Bagikan melalui

InstanceDescriptor Kelas

  • Referensi

Definisi

Ruang nama:
System.ComponentModel.Design.Serialization
Rakitan:
System.ComponentModel.TypeConverter.dll
Rakitan:
System.dll
Rakitan:
netstandard.dll
Sumber:
InstanceDescriptor.cs
Sumber:
InstanceDescriptor.cs
Sumber:
InstanceDescriptor.cs

Menyediakan informasi yang diperlukan untuk membuat instans objek. Kelas ini tidak dapat diwariskan.

public ref class InstanceDescriptor sealed
public sealed class InstanceDescriptor
type InstanceDescriptor = class
Public NotInheritable Class InstanceDescriptor
Warisan
Object
InstanceDescriptor

Contoh

Contoh kode berikut menggambarkan cara menggunakan pengonversi jenis yang berpartisipasi dalam pembuatan kode melalui penggunaan deskriptor instans.

#using <system.dll>
#using <system.drawing.dll>

using namespace System;
using namespace System::ComponentModel;
using namespace System::ComponentModel::Design::Serialization;
using namespace System::Drawing;
using namespace System::Globalization;
using namespace System::Collections;
using namespace System::Reflection;

/*   This sample shows how to support code generation for a custom type of object 
         using a type converter and InstanceDescriptor objects.

         To use this code, copy it to a file and add the file to a project. Then add
         a component to the project and declare a Triangle field and a public property 
         with accessors for the Triangle field on the component.

         The Triangle property will be persisted using code generation.
    */
ref class TriangleConverter;

[TypeConverter(TriangleConverter::typeid)]
public ref class Triangle
{
private:

   // Triangle members
   Point P1;
   Point P2;
   Point P3;

public:

   property Point Point1 
   {
      Point get()
      {
         return P1;
      }

      void set( Point value )
      {
         P1 = value;
      }
   }

   property Point Point2 
   {
      Point get()
      {
         return P2;
      }

      void set( Point value )
      {
         P2 = value;
      }
   }

   property Point Point3 
   {
      Point get()
      {
         return P3;
      }

      void set( Point value )
      {
         P3 = value;
      }

   }
   Triangle( Point point1, Point point2, Point point3 )
   {
      P1 = point1;
      P2 = point2;
      P3 = point3;
   }


   /* A TypeConverter for the Triangle object.  Note that you can make it internal,
      private, or any scope you want and the designers will still be able to use
      it through the TypeDescriptor object.  This type converter provides the
      capability to convert to an InstanceDescriptor.  This object can be used by 
      the .NET Framework to generate source code that creates an instance of a 
      Triangle object. */
   [System::Security::Permissions::PermissionSet(System::Security::
      Permissions::SecurityAction::Demand, Name = "FullTrust")]
   ref class TriangleConverter: public TypeConverter
   {
   public:

      /* This method overrides CanConvertTo from TypeConverter. This is called when someone
            wants to convert an instance of Triangle to another type.  Here,
            only conversion to an InstanceDescriptor is supported. */
      virtual bool CanConvertTo( ITypeDescriptorContext^ context, Type^ destinationType ) override
      {
         if ( destinationType == InstanceDescriptor::typeid )
         {
            return true;
         }

         
         // Always call the base to see if it can perform the conversion.
         return TypeConverter::CanConvertTo( context, destinationType );
      }

      /* This code performs the actual conversion from a Triangle to an InstanceDescriptor. */
      virtual Object^ ConvertTo( ITypeDescriptorContext^ context, CultureInfo^ culture, Object^ value, Type^ destinationType ) override
      {
         if ( destinationType == InstanceDescriptor::typeid )
         {
            array<Type^>^type1 = {Point::typeid,Point::typeid,Point::typeid};
            ConstructorInfo^ ci = Triangle::typeid->GetConstructor( type1 );
            Triangle^ t = safe_cast<Triangle^>(value);
            array<Object^>^obj1 = {t->Point1,t->Point2,t->Point3};
            return gcnew InstanceDescriptor( ci,safe_cast<ICollection^>(obj1) );
         }

         // Always call base, even if you can't convert.
         return TypeConverter::ConvertTo( context, culture, value, destinationType );
      }
   };
};

public ref class TestComponent: public System::ComponentModel::Component
{
private:
   Triangle^ myTriangle;

public:
   TestComponent()
   {
      myTriangle = gcnew Triangle( Point(5,5),Point(10,10),Point(1,8) );
   }

   property Triangle^ MyTriangle 
   {
      Triangle^ get()
      {
         return myTriangle;
      }

      void set( Triangle^ value )
      {
         myTriangle = value;
      }
   }
};

namespace Microsoft.Samples.InstanceDescriptorSample
{
    using System;
    using System.ComponentModel;
    using System.ComponentModel.Design.Serialization;
    using System.Drawing;
    using System.Globalization;
    using System.Reflection;

    //  This sample shows how to support code generation for a custom type 
    //  of object using a type converter and InstanceDescriptor objects.

    //  To use this code, copy it to a file and add the file to a project. 
    //  Then add a component to the project and declare a Triangle field and 
    //  a public property with accessors for the Triangle field on the component.

    //  The Triangle property will be persisted using code generation.

    [TypeConverter(typeof(Triangle.TriangleConverter))]
    public class Triangle
    {
        // Triangle members.
        Point P1;
        Point P2;
        Point P3;

        public Point Point1 {
            get {
                return P1;
            }
            set {
                P1 = value;
            }
        }
        public Point Point2 {
            get 
            {
                return P2;
            }
            set 
            {
                P2 = value;
            }
        }
        public Point Point3 {
            get 
            {
                return P3;
            }
            set 
            {
                P3 = value;
            }
        }

        public Triangle(Point point1,Point point2,Point point3) {
            P1 = point1;
            P2 = point2;
            P3 = point3;
        }

        // A TypeConverter for the Triangle object.  Note that you can make it internal,
        //  private, or any scope you want and the designers will still be able to use
        //  it through the TypeDescriptor object.  This type converter provides the
        //  capability to convert to an InstanceDescriptor.  This object can be used by 
    //  the .NET Framework to generate source code that creates an instance of a 
    //  Triangle object.
        internal class TriangleConverter : TypeConverter
        {
            // This method overrides CanConvertTo from TypeConverter. This is called when someone
            //  wants to convert an instance of Triangle to another type.  Here,
            //  only conversion to an InstanceDescriptor is supported.
            public override bool CanConvertTo(ITypeDescriptorContext context, Type destinationType)
            {
                if (destinationType == typeof(InstanceDescriptor))
                {
                    return true;
                }

                // Always call the base to see if it can perform the conversion.
                return base.CanConvertTo(context, destinationType);
            }

            // This code performs the actual conversion from a Triangle to an InstanceDescriptor.
            public override object ConvertTo(ITypeDescriptorContext context, CultureInfo culture, object value, Type destinationType)
            {
                if (destinationType == typeof(InstanceDescriptor))
                {
                    ConstructorInfo ci = typeof(Triangle).GetConstructor(new Type[]{typeof(Point),
                                                    typeof(Point),typeof(Point)});
                    Triangle t = (Triangle) value;
                    return new InstanceDescriptor(ci,new object[]{t.Point1,t.Point2,t.Point3});
                }

                // Always call base, even if you can't convert.
                return base.ConvertTo(context, culture, value, destinationType);
            }
        }
    }

    public class TestComponent : System.ComponentModel.Component 
    {
        Triangle myTriangle;

        public TestComponent() {
            myTriangle = new Triangle(
                new Point(5,5),
                new Point(10,10),
                new Point(1,8)
                );
        }

        public Triangle MyTriangle {
            get {
                return myTriangle;
            }
            set {
                myTriangle = value;
            }
        }
    }
}

Imports System.ComponentModel
Imports System.ComponentModel.Design.Serialization
Imports System.Drawing
Imports System.Globalization
Imports System.Reflection
Namespace Microsoft.Samples.InstanceDescriptorSample

   '  This sample shows how to support code generation for a custom type 
   '  of object using a type converter and InstanceDescriptor objects.
   '
   '  To use this code, copy it to a file and add the file to a project.  
   '  Then add a component to the project and declare a Triangle field and 
   '  a public property with accessors for the Triangle field on the component.
   '
   '  The Triangle property will be persisted using code generation.

   <TypeConverter(GetType(Triangle.TriangleConverter))> _
   Public Class Triangle
      ' Triangle members.
      Private P1 As Point
      Private P2 As Point
      Private P3 As Point

      Public Property Point1() As Point
         Get
            Return P1
         End Get
         Set(ByVal Value As Point)
            P1 = Value
         End Set
      End Property

      Public Property Point2() As Point
         Get
            Return P2
         End Get
         Set(ByVal Value As Point)
            P2 = Value
         End Set
      End Property

      Public Property Point3() As Point
         Get
            Return P3
         End Get
         Set(ByVal Value As Point)
            P3 = Value
         End Set
      End Property

      Public Sub New(ByVal point1 As Point, ByVal point2 As Point, ByVal point3 As Point)
         P1 = point1
         P2 = point2
         P3 = point3
      End Sub

      ' A TypeConverter for the Triangle object.  Note that you can make it internal,
      '  private, or any scope you want and the designers will still be able to use
      '  it through the TypeDescriptor object.  This type converter provides the
      '  capability to convert to an InstanceDescriptor.  This object can be used by 
      '  the .NET Framework to generate source code that creates an instance of a 
      '  Triangle object.

      Friend Class TriangleConverter
         Inherits TypeConverter

         ' This method overrides CanConvertTo from TypeConverter.  This is called when someone
         '  wants to convert an instance of Triangle to another type.  Here,
         '  only coversition to an InstanceDescriptor is supported.
         Public Overloads Overrides Function CanConvertTo(ByVal context As ITypeDescriptorContext, ByVal destinationType As Type) As Boolean
            If destinationType Is GetType(InstanceDescriptor) Then
               Return True
            End If

            ' Always call the base to see if it can perform the conversion.
            Return MyBase.CanConvertTo(context, destinationType)
         End Function

         ' This code performs the actual conversion from a Triangle to an InstanceDescriptor.
         Public Overloads Overrides Function ConvertTo(ByVal context As ITypeDescriptorContext, ByVal culture As CultureInfo, ByVal value As Object, ByVal destinationType As Type) As Object
            If destinationType Is GetType(InstanceDescriptor) Then
               Dim ci As ConstructorInfo = GetType(Triangle).GetConstructor(New Type() {GetType(Point), GetType(Point), GetType(Point)})
               Dim t As Triangle = CType(value, Triangle)
               Return New InstanceDescriptor(ci, New Object() {t.Point1, t.Point2, t.Point3})
            End If

            ' Always call base, even if you can't convert.
            Return MyBase.ConvertTo(context, culture, value, destinationType)
         End Function 
      End Class 
   End Class 

   Public Class TestComponent
      Inherits System.ComponentModel.Component
      Private myTriangleProp As Triangle

      Public Sub New()
         myTriangleProp = New Triangle(New Point(5, 5), _
                                    New Point(10, 10), New Point(1, 8))
      End Sub

      Public Property MyTriangle() As Triangle
         Get
            Return myTriangleProp
         End Get
         Set(ByVal Value As Triangle)
            myTriangleProp = Value
         End Set
      End Property

   End Class

End Namespace

Keterangan

InstanceDescriptor dapat menyimpan informasi yang menjelaskan instans objek. Informasi ini dapat digunakan untuk membuat instans objek.

Beberapa serializer kustom menggunakan InstanceDescriptor untuk mewakili objek yang dapat diserialisasikan. Beberapa metode penggunaan TypeDescriptorInstanceDescriptor untuk mewakili atau membuat instans objek.

Menyediakan InstanceDescriptor anggota berikut:

  • Properti MemberInfo yang menjelaskan objek ini.

  • Properti Arguments yang terdiri dari argumen konstruktor yang dapat digunakan untuk membuat instans objek ini.

  • Properti Boolean IsComplete yang menunjukkan apakah objek benar-benar diwakili oleh informasi saat ini.

  • Metode Invoke yang dapat digunakan untuk membuat instans objek yang diwakili.

Konstruktor

InstanceDescriptor(MemberInfo, ICollection)

Menginisialisasi instans InstanceDescriptor baru kelas menggunakan informasi dan argumen anggota yang ditentukan.
InstanceDescriptor(MemberInfo, ICollection, Boolean)

Menginisialisasi instans InstanceDescriptor baru kelas menggunakan informasi anggota, argumen, dan nilai yang ditentukan yang menunjukkan apakah informasi yang ditentukan sepenuhnya menjelaskan instans.

Properti

Arguments

Mendapatkan kumpulan argumen yang dapat digunakan untuk merekonstruksi instans objek yang diwakili deskriptor instans ini.
IsComplete

Mendapatkan nilai yang menunjukkan apakah konten ini InstanceDescriptor sepenuhnya mengidentifikasi instans.
MemberInfo

Mendapatkan informasi anggota yang menjelaskan instans yang dikaitkan dengan deskriptor ini.

Metode

Equals(Object)

Menentukan apakah objek yang ditentukan sama dengan objek saat ini.

(Diperoleh dari Object)
GetHashCode()

Berfungsi sebagai fungsi hash default.

(Diperoleh dari Object)
GetType()

Mendapatkan dari instans Type saat ini.

(Diperoleh dari Object)
Invoke()

Memanggil deskriptor instans ini dan mengembalikan objek yang dijelaskan deskriptor.
MemberwiseClone()

Membuat salinan dangkal dari saat ini Object.

(Diperoleh dari Object)
ToString()

Mengembalikan string yang mewakili objek saat ini.

(Diperoleh dari Object)

Berlaku untuk

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