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<Type Name="StructLayoutAttribute" FullName="System.Runtime.InteropServices.StructLayoutAttribute" FullNameSP="System_Runtime_InteropServices_StructLayoutAttribute" Maintainer="ecma">
<TypeSignature Language="ILASM" Value=".class public sealed StructLayoutAttribute extends System.Attribute" />
<TypeSignature Language="C#" Value="public sealed class StructLayoutAttribute : System.Attribute" />
<MemberOfLibrary>RuntimeInfrastructure</MemberOfLibrary>
<AssemblyInfo>
<AssemblyName>mscorlib</AssemblyName>
<AssemblyPublicKey>[00 00 00 00 00 00 00 00 04 00 00 00 00 00 00 00 ]</AssemblyPublicKey>
<AssemblyVersion>1.0.5000.0</AssemblyVersion>
</AssemblyInfo>
<ThreadingSafetyStatement>All public static members of this type are safe for multithreaded operations. No instance members are guaranteed to be thread safe.</ThreadingSafetyStatement>
<Docs>
<summary>
<para>The <see cref="T:System.Runtime.InteropServices.StructLayoutAttribute" />
allows the user to control the physical layout
of the data members of a class or structure.</para>
</summary>
<remarks>
<para> The target objects for this attribute are classes and structures. By default, the physical layout of the data members of a target object is automatically arranged.
When managed objects are passed as arguments to unmanaged code,
the system creates their unmanaged representations. These unmanaged representations can
be controlled with the <see cref="T:System.Runtime.InteropServices.StructLayoutAttribute" /> .
Such control is necessary if the unmanaged code expects a specific layout, packing
size, or character set.</para>
<para>
<block subset="none" type="note">See the <see cref="T:System.Runtime.InteropServices.LayoutKind" />
enumeration for a description of the possible layout schemes, and the <see cref="T:System.Runtime.InteropServices.FieldOffsetAttribute" /> for further information on the layout of exported objects.</block>
</para>
<para>Compilers are required to not preserve this type
in metadata as a custom attribute. Instead, compilers are required to emit it
directly in the file format, as described in Partition II of the CLI
Specification. Metadata consumers, such as the Reflection API, are required to
retrieve this data from the file format and return it as if it were a custom
attribute. </para>
</remarks>
<example>
<para>The following example demonstrates the use of the <see cref="T:System.Runtime.InteropServices.StructLayoutAttribute" />, and the <see cref="T:System.Runtime.InteropServices.FieldOffsetAttribute" />.</para>
<para>
<block subset="none" type="note">The non-standard
<see langword=" PtInRect" />
function used in this example indicates whether the specified point is
located inside the specified rectangle. In this example, the layout setting on the
<see langword="Rect" />
structure can be
set to <see cref="F:System.Runtime.InteropServices.LayoutKind.Sequential" />
with no bearing on the end
result.</block>
</para>
<code lang="C#">using System;
using System.Runtime.InteropServices;
[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;
}
class NativeCodeAPI {
[DllImport("User32.dll")]
public static extern bool PtInRect(ref Rect r, Point p);
}
public class StructLayoutTest {
public static void Main() {
Rect r;
Point p1, p2;
r.left = 0;
r.right = 100;
r.top = 0;
r.bottom = 100;
p1.x = 20;
p1.y = 30;
p2.x = 110;
p2.y = 5;
bool isInside1 = NativeCodeAPI.PtInRect(ref r, p1);
bool isInside2 = NativeCodeAPI.PtInRect(ref r, p2);
if(isInside1)
Console.WriteLine("The first point is inside the rectangle.");
else
Console.WriteLine("The first point is outside the rectangle.");
if(isInside2)
Console.WriteLine("The second point is inside the rectangle.");
else
Console.WriteLine("The second point is outside the rectangle.");
}
}
</code>
<para>The output is</para>
<c>
<para>The first point is inside the rectangle.</para>
<para>The second point is outside the rectangle.</para>
</c>
</example>
</Docs>
<Base>
<BaseTypeName>System.Attribute</BaseTypeName>
</Base>
<Interfaces />
<Attributes>
<Attribute>
<AttributeName>System.AttributeUsage(System.AttributeTargets.All, Inherited=false)</AttributeName>
</Attribute>
</Attributes>
<Members>
<Member MemberName="Pack">
<MemberSignature Language="ILASM" Value=".field public int32 Pack" />
<MemberSignature Language="C#" Value="public int Pack;" />
<MemberType>Field</MemberType>
<ReturnValue>
<ReturnType>System.Int32</ReturnType>
</ReturnValue>
<Parameters />
<Docs>
<summary>
<para> A <see cref="T:System.Int32" /> that indicates the packing alignment used with the
<see cref="F:System.Runtime.InteropServices.LayoutKind.Sequential" /> layout. </para>
</summary>
<remarks>
<para>The <see cref="F:System.Runtime.InteropServices.StructLayoutAttribute.Pack" /> field determines memory
alignment of data fields of a target object.</para>
<para>Data fields of a target object exported to unmanaged
memory are
aligned on
a byte boundary that is a multiple of <see cref="F:System.Runtime.InteropServices.StructLayoutAttribute.Pack" /> bytes, or at
some natural alignment for that field type, whichever is smaller.</para>
<para>The value of <see cref="F:System.Runtime.InteropServices.StructLayoutAttribute.Pack" /> is
required to be 0, 1, 2, 4, 8, 16, 32, 64, or 128. A value of zero indicates that
the packing alignment is set to the default for the current platform.
The default value is implementation-defined.</para>
</remarks>
</Docs>
<Excluded>0</Excluded>
</Member>
<Member MemberName="Size">
<MemberSignature Language="ILASM" Value=".field public int32 Size" />
<MemberSignature Language="C#" Value="public int Size;" />
<MemberType>Field</MemberType>
<ReturnValue>
<ReturnType>System.Int32</ReturnType>
</ReturnValue>
<Parameters />
<Docs>
<summary>
<para>A <see cref="T:System.Int32" /> that indicates the size of the memory block to be allocated
for an instance of the type qualified by the current <see cref="T:System.Runtime.InteropServices.StructLayoutAttribute" />.</para>
</summary>
<remarks>
<para>
<see cref="F:System.Runtime.InteropServices.StructLayoutAttribute.Size" /> is required to
be zero, or greater than or equal to the calculated size of the target object,
based on the <see cref="F:System.Runtime.InteropServices.StructLayoutAttribute.Pack" /> field indicating the packing
alignment. A <see cref="F:System.Runtime.InteropServices.StructLayoutAttribute.Size" qualify="true" /> of zero
indicates that the size is calculated from the field types, their specified offsets, the packing size (default or
specified) and natural alignment on the target, runtime platform.</para>
<para>
<block subset="none" type="note">For additional
information on the <see cref="F:System.Runtime.InteropServices.StructLayoutAttribute.Size" qualify="true" />
field, see Partition II of the CLI Specification.</block>
</para>
</remarks>
</Docs>
<Excluded>0</Excluded>
</Member>
<Member MemberName="CharSet">
<MemberSignature Language="ILASM" Value=".field public valuetype System.Runtime.InteropServices.CharSet CharSet" />
<MemberSignature Language="C#" Value="public System.Runtime.InteropServices.CharSet CharSet;" />
<MemberType>Field</MemberType>
<ReturnValue>
<ReturnType>System.Runtime.InteropServices.CharSet</ReturnType>
</ReturnValue>
<Parameters />
<Docs>
<summary>
<para>A <see cref="T:System.Runtime.InteropServices.CharSet" /> value that indicates the character set in which strings of an object are
marshaled.</para>
</summary>
<remarks>
<para>
<block subset="none" type="note">See the <see cref="T:System.Runtime.InteropServices.CharSet" />
enumeration for a description of different character sets.</block>
</para>
<para>The default value of this field is
<see cref="F:System.Runtime.InteropServices.CharSet.Ansi" />.</para>
</remarks>
</Docs>
<Excluded>0</Excluded>
</Member>
<Member MemberName=".ctor">
<MemberSignature Language="ILASM" Value="public rtspecialname specialname instance void .ctor(valuetype System.Runtime.InteropServices.LayoutKind layoutKind)" />
<MemberSignature Language="C#" Value="public StructLayoutAttribute (System.Runtime.InteropServices.LayoutKind layoutKind);" />
<MemberType>Constructor</MemberType>
<ReturnValue />
<Parameters>
<Parameter Name="layoutKind" Type="System.Runtime.InteropServices.LayoutKind" />
</Parameters>
<Docs>
<summary>
<para>Constructs and initializes a new instance of the <see cref="T:System.Runtime.InteropServices.StructLayoutAttribute" /> class
with the specified <see cref="T:System.Runtime.InteropServices.LayoutKind" /> value.</para>
</summary>
<param name="layoutKind">A <see cref="T:System.Runtime.InteropServices.LayoutKind" /> value that specifies how the class or structure is arranged in memory.</param>
<remarks>
<para> If <paramref name="layoutKind" /> contains an invalid
<see cref="T:System.Runtime.InteropServices.LayoutKind" /> value,
a runtime error occurs.</para>
</remarks>
</Docs>
<Excluded>0</Excluded>
</Member>
<Member MemberName=".ctor">
<MemberSignature Language="ILASM" Value="public rtspecialname specialname instance void .ctor(int16 layoutKind)" />
<MemberSignature Language="C#" Value="public StructLayoutAttribute (short layoutKind);" />
<MemberType>Constructor</MemberType>
<ReturnValue />
<Parameters>
<Parameter Name="layoutKind" Type="System.Int16" />
</Parameters>
<Docs>
<summary>
<para>Constructs and initializes a new instance of the
<see cref="T:System.Runtime.InteropServices.StructLayoutAttribute" /> class
with the specified value.</para>
</summary>
<param name="layoutKind">A <see cref="T:System.Int16" /> set to a <see cref="T:System.Runtime.InteropServices.LayoutKind" /> value that specifies how the class or structure is arranged in memory.</param>
<remarks>
<para>If the <paramref name="layoutKind" />
parameter does not represent a valid <see cref="T:System.Runtime.InteropServices.LayoutKind" />
value, a
runtime error occurs.</para>
</remarks>
</Docs>
<Excluded>0</Excluded>
</Member>
<Member MemberName="Value">
<MemberSignature Language="ILASM" Value=".property valuetype System.Runtime.InteropServices.LayoutKind Value { public hidebysig specialname instance valuetype System.Runtime.InteropServices.LayoutKind get_Value() }" />
<MemberSignature Language="C#" Value="public System.Runtime.InteropServices.LayoutKind Value { get; };" />
<MemberType>Property</MemberType>
<ReturnValue>
<ReturnType>System.Runtime.InteropServices.LayoutKind</ReturnType>
</ReturnValue>
<Parameters />
<Docs>
<summary>
<para>Gets the <see cref="T:System.Runtime.InteropServices.LayoutKind" /> value that specifies how
the target object is arranged.</para>
</summary>
<value>
<para>A <see cref="T:System.Runtime.InteropServices.LayoutKind" /> value that specifies how
the target object is arranged.</para>
</value>
<remarks>
<para>This property is read-only.</para>
</remarks>
</Docs>
<Excluded>0</Excluded>
</Member>
</Members>
<TypeExcluded>0</TypeExcluded>
</Type>
|
