Pen( System::Drawing::Color::Black,2 ), Rectangle(e->Bounds.X,e->Bounds.Y,(System::Int32)stringSize.Width,(System::Int32)stringSize.Height) );
   }
// Declare the MainMenu control.
internal System.Windows.Forms.MainMenu MainMenu1;

// Declare MenuItem2 as With-Events because it will be user drawn.
internal System.Windows.Forms.MenuItem MenuItem2;


private void InitializeMenu()
{

    // Create MenuItem1, which will be drawn by the operating system.
    MenuItem MenuItem1 = new MenuItem("Regular Menu Item");

    // Create MenuItem2.
    MenuItem2 = new MenuItem("Custom Menu Item");

    // Set OwnerDraw property to true. This requires handling the
    // DrawItem event for this menu item.
    MenuItem2.OwnerDraw = true;

    //Add the event-handler delegate to handle the DrawItem event.
    MenuItem2.DrawItem += new DrawItemEventHandler(DrawCustomMenuItem);
    
    // Add the items to the menu.
    MainMenu1 = new MainMenu(new MenuItem[]{MenuItem1, MenuItem2});																													  

    // Add the menu to the form.
    this.Menu = this.MainMenu1;
}

// Draw the custom menu item.
private void DrawCustomMenuItem(object sender, 
    DrawItemEventArgs e)
{

    // Cast the sender to MenuItem so you can access text property.
    MenuItem customItem = (MenuItem) sender;

    // Create a Brush and a Font to draw the MenuItem.
    System.Drawing.Brush aBrush = System.Drawing.Brushes.DarkMagenta;
    Font aFont = new Font("Garamond", 10, 
        FontStyle.Italic, GraphicsUnit.Point);

    // Get the size of the text to use later to draw an ellipse
    // around the item.
    SizeF stringSize = e.Graphics.MeasureString(
        customItem.Text, aFont);

    // Draw the item and then draw the ellipse.
    e.Graphics.DrawString(customItem.Text, aFont, 
        aBrush, e.Bounds.X, e.Bounds.Y);
    e.Graphics.DrawEllipse(new Pen(System.Drawing.Color.Black, 2),
        new Rectangle(e.Bounds.X, e.Bounds.Y, 
        (System.Int32)stringSize.Width,
        (System.Int32)stringSize.Height));
}
' Declare the MainMenu control.
Friend WithEvents MainMenu1 As System.Windows.Forms.MainMenu

' Declare MenuItem2 as With-Events because it will be user drawn.
Friend WithEvents MenuItem2 As System.Windows.Forms.MenuItem


Private Sub InitializeMenu()

    ' Create MenuItem1, which will be drawn by the operating system.
    Dim MenuItem1 As New MenuItem("Regular Menu Item")

    ' Create MenuItem2.
    MenuItem2 = New MenuItem("Custom Menu Item")

    ' Set OwnerDraw property to true. This requires handling the
    ' DrawItem event for this menu item.
    MenuItem2.OwnerDraw = True

    'Add the event-handler delegate to handle the DrawItem event.
    AddHandler MenuItem2.DrawItem, New DrawItemEventHandler(AddressOf DrawCustomMenuItem)

    ' Add the items to the menu.
    MainMenu1 = New MainMenu(New MenuItem() {MenuItem1, MenuItem2})

    ' Add the menu to the form.
    Me.Menu = Me.MainMenu1
End Sub

' Draw the custom menu item.
Private Sub DrawCustomMenuItem(ByVal sender As Object, ByVal e As _
        System.Windows.Forms.DrawItemEventArgs)

    ' Cast the sender to MenuItem so you can access text property.
    Dim customItem As MenuItem = CType(sender, MenuItem)

    ' Create a Brush and a Font to draw the MenuItem.
    Dim aBrush As System.Drawing.Brush = System.Drawing.Brushes.DarkMagenta
    Dim aFont As New Font("Garamond", 10, FontStyle.Italic, _
        GraphicsUnit.Point)

    ' Get the size of the text to use later to draw an ellipse
    ' around the item.
    Dim stringSize As SizeF = e.Graphics.MeasureString( _
        customItem.Text, aFont)

    ' Draw the item and then draw the ellipse.
    e.Graphics.DrawString(customItem.Text, aFont, _
        aBrush, e.Bounds.X, e.Bounds.Y)
    e.Graphics.DrawEllipse(New Pen(System.Drawing.Color.Black, 2), _
        New Rectangle(e.Bounds.X, e.Bounds.Y, CInt(stringSize.Width), _
        CInt(stringSize.Height)))
End Sub

Комментарии

При создании делегата DrawItemEventArgs необходимо указать метод, обрабатывающий событие.When you create a DrawItemEventArgs delegate, you identify the method that will handle the event. Чтобы связать событие с обработчиком событий, нужно добавить в событие экземпляр делегата.To associate the event with your event handler, add an instance of the delegate to the event. Обработчик событий вызывается всякий раз, когда происходит событие, если делегат не удален.The event handler is called whenever the event occurs, unless you remove the delegate. Дополнительные сведения о делегатах обработчиков событий см. в разделе обработка и вызов событий.For more information about event handler delegates, see Handling and Raising Events.

Методы расширения

GetMethodInfo(Delegate)

Получает объект, представляющий метод, представленный указанным делегатом.Gets an object that represents the method represented by the specified delegate.

Применяется к

Дополнительно