COM Discussion Boards

4-Feb-04 3:53

I'm trying to get a file path from a pointer to a PIDL.

This is using the following function:

BOOL SHGetPathFromIDList(
LPCITEMIDLIST pidl,
LPTSTR pszPath
);

where pidl is an IntPtr to a pidl pulled from the SHBrowseForFolder.

I am using the following lines of code to call it:

<br />
			IntPtr pidl = SHBrowseForFolder(lpbi);<br />
			string filePath = new string(' ', 200);<br />
			SHGetPathFromIDList(pidl,out filePath);<br />

via the wrapped method:

<br />
		[DllImport("shell32.dll", CharSet=CharSet.Auto)]<br />
		public static extern int SHGetPathFromIDList(<br />
			IntPtr pidl,<br />
			[Out, MarshalAs(UnmanagedType.BStr)]<br />
				out string pszPath); <br />

The problem is that while pidl has a value, the method crashes when I try and interpret a file / folder greater than 1 depth.
And if it does not crash, I get the unmodified string returned to me.

Any ideas what I'm doing wrong?

Cheers

Cata

Edit: I suppose the question is - How do I construct a buffer of size Max_Path, and then create a pointer to it?

Solved

Tristan Rhodes4-Feb-04 10:55

Re: SHGetPathFromIDList - Problem

4-Feb-04 10:55

Solved it, no need to reply ^^

Mike Dimmick5-Feb-04 0:58

Mike Dimmick

5-Feb-04 0:58

Use a StringBuilder. Note: wrong forum, please use the NET Framework forum for .NET questions.

SHBrowseForFolder problem

Tristan Rhodes4-Feb-04 1:19

Re: SHBrowseForFolder problem

4-Feb-04 1:19

I'm new to COM, so I am experimenting with some simple functions. I've had a degree of success with the SHBrowseForFolder function, in that I can open the dialog, setup the flags, rename it etc.
These are all parameters in the in/out structure struct_browseinfo.

The problem I have is, this inout structure is supposed to return a field pszDisplayName which contains the path of the folder right?

I've tried marshaling it as a number of different types of strings, and even an intptr (I am using C#), but it's always null, no matter what I do.

I'm using no owner for the dialog, no pidl root value, and the function still returns a folder index, But no string name.

Any idea why this is?

Cheers

Cata

Tristan Rhodes4-Feb-04 2:01

4-Feb-04 2:01

I've looked into it a bit further, and the pszDisplayName is a pointer to a buffer of MAX_PATH charachters.

How would I go about marshaling this in C#?

I'm assuming that is what causes it to be a null value...

Any help appreciated.

Cheers

Cata

Partial Solution

Tristan Rhodes4-Feb-04 2:55

4-Feb-04 2:55

Ok, I've solved it using a pre initialised string. Thank you VS.NET for helpful error messages ^^

Anyway, Does this dialog box return the full path? Or am I stuck with only getting the folders name...

There has to be some way to fetch the full path... but i'll carry on looking at the tutorial now I have this solved.

Regards

Cata

Method overloading

Anonymous3-Feb-04 4:19

Anonymous

3-Feb-04 4:19

Hello

Can I overload my COM object methods? I want to have two methods:

addMyObject(BSTR name);
addMyObject(BSTR name, BSTR address);

Can I do this? If not, is there a way of doing it or must I use different names for my methods?

Re: Method overloading

Steve S3-Feb-04 22:55

Paste img from any application like Paint, Ms Photoeditor,etc

3-Feb-04 22:55

No, use different names. Technically it's possible, but it's a nightmare. Using different names is easier.

From an "official" point of view, the names of the methods are irrelevant, unless it's IDispatch based, but it's sooo much easier with different names;

addMyObject(BSTR name);
addMyObjectWithAddress(BSTR name, BSTR address);

Remember, the IDL will produce a header file; it could be used in a C++ app, which supports overloading, or in a C app, which doesn't...

Steve S

Re: Method overloading

Anonymous4-Feb-04 0:03

Anonymous

4-Feb-04 0:03

Thank you

Filomela2-Feb-04 20:47

Filomela

2-Feb-04 20:47

I want to paste in my app img. It pastes only from MS Word and IE.Can anyone help me? My app is a rtf app based on dialog box.

Tanks a lot.

how to use ActiveX contrl listview and imagelist in mscomctl.ocx

Dababa2-Feb-04 14:29

Dababa

2-Feb-04 14:29

Anyone who use VB will know it's esay to use ListView and ImageList in VB, however i want to use it in VC. I found that i cannot create ListImages object which is used by ImageList, i use the following codes:

I use import directive to import the com class

IImageListPtr imgs;
imgs.CreateInstance(__uuidof(ImageList));    //it's created successfully

IImagesPtr img;
img.CreateInstance(__uuidof(ListImages));    //it's failed to create

Can any one tell me what the problem is?
Thanks a lot! Smile | :)

I love C++

Parameter in ActiveX control

TrungHuynh1-Feb-04 19:43

1-Feb-04 19:43

Hi all

I have a trouble in My ActiveX control

I have written a method that has a parameter as VARIANT pointer (VARIANT FAR* lpVarFileInfo)

in my application that use this ActiveX, i passs a struct : FILE_INFO (it's a struct), and in my ActiveX control i want to get all parameter of this struct, but it alway is wrong.

here my code

IN APPLICATION

FILE_INFO FileInfo;
FileInfo.FileName = _T("D:\\GUI");
m_EditorLoader.SetInfo((VARIANT*)&FileInfo);
// m_EditorLoader is an instance of ActiveX control

IN ACTIVEX CONTROL

void CEditorCtrl::SetInfo(VARIANT FAR* lpVarFileInfo)
{
FILE_INFO FileInfo;
FileInfo = *(FILE_INFO*)(lpVarFileInfo);

AfxMessageBox(FileInfo.FileName);
// Value is wrong
}

Steve S2-Feb-04 4:23

2-Feb-04 4:23

A variant per se cannot contain an arbitrary user-defined type. However, it can be a SAFEARRAY of VT_RECORD, providing the record type is assigned a GUID, and is defined somewhere in a type library.
You don't show the rest of your FILE_INFO structure, but if you only want a name, you could pass a BSTR, and if you must have other members, could you not pass OLE Automation compatible types as multiple parameters, rather than as a structure, to keep things 'simpler'...?

Steve S

TrungHuynh2-Feb-04 14:30

2-Feb-04 14:30

ok, FILE_INFO struct is

typedef struct tagFILE_INFO
{
CString FileName;
CString Location;
CString LocationTemp;
}
FILE_INFO;

Because my ActiveX control communicate with an application. I need passing a lot of pararameters as struct.

could you give me example code.

regards

Steve S2-Feb-04 22:07

2-Feb-04 22:07

If you want your active X control to be useful to non-MFC programmers, then don't use CStrings!

In your IDL you can define your structure as you might in C++ (but with no member functions). Your types should be simple oleautomation compatible ones, so CStrings are out, because they can't be marshalled by OLEAUT32.

Steve S

TrungHuynh2-Feb-04 22:25

2-Feb-04 22:25

ok, i have change CString to BSTR, but how can add a method in my ActiveX has parameters as FILE_INFO (example)

define FILE_INFO struct in odl file
typedef struct tagFILE_INFO
{
BSTR szFileName;
BSTR szLocation;
BSTR szLocationTemp;
}
FILE_INFO;

because my component is an ActiveX control so, in my odl file

[id(7)] void SetInfo(FILE_INFO FileInfo);

it will appear Error when you launch to class wizard (passer error). Because in ActiveX control,when you add one method. The parameter type alway has some
PREDEFINE TYPE (short, long ,CURRENTCY... VARIANT....

So how can we define a new type(UDT) for parameter in method.

Regards
TrungHuynh

Steve S3-Feb-04 0:18

3-Feb-04 0:18

Firstly, you should give MIDL some hint about your parameter. Is it being passed into the function ([in] FILE_INFO FileInfo) or being passed back?
([out] FILE_INFO* FileInfo).
Secondly, it's customary for methods to return a status indication (or HRESULT) so that you can easily determine that an error has occurred.

To use a UDT, assign a GUID to the structure definition. Something like this will help.

#ifdef __midl
[
uuid(FFFFFFFF-FFFF-FFFF-FFFF-FFFFFFFFFFFF),
version(1.0),
helpstring("My FILEINFO structure")
]
#else
struct __declspec(uuid("FFFFFFFF-FFFF-FFFF-FFFF-FFFFFFFFFFFF")) FILE_INFO;
typedef
#endif
struct FILE_INFO
{
BSTR szFileName;
BSTR szLocation;
BSTR szLocationTemp;
} FILE_INFO;

except you'd replace the dummy guid FFFFFFFF-FFFF-FFFF-FFFF-FFFFFFFFFFFF with your own.

You should then have

[id(7)] HRESULT SetInfo([in] struct FILE_INFO* pFileInfo);

Note that it's a pointer you pass in now, not a structure. UDTs must be passed by reference, not by value.

I suggest you read the MSDN articles located by searching for
UDT IDL parameter
and if you're going to do a lot of this, read the Martin Gudgin book, Essential IDL.

Steve S

TrungHuynh3-Feb-04 14:44