ComponentEditor Class
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ComponentEditor Class

Provides the base class for a custom component editor.

Namespace: System.ComponentModel
Assembly: System (in system.dll)

public ref class ComponentEditor abstract
public abstract class ComponentEditor
public abstract class ComponentEditor
Not applicable.

A component editor is used to edit a component as a whole and can be used to implement a user interface similar to that of the property pages. You associate a component editor with a component by using the EditorAttribute attribute.

Notes to Inheritors: When you inherit from this class, you must override the EditComponent method.

The following code example demonstrates an example ComponentEditor implementation.

#using <System.Windows.Forms.dll>
#using <System.Drawing.dll>
#using <System.dll>

using namespace System;
using namespace System::ComponentModel;
using namespace System::ComponentModel::Design;
using namespace System::Collections;
using namespace System::Drawing;
using namespace System::IO;
using namespace System::Runtime::Serialization;
using namespace System::Runtime::Serialization::Formatters::Binary;
using namespace System::Windows::Forms;
using namespace System::Windows::Forms::Design;

// This example demonstrates how to implement a component editor that hosts 
// component pages and associate it with a component. This example also 
// demonstrates how to implement a component page that provides a panel-based 
// control system and Help keyword support.

   ref class ExampleComponentEditorPage;

   // The ExampleComponentEditor displays two ExampleComponentEditorPage pages.
   public ref class ExampleComponentEditor: public System::Windows::Forms::Design::WindowsFormsComponentEditor

      // This method override returns an type array containing the type of 
      // each component editor page to display.
      virtual array<Type^>^ GetComponentEditorPages() override
         array<Type^>^temp0 = {ExampleComponentEditorPage::typeid,ExampleComponentEditorPage::typeid};
         return temp0;

      // This method override returns the index of the page to display when the 
      // component editor is first displayed.
      virtual int GetInitialComponentEditorPageIndex() override
         return 1;

   // This example component editor page type provides an example 
   // ComponentEditorPage implementation.
   private ref class ExampleComponentEditorPage: public System::Windows::Forms::Design::ComponentEditorPage
      Label^ l1;
      Button^ b1;
      PropertyGrid^ pg1;

      // Base64-encoded serialized image data for the required component editor page icon.
      String^ icon;

         String^ temp = "AAEAAAD/////AQAAAAAAAAAMAgAAAFRTeXN0ZW0uRHJhd2luZywgVmVyc2lvbj0xLjAuNTAwMC4wLCBDdWx0dXJlPW5ldXRyYWwsIFB1YmxpY0tleVRva2VuPWIwM2Y1ZjdmMTFkNTBhM2EFAQAAABNTeXN0ZW0uRHJhd2luZy5JY29uAgAAAAhJY29uRGF0Y"
         icon = temp;
         // Initialize the page, which inherits from Panel, and its controls.
         this->Size = System::Drawing::Size( 400, 250 );
         this->Icon = DeserializeIconFromBase64Text( icon );
         this->Text = "Example Page";
         b1 = gcnew Button;
         b1->Size = System::Drawing::Size( 200, 20 );
         b1->Location = Point(200,0);
         b1->Text = "Set a random background color";
         b1->Click += gcnew EventHandler( this, &ExampleComponentEditorPage::randomBackColor );
         this->Controls->Add( b1 );
         l1 = gcnew Label;
         l1->Size = System::Drawing::Size( 190, 20 );
         l1->Location = Point(4,2);
         l1->Text = "Example Component Editor Page";
         this->Controls->Add( l1 );
         pg1 = gcnew PropertyGrid;
         pg1->Size = System::Drawing::Size( 400, 280 );
         pg1->Location = Point(0,30);
         this->Controls->Add( pg1 );

      // This method indicates that the Help button should be enabled for this 
      // component editor page.
      virtual bool SupportsHelp() override
         return true;

      // This method is called when the Help button for this component editor page is pressed.
      // This implementation uses the IHelpService to show the Help topic for a sample keyword.
      virtual void ShowHelp() override
         // The GetSelectedComponent method of a ComponentEditorPage retrieves the
         // IComponent associated with the WindowsFormsComponentEditor.
         IComponent^ selectedComponent = this->GetSelectedComponent();

         // Retrieve the Site of the component, and return if null.
         ISite^ componentSite = selectedComponent->Site;
         if ( componentSite == nullptr )

         // Acquire the IHelpService to display a help topic using a indexed keyword lookup.
         IHelpService^ helpService = dynamic_cast<IHelpService^>(componentSite->GetService( IHelpService::typeid ));
         if ( helpService != nullptr )
                  helpService->ShowHelpFromKeyword( "System.Windows.Forms.ComboBox" );


      // The LoadComponent method is raised when the ComponentEditorPage is displayed.
      virtual void LoadComponent() override
         this->pg1->SelectedObject = this->Component;

      // The SaveComponent method is raised when the WindowsFormsComponentEditor is closing 
      // or the current ComponentEditorPage is closing.
      virtual void SaveComponent() override {}


      // If the associated component is a Control, this method sets the BackColor to a random color.
      // This method is invoked by the button on this ComponentEditorPage.
      void randomBackColor( Object^ /*sender*/, EventArgs^ /*e*/ )
         if ( System::Windows::Forms::Control::typeid->IsAssignableFrom( this->::Component::GetType() ) )
            // Sets the background color of the Control associated with the
            // WindowsFormsComponentEditor to a random color.
            Random^ rnd = gcnew Random;
            (dynamic_cast<System::Windows::Forms::Control^>(this->Component))->BackColor = Color::FromArgb( rnd->Next( 255 ), rnd->Next( 255 ), rnd->Next( 255 ) );

      // This method can be used to retrieve an Icon from a block 
      // of Base64-encoded text.
      System::Drawing::Icon^ DeserializeIconFromBase64Text( String^ text )
         System::Drawing::Icon^ img = nullptr;
         array<Byte>^memBytes = Convert::FromBase64String( text );
         IFormatter^ formatter = gcnew BinaryFormatter;
         MemoryStream^ stream = gcnew MemoryStream( memBytes );
         img = dynamic_cast<System::Drawing::Icon^>(formatter->Deserialize( stream ));
         return img;

   // This example control is associated with the ExampleComponentEditor 
   // through the following EditorAttribute.

   public ref class ExampleUserControl: public System::Windows::Forms::UserControl{};

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

Windows 98, Windows Server 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0, 1.1, 1.0

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