Video Window does not respond, windowed mode, DirectShow - c++

Question

I wanted to use Vmr 9 instead of default Vmr 7, so I created it with CoCreateInstance and added to the graph with AddFilter method. Next, I build graph with RenderFile method. Now renderer is connected, so I query for IVideoWindow interface and call put_Owner method with window handle created in child thread. When Run method is called, video is displayed in the window, but window doesn't handle messages, so you can't move it or resize. Windowless mode works fine. Why window behaves this way?
#include <dshow.h>
#include <D3D9.h>
#include <Vmr9.h>
#pragma comment(lib, "Strmiids.lib")
#pragma comment(lib, "D3d9.lib")
#define WM_GRAPHNOTIFY WM_APP + 1
DWORD HandleGraphEvent(IMediaEventEx* media_event)
{
long EvCode;
LONG_PTR param1, param2;
while (media_event->GetEvent(&EvCode, &param1, &param2, 0) == S_OK)
{
media_event->FreeEventParams(EvCode, param1, param2);
switch (EvCode)
{
case EC_COMPLETE:
printf("All data is rendered\n");
return 0;
case EC_USERABORT:
printf("User has closed the window\n");
return 0;
case EC_ERRORABORT:
printf("Error occured\n");
return 0;
}
}
return 1;
}
struct WindowThreadParam
{
HANDLE event;
HWND window;
IMediaEventEx* media_event;
};
LRESULT WINAPI WindowProcedure(HWND window, unsigned int msg, WPARAM wp, LPARAM lp)
{
WindowThreadParam* param = (WindowThreadParam*)lp;
switch (msg)
{
case WM_DESTROY:
PostQuitMessage(0);
return 0;
case WM_GRAPHNOTIFY:
HandleGraphEvent(param->media_event);
default:
return DefWindowProc(window, msg, wp, lp);
}
}
DWORD WINAPI WindowThread(WindowThreadParam* param)
{
LPCWSTR myclass = TEXT("myclass");
WNDCLASSEX wndclass =
{ sizeof(WNDCLASSEX), CS_DBLCLKS, WindowProcedure,
0, 0, GetModuleHandle(0), LoadIcon(0, IDI_APPLICATION),
LoadCursor(0, IDC_ARROW), HBRUSH(COLOR_WINDOW + 1),
0, myclass, LoadIcon(0, IDI_APPLICATION) };
HWND window = NULL;
if (RegisterClassEx(&wndclass))
{
window = CreateWindowEx(0, myclass, TEXT("title"),
WS_OVERLAPPEDWINDOW, CW_USEDEFAULT, CW_USEDEFAULT,
CW_USEDEFAULT, CW_USEDEFAULT, 0, 0, GetModuleHandle(0), 0);
if (window)
{
ShowWindow(window, SW_SHOWDEFAULT);
param->window = window;
SetEvent(param->event);
MSG msg;
while (GetMessage(&msg, 0, 0, 0)) DispatchMessage(&msg);
}
else SetEvent(param->event);
UnregisterClass(myclass, GetModuleHandle(0));
}
else SetEvent(param->event);
return 0;
}
void _tmain(int argc, _TCHAR* argv[])
{
HANDLE event_handle;
event_handle = CreateEvent(NULL, 0, 0, NULL); // auto, unsignaled
WindowThreadParam param;
ZeroMemory(&param, sizeof(param));
param.event = event_handle;
CreateThread(NULL, 0, (LPTHREAD_START_ROUTINE)WindowThread, &param, 0, NULL);
IMediaControl *pControl = NULL;
IMediaEventEx *pEvent = NULL;
HRESULT hr = CoInitialize(NULL);
if (FAILED(hr))
{
printf("ERROR - Could not initialize COM library");
return;
}
IGraphBuilder* graph_builder;
hr = CoCreateInstance(CLSID_FilterGraph, NULL, CLSCTX_INPROC_SERVER, IID_IGraphBuilder, (void**)&graph_builder);
IBaseFilter* Vrm;
hr = CoCreateInstance(CLSID_VideoMixingRenderer9, NULL, CLSCTX_INPROC_SERVER, IID_IBaseFilter, (void**)&Vrm);
hr = graph_builder->AddFilter(Vrm, L"Video Mixing Renderer");
hr = graph_builder->RenderFile(L"anim.avi", NULL);
hr = graph_builder->QueryInterface(IID_IMediaControl, (void **)&pControl);
hr = graph_builder->QueryInterface(IID_IMediaEventEx, (void **)&pEvent);
IVideoWindow* VideoWindow;
RECT window_client_area;
WaitForSingleObject(param.event, INFINITE);
if (param.window)
{
// set window
hr = graph_builder->QueryInterface(IID_IVideoWindow, (void**)&VideoWindow);
hr = VideoWindow->put_Owner((OAHWND)param.window);
hr = VideoWindow->put_WindowStyle(WS_CHILD | WS_CLIPSIBLINGS);
// set video position
GetClientRect(param.window, &window_client_area);
hr = VideoWindow->SetWindowPosition(0, 0, window_client_area.right, window_client_area.bottom);
param.media_event = pEvent;
hr = pEvent->SetNotifyWindow((OAHWND)param.window, WM_GRAPHNOTIFY, (LONG_PTR)&param);
}
hr = pControl->Run();
// allow child thread to run
getchar();
pControl->Release();
pEvent->Release();
graph_builder->Release();
CoUninitialize();
}

Answer 1

Your main thread sleeps in getchar(); when it is supposed to implement message pump and deliver window messages, both as COM requirement and for the helper window VMR creates in the main thread.
Your background thread is irrelevant here since your controlling DirectShow activity takes place in _tmain.