DrawItemState DrawItemState DrawItemState DrawItemState Enum

定义

指定正在绘制的项的状态。Specifies the state of an item that is being drawn.

此枚举有一个 FlagsAttribute 属性,允许按位组合成员值。

public enum class DrawItemState
[System.Flags]
public enum DrawItemState
type DrawItemState = 
Public Enum DrawItemState
继承
DrawItemStateDrawItemStateDrawItemStateDrawItemState
属性

字段

Checked Checked Checked Checked 8

已选中该项。The item is checked. 仅菜单控件使用此值。Only menu controls use this value.

ComboBoxEdit ComboBoxEdit ComboBoxEdit ComboBoxEdit 4096

该项是 ComboBox 的编辑部分。The item is the editing portion of a ComboBox.

Default Default Default Default 32

该项处于它的默认可视状态。The item is in its default visual state.

Disabled Disabled Disabled Disabled 4

该项不可用。The item is unavailable.

Focus Focus Focus Focus 16

该项有焦点。The item has focus.

Grayed Grayed Grayed Grayed 2

该项变灰。The item is grayed. 仅菜单控件使用此值。Only menu controls use this value.

HotLight HotLight HotLight HotLight 64

该项被热跟踪(当鼠标指针移到该项上时,该项被突出显示)。The item is being hot-tracked, that is, the item is highlighted as the mouse pointer passes over it.

Inactive Inactive Inactive Inactive 128

该项处于非活动状态。The item is inactive.

NoAccelerator NoAccelerator NoAccelerator NoAccelerator 256

该项显示时没有键盘加速键。The item displays without a keyboard accelerator.

NoFocusRect NoFocusRect NoFocusRect NoFocusRect 512

该项显示时没有指示它是否有焦点的可视化提示。The item displays without the visual cue that indicates it has focus.

None None None None 0

该项当前没有状态。The item currently has no state.

Selected Selected Selected Selected 1

该项已选定。The item is selected.

示例

下面的代码示例演示如何使用Graphics属性来对ListBox中的项执行自定义绘制。The following code example demonstrates using the Graphics property to perform custom drawing of the items in a ListBox.

public ref class Form1: public System::Windows::Forms::Form
{
private:
   System::Windows::Forms::ListBox^ listBox1;
   System::ComponentModel::Container^ components;

public:
   ~Form1()
   {
      if ( components != nullptr )
      {
         delete components;
      }
   }

private:

   /// <summary>
   /// Required method for Designer support - do not modify
   /// the contents of this method with the code editor.
   /// </summary>
   void InitializeComponent()
   {
      this->listBox1 = gcnew System::Windows::Forms::ListBox;
      this->SuspendLayout();

      // 
      // listBox1
      // 
      this->listBox1->DrawMode = System::Windows::Forms::DrawMode::OwnerDrawVariable;
      this->listBox1->Location = System::Drawing::Point( 16, 48 );
      this->listBox1->Name = "listBox1";
      this->listBox1->SelectionMode = System::Windows::Forms::SelectionMode::MultiExtended;
      this->listBox1->Size = System::Drawing::Size( 256, 134 );
      this->listBox1->TabIndex = 0;
      this->listBox1->MeasureItem += gcnew System::Windows::Forms::MeasureItemEventHandler( this, &Form1::listBox1_MeasureItem );
      this->listBox1->DrawItem += gcnew System::Windows::Forms::DrawItemEventHandler( this, &Form1::listBox1_DrawItem );

      // 
      // Form1
      // 
      this->ClientSize = System::Drawing::Size( 292, 273 );
      array<System::Windows::Forms::Control^>^temp0 = {this->listBox1};
      this->Controls->AddRange( temp0 );
      this->Name = "Form1";
      this->Text = "Form1";
      this->ResumeLayout( false );
   }

   void listBox1_MeasureItem( Object^ /*sender*/, MeasureItemEventArgs^ e )
   {
      System::Drawing::Font^ font = (dynamic_cast<ListBoxFontItem^>(listBox1->Items[ e->Index ]))->Font;
      SizeF stringSize = e->Graphics->MeasureString( font->Name, font );
      
      // Set the height and width of the item
      e->ItemHeight = (int)stringSize.Height;
      e->ItemWidth = (int)stringSize.Width;
   }

   // For efficiency, cache the brush to use for drawing.
   SolidBrush^ foreColorBrush;
   void listBox1_DrawItem( Object^ /*sender*/, DrawItemEventArgs^ e )
   {
      Brush^ brush;

      // Create the brush using the ForeColor specified by the DrawItemEventArgs
      if ( foreColorBrush == nullptr )
            foreColorBrush = gcnew SolidBrush( e->ForeColor );
      else
      if ( foreColorBrush->Color != e->ForeColor )
      {
         // The control's ForeColor has changed, so dispose of the cached brush and
         // create a new one.
         delete foreColorBrush;
         foreColorBrush = gcnew SolidBrush( e->ForeColor );
      }

      // Select the appropriate brush depending on if the item is selected.
      // Since State can be a combinateion (bit-flag) of enum values, you can't use
      // "==" to compare them.
      if ( (e->State & DrawItemState::Selected) == DrawItemState::Selected )
            brush = SystemBrushes::HighlightText;
      else
            brush = foreColorBrush;

      // Perform the painting.
      System::Drawing::Font^ font = (dynamic_cast<ListBoxFontItem^>(listBox1->Items[ e->Index ]))->Font;
      e->DrawBackground();
      e->Graphics->DrawString( font->Name, font, brush, e->Bounds );
      e->DrawFocusRectangle();
   }

public:

   /// <summary>
   ///  A wrapper class for use with storing Fonts in a ListBox.  Since ListBox uses the
   ///  ToString() of its items for the text it displays, this class is needed to return
   ///  the name of the font, rather than its ToString() value.
   /// </summary>
   ref class ListBoxFontItem
   {
   public:
      System::Drawing::Font^ Font;
      ListBoxFontItem( System::Drawing::Font^ f )
      {
         Font = f;
      }

      virtual String^ ToString() override
      {
         return Font->Name;
      }
   };
};

[STAThread]
int main()
{
   Application::Run( gcnew Form1 );
}
 public class Form1 : System.Windows.Forms.Form
 {
    private System.Windows.Forms.ListBox listBox1;
    private System.ComponentModel.Container components = null;


    protected override void Dispose(bool disposing)
    {
       if( disposing )
       {
          if ( components != null ) 
             components.Dispose();

          if ( foreColorBrush != null )
             foreColorBrush.Dispose();
       }
       base.Dispose(disposing);
    }

#region Windows Form Designer generated code
    /// <summary>
    /// Required method for Designer support - do not modify
    /// the contents of this method with the code editor.
    /// </summary>
    private void InitializeComponent()
    {
       this.listBox1 = new System.Windows.Forms.ListBox();
       this.SuspendLayout();
       // 
       // listBox1
       // 
       this.listBox1.DrawMode = System.Windows.Forms.DrawMode.OwnerDrawVariable;
       this.listBox1.Location = new System.Drawing.Point(16, 48);
       this.listBox1.Name = "listBox1";
       this.listBox1.SelectionMode = System.Windows.Forms.SelectionMode.MultiExtended;
       this.listBox1.Size = new System.Drawing.Size(256, 134);
       this.listBox1.TabIndex = 0;
       this.listBox1.MeasureItem += new System.Windows.Forms.MeasureItemEventHandler(this.listBox1_MeasureItem);
       this.listBox1.DrawItem += new System.Windows.Forms.DrawItemEventHandler(this.listBox1_DrawItem);
       // 
       // Form1
       // 
       this.ClientSize = new System.Drawing.Size(292, 273);
       this.Controls.AddRange(new System.Windows.Forms.Control[] {
                                                                    this.listBox1});
       this.Name = "Form1";
       this.Text = "Form1";
       this.ResumeLayout(false);

    }
#endregion

    [STAThread]
    static void Main() 
    {
       Application.Run(new Form1());
    }

    private void listBox1_MeasureItem(object sender, System.Windows.Forms.MeasureItemEventArgs e)
    {
       Font font = ((ListBoxFontItem)listBox1.Items[e.Index]).Font;
       SizeF stringSize = e.Graphics.MeasureString(font.Name, font);

       // Set the height and width of the item
       e.ItemHeight = (int)stringSize.Height;
       e.ItemWidth = (int)stringSize.Width;
    }

    // For efficiency, cache the brush to use for drawing.
    private SolidBrush foreColorBrush;

    private void listBox1_DrawItem(object sender, System.Windows.Forms.DrawItemEventArgs e)
    {
       Brush brush;

       // Create the brush using the ForeColor specified by the DrawItemEventArgs
       if ( foreColorBrush == null )
          foreColorBrush = new SolidBrush(e.ForeColor);
       else if ( foreColorBrush.Color != e.ForeColor )
       {
          // The control's ForeColor has changed, so dispose of the cached brush and
          // create a new one.
          foreColorBrush.Dispose();
          foreColorBrush = new SolidBrush(e.ForeColor);
       }

       // Select the appropriate brush depending on if the item is selected.
       // Since State can be a combinateion (bit-flag) of enum values, you can't use
       // "==" to compare them.
       if ( (e.State & DrawItemState.Selected) == DrawItemState.Selected )
          brush = SystemBrushes.HighlightText;
       else
          brush = foreColorBrush;

       // Perform the painting.
       Font font = ((ListBoxFontItem)listBox1.Items[e.Index]).Font;
       e.DrawBackground();
       e.Graphics.DrawString(font.Name, font, brush, e.Bounds);
       e.DrawFocusRectangle();
    }

    /// <summary>
    ///  A wrapper class for use with storing Fonts in a ListBox.  Since ListBox uses the
    ///  ToString() of its items for the text it displays, this class is needed to return
    ///  the name of the font, rather than its ToString() value.
    /// </summary>
    public class ListBoxFontItem 
    {
       public Font Font;

       public ListBoxFontItem(Font f) 
       {
          Font = f;
       }

       public override string ToString() 
       {
          return Font.Name;
       }
    }
 }
Public Class Form1
   Inherits System.Windows.Forms.Form
   Private WithEvents listBox1 As System.Windows.Forms.ListBox
   Private components As System.ComponentModel.Container = Nothing

   Private FontSize As Single = 12.0F

   '
   '  This sample displays a ListBox that contains a list of all the fonts
   '  installed on the system and draws each item in its respective font.
   '
   Public Sub New()
      InitializeComponent()

      ' Populate control with the fonts installed on the system.
      Dim families As FontFamily() = FontFamily.Families

      Dim family As FontFamily
      For Each family In families
         Dim style As FontStyle = FontStyle.Regular

         ' Monotype Corsiva is only available in italic
         If family.Name = "Monotype Corsiva" Then
            style = style Or FontStyle.Italic
         End If

         listBox1.Items.Add(New ListBoxFontItem(New Font(family.Name, FontSize, style, GraphicsUnit.Point)))
      Next family
   End Sub


   Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
      If disposing Then
         If (components IsNot Nothing) Then
            components.Dispose()
         End If

         If (foreColorBrush IsNot Nothing) Then
            foreColorBrush.Dispose()
         End If
      End If

      MyBase.Dispose(disposing)
   End Sub

   Private Sub InitializeComponent()
      Me.listBox1 = New System.Windows.Forms.ListBox()
      Me.SuspendLayout()
      ' 
      ' listBox1
      ' 
      Me.listBox1.DrawMode = System.Windows.Forms.DrawMode.OwnerDrawVariable
      Me.listBox1.Location = New System.Drawing.Point(16, 48)
      Me.listBox1.Name = "listBox1"
      Me.listBox1.SelectionMode = System.Windows.Forms.SelectionMode.MultiExtended
      Me.listBox1.Size = New System.Drawing.Size(256, 134)
      Me.listBox1.TabIndex = 0
      ' 
      ' Form1
      ' 
      Me.ClientSize = New System.Drawing.Size(292, 273)
      Me.Controls.AddRange(New System.Windows.Forms.Control() {Me.listBox1})
      Me.Name = "Form1"
      Me.Text = "Form1"
      Me.ResumeLayout(False)
   End Sub

   <STAThread()> Shared Sub Main()
      Application.Run(New Form1())
   End Sub

   Private Sub listBox1_MeasureItem(ByVal sender As Object, ByVal e As System.Windows.Forms.MeasureItemEventArgs) Handles listBox1.MeasureItem
      Dim font As Font = CType(listBox1.Items(e.Index), ListBoxFontItem).Font
      Dim stringSize As SizeF = e.Graphics.MeasureString(font.Name, font)

      ' Set the height and width of the item
      e.ItemHeight = CInt(stringSize.Height)
      e.ItemWidth = CInt(stringSize.Width)
   End Sub

   ' For efficiency, cache the brush used for drawing.
   Private foreColorBrush As SolidBrush

   Private Sub listBox1_DrawItem(ByVal sender As Object, ByVal e As System.Windows.Forms.DrawItemEventArgs) Handles listBox1.DrawItem
      Dim brush As Brush

      ' Create the brush using the ForeColor specified by the DrawItemEventArgs
      If foreColorBrush Is Nothing Then
         foreColorBrush = New SolidBrush(e.ForeColor)
      Else
         If Not foreColorBrush.Color.Equals(e.ForeColor) Then
            ' The control's ForeColor has changed, so dispose of the cached brush and
            ' create a new one.
            foreColorBrush.Dispose()
            foreColorBrush = New SolidBrush(e.ForeColor)
         End If
      End If

      ' Select the appropriate brush depending on if the item is selected.
      ' Since State can be a combinateion (bit-flag) of enum values, you can't use
      ' "==" to compare them.
      If (e.State And DrawItemState.Selected) = DrawItemState.Selected Then
         brush = SystemBrushes.HighlightText
      Else
         brush = foreColorBrush
      End If

      ' Perform the painting.
      Dim font As Font = CType(listBox1.Items(e.Index), ListBoxFontItem).Font
      e.DrawBackground()
      e.Graphics.DrawString(font.Name, font, brush, e.Bounds.X, e.Bounds.Y)
      e.DrawFocusRectangle()
   End Sub

   '
   '  A wrapper class for use with storing Fonts in a ListBox.  Since ListBox uses the
   '  ToString() of its items for the text it displays, this class is needed to return
   '  the name of the font, rather than its ToString() value.
   '
   Public Class ListBoxFontItem
      Public Font As Font

      Public Sub New(ByVal f As Font)
         Font = f
      End Sub

      Public Overrides Function ToString() As String
         Return Font.Name
      End Function
   End Class
End Class

注解

此枚举由成员 (如) DrawItemEventArgs.State使用。This enumeration is used by members such as DrawItemEventArgs.State.

适用于

另请参阅