C# 将结构数组转换为 IntPtr
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原文地址: http://stackoverflow.com/questions/1086294/
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Convert array of structs to IntPtr
提问by Vegard Larsen
I am trying to convert an array of the RECT structure (given below) into an IntPtr, so I can send the pointer using PostMessage to another application.
我正在尝试将 RECT 结构的数组（如下所示）转换为 IntPtr，因此我可以使用 PostMessage 将指针发送到另一个应用程序。
[StructLayout(LayoutKind.Sequential)]
public struct RECT
{
public int Left;
public int Top;
public int Right;
public int Bottom;
// lots of functions snipped here
}
// so we have something to send, in reality I have real data here
// also, the length of the array is not constant
RECT[] foo = new RECT[4];
IntPtr ptr = Marshal.AllocHGlobal(Marshal.SizeOf(foo[0]) * 4);
Marshal.StructureToPtr(foo, ptr, true); // -- FAILS
This gives an ArgumentException on the last line ("The specified structure must be blittable or have layout information."). I need to somehow get this array of RECTs over to another application using PostMessage, so I really need a pointer to this data.
这在最后一行给出了一个 ArgumentException（“指定的结构必须是 blittable 或具有布局信息。”）。我需要以某种方式使用 PostMessage 将这个 RECT 数组传递给另一个应用程序，所以我真的需要一个指向这个数据的指针。
What are my options here?
我在这里有哪些选择？
UPDATE: This seems to work:
更新：这似乎有效：
IntPtr result = Marshal.AllocHGlobal(Marshal.SizeOf(typeof(Win32.RECT)) * foo.Length);
IntPtr c = new IntPtr(result.ToInt32());
for (i = 0; i < foo.Length; i++)
{
Marshal.StructureToPtr(foo[i], c, true);
c = new IntPtr(c.ToInt32() + Marshal.SizeOf(typeof(Win32.RECT)));
}
UPDATED AGAINto fix what arbiter commented on.
再次更新以修复仲裁者评论的内容。
采纳答案by arbiter
StructureToPtr expects struct object, and foo is not structure it is array, that is why exception occurs.
StructureToPtr 需要 struct 对象，而 foo 不是结构，而是数组，这就是发生异常的原因。
I can suggest you to write structures in cycle (sadly, StructureToPtr does not have overload with Index):
我可以建议您循环编写结构（遗憾的是，StructureToPtr 没有索引过载）：
long LongPtr = ptr.ToInt64(); // Must work both on x86 and x64
for (int I = 0; I < foo.Length; I++)
{
IntPtr RectPtr = new IntPtr(LongPtr);
Marshal.StructureToPtr(foo[I], RectPtr, false); // You do not need to erase struct in this case
LongPtr += Marshal.SizeOf(typeof(Rect));
}
Another option is to write structure as four integers, using Marshal.WriteInt32:
另一种选择是使用 Marshal.WriteInt32 将结构写为四个整数：
for (int I = 0; I < foo.Length; I++)
{
int Base = I * sizeof(int) * 4;
Marshal.WriteInt32(ptr, Base + 0, foo[I].Left);
Marshal.WriteInt32(ptr, Base + sizeof(int), foo[I].Top);
Marshal.WriteInt32(ptr, Base + sizeof(int) * 2, foo[I].Right);
Marshal.WriteInt32(ptr, Base + sizeof(int) * 3, foo[I].Bottom);
}
And the last, you can use unsafekeyword, and work with pointers directly.
最后，您可以使用unsafe关键字，并直接使用指针。
回答by devdimi
You could try the following:
您可以尝试以下操作：
RECT[] rects = new RECT[ 4 ];
IntPtr[] pointers = new IntPtr[4];
IntPtr result = Marshal.AllocHGlobal(IntPtr.Size * rects.Length);
for (int i = 0; i < rects.Length; i++)
{
pointers[i] = Marshal.AllocHGlobal (IntPtr.Size);
Marshal.StructureToPtr(rects[i], pointers[i], true);
Marshal.WriteIntPtr(result, i * IntPtr.Size, pointers[i]);
}
// the array that you need is stored in result
And don't forget to free everything after you are finished.
完成后不要忘记释放所有内容。
回答by Stephen Martin
Arbiter has given you one good answer for how to marshal arrays of structs. For blittable structs like these I, personally, would use unsafe code rather than manually marshaling each element to unmanaged memory. Something like this:
Arbiter 为您提供了一个关于如何编组结构数组的好答案。对于像这样的 blittable 结构，我个人会使用不安全的代码，而不是手动将每个元素编组到非托管内存。像这样的东西：
RECT[] foo = new RECT[4];
unsafe
{
fixed (RECT* pBuffer = foo)
{
//Do work with pointer
}
}
or you could pin the array using a GCHandle.
或者您可以使用 GCHandle 固定数组。
Unfortunately, you say you need to send this information to another process. If the message you are posting is not one of the ones for which Windows provides automatic marshaling then you have another problem. Since the pointer is relative to the local process it means nothing in the remote process and posting a message with this pointer will cause unexpected behavior, including likely program crash. So what you need to do is write the RECT array to the other process' memory not your own. To do this you need to use OpenProcess to get a handle to the process, VitualAllocEx to allocate the memory in the other process and then WriteProcessMemory to write the array into the other process' virtual memory.
不幸的是，您说您需要将此信息发送到另一个进程。如果您发布的消息不是 Windows 为其提供自动封送处理的消息之一，那么您还有另一个问题。由于该指针是相对于本地进程的，因此在远程进程中没有任何意义，使用此指针发布消息将导致意外行为，包括可能的程序崩溃。所以你需要做的是将 RECT 数组写入另一个进程的内存而不是你自己的内存。为此，您需要使用 OpenProcess 来获取进程的句柄，使用 VitualAllocEx 在另一个进程中分配内存，然后使用 WriteProcessMemory 将数组写入另一个进程的虚拟内存。
Unfortunately again, if you are going from a 32bit process to a 32bit process or from a 64bit process to a 64bit process things are quite straightforward but from a 32bit process to a 64bit process things can get a little hairy. VirtualAllocEx and WriteProcessMemory are not really supported from 32 to 64. You may have success by trying to force VirtualAllocEx to allocate its memory in the bottom 4GB of the 64bit memory space so that the resultant pointer is valid for the 32bit process API calls and then write with that pointer. In addition, you may have struct size and packing differences between the two process types. With RECT there is no problem but some other structs with packing or alignment issues might need to be manually written field by field to the 64bit process in order to match the 64bit struct layout.
再次不幸的是，如果您从 32 位进程转到 32 位进程或从 64 位进程转到 64 位进程，事情非常简单，但从 32 位进程到 64 位进程，事情可能会变得有点麻烦。从 32 到 64，VirtualAllocEx 和 WriteProcessMemory 并没有真正得到支持。您可能会成功通过尝试强制 VirtualAllocEx 在 64 位内存空间的底部 4GB 中分配其内存，以便结果指针对 32 位进程 API 调用有效，然后写入用那个指针。此外，您可能在两种进程类型之间存在结构大小和打包差异。使用 RECT 没有问题，但其他一些具有打包或对齐问题的结构可能需要逐个字段手动写入 64 位进程，以便匹配 64 位结构布局。
回答by Dan H
I was unable to get this solution to work. So, I did some searching and the solution given here worked for me.
我无法使此解决方案起作用。所以，我做了一些搜索，这里给出的解决方案对我有用。
http://social.msdn.microsoft.com/Forums/en-US/clr/thread/dcfd6310-b03b-4552-b4c7-6c11c115eb45
http://social.msdn.microsoft.com/Forums/en-US/clr/thread/dcfd6310-b03b-4552-b4c7-6c11c115eb45
