[英]Can this COM interface be implemented in C#?
A COM component is currently implemented in C++ and the next version must be implemented in C#. COM 组件目前是用 C++ 实现的,下一个版本必须用 C# 实现。 The component is called from C++ (not CLI) code.该组件是从 C++(不是 CLI)代码调用的。 The major part of the not so small component is already ported to C#, but I have trouble to figure out how one specific method can be translated.不是那么小的组件的主要部分已经移植到 C#,但我很难弄清楚如何翻译一种特定的方法。
The following imports are used in the IDL: IDL 中使用了以下导入:
import "oaidl.idl";
import "ocidl.idl";
The major part of the interface is already translated to the corresponding C# attributes, interfaces and classes.接口的主要部分已经转换为相应的 C# 属性、接口和类。 Most of it works without problems.它的大部分工作没有问题。
But one of the interface members is defined in IDL as但是接口成员之一在 IDL 中定义为
[
object,
uuid(<guid>),
helpstring("Help"),
pointer_default(unique)
]
interface IStuff : IUnknown
{
...
HRESULT GetShortText([in] int i, [in] BOOL b, [out, string] TCHAR shortText[10]);
...
}
To use the interface, a local TCHAR[10]
array is passed as the name of the array (therefore, as a TCHAR*
).要使用该接口,将本地TCHAR[10]
数组作为数组的名称(因此,作为TCHAR*
)传递。 The COM server must put a short string in the TCHAR array. COM 服务器必须在 TCHAR 数组中放置一个短字符串。
I can't manage to call the method.我无法调用该方法。 Breakpoints set in the C# COM server in the GetShortText
method are never hit.在 C# COM 服务器中GetShortText
方法中设置的断点永远不会被命中。 COM simply doensn't find my implementation in .NET. COM 根本没有在 .NET 中找到我的实现。
How can this method that is called with a fixed size TCHAR*
be correctly implemented in C#?这个以固定大小TCHAR*
调用的方法如何在 C# 中正确实现?
I am not aware of any standard marshalling for this rather unusual construct.我不知道这个相当不寻常的构造有任何标准编组。 You might do the following, however:但是,您可以执行以下操作:
void GetShortText(int i, [MarshalAs:UnmanagedType.Bool] bool b, IntPtr shortTextPtr)
{
string s = "Test";
byte[] buffer;
if (UseUnicode)
buffer = Encoding.Unicode.GetBytes(s + '\0');
else
buffer = Encoding.Default.GetBytes(s + '\0');
Marshal.Copy(buffer, 0, shortTextPtr, buffer.Length);
}
Notes:笔记:
+ '\\0'
is for null-terminating the returned string + '\\0'
用于空终止返回的字符串This sort of interface can be implemented in .Net by specifying the parameter as an IntPtr
and manually marshalling the string.通过将参数指定为IntPtr
并手动编组字符串,可以在 .Net 中实现这种接口。 A full demo can be found on Github .可以在 Github上找到完整的演示。
Example Implementation:示例实现:
[ComVisible(true), Guid("E559D616-4C46-4434-9DF7-E9D7C91F3BA5"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
public interface IStuff
{
void GetShortTest(int i, [MarshalAs(UnmanagedType.Bool)] bool b, IntPtr shortText);
}
[ComVisible(true), ProgId("InProcTargetTest.Class1"), Guid("BA5088D4-7F6A-4C76-983C-EC7F1BA51CAA"), ClassInterface(ClassInterfaceType.None)]
public class Class1 : IStuff
{
public void GetShortTest(int i, bool b, IntPtr shortText)
{
var data = Encoding.Unicode.GetBytes("Hello");
Marshal.Copy(data, 0, shortText, data.Length);
}
}
Example caller:示例调用者:
if (FAILED(CoInitialize(nullptr))) {
std::cout << "Failed to initialize COM\n";
}
IStuff *pStuff = nullptr;
CLSID clsClass1 = { 0 };
if (FAILED(CLSIDFromProgID(L"InProcTargetTest.Class1", &clsClass1))
|| FAILED(CoCreateInstance(clsClass1, nullptr, CLSCTX_INPROC_SERVER, IID_IStuff, (LPVOID*)&pStuff))) {
std::cout << "Failed to create COM instance\n";
}
TCHAR test[10] = { 0 };
pStuff->GetShortTest(5, true, test);
std::cout << "From C#: " << test << "\n";
Example IDL:示例 IDL:
import "unknwn.idl";
[
odl,
uuid(E559D616-4C46-4434-9DF7-E9D7C91F3BA5),
version(1.0),
pointer_default(unique),
custom(0F21F359-AB84-41E8-9A78-36D110E6D2F9, "InProcTargetTest.IStuff")
]
interface IStuff : IUnknown {
HRESULT _stdcall GetShortTest(
[in] long i,
[in] BOOL b,
[out, string] TCHAR shortText[10]);
};
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