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MeasureItemEventArgs Class

Provides data for the MeasureItem event of the ListBox, ComboBox, CheckedListBox, and MenuItem controls.

System::Object
  System::EventArgs
    System.Windows.Forms::MeasureItemEventArgs

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

public ref class MeasureItemEventArgs : public EventArgs

The MeasureItemEventArgs type exposes the following members.

  NameDescription
Public methodMeasureItemEventArgs(Graphics, Int32)Initializes a new instance of the MeasureItemEventArgs class.
Public methodMeasureItemEventArgs(Graphics, Int32, Int32)Initializes a new instance of the MeasureItemEventArgs class providing a parameter for the item height.
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  NameDescription
Public propertyGraphicsGets the Graphics object to measure against.
Public propertyIndexGets the index of the item for which the height and width is needed.
Public propertyItemHeightGets or sets the height of the item specified by the Index.
Public propertyItemWidthGets or sets the width of the item specified by the Index.
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  NameDescription
Public methodEquals(Object)Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
Protected methodFinalizeAllows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
Public methodGetHashCodeServes as a hash function for a particular type. (Inherited from Object.)
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Protected methodMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Public methodToStringReturns a string that represents the current object. (Inherited from Object.)
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This event is sent when the OwnerDraw property of ListBox, ComboBox, CheckedListBox, or MenuItem is set to true. It is used to tell the drawing function how to size an item.

For information about the event model, see Events and Delegates.

The following code example demonstrates how to use 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 );
}


.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.

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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