LayoutKind LayoutKind LayoutKind LayoutKind Enum

Definizione

Controlla il layout di un oggetto durante l'esportazione nel codice non gestito.Controls the layout of an object when exported to unmanaged code.

public enum class LayoutKind
[System.Runtime.InteropServices.ComVisible(true)]
[System.Serializable]
public enum LayoutKind
type LayoutKind = 
Public Enum LayoutKind
Ereditarietà
Attributi

Campi

Auto Auto Auto Auto 3

Durante il runtime viene automaticamente scelto un layout appropriato per i membri di un oggetto nella memoria non gestita.The runtime automatically chooses an appropriate layout for the members of an object in unmanaged memory. Gli oggetti definiti con questo membro di enumerazione non possono essere esposti all'esterno del codice gestito.Objects defined with this enumeration member cannot be exposed outside of managed code. Qualsiasi tentativo di eseguire tale operazione genera un'eccezione.Attempting to do so generates an exception.

Explicit Explicit Explicit Explicit 2

La posizione esatta di ogni membro di un oggetto nella memoria non gestita viene controllata in modo esplicito ed è soggetta all'impostazione del campo Pack.The precise position of each member of an object in unmanaged memory is explicitly controlled, subject to the setting of the Pack field. Ogni membro deve utilizzare FieldOffsetAttribute per indicare la posizione di tale campo all'interno del tipo.Each member must use the FieldOffsetAttribute to indicate the position of that field within the type.

Sequential Sequential Sequential Sequential 0

I membri dell'oggetto vengono disposti in sequenza, nell'ordine in cui si trovano al momento dell'esportazione nella memoria non gestita.The members of the object are laid out sequentially, in the order in which they appear when exported to unmanaged memory. I membri vengono disposti in base alla compressione specificata in Pack e possono essere non contigui.The members are laid out according to the packing specified in Pack, and can be noncontiguous.

Esempi

L'esempio seguente illustra la dichiarazione di gestito il PtInRect funzione, che controlla se un punto si trova all'interno di un rettangolo e definisce un Point struttura con un layout sequenziale e un Rect struttura con layout esplicito.The following example shows the managed declaration of the PtInRect function, which checks whether a point lies within a rectangle, and defines a Point structure with Sequential layout and a Rect structure with Explicit layout.

enum class Bool
{
   False = 0,
   True
};


[StructLayout(LayoutKind::Sequential)]
value struct Point
{
public:
   int x;
   int y;
};


[StructLayout(LayoutKind::Explicit)]
value struct Rect
{
public:

   [FieldOffset(0)]
   int left;

   [FieldOffset(4)]
   int top;

   [FieldOffset(8)]
   int right;

   [FieldOffset(12)]
   int bottom;
};

ref class NativeMethods
{
public:

   [DllImport("user32.dll",CallingConvention=CallingConvention::StdCall)]
   static Bool PtInRect( Rect * r, Point p );
};

int main()
{
   try
   {
      Bool bPointInRect = (Bool)0;
      Rect myRect = Rect(  );
      myRect.left = 10;
      myRect.right = 100;
      myRect.top = 10;
      myRect.bottom = 100;
      Point myPoint = Point(  );
      myPoint.x = 50;
      myPoint.y = 50;
      bPointInRect = NativeMethods::PtInRect(  &myRect, myPoint );
      if ( bPointInRect == Bool::True )
            Console::WriteLine( "Point lies within the Rect" );
      else
            Console::WriteLine( "Point did not lie within the Rect" );
   }
   catch ( Exception^ e ) 
   {
      Console::WriteLine( "Exception : {0}", e->Message );
   }

}

enum Bool
{
   False = 0,
   True
};
[StructLayout(LayoutKind.Sequential)]
public struct Point 
{
   public int x;
   public int y;
}   

[StructLayout(LayoutKind.Explicit)]
public struct Rect 
{
   [FieldOffset(0)] public int left;
   [FieldOffset(4)] public int top;
   [FieldOffset(8)] public int right;
   [FieldOffset(12)] public int bottom;
}   

internal static class NativeMethods
{
   [DllImport("user32.dll", CallingConvention=CallingConvention.StdCall)]
   internal static extern Bool PtInRect(ref Rect r, Point p);
};

class TestApplication
{
   public static void Main()
   {
      try
      {
         Bool bPointInRect = 0;
         Rect myRect = new Rect();
         myRect.left = 10;
         myRect.right = 100;
         myRect.top = 10;
         myRect.bottom = 100;
         Point myPoint = new Point();
         myPoint.x = 50;
         myPoint.y = 50;
         bPointInRect = NativeMethods.PtInRect(ref myRect, myPoint);
         if(bPointInRect == Bool.True)
            Console.WriteLine("Point lies within the Rect");
         else
            Console.WriteLine("Point did not lie within the Rect");
      }
      catch(Exception e)
      {
         Console.WriteLine("Exception : " + e.Message);
      }
   }
}
'  The program shows a managed declaration of the PtInRect function and defines Point
'  structure with sequential layout and Rect structure with explicit layout. The PtInRect
'  checks the point lies within the rectangle or not.
Imports System
Imports System.Runtime.InteropServices

   Enum Bool
      [False] = 0
      [True]
   End Enum 
   <StructLayout(LayoutKind.Sequential)>  _
   Public Structure Point
      Public x As Integer
      Public y As Integer
   End Structure 
   
   <StructLayout(LayoutKind.Explicit)>  _   
   Public Structure Rect
      <FieldOffset(0)> Public left As Integer
      <FieldOffset(4)> Public top As Integer
      <FieldOffset(8)> Public right As Integer
      <FieldOffset(12)> Public bottom As Integer
   End Structure 
   
   
   Friend Class NativeMethods
      
      <DllImport("user32.dll", CallingConvention := CallingConvention.StdCall)>  _
      Friend Shared Function PtInRect(ByRef r As Rect, p As Point) As Bool
      End Function	
   End Class 'NativeMethods
   
   
   Class TestApplication
      
      Public Shared Sub Main()
         Try
            Dim bPointInRect As Bool = 0
            Dim myRect As New Rect()
            myRect.left = 10
            myRect.right = 100
            myRect.top = 10
            myRect.bottom = 100
            Dim myPoint As New Point()
            myPoint.x = 50
            myPoint.y = 50
            bPointInRect = NativeMethods.PtInRect(myRect, myPoint)
            If bPointInRect = Bool.True Then
               Console.WriteLine("Point lies within the Rect")
            Else
               Console.WriteLine("Point did not lie within the Rect")
            End If
         Catch e As Exception
            Console.WriteLine(("Exception : " + e.Message.ToString()))
         End Try
      End Sub 
   End Class 

Commenti

Questa enumerazione viene utilizzata con StructLayoutAttribute.This enumeration is used with StructLayoutAttribute. Common language runtime usa la Auto valore layout per impostazione predefinita.The common language runtime uses the Auto layout value by default. Per ridurre i problemi correlati al layout associati con il Auto valore, i compilatori c#, Visual Basic e C++ specificano Sequential layout per i tipi di valore.To reduce layout-related problems associated with the Auto value, C#, Visual Basic, and C++ compilers specify Sequential layout for value types.

Importante

Il StructLayoutAttribute.Pack campo controlla l'allineamento dei campi dati e pertanto influisce sul layout indipendentemente il LayoutKind valore specificato.The StructLayoutAttribute.Pack field controls the alignment of data fields, and thus affects the layout regardless of the LayoutKind value you specify. Per impostazione predefinita, il valore di Pack è 0, che indica il valore predefinito di compressione delle dimensioni per la piattaforma corrente.By default, the value of Pack is 0, which indicates the default packing size for the current platform. Ad esempio, quando si usa la Explicit layout e indicare gli allineamenti campo nei limiti di byte, è necessario impostare Pack su 1 per ottenere il risultato desiderato.For example, when you use the Explicit layout value and specify field alignments on byte boundaries, you must set Pack to 1 to get the desired result.

Si applica a