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MeasureItemEventHandler Delegate

Represents the method that will handle the MeasureItem event of the ListBox, ComboBox, CheckedListBox, or MenuItem controls.

Namespace:  System.Windows.Forms
Assembly:  System.Windows.Forms (in System.Windows.Forms.dll)
public delegate void MeasureItemEventHandler(
	Object sender,
	MeasureItemEventArgs e
)

Parameters

sender
Type: System.Object
The source of the event.
e
Type: System.Windows.Forms.MeasureItemEventArgs
A MeasureItemEventArgs that contains the event data.

When you create a MeasureItemEventHandler delegate, you identify the method that will handle the event. To associate the event with your event handler, add an instance of the delegate to the event. The event handler is called whenever the event occurs, unless you remove the delegate. For more information about event handler delegates, see Events and Delegates.

The following code example demonstrates using the Graphics property to perform custom drawing of the items in a ListBox.


   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;
         }
      }
   }


.NET Framework

Supported in: 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
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