C / C++ / MFC Discussion Boards

27-Sep-01 5:51

Hi
About 2 threads ago I asked how to compile my dll which works as a Browser Helper Object with InternetExplorer.
Now it works fine, although I have one question. I searched www.google.com and other sites but did not find an answer (only how to do with VisualBasic Frown | :(

My question is how to handle the BeforeNavigate2 event.

What I have so far is as follows:

STDMETHODIMP CIEHlprObj::BeforeNavigate2(IDispatch *pDisp, VARIANT *url, VARIANT *Flags, VARIANT *TargetFrameName, VARIANT *PostData, VARIANT *Headers, VARIANT_BOOL *Cancel) 
{
        return S_OK;
}

I want to be able to cancel the navigation if the user entered a restricted site.
Furthermore I want to change the url in order to redirect the navigation to a different site

how can I do this Confused | :confused:

thanks in advance

Re: InternetExplorer - BeforeNavigate2

Carlos Antollini27-Sep-01 6:49

Carlos Antollini

27-Sep-01 6:49

STDMETHODIMP CIEHlprObj::BeforeNavigate2(IDispatch *pDisp, VARIANT *url, VARIANT *Flags, VARIANT *TargetFrameName, VARIANT *PostData, VARIANT *Headers, VARIANT_BOOL *Cancel) 
{  
CString TheBestURL = _T("http://www.codeproject.com");
*Cancel = TRUE;
Navigate2(TheBestURL);      
return S_OK;
}

Cheers!!!! Big Grin | :-D

Carlos Antollini.

Re: InternetExplorer - BeforeNavigate2

27-Sep-01 6:54

Hey great!!!! THANKS!!! Smile | :)

And how can I find out what the url is the browser wants to navigate to?
What do I need to do with the VARIANT *url? Confused | :confused:

I also want to change the *url to redirect the browser to a different site

Re: InternetExplorer - BeforeNavigate2

Not Active27-Sep-01 6:56

Not Active

27-Sep-01 6:56

That is the URL being navigated to.

Re: InternetExplorer - BeforeNavigate2

27-Sep-01 7:09

I know, but it is of type VARIANT.
How can I convert it into a "readable" format like char?
And how can I modify the variable *url?

Re: InternetExplorer - BeforeNavigate2

27-Sep-01 7:23

u can use this : CString strUrl = CString(URL->bstrVal);

Re: InternetExplorer - BeforeNavigate2

27-Sep-01 7:28

My DLL does not use MFC extension, therefore CString does not work Frown | :(

And how can I modify the variable "url"?
(for example like url = "something") Confused | :confused:

Re: InternetExplorer - BeforeNavigate2

Erik Thompson27-Sep-01 7:35

Erik Thompson

27-Sep-01 7:35

The variant holds all kinds of types. check to see if the url.vt == VT_BSTR (it will or it will be VT_BYREF|VT_BSTR) then you can use the url.bstrVal (or if byref url.pbstrVal) to see the url which will be a unicode string.

if (!wcscmp(bstrVal, "http://thesitetheyshouldnotgoto.com")
{
   SysFreeString(url.bstrVal);
   url.bstrVal = SysAllocString("http://younaughtyuser.com");
}

Cheers,
-Erik
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
My thoughts are my own and reflect on no other.

Re: InternetExplorer - BeforeNavigate2

27-Sep-01 7:51

I don't know whether I understand what you mean.
Here is what I have so far

STDMETHODIMP CIEHlprObj::BeforeNavigate2(IDispatch *pDisp, VARIANT *url, VARIANT *Flags, VARIANT *TargetFrameName, VARIANT *PostData, VARIANT *Headers, VARIANT_BOOL *Cancel) 
{
	if(url->vt == VT_BSTR)
	{
		if (!wcscmp(url->bstrVal, "http://thesitetheyshouldnotgoto.com"))
		{  
			SysFreeString(url->bstrVal); 
			url->bstrVal = SysAllocString("http://younaughtyuser.com");
		}
	}
	if(url->vt == VT_BSTR | VT_BYREF)
	{
		if (!wcscmp(url->pbstrVal, "http://thesitetheyshouldnotgoto.com"))
		{  
			SysFreeString(url->pbstrVal); 
			url->pbstrVal = SysAllocString("http://younaughtyuser.com");
		}
	}
	
	return S_OK;
}

But I get 5 compiler errors and 1 warning Frown | :(

Re: InternetExplorer - BeforeNavigate2

Erik Thompson27-Sep-01 10:58

Erik Thompson

27-Sep-01 10:58

Well since you haven't given the compiler errors I can only venture to guess that the reason is you are doing string compares of unicode vs ansi strings. For example in the code in your previous message you state

if (!wcscmp(url->bstrVal, "http://thesitetheyshouldnotgoto.com"))
{
SysFreeString(url->bstrVal);
url->bstrVal = SysAllocString("http://younaughtyuser.com");
}

It should be

if (!wcscmp(url->bstrVal, L"http://thesitetheyshouldnotgoto.com"))
{
SysFreeString(url->bstrVal);
url->bstrVal = SysAllocString(L"http://younaughtyuser.com");
}

I probably forgot the "L" in my sample above. that would account for 4 of the errors. What's the fifth?

Cheers,
-Erik
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
My thoughts are my own and reflect on no other.

Re: InternetExplorer - BeforeNavigate2

Carlos Antollini27-Sep-01 8:19

Carlos Antollini

27-Sep-01 8:19

You have the URL in url.bstrval
And you can redirect the Browser with Navigate2.

But A question, you want to control the IE or you ar making your own Explorer???

Cheers!!!

Carlos Antollini.

Re: InternetExplorer - BeforeNavigate2

27-Sep-01 8:32

url.bstrval is of type unsigned short*, isn't it?
How to convert to char?

I have this code so far:

CComVariant varURL(url->bstrVal);
varURL.ChangeType(VT_BSTR);

??? << OLE2T(varURL);

I need a variable for "???"

I want to control the IE

Re: InternetExplorer - BeforeNavigate2

Carlos Antollini27-Sep-01 8:41

Carlos Antollini

27-Sep-01 8:41

First
I always do that in this mode:

CString str = _T("");
str = vtFld.bstrVal;

Second
If you want to control the IE, read the answer that Michael Dunn posted you...

Best Regards!!! Big Grin | :-D

Carlos Antollini.

Re: InternetExplorer - BeforeNavigate2

Michael Dunn27-Sep-01 8:12

Michael Dunn

27-Sep-01 8:12

Check out KB article Q179230 which contains a complete BHO sample, including how to grab the URL and how to cancel navigation.

--Mike--
http://home.inreach.com/mdunn/
Trillian: What are you supposed to do with a manically depressed robot?
Marvin: You think you've got problems. What are you supposed to do if you are a manically depressed robot?

Re: InternetExplorer - BeforeNavigate2

27-Sep-01 8:23

I already took a look at this article, but the example doesn't use BeforeNavigate2 and no variable "url" of type VARIANT.

btw I hate the type VARIANT Big Grin | :-D

Passing a CList (or reference to a CList) as a function parameter??

27-Sep-01 5:34

I have defined a class foo, and I have a CList of the class, defined as:

CList <foo, foo&=""> fooList;

After populating the list, I want to process items from that list in a function within another class. The ways I have tried keep giving me C2664 and C2440 errors.

This sounds pretty basic, but what is the proper way to declare my function parameters and make the call with the CList?

TIA.

Re: Passing a CList (or reference to a CList) as a function parameter??

Michael Dunn27-Sep-01 8:16

Michael Dunn

27-Sep-01 8:16

Here's how you prototype a CList reference parameter:

void YourFunction ( CList<foo, foo&>& refList );

--Mike--
http://home.inreach.com/mdunn/
Trillian: What are you supposed to do with a manically depressed robot?
Marvin: You think you've got problems. What are you supposed to do if you are a manically depressed robot?

WebBrowser Control & 3D Borders

27-Sep-01 4:43

I would like to disable borders which appears with WebBrowser ActiveX. I saw that a solution would be to implement IDocHostUIHandler interface and to use GetHostInfo(), but how to implement that interface from a MFC Dialog Exe. AtlBrowser and WBCustomizer implement IDocHostUIHandler from COM interface.

Thanks in advance.

Dead | X|

Ref Counting

User 988527-Sep-01 4:36

User 9885

27-Sep-01 4:36

I was implementing a reference counting mechanism. How do I address the situation, where I store the pointers in a list or a map and does not have any other references to it. If I use the MFC map or list classes, will the addition to the list/map increment one count. As far as I understand, they either add it as a void* or a CObject*. Is it different in STL lists?

- Thomas

modified 29-Aug-18 21:01pm.

Re: Ref Counting

Not Active27-Sep-01 6:55

Not Active

27-Sep-01 6:55

I was implementing a reference counting mechanism You mean something other than what is available anyway?

If you are adding the pointer to a list you do not need to AddRef. You would AddRef if you were copying the interface.

Re: Ref Counting

Joaquín M López Muñoz27-Sep-01 8:28

Joaquín M López Muñoz

27-Sep-01 8:28

If I understood you well, it's some class you're designing (say CYourClass) that has the ref counting methods (AddRef() and Relase or something similar). In this situation, no container, be it from MFC or STL, is going to call that methods automatically if all you store in them is plain pointers to CYourClass. What you should have to do is store instead some suitable smart pointer that does the job of incrementing/decrementing the objects count at construction, destruction and assignment time. Have a look here at CodeProject or any other major programming site to find a wealth of info about smart pointers.
Once you have your smart pointers up and running, both MFC and STL containers will work OK with them. IMHO, however, STL is preferrable because of portability and design issues.

Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo

Re: Ref Counting

User 988527-Sep-01 8:52

User 9885

27-Sep-01 8:52

Thankyou for the reply. I have already made the pointer that does the job of inc/dec, assignment etc.

I have a smart pointer implemented, that is used like this:

CPtr<CMyClass> p1 = new CMyClass;

This will make an object of type CMyClass inside the smart pointer and increment the ref count.

if I did

p1 = NULL;

the object would be deleted, because the reference count = 0;

Consider the following case :

I have a class with a member variable m_ptrList of type CPtrList or CTypedPtrList.

CClass::MyFunc()
{
 CPtr<CMyClass> p1 = new CMyClass;
 m_ptrList.AddHead(p1);
}

The problem that I foresee is that the AddHead will not increment the reference count. So will the object get deleted when MyFunc returns.

Is there something wrong in my understanding of the situation?

-Thomas

modified 29-Aug-18 21:01pm.

Re: Ref Counting

Joaquín M López Muñoz27-Sep-01 9:28

Joaquín M López Muñoz

27-Sep-01 9:28

Is there something wrong in my understanding of the situation?

No, your understanding of the situation is absolutely correct, and the object will get deleted when MyFunc returns. CPtrList is a beast every reasonable programmer should try to avoid, because it forces you to abandon type information when storing things in it and reinferring it later thru an explicit cast. Things are no better with CTypedPtrList, as the poor patch it proposes to bring type information back does not permit you to deal with smart pointers.

If you can make the switch, I recommend you enter the wondrous land of STL and substitute list<CPtr<CMyclass> > for your former MFC lists everywhere. Additionally, you might want to reconsider having defined operator CMyClass * (), as it paves the way to errors resulting from inadvertently casting your smart pointers away thus loosing track of the right ref count (as in your example). It'd be better to have an explicit method for casting like T * get() so the programmer is aware of entering a risk zone when she/he uses it.

Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo

How to change a item's parent of a tree control?

27-Sep-01 3:52

Is there any simple way to change a item's
parent of a tree control?thank you.

Re: How to change a item's parent of a tree control?

Derek Lakin27-Sep-01 4:26

Derek Lakin

27-Sep-01 4:26

Do you mean the "parent of a tree control" or the "parent of a node in a tree control"?

Derek Lakin.
Salamander Software Ltd.

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