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12.04.2008 at 01:18AM PST, ID: 23956109 | Points: 500
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Implementing IBindStatusCallback for progressive download.

Zones:

C++ Programming Language, Internet Explorer Web Browser, Windows ATL / WTL / COM Programming

Tags:

IBindStatusCallback, implementing, ATL, C++, Internet Explorer, BHO
I'm trying to progressively download a file in a BHO I'm creating for Internet Explorer.  I've tried to implement IBindStatusCallback, but when URLDownloadToFile is called, Internet Explorer locks up, and OnProgress in the implemented class is only ever called with ulProgressMax = 0.

Most of this BHO creation has been hit-and-miss because there is no good documentation out there, so any improvements I can make to this code as well as solving the problem would be much appreciated.
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#include <urlmon.h>
//#include <afx.h>
 
class YDownloadMonitor : public IBindStatusCallback
{
private:
	long m_dwRef;
public:
	inline YDownloadMonitor() : m_dwRef(0) {}
 
	inline ~YDownloadMonitor() { }
 
	STDMETHOD_(ULONG, AddRef)()
	{
		return InterlockedIncrement(&m_dwRef);
	}
 
	STDMETHOD_(ULONG, Release)()
	{
		unsigned long lResult = InterlockedDecrement(&m_dwRef);
		if (lResult == 0)
			delete this;
		return lResult;
	}
 
	IHTMLElement* Status;
 
/*BEGIN_COM_MAP(YDownloadMonitor)
	COM_INTERFACE_ENTRY(IBindStatusCallback)
END_COM_MAP()*/
 
	STDMETHOD(OnProgress)(ULONG ulProgress, ULONG ulProgressMax, ULONG ulStatusCode, LPCWSTR szStatusText)
	{
		CComBSTR newStatus(L"Buffering...");
		std::wstring text = L"Buffering... ";
		//text = szStatusText; // causes an exception so it is commented out
		if (ulProgressMax!=0)
			text += (100/ulProgressMax*ulProgress);
		newStatus = W2BSTR((text).c_str());
		this->Status->put_innerHTML(newStatus);
		return S_OK;
	}
 
	STDMETHOD(OnStartBinding)(DWORD a, IBinding* b)
	{
		return E_NOTIMPL;
	}
 
	STDMETHOD(OnStopBinding)(HRESULT a, LPCWSTR b)
	{
		return E_NOTIMPL;
	}
 
	STDMETHOD(GetPriority)(LONG* a)
	{
		return E_NOTIMPL;
	}
 
	STDMETHOD(OnLowResource)(DWORD a)
	{
		return E_NOTIMPL;
	}
 
	STDMETHOD(GetBindInfo)(DWORD* a, BINDINFO* b)
	{
		return E_NOTIMPL;
	}
 
	STDMETHOD(OnDataAvailable)(DWORD a, DWORD b, FORMATETC* c, STGMEDIUM* d)
	{
		return E_NOTIMPL;
	}
 
	STDMETHOD(OnObjectAvailable)(REFIID a, IUnknown* b)
	{
		return E_NOTIMPL;
	}
 
	STDMETHOD(QueryInterface)(REFIID iid, void** ppvObject)
	{
		if (!ppvObject)
			return E_POINTER;
 
		// check for the interfaces this object knows about
		if (iid == IID_IUnknown || iid == IID_IBindStatusCallback)
		{
			*ppvObject = (IBindStatusCallback*)this;
			InterlockedIncrement(&m_dwRef);
			return S_OK;
		}
 
		// otherwise, incorrect IID, and thus error
		return E_NOINTERFACE;
	}
};
 
void CBhoApp::RunYAIPP(IHTMLElement* Status)
{
	HRESULT hr;
	hr = Status->put_innerHTML(CComBSTR("Buffering..."));
	if (hr!=S_OK) return;
 
//	CBindStatusCallback<YDownloadMonitor>::Download(this, 
//             OnData, m_bstrURL, m_spClientSite, FALSE);
 
	YDownloadMonitor* yaippdownloader = new YDownloadMonitor();
	yaippdownloader->Status = Status; // pass the HTML element
	yaippdownloader->AddRef();
	hr = URLDownloadToFile(reinterpret_cast<LPUNKNOWN>(this),"http://www.roket-games.com/games/","C:\\test.htm",0,yaippdownloader);
 
	/*
	if (hr)
	{
		hr = Status->put_innerHTML(CComBSTR("Unable to download file."));
		if (hr!=S_OK) return;
	}
	else
	{
		hr = Status->put_innerHTML(CComBSTR("Downloaded file."));
		if (hr!=S_OK) return;
	}
	*/
}
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