LayoutKind 枚举

参考

定义

命名空间:: System.Runtime.InteropServices

程序集:: System.Runtime.dll

程序集:: mscorlib.dll

程序集:: netstandard.dll

重要

一些信息与预发行产品相关，相应产品在发行之前可能会进行重大修改。对于此处提供的信息，Microsoft 不作任何明示或暗示的担保。

当将对象导出到非托管代码时，控制该对象的布局。

public enum class LayoutKind

public enum LayoutKind

[System.Serializable]
public enum LayoutKind

[System.Serializable]
[System.Runtime.InteropServices.ComVisible(true)]
public enum LayoutKind

type LayoutKind =

[<System.Serializable>]
type LayoutKind =

[<System.Serializable>]
[<System.Runtime.InteropServices.ComVisible(true)>]
type LayoutKind =

Public Enum LayoutKind

继承: Object

ValueType

Enum
LayoutKind

属性: SerializableAttribute ComVisibleAttribute

字段

名称	值	说明
Auto	3	运行库自动为非托管内存中的对象的成员选择适当的布局。使用此枚举成员定义的对象不能在托管代码的外部公开。尝试这样做将引发异常。
Explicit	2	在未管理内存中的每一个对象成员的精确位置是被显式控制的，服从于 Pack 字段的设置。每个成员必须使用 FieldOffsetAttribute 指示该字段在类型中的位置。
Sequential	0	对象的成员按照它们在被导出到非托管内存时出现的顺序依次布局。这些成员根据在 Pack 中指定的封装进行布局，并且可以是不连续的。

示例

以下示例演示函数的 PtInRect 托管声明，该函数检查点是否位于矩形内，并定义 Point 具有顺序布局的结构和 Rect 具有显式布局的结构。

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.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
   
   
   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

注解

此枚举与一 StructLayoutAttribute起使用。默认情况下，公共语言运行时使用 Auto 布局值。为了减少与值相关的 Auto 布局相关问题，C#、Visual Basic 和 C++ 编译器为值类型指定 Sequential 布局。

重要

字段 StructLayoutAttribute.Pack 控制数据字段的对齐方式，因此无论指定的值如何 LayoutKind ，都会影响布局。默认情况下，的 Pack 值为 0，表示当前平台的默认打包大小。例如，使用 Explicit 布局值并在字节边界上指定字段对齐时，必须将设置为 Pack 1 才能获得所需的结果。

适用于

产品	版本
.NET	Core 1.0, Core 1.1, Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9
.NET Framework	1.1, 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1
.NET Standard	1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 2.0, 2.1
UWP	10.0

通过

LayoutKind 枚举

定义

字段

示例

注解

适用于

其他资源