Why my IWMPEvents functions are never called? - c++

Question

I have problem with IWMPEvents, which I advised successfully but never raised. Here is how I create embeded Windows Media Player:
HRESULT MyWMP::setURL(wchar_t* url)
{
return pMediaPlayer->put_URL(url); // Load and play songs successfully;
}
bool MyWMP::CreatePlayer()
{
HRESULT hr;
const CLSID CLSID_WindowsMediaPlayer = { 0x6BF52A52, 0x394A, 0x11d3,{ 0xB1, 0x53, 0x00, 0xC0, 0x4F, 0x79, 0xFA, 0xA6 } };
hr = ::OleCreate(CLSID_WindowsMediaPlayer, IID_IOleObject, OLERENDER_DRAW, 0, this, this, (void**)&oleObject);
if (SUCCEEDED(hr) && oleObject)
{
if (SUCCEEDED(hr)) hr = oleObject->SetClientSite(this);
if (SUCCEEDED(hr)) hr = OleSetContainedObject(oleObject, TRUE);
if (SUCCEEDED(hr))
{
RECT posRect;
::SetRect(&posRect, -300, -300, 300, 300);
hr = oleObject->DoVerb(OLEIVERB_INPLACEACTIVATE, NULL, this, -1, this->hwnd, &posRect);
}
hr = oleObject->QueryInterface(&pMediaPlayer);
}
if (FAILED(hr) || !pMediaPlayer)
{
MessageBox(NULL, L"Create Browser failed!", L"Error", MB_ICONERROR);
return false;
}
return true;
}
MyWMP::MyWMP(HWND parentHWND, HINSTANCE hInstance) :
isFullyCreated(false)
{
OleInitialize(NULL);
HRESULT hr = E_FAIL;
IConnectionPointContainer* container = nullptr;
IUnknown* punk = nullptr;
this->parentHWND = parentHWND;
this->hwnd = CreateWindow(L"Static", NULL, WS_CHILD | WS_VISIBLE, 221, 0, 300, 300, parentHWND, NULL, hInstance, 0);
iComRefCount = 0;
::SetRect(&rObject, 0, 0, 300, 300);
if (CreatePlayer())
{
hr = pMediaPlayer->get_settings(&pMediaPlayerSettings);
if (SUCCEEDED(hr) && pMediaPlayerSettings)
{
pMediaPlayerSettings->put_autoStart(VARIANT_TRUE);
pMediaPlayerSettings->put_volume(100);
}
hr = pMediaPlayer->QueryInterface(IID_IConnectionPointContainer, (void**)&container);
if (SUCCEEDED(hr) && container) hr = container->FindConnectionPoint(__uuidof(IWMPEvents), &callback);
if (FAILED(hr) && container)
{
hr = container->FindConnectionPoint(__uuidof(_WMPOCXEvents), &callback);
}
if (SUCCEEDED(hr) && callback)
{
CWMPEventDispatch *cw = new CWMPEventDispatch();
IUnknown *cwUnk = NULL;
if (SUCCEEDED(cw->QueryInterface(IID_IUnknown, (void**)&cwUnk)))
{
if (SUCCEEDED(hr) && container)
{
hr = callback->Advise(cwUnk, &eventCookie);
if (SUCCEEDED(hr) && eventCookie)
{
isFullyCreated = true; // Set breakpoint here and is triggered
// by debugger
// hr = S_OK
}
}
}
if (cwUnk) cwUnk->Release();
}
if (punk) punk->Release();
if (container) container->Release();
}
}
Bellow is the CWMPEventDispatch class. I set breakpoint at all IDispatch functions and none of them get triggered by debugger. When I load new songs, play/pause (on the embeded UI control buttons), these functions is never called.
// CWMPEventDispatch.h : Declaration of the event dispatcher
//
// Copyright (c) Microsoft Corporation. All rights reserved.
//
#include "stdafx.h"
#include "wmpids.h"
#include "wmp.h"
class CWMPEventDispatch :
public IWMPEvents,
public _WMPOCXEvents
{
public:
// ----- IUnknown -----
virtual HRESULT STDMETHODCALLTYPE QueryInterface(REFIID riid, void**ppvObject) override;
virtual ULONG STDMETHODCALLTYPE AddRef(void);
virtual ULONG STDMETHODCALLTYPE Release(void);
// IDispatch methods
STDMETHOD(GetIDsOfNames)(REFIID /*riid*/,
__in_ecount(cNames) LPOLESTR FAR * /*rgszNames*/,
unsigned int /*cNames*/,
LCID /*lcid*/,
DISPID FAR * /*rgDispId*/)
{
return(E_NOTIMPL);
}
STDMETHOD(GetTypeInfo)(unsigned int /*iTInfo*/,
LCID /*lcid*/,
ITypeInfo FAR *FAR * /*ppTInfo*/)
{
return(E_NOTIMPL);
}
STDMETHOD(GetTypeInfoCount)(unsigned int FAR * /*pctinfo*/)
{
return(E_NOTIMPL);
}
STDMETHOD(Invoke)(DISPID dispIdMember,
REFIID /*riid*/,
LCID /*lcid*/,
WORD /*wFlags*/,
DISPPARAMS FAR* pDispParams,
VARIANT FAR* /*pVarResult*/,
EXCEPINFO FAR* /*pExcepInfo*/,
unsigned int FAR* /*puArgErr*/);
private:
int iComRefCount;
};
#include "stdafx.h"
#include "myWMPEventDispatch.h"
#pragma region ----- IUnknown -----
ULONG STDMETHODCALLTYPE CWMPEventDispatch::AddRef(void) { return ++iComRefCount; }
ULONG STDMETHODCALLTYPE CWMPEventDispatch::Release(void) { return --iComRefCount; }
HRESULT STDMETHODCALLTYPE CWMPEventDispatch::QueryInterface(REFIID riid, void**ppvObject)
{
if (riid == __uuidof(IUnknown)) *ppvObject = static_cast<IDispatch*>(this);
else if (riid == __uuidof(IDispatch)) *ppvObject = static_cast<IDispatch*>(this);
else if (riid == __uuidof(IWMPEvents)) *ppvObject = static_cast<IWMPEvents*>(this);
else if (riid == __uuidof(_WMPOCXEvents)) *ppvObject = static_cast<_WMPOCXEvents*>(this);
else
return E_NOINTERFACE;
AddRef();
return S_OK;
}
#pragma endregion
HRESULT CWMPEventDispatch::Invoke(
DISPID dispIdMember,
REFIID /*riid*/,
LCID /*lcid*/,
WORD /*wFlags*/,
DISPPARAMS FAR* pDispParams,
VARIANT FAR* /*pVarResult*/,
EXCEPINFO FAR* /*pExcepInfo*/,
unsigned int FAR* /*puArgErr*/)
{
if (!pDispParams)
return E_POINTER;
if (pDispParams->cNamedArgs != 0)
return DISP_E_NONAMEDARGS;
HRESULT hr = DISP_E_MEMBERNOTFOUND;
return(hr);
}
Question:
Why my IWMPEvents functions are never called, and how to fix it?
I attack full source code as a 7z archive. You can download it here.
Environment: Win 10 x64, VS 2017 Community

Answer 1

This piece of code:
if (SUCCEEDED(hr) && container) hr = container->FindConnectionPoint(__uuidof(IWMPEvents), &callback);
if (FAILED(hr) && container)
{
hr = container->FindConnectionPoint(__uuidof(_WMPOCXEvents), &callback);
}
Will succeed on the first line, so you will hook events on the IWMPEvents only, you will not continue and hook _WMPOCXEvents.
IWMPEvents are early-bound (IUnknown derived) events, so the Media Player will indeed call IWMPEvents::PlayStateChange(...) IWMPEvents::StatusChange(...) etc. but it won't call IDispatch::Invoke with corresponding DISPIDs.
If you want IDispatch events, just remove the first FindConnectionPoint, or call both.