使用 IStorage/IStream 从 C# 拖放到 Windows 资源管理器
我已经在听起来简单的功能上工作了太久了。 我的想法是我有一个带有 TreeView 的应用程序。 此树视图表示组织为文件和文件夹的数据库内容，与 Windows 资源管理器非常相似。 因此，用户应该能够将这些文件/文件夹从我的应用程序拖到 Windows 资源管理器中，这是有道理的。
我决定，如果他们拖动文件，我应该使用 IStream；如果他们拖动文件夹，我应该使用 IStorage。 经过很长一段时间并学习了比我想了解的更多有关 Win32/COM 的知识（以及这里一位非常乐于助人的人的推动），我终于有了 IStream 或 IStorage已创建。
然后我发现要将这个 IStream 或 IStorage 传递给 Windows 资源管理器，我必须将其放入 STGMEDIUM 中。 当然，medium.tymed 将是 IStream 或 IStorage，具体取决于我使用的，但据我了解，medium.unionmember code> 必须是指向 IStream/IStorage 的指针。
我尝试过使用fixed关键字（但它当然不是blittable），我尝试过将被破坏的东西转换为字节数组，但无法想出一种方法来实现这一点，我尝试过使用 GCHandle 来固定它（但它仍然不可 blittable），以及其他一些不起作用的东西。
所以我的问题是这样的：给定 IStorage s 和 STGMEDIUM m，我如何填充 m.unionmember 以便 Windows 资源管理器会高兴并接受下降？
I've been working on what sounds like simple functionality for way too long now. The idea is that I have an application with a TreeView. This treeview represents contents of a database organized into files and folders, much like Windows Explorer. So it makes sense that the user should be able to drag those files/folders out of my app and into Windows Explorer.
I decided that I should use an IStream if they drag a file or an IStorage if they drag a folder. After a very long time and learning way more than I ever wanted to know about Win32/COM (and a nudge from a very helpful person here), I finally have that IStream or IStorage created.
Then I found that to pass this IStream or IStorage off to Windows Explorer, I had to get it in an STGMEDIUM. Of course, the medium.tymed will be either IStream or IStorage, depending on which I'm using, but as I understand it the medium.unionmember must be a pointer to the IStream/IStorage.
I've tried using the fixed keyword (but it's not blittable, of course), I've tried just converting the blasted thing to a byte array, but can't come up with a way to make that happen, I've tried using GCHandle to pin it (but it still isn't blittable), and several other things that didn't work.
So my question is this: Given IStorage s and STGMEDIUM m, how do I populate m.unionmember so that Windows Explorer will be happy and accept the drop?
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通常，C 联合在 C# 中使用
StructLayout.Explicit表示。 然而，这可能不适用于您的情况 - 虽然您可以像这样覆盖IStream和IStorage引用，但编组器将尝试编组两者。 您最好的选择可能是在STGMEDIUM声明中将该字段声明为IntPtr，并使用Marshal.GetIUnknownForObject对其进行初始化。Normally, C unions are represented using
StructLayout.Explicitin C#. This probably won't work in your case, however - while you can overlayIStreamandIStoragereferences like that, the marshaller will try to marshal both. Your best bet is probably to just declare the field asIntPtrin your declaration ofSTGMEDIUM, and useMarshal.GetIUnknownForObjectto initialize it.我认为这个主题已经过时很久了，但是任何想要文件拖放的人都可以查看此讨论，尤其是 dbirdz 的帖子： http://www.daniweb.com/forums/thread166429.html
在我看来，这甚至适用于这个应用程序，我会尝试将我的流写入一个临时文件，该文件可以然后被移动到它的位置。
I think the topic is outdated by long, however anyone looking for a file drag and drop check out this discussion and especially the post of dbirdz: http://www.daniweb.com/forums/thread166429.html
In my eyes this would even apply to this application, I'd try to write my stream into a temporary file which could then be moved to its location.