ComboBox.DropDownWidth-Eigenschaft

Ruft die Breite des Dropdownteiles eines Kombinationsfelds ab oder legt diese fest.

Namespace: System.Windows.Forms
Assembly: System.Windows.Forms (in system.windows.forms.dll)

Syntax

'Declaration
Public Property DropDownWidth As Integer
'Usage
Dim instance As ComboBox
Dim value As Integer

value = instance.DropDownWidth

instance.DropDownWidth = value

public int DropDownWidth { get; set; }

public:
property int DropDownWidth {
    int get ();
    void set (int value);
}

/** @property */
public int get_DropDownWidth ()

/** @property */
public void set_DropDownWidth (int value)

public function get DropDownWidth () : int

public function set DropDownWidth (value : int)

Eigenschaftenwert

Die Breite des Dropdownfelds in Pixel.

Ausnahmen

Ausnahmetyp	Bedingung
ArgumentException	Der angegebene Wert ist kleiner als 1.

Hinweise

Wenn für DropDownWidth kein Wert festgelegt wurde, gibt diese Eigenschaft die Width des Kombinationsfelds zurück.

Hinweis

Die Breite des Dropdownfelds kann nicht kleiner sein als die ComboBox-Breite.

Beispiel

Im folgenden Codebeispiel wird das Erstellen eines Ownerdrawn-Kombinationsfelds veranschaulicht. Dazu wird die DrawMode-Eigenschaft auf OwnerDrawnVariable festgelegt, und anschließend werden das DrawItem-Ereignis und das MeasureItem-Ereignis behandelt. Außerdem wird gezeigt, wie die DropDownWidth-Eigenschaft und die DropDownStyle-Eigenschaft festgelegt werden. Fügen Sie zum Ausführen des Beispiels den folgenden Code in ein Formular ein. Rufen Sie die InitializeComboBox-Methode im Konstruktor oder im Load-Ereignis des Formulars auf.

Friend WithEvents ComboBox1 As System.Windows.Forms.ComboBox
Private animals() As String
  
' This method initializes the owner-drawn combo box.
' The drop-down width is set much wider than the size of the combo box
' to accomodate the large items in the list.  The drop-down style is set to 
' ComboBox.DropDown, which requires the user to click on the arrow to 
' see the list.
Private Sub InitializeComboBox()
    Me.ComboBox1 = New ComboBox
    Me.ComboBox1.DrawMode = System.Windows.Forms.DrawMode.OwnerDrawVariable
    Me.ComboBox1.Location = New System.Drawing.Point(10, 20)
    Me.ComboBox1.Name = "ComboBox1"
    Me.ComboBox1.Size = New System.Drawing.Size(100, 120)
    Me.ComboBox1.DropDownWidth = 250
    Me.ComboBox1.TabIndex = 0
    Me.ComboBox1.DropDownStyle = ComboBoxStyle.DropDown
    animals = New String() {"Elephant", "c r o c o d i l e", "lion"}
    ComboBox1.DataSource = animals
    Me.Controls.Add(Me.ComboBox1)
End Sub

' If you set the Draw property to DrawMode.OwnerDrawVariable, 
' you must handle the MeasureItem event. This event handler 
' will set the height and width of each item before it is drawn. 
 Private Sub ComboBox1_MeasureItem(ByVal sender As Object, _
    ByVal e As System.Windows.Forms.MeasureItemEventArgs) _
        Handles ComboBox1.MeasureItem

    Select Case e.Index
        Case 0
            e.ItemHeight = 45
        Case 1
            e.ItemHeight = 20
        Case 2
            e.ItemHeight = 35
    End Select
    e.ItemWidth = 260

End Sub

' You must handle the DrawItem event for owner-drawn combo boxes.  
' This event handler changes the color, size and font of an 
' item based on its position in the array.
Private Sub ComboBox1_DrawItem(ByVal sender As Object,  _ 
    ByVal e As System.Windows.Forms.DrawItemEventArgs) _
    Handles ComboBox1.DrawItem

    Dim size As Single
    Dim myFont As System.Drawing.Font
    Dim family As FontFamily

    Dim animalColor As New System.Drawing.Color
    Select Case e.Index
        Case 0
            size = 30
            animalColor = System.Drawing.Color.Gray
            family = FontFamily.GenericSansSerif
        Case 1
            size = 10
            animalColor = System.Drawing.Color.LawnGreen
            family = FontFamily.GenericMonospace
        Case 2
            size = 15
            animalColor = System.Drawing.Color.Tan
            family = FontFamily.GenericSansSerif
    End Select

    ' Draw the background of the item.
    e.DrawBackground()

    ' Create a square filled with the animals color. Vary the size
    ' of the rectangle based on the length of the animals name.
    Dim rectangle As Rectangle = New Rectangle(2, e.Bounds.Top + 2, _
        e.Bounds.Height, e.Bounds.Height - 4)
    e.Graphics.FillRectangle(New SolidBrush(animalColor), rectangle)

    ' Draw each string in the array, using a different size, color,
    ' and font for each item.
    myFont = New Font(family, size, FontStyle.Bold)
    e.Graphics.DrawString(animals(e.Index), myFont, System.Drawing.Brushes.Black, _
        New RectangleF(e.Bounds.X + rectangle.Width, e.Bounds.Y, _ 
        e.Bounds.Width, e.Bounds.Height))

    ' Draw the focus rectangle if the mouse hovers over an item.
    e.DrawFocusRectangle()
End Sub

internal System.Windows.Forms.ComboBox ComboBox1;
private string[] animals;
  
// This method initializes the owner-drawn combo box.
// The drop-down width is set much wider than the size of the combo box
// to accomodate the large items in the list.  The drop-down style is set to 
// ComboBox.DropDown, which requires the user to click on the arrow to 
// see the list.
private void InitializeComboBox()
{
    this.ComboBox1 = new ComboBox();
    this.ComboBox1.DrawMode = 
        System.Windows.Forms.DrawMode.OwnerDrawVariable;
    this.ComboBox1.Location = new System.Drawing.Point(10, 20);
    this.ComboBox1.Name = "ComboBox1";
    this.ComboBox1.Size = new System.Drawing.Size(100, 120);
    this.ComboBox1.DropDownWidth = 250;
    this.ComboBox1.TabIndex = 0;
    this.ComboBox1.DropDownStyle = ComboBoxStyle.DropDown;
    animals = new string[]{"Elephant", "c r o c o d i l e", "lion"};
    ComboBox1.DataSource = animals;
    this.Controls.Add(this.ComboBox1);

    // Hook up the MeasureItem and DrawItem events
    this.ComboBox1.DrawItem += 
        new DrawItemEventHandler(ComboBox1_DrawItem);
    this.ComboBox1.MeasureItem += 
        new MeasureItemEventHandler(ComboBox1_MeasureItem);
}

// If you set the Draw property to DrawMode.OwnerDrawVariable, 
// you must handle the MeasureItem event. This event handler 
// will set the height and width of each item before it is drawn. 
private void ComboBox1_MeasureItem(object sender, 
    System.Windows.Forms.MeasureItemEventArgs e)
{

    switch(e.Index)
    {
        case 0:
            e.ItemHeight = 45;
            break;
        case 1:
            e.ItemHeight = 20;
            break;
        case 2:
            e.ItemHeight = 35;
            break;
    }
    e.ItemWidth = 260;

}

// You must handle the DrawItem event for owner-drawn combo boxes.  
// This event handler changes the color, size and font of an 
// item based on its position in the array.
private void ComboBox1_DrawItem(object sender, 
    System.Windows.Forms.DrawItemEventArgs e)
{

    float size = 0;
    System.Drawing.Font myFont;
    FontFamily family = null;

    System.Drawing.Color animalColor = new System.Drawing.Color();
    switch(e.Index)
    {
        case 0:
            size = 30;
            animalColor = System.Drawing.Color.Gray;
            family = FontFamily.GenericSansSerif;
            break;
        case 1:
            size = 10;
            animalColor = System.Drawing.Color.LawnGreen;
            family = FontFamily.GenericMonospace;
            break;
        case 2:
            size = 15;
            animalColor = System.Drawing.Color.Tan;
            family = FontFamily.GenericSansSerif;
            break;
    }

    // Draw the background of the item.
    e.DrawBackground();

    // Create a square filled with the animals color. Vary the size
    // of the rectangle based on the length of the animals name.
    Rectangle rectangle = new Rectangle(2, e.Bounds.Top+2, 
            e.Bounds.Height, e.Bounds.Height-4);
    e.Graphics.FillRectangle(new SolidBrush(animalColor), rectangle);

    // Draw each string in the array, using a different size, color,
    // and font for each item.
    myFont = new Font(family, size, FontStyle.Bold);
    e.Graphics.DrawString(animals[e.Index], myFont, System.Drawing.Brushes.Black, new RectangleF(e.Bounds.X+rectangle.Width, e.Bounds.Y, e.Bounds.Width, e.Bounds.Height));

    // Draw the focus rectangle if the mouse hovers over an item.
    e.DrawFocusRectangle();
}

internal:
   System::Windows::Forms::ComboBox^ ComboBox1;

private:
   array<String^>^ animals;

   // This method initializes the owner-drawn combo box.
   // The drop-down width is set much wider than the size of the combo box
   // to accomodate the large items in the list.  The drop-down style is set to 
   // ComboBox.DropDown, which requires the user to click on the arrow to 
   // see the list.
   void InitializeComboBox()
   {
      this->ComboBox1 = gcnew ComboBox;
      this->ComboBox1->DrawMode = System::Windows::Forms::DrawMode::OwnerDrawVariable;
      this->ComboBox1->Location = System::Drawing::Point( 10, 20 );
      this->ComboBox1->Name = "ComboBox1";
      this->ComboBox1->Size = System::Drawing::Size( 100, 120 );
      this->ComboBox1->DropDownWidth = 250;
      this->ComboBox1->TabIndex = 0;
      this->ComboBox1->DropDownStyle = ComboBoxStyle::DropDown;
      animals = gcnew array<String^>{"Elephant","c r o c o d i l e","lion"};
      ComboBox1->DataSource = animals;
      this->Controls->Add( this->ComboBox1 );
      
      // Hook up the MeasureItem and DrawItem events
      this->ComboBox1->DrawItem +=
         gcnew DrawItemEventHandler( this, &Form1::ComboBox1_DrawItem );
      this->ComboBox1->MeasureItem +=
         gcnew MeasureItemEventHandler( this, &Form1::ComboBox1_MeasureItem );
   }

   // If you set the Draw property to DrawMode.OwnerDrawVariable, 
   // you must handle the MeasureItem event. This event handler 
   // will set the height and width of each item before it is drawn. 
private:
   void ComboBox1_MeasureItem( Object^ sender,
      System::Windows::Forms::MeasureItemEventArgs^ e )
   {
      switch ( e->Index )
      {
         case 0:
            e->ItemHeight = 45;
            break;
         case 1:
            e->ItemHeight = 20;
            break;
         case 2:
            e->ItemHeight = 35;
            break;
      }
      e->ItemWidth = 260;
   }

private:
   // You must handle the DrawItem event for owner-drawn combo boxes.  
   // This event handler changes the color, size and font of an 
   // item based on its position in the array.
   void ComboBox1_DrawItem( Object^ sender,
      System::Windows::Forms::DrawItemEventArgs^ e )
   {
      float size = 0;
      System::Drawing::Font^ myFont;
      FontFamily^ family = nullptr;

      System::Drawing::Color animalColor;
      switch ( e->Index )
      {
         case 0:
            size = 30;
            animalColor = System::Drawing::Color::Gray;
            family = FontFamily::GenericSansSerif;
            break;
         case 1:
            size = 10;
            animalColor = System::Drawing::Color::LawnGreen;
            family = FontFamily::GenericMonospace;
            break;
         case 2:
            size = 15;
            animalColor = System::Drawing::Color::Tan;
            family = FontFamily::GenericSansSerif;
            break;
      }

      // Draw the background of the item.
      e->DrawBackground();
      
      // Create a square filled with the animals color. Vary the size
      // of the rectangle based on the length of the animals name.
      Rectangle rectangle = Rectangle( 2, e->Bounds.Top + 2,
         e->Bounds.Height, e->Bounds.Height - 4 );
      e->Graphics->FillRectangle( gcnew SolidBrush( animalColor ), rectangle );
      
      // Draw each string in the array, using a different size, color,
      // and font for each item.
      myFont = gcnew System::Drawing::Font( family, size, FontStyle::Bold );
      e->Graphics->DrawString( animals[ e->Index ], myFont,
         System::Drawing::Brushes::Black, RectangleF(
            e->Bounds.X + rectangle.Width, e->Bounds.Y,
            e->Bounds.Width, e->Bounds.Height) );
      
      // Draw the focus rectangle if the mouse hovers over an item.
      e->DrawFocusRectangle();
   }

System.Windows.Forms.ComboBox comboBox1;

private String animals[];

// This method initializes the owner-drawn combo box.
// The drop-down width is set much wider than the size of the combo box
// to accomodate the large items in the list.  The drop-down style is set to 
// ComboBox.DropDown, which requires the user to click on the arrow to 
// see the list.
private void InitializeComboBox()
{
    this.comboBox1 = new ComboBox();
    this.comboBox1.set_DrawMode(
        System.Windows.Forms.DrawMode.OwnerDrawVariable);
    this.comboBox1.set_Location(new System.Drawing.Point(10, 20));
    this.comboBox1.set_Name("comboBox1");
    this.comboBox1.set_Size(new System.Drawing.Size(100, 120));
    this.comboBox1.set_DropDownWidth(250);
    this.comboBox1.set_TabIndex(0);
    this.comboBox1.set_DropDownStyle(ComboBoxStyle.DropDown);
    animals = new String[] { "Elephant", "c r o c o d i l e", "lion" };
    comboBox1.set_DataSource(animals);
    this.get_Controls().Add(this.comboBox1);
    // Hook up the MeasureItem and DrawItem events
    this.comboBox1.add_DrawItem(
        new DrawItemEventHandler(comboBox1_DrawItem));
    this.comboBox1.add_MeasureItem(
        new MeasureItemEventHandler(comboBox1_MeasureItem));
} //InitializeComboBox

// If you set the Draw property to DrawMode.OwnerDrawVariable, 
// you must handle the MeasureItem event. This event handler 
// will set the height and width of each item before it is drawn. 
private void comboBox1_MeasureItem(Object sender, 
    System.Windows.Forms.MeasureItemEventArgs e)
{
    switch (e.get_Index()) {
        case 0:
            e.set_ItemHeight(45);
            break;

        case 1:
            e.set_ItemHeight(20);
            break;

        case 2:
            e.set_ItemHeight(35);
            break;
    }
    e.set_ItemWidth(260);
} //comboBox1_MeasureItem

// You must handle the DrawItem event for owner-drawn combo boxes.  
// This event handler changes the color, size and font of an 
// item based on its position in the array.
private void comboBox1_DrawItem(Object sender, 
    System.Windows.Forms.DrawItemEventArgs e)
{
    float size = 0;
    System.Drawing.Font myFont;
    FontFamily family = null;

    System.Drawing.Color animalColor = new System.Drawing.Color();
    switch (e.get_Index()) {
        case 0:
            size = 30;
            animalColor = System.Drawing.Color.get_Gray();
            family = FontFamily.get_GenericSansSerif();
            break;

        case 1:
            size = 10;
            animalColor = System.Drawing.Color.get_LawnGreen();
            family = FontFamily.get_GenericMonospace();
            break;

        case 2:
            size = 15;
            animalColor = System.Drawing.Color.get_Tan();
            family = FontFamily.get_GenericSansSerif();
            break;
    }
    // Draw the background of the item.
    e.DrawBackground();
    // Create a square filled with the animals color. Vary the size
    // of the rectangle based on the length of the animals name.
    Rectangle rectangle = new Rectangle(2, e.get_Bounds().get_Top() + 2, 
        e.get_Bounds().get_Height(),
        e.get_Bounds().get_Height() - 4);
    e.get_Graphics().FillRectangle(new SolidBrush(animalColor), rectangle);
    // Draw each string in the array, using a different size, color,
    // and font for each item.
    myFont = new Font(family, size, FontStyle.Bold);
    e.get_Graphics().DrawString((String)animals.get_Item(e.get_Index()), 
        myFont, System.Drawing.Brushes.get_Black(), 
        new RectangleF(e.get_Bounds().get_X() + rectangle.get_Width(),
        e.get_Bounds().get_Y(), e.get_Bounds().get_Width(),
        e.get_Bounds().get_Height()));
    // Draw the focus rectangle if the mouse hovers over an item.
    e.DrawFocusRectangle();
} //comboBox1_DrawItem

Plattformen

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

.NET Framework unterstützt nicht alle Versionen sämtlicher Plattformen. Eine Liste der unterstützten Versionen finden Sie unter Systemanforderungen.

Versionsinformationen

.NET Framework

Unterstützt in: 2.0, 1.1, 1.0

Siehe auch

Referenz

ComboBox-Klasse
ComboBox-Member
System.Windows.Forms-Namespace