Re: simple nsIWebProgressListener question

Christian Biesinger <[email protected]> wrote in message news:<[email protected]>...
> On Wed, Jul 14, 2004 at 03:02:24AM -0700, yueweng wrote:
> > I have implement the suggestion in the following code, but, I am still
> > not able to capture any browser signal yet.  May I know if there is
> > anything I missed out in the following code in order to start
> > receiving Mozilla browser event?
> 
> It seems that you never make sure that your component gets called at any
> time. See for example
> http://www.mozilla.org/projects/xpcom/book/cxc/html/weblock.html#1001977
> for how to make sure that your component gets instantiated on each app
> startup.
> 
> --
Hi Christian ,

Thanks for the help again.  I have made changes by inherit one more
interface from nsIObserver.  Then program is able to perform
nsSampleRegistrationProc() to do AddCategoryEntry("xpcom-startup",....
similar to what weblock has done.

Then I restart the mozilla again.  This time my constructor
nsSampleImpl() is being called, I think it should be, during starting
of mozilla.  However, mozilla crashed inside the constructor,
nsSampleImpl() at the function AddProgressListener().  I don't know
what's wrong with my implementation, I am wondering if you can help me
up again?

/////////////////////////////////////////////////////////////
The implementation of nsSampleImpl() is as follows:

static NS_DEFINE_IID(kDocLoaderServiceCID,
NS_DOCUMENTLOADER_SERVICE_CID);

nsSampleImpl::nsSampleImpl()
{
    nsCOMPtr<nsIWebProgress>
progress(do_GetService(kDocLoaderServiceCID));
    if (progress)
	progress->AddProgressListener((nsIWebProgressListener*)this,						   
  nsIWebProgress::NOTIFY_STATE_DOCUMENT);
}

//////////////////////////////////////////////////////////
The following is the callstack when crashed:

nsQueryInterface::operator()() line 47 + 21 bytes
nsCOMPtr<nsIWeakReference>::assign_from_qi() line 1030 + 17 bytes
nsCOMPtr<nsIWeakReference>::nsCOMPtr<nsIWeakReference>() line 572
nsCOMPtr<nsIWeakReference>::Assert_NoQueryNeeded() line 520
nsCOMPtr<nsIWeakReference>::nsCOMPtr<nsIWeakReference>() line 590
nsDocLoaderImpl::AddProgressListener() line 891 <---------MY PROGRAM
nsSampleImpl::nsSampleImpl() line 79 <---------MY PROGRAM 
nsSampleImplConstructor() line 89 + 27 bytes <---------MY PROGRAM
nsGenericFactory::CreateInstance() line 82 + 21 bytes 
nsComponentManagerImpl::CreateInstanceByContractID() line 2000 + 24
bytes
nsComponentManagerImpl::GetServiceByContractID() line 2420 + 50 bytes
nsGetServiceByContractID::operator()() line 121 + 38 bytes
nsCOMPtr_base::assign_from_helper() line 114 + 18 bytes
nsCOMPtr<nsISupports>::nsCOMPtr<nsISupports>() line 846
NS_CreateServicesFromCategory() line 785 + 37 bytes
NS_InitXPCOM2() line 633 + 17 bytes
NS_InitXPCOM2() line 173 + 18 bytes
GRE_Startup() line 477 + 35 bytes
main() line 1705 + 5 bytes
mainCRTStartup() line 338 + 17 bytes

//////////////////////////////////////////////////////////////////////
The implementation of other parts of the program is as follows:

NS_IMETHODIMP
nsSampleImpl::QueryInterface(REFNSIID aIID, void** aInstancePtr)
{
  if (NULL == aInstancePtr) {
    return NS_ERROR_NULL_POINTER;
  }
  *aInstancePtr = NULL;
  if (aIID.Equals(NS_GET_IID(nsISample))) {
    *aInstancePtr = (void*) NS_STATIC_CAST(nsISample*,this);
    NS_ADDREF_THIS();
    return NS_OK;
  }
  if (aIID.Equals(NS_GET_IID(nsSupportsWeakReference))) {
    *aInstancePtr = (void*) NS_STATIC_CAST(nsISample*,this);
    NS_ADDREF_THIS();
    return NS_OK;
  }
  if (aIID.Equals(NS_GET_IID(nsIObserver))) {
    *aInstancePtr = (void*) NS_STATIC_CAST(nsISample*,this);
    NS_ADDREF_THIS();
    return NS_OK;
  }
  if (aIID.Equals(NS_GET_IID(nsIWebProgressListener))) {
    *aInstancePtr = (void*) NS_STATIC_CAST(nsISample*,this);
    NS_ADDREF_THIS();
    return NS_OK;
  }
  if (aIID.Equals(NS_GET_IID(nsISupports))) {
    *aInstancePtr = (void*) NS_STATIC_CAST(nsISupports*,
                                          
NS_STATIC_CAST(nsISample*,this));
    NS_ADDREF_THIS();
    return NS_OK;
  }
  return NS_NOINTERFACE;
}

NS_IMPL_ADDREF(nsSampleImpl)
NS_IMPL_RELEASE(nsSampleImpl)

#define NS_SAMPLE_CONTRACTID "@mozilla.org/sample;1"

class nsSampleImpl : public nsIWebProgressListener,
		     public nsSupportsWeakReference,
		     public nsIObserver,
		     public nsISample
{
public:
    nsSampleImpl();

    NS_DECL_ISUPPORTS;
    NS_DECL_NSISAMPLE
    NS_DECL_NSIOBSERVER;
    NS_DECL_NSIWEBPROGRESSLISTENER;
	
private:
    ~nsSampleImpl();
    char* mValue;
};

static NS_METHOD nsSampleRegistrationProc(nsIComponentManager
*aCompMgr,
                                          nsIFile *aPath,
                                          const char
*registryLocation,
                                          const char *componentType,
                                          const nsModuleComponentInfo
*info)
{
	nsresult rv;

	nsCOMPtr<nsIServiceManager> servman =
do_QueryInterface((nsISupports*)aCompMgr, &rv);

	if (NS_FAILED(rv))
	     return rv;

	nsCOMPtr<nsICategoryManager> catman;
	servman->GetServiceByContractID(NS_CATEGORYMANAGER_CONTRACTID,
									NS_GET_IID(nsICategoryManager),
									getter_AddRefs(catman));
	if (NS_FAILED(rv))
		return rv;

	char* previous = nsnull;
	rv = catman->AddCategoryEntry("xpcom-startup",
				      "nsSampleImpl",
	                              NS_SAMPLE_CONTRACTID,
				      PR_TRUE,
				      PR_TRUE,
				      &previous);
	if (previous)
  	    nsMemory::Free(previous);
	return rv;
}

static NS_METHOD nsSampleUnregistrationProc(nsIComponentManager
*aCompMgr, nsIFile *aPath, const char *registryLocation, const
nsModuleComponentInfo *info)
{
	nsresult rv;
	nsCOMPtr<nsIServiceManager> servman =
do_QueryInterface((nsISupports*)aCompMgr, &rv);
	
	if (NS_FAILED(rv))
            return rv;
	nsCOMPtr<nsICategoryManager> catman;
	servman->GetServiceByContractID(NS_CATEGORYMANAGER_CONTRACTID,NS_GET_IID(nsICategoryManager),
getter_AddRefs(catman));
	if (NS_FAILED(rv))
	    return rv;
	rv = catman->DeleteCategoryEntry("xpcom-startup",
	                                 "nsSampleImpl",
                                         PR_TRUE);
	return rv;
}

NS_GENERIC_FACTORY_CONSTRUCTOR(nsSampleImpl);

static const nsModuleComponentInfo components[] =
{
  { "Sample Component", 
    NS_SAMPLE_CID, 
    NS_SAMPLE_CONTRACTID, 
    nsSampleImplConstructor,
    nsSampleRegistrationProc,
    nsSampleUnregistrationProc
  }
};

NS_IMPL_NSGETMODULE(nsSampleModule, components)

Thanks very much,
yueweng