ComboBox::DropDownStyle Property

 
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Gets or sets a value specifying the style of the combo box.

Namespace:   System.Windows.Forms
Assembly:  System.Windows.Forms (in System.Windows.Forms.dll)

public:
property ComboBoxStyle DropDownStyle {
	ComboBoxStyle get();
	void set(ComboBoxStyle value);
}

Property Value

Type: System.Windows.Forms::ComboBoxStyle

One of the ComboBoxStyle values. The default is DropDown.

Exception Condition
InvalidEnumArgumentException

The assigned value is not one of the ComboBoxStyle values.

The DropDownStyle property specifies whether the list is always displayed or whether the list is displayed in a drop-down. The DropDownStyle property also specifies whether the text portion can be edited. See ComboBoxStyle for the available settings and their effects. There is no setting to always display the list and disallow entering a new value. To display a list to which no new values can be added, use a ListBox control.

The following code example demonstrates setting the DropDownStyle property. To run the example, paste the following code in a form. Call the InitializeComboBox method in the form's constructor or Load event.

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();
   }

.NET Framework
Available since 1.1
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