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I'm attempting to host a file preview handler within a dialog. I've set up an event sink for selection changes in Explorer. When the selection changes, I feed the selected shell item to the dialog, which in turn feeds it to a function that prepares the preview frame.
In general, it successfully loads the correct handler and displays the contents of the file, but for certain file types (namely, Excel and Word files), it runs into various problems like focus-loss or flashing. Here's a demo of the Excel preview handler messing up focus (and by mess up, I mean it wrongfully steals the focus from Explorer, which I'd like to maintain focus):
Word files may load successfully once, but they'll subsequently fail, especially if Word is opened.
As for the code:
For starters, here's my function for obtaining the preview handler from the file extension. This seems to work fine:
HRESULT PreviewHandlerFromExt(LPCWSTR pszExt, IPreviewHandler** ppph)
{
WCHAR szCLSID[CLSID_LEN] = { 0 };
DWORD cchOut = CLSID_LEN;
HRESULT hr = AssocQueryString( ASSOCF_INIT_DEFAULTTOSTAR,
ASSOCSTR_SHELLEXTENSION,
pszExt,
L"{8895b1c6-b41f-4c1c-a562-0d564250836f}",
szCLSID,
&cchOut );
if (FAILED(hr))
{
return hr;
}
CLSID clsid;
hr = CLSIDFromString(szCLSID, &clsid);
if (FAILED(hr))
{
return hr;
}
CComPtr<IUnknown> punk;
hr = punk.CoCreateInstance(clsid, NULL, CLSCTX_LOCAL_SERVER);
if (FAILED(hr))
{
return hr;
}
CComPtr<IPreviewHandler> pPrevHandler;
hr = punk->QueryInterface(&pPrevHandler);
if (FAILED(hr) || !pPrevHandler)
{
return hr;
}
return pPrevHandler.CopyTo(ppph);
}
And now here's the function in my dialog that prepares the preview, given a shell item (m_pPreviewHandler is the active preview handler, IDC_PREVIEWFRAME is a placeholder in the dialog for the preview pane, and m_mapExtsToPreviewHandlers is just a map for storing preview handlers as the user comes across them):
void CMyDialog::ShowPreview(IShellItem* pShItem)
{
HRESULT hr;
if (m_pPreviewHandler)
{
m_pPreviewHandler->Unload();
m_pPreviewHandler.Release();
}
CComHeapPtr<WCHAR> pszPath;
hr = pShItem->GetDisplayName(SIGDN_FILESYSPATH, &pszPath);
if (FAILED(hr))
{
return;
}
LPWSTR pszExt = CharLower(PathFindExtension(pszPath));
auto it = m_mapExtsToPreviewHandlers.find(pszExt);
if (it == m_mapExtsToPreviewHandlers.end())
{
hr = PreviewHandlerFromExt(pszExt, &m_pPreviewHandler);
if (FAILED(hr) || !m_pPreviewHandler)
{
return;
}
m_mapExtsToPreviewHandlers[pszExt] = m_pPreviewHandler;
}
else
{
m_pPreviewHandler = m_mapExtsToPreviewHandlers[pszExt];
}
CComPtr<IInitializeWithFile> pInitWithFile;
hr = m_pPreviewHandler->QueryInterface(&pInitWithFile);
if (SUCCEEDED(hr))
{
hr = pInitWithFile->Initialize(pszPath, STGM_READ);
if (FAILED(hr))
{
return;
}
}
else
{
CComPtr<IInitializeWithStream> pInitWithStream;
hr = m_pPreviewHandler->QueryInterface(&pInitWithStream);
if (SUCCEEDED(hr))
{
CComPtr<IStream> pStream;
hr = SHCreateStreamOnFile(pszPath, STGM_READ, &pStream);
if (FAILED(hr) || !pStream)
{
return;
}
hr = pInitWithStream->Initialize(pStream, STGM_READ);
if (FAILED(hr))
{
return;
}
}
}
CWindow wndPreviewFrame( GetDlgItem(IDC_PREVIEWFRAME) );
CRect rectPreviewFrame;
wndPreviewFrame.GetClientRect(&rectPreviewFrame);
hr = m_pPreviewHandler->SetWindow(wndPreviewFrame, &rectPreviewFrame);
if (FAILED(hr))
{
return;
}
hr = m_pPreviewHandler->DoPreview();
if (FAILED(hr))
{
return;
}
hr = m_pPreviewHandler->SetRect(&rectPreviewFrame);
if (FAILED(hr))
{
return;
}
}
Does anyone know what I'm doing wrong or what might fix these focus problems?
I've also tried placing LockSetForegroundWindow at various places, but no lock.
Also, this is what the dialog resource looks like:
I could capture the image from webcam and save it as bitmap by using sampleGrabber. And I know I could use the IAMStreamConfig interface to GetFormat and SetFormat the video resolution. My question is, I using FindInterface() to get IAMStreamConfig* but always failed.Is it because I place it in a wrong place or something else I didn't notice. I placed it before RenderStream. Here are some code below, thanks for your patient and help!
INT USBDeviceApp::GetInterfaces()
{
HRESULT hr;
hr = CoCreateInstance (CLSID_FilterGraph, NULL, CLSCTX_INPROC,
IID_IGraphBuilder, (void **) &pGraphBuilder);
if (FAILED(hr))
return hr;
hr = CoCreateInstance (CLSID_CaptureGraphBuilder2 , NULL, CLSCTX_INPROC,
IID_ICaptureGraphBuilder2, (void **) &pCaptureGraphBuilder2);
if (FAILED(hr))
return hr;
hr = pGraphBuilder->QueryInterface(IID_IMediaControl,(LPVOID *)
&pMediaControl);
if (FAILED(hr))
return hr;
hr = pGraphBuilder->QueryInterface(IID_IVideoWindow, (LPVOID *)
&pVideoWindow);
if(FAILED(hr))
{
return hr;
}
hr = pGraphBuilder->QueryInterface(IID_IMediaEvent,(LPVOID *)
&pMediaEvent);
if(FAILED(hr))
{
return hr;
}
// ------------------------
// Create the Sample Grabber.
hr = CoCreateInstance(CLSID_SampleGrabber, NULL, CLSCTX_INPROC_SERVER,
IID_IBaseFilter, (void**)&pGrabberF);
if (FAILED(hr))
{
return hr;
}
hr = pGrabberF->QueryInterface(IID_ISampleGrabber,
(void**)&pSampleGrabber);
if(FAILED(hr))
{
AfxMessageBox(_T("Error SampleGrabber QueryInterface"));
}
return 1;
}
INT USBDeviceApp::InitMonikers()
{
HRESULT hr;
ULONG cFetched;
ICreateDevEnum *pCreateDevEnum;
hr = CoCreateInstance(CLSID_SystemDeviceEnum, NULL,
CLSCTX_INPROC_SERVER, IID_ICreateDevEnum, (void**)&pCreateDevEnum);
if (FAILED(hr))
{
return hr;
}
IEnumMoniker *pEnumMoniker;
hr = pCreateDevEnum->
CreateClassEnumerator(CLSID_VideoInputDeviceCategory,&pEnumMoniker, 0);
if (FAILED(hr) || !pEnumMoniker)
{
return -1;
}
hr = pEnumMoniker->Next(1, &pMonikerVideo, &cFetched);
if (S_OK == hr)
{
hr = pMonikerVideo->BindToObject(0,0,IID_IBaseFilter,
(void**)&pVideoCaptureFilter);
if (FAILED(hr))
{
return hr;
}
}
pEnumMoniker->Release();
return 1;
}
INT USBDeviceApp::CaptureVideo()
{
HRESULT hr = CoInitialize(NULL);
hr = GetInterfaces();
if (FAILED(hr))
{
AfxMessageBox(_T("Failed to get video interfaces!"));
return hr;
}
hr = pCaptureGraphBuilder2->SetFiltergraph(pGraphBuilder);
if (FAILED(hr))
{
AfxMessageBox(_T("Failed to attach the filter graph to the capture graph!"));
return hr;
}
//IAMStreamConfig *pConfig
hr = pCaptureGraphBuilder2->FindInterface(&PIN_CATEGORY_PREVIEW,
&MEDIATYPE_Video,
pVideoCaptureFilter,IID_IAMStreamConfig, (void **)&pConfig);
if (FAILED(hr))
{
AfxMessageBox(_T("Couldn't initialize IAMStreamConfig!"));
}
else
{////
int iCount = 0,iSize = 0;
hr = pConfig->GetNumberOfCapabilities(&iCount,&iSize);
if(iSize == sizeof(VIDEO_STREAM_CONFIG_CAPS))
{
for(int iFormat = 0;iFormat < iCount;iFormat++)
{
VIDEO_STREAM_CONFIG_CAPS scc;
AM_MEDIA_TYPE *pmtConfig;
hr = pConfig->GetStreamCaps(iFormat, &pmtConfig, (BYTE*)&scc);
if(hr)
{
if((pmtConfig->majortype == MEDIATYPE_Video) &&
(pmtConfig->subtype == MEDIASUBTYPE_RGB24) &&
(pmtConfig->formattype == FORMAT_VideoInfo) &&
(pmtConfig->cbFormat >= sizeof (VIDEOINFOHEADER)) &&
(pmtConfig->pbFormat != NULL))
{
VIDEOINFOHEADER *pVih = (VIDEOINFOHEADER*)pmtConfig->pbFormat;
pVih->bmiHeader.biWidth = 1280;
pVih->bmiHeader.biHeight = 720;
pVih->bmiHeader.biSizeImage = DIBSIZE(pVih->bmiHeader);
hr = pConfig->SetFormat(pmtConfi);
}
DeleteMediaType(pmtConfig);
}
}
}
}////
hr = InitMonikers();
if(FAILED(hr))
{
return hr;
}
hr = pGraphBuilder->AddFilter(pVideoCaptureFilter, L"Video Capture");
if (FAILED(hr))
{
pVideoCaptureFilter->Release();
return hr;
}
AM_MEDIA_TYPE mt;
ZeroMemory(&mt, sizeof(AM_MEDIA_TYPE));
mt.majortype = MEDIATYPE_Video;
mt.subtype = MEDIASUBTYPE_RGB24;
hr = pSampleGrabber->SetMediaType(&mt);
hr = pSampleGrabber->SetOneShot(FALSE);
hr = pSampleGrabber->SetBufferSamples(TRUE);
hr = pGraphBuilder->AddFilter(pGrabberF, L"Sample Grabber");
if (FAILED(hr))
{
return hr;
}
hr = pCaptureGraphBuilder2->RenderStream(&PIN_CATEGORY_PREVIEW, &MEDIATYPE_Video, pVideoCaptureFilter, pGrabberF, 0 );
if (FAILED(hr))
{
pVideoCaptureFilter->Release();
return hr;
}
hr = pSampleGrabber->GetConnectedMediaType( &mt );
if(FAILED( hr ))
{
return -1;
}
VIDEOINFOHEADER * vih = (VIDEOINFOHEADER*) mt.pbFormat;
pVih = (VIDEOINFOHEADER*) mt.pbFormat;
CSampleGrabberCB *CB = new CSampleGrabberCB() ;
if(!FAILED( hr ))
{
CB->Width = vih->bmiHeader.biWidth;
CB->Height = vih->bmiHeader.biHeight;
FreeMediaType( mt );
}
hr = pSampleGrabber->SetCallback( CB, 1 );
pVideoCaptureFilter->Release();
this->SetUpVideoWindow();
hr = pMediaControl->Run();
if (FAILED(hr))
{
return hr;
}
return hr;
}
hr = pCaptureGraphBuilder2->FindInterface()
always failed to get the IAMStreamConfig interface, I really don't know why. Can someone help me, thanks so much!
Your API call below
pCaptureGraphBuilder2->FindInterface(&PIN_CATEGORY_PREVIEW,
&MEDIATYPE_Video,
pVideoCaptureFilter,IID_IAMStreamConfig, (void **) &pConfig);
applies several restrictions to the search, including pin category: you are looking for a preview pin. For example, the graph below features three video capture devices and none of them has the dedicated preview pin: preview pin is optional.
You need to take this into account and either relax the search criteria or I would rather suggest that you locate the pin of your interest directly on the capture filter. Then you will set it and and connect it with downstream peer filters. FindInterface is powerful but it also adds chances to get into confusion.
By using Microsoft windows SDK 7.0, explorerDataProvider, I installed a virtual folder on windows 7.
When I open the file browse dialog from an application,
CFileDialog dlg(TRUE, NULL, 0, OFN_ENABLESIZING | OFN_ALLOWMULTISELECT, L"all(*.*)|*.*||", this);
INT_PTR result = dlg.DoModal();
if (result == IDOK)
{
.
.
.
//some actions
}
it can also display the virtual folder:
But when I select the file, like "Zero" can then clicks "Open",
I tried to add breakpoints to
INT_PTR result = dlg.DoModal();
But it seems that this error happens inside DoModal().
I doing some research and revise the code of virtual folder:
HRESULT CFolderViewImplFolder::GetAttributesOf(UINT cidl, PCUITEMID_CHILD_ARRAY apidl, ULONG *rgfInOut)
{
// If SFGAO_FILESYSTEM is returned, GetDisplayNameOf(SHGDN_FORPARSING) on that item MUST
// return a filesystem path.
HRESULT hr = E_INVALIDARG;
DWORD dwAttribs = 0;
dwAttribs |= SFGAO_BROWSABLE;
if (1 == cidl)
{
int nLevel = 0;
hr = _GetLevel(apidl[0], &nLevel);
if (SUCCEEDED(hr))
{
BOOL fIsFolder = FALSE;
hr = _GetFolderness(apidl[0], &fIsFolder);
if (SUCCEEDED(hr))
{
if (fIsFolder)
{
dwAttribs |= SFGAO_FOLDER;
dwAttribs |= SFGAO_FILESYSANCESTOR;
}
else
{
dwAttribs |= SFGAO_SYSTEM;
dwAttribs |= SFGAO_FILESYSTEM;
}
if (nLevel < g_nMaxLevel)
{
dwAttribs |= SFGAO_HASSUBFOLDER;
}
}
}
}
*rgfInOut &= dwAttribs;
return hr;
}
And return the path inGetDisplayNameOf()
HRESULT CFolderViewImplFolder::GetDisplayNameOf(PCUITEMID_CHILD pidl, SHGDNF shgdnFlags, STRRET *pName)
{
HRESULT hr = S_OK;
if (shgdnFlags & SHGDN_FORPARSING)
{
WCHAR szDisplayName[MAX_PATH];
if (shgdnFlags & SHGDN_INFOLDER)
{
// This form of the display name needs to be handled by ParseDisplayName.
hr = _GetName(pidl, szDisplayName, ARRAYSIZE(szDisplayName));
}
else
{
PWSTR pszThisFolder = L"Computer\\Jerry";
StringCchCopy(szDisplayName, ARRAYSIZE(szDisplayName), pszThisFolder);
StringCchCat(szDisplayName, ARRAYSIZE(szDisplayName), L"\\");
WCHAR szName[MAX_PATH];
hr = _GetName(pidl, szName, ARRAYSIZE(szName));
if (SUCCEEDED(hr))
{
StringCchCat(szDisplayName, ARRAYSIZE(szDisplayName), szName);
}
}
if (SUCCEEDED(hr))
{
hr = StringToStrRet(szDisplayName, pName);
}
}
else
{
PWSTR pszName;
hr = _GetName(pidl, &pszName);
if (SUCCEEDED(hr))
{
hr = StringToStrRet(pszName, pName);
CoTaskMemFree(pszName);
}
}
return hr;
}
But it still stats error message of "Path does not exist" in the application.
I add breakpoints in GetDisplayNameOf, but it is never triggered when the application opens a file browse dialog. But if I open a regular folder just by double click "Computer", it will be triggered.
The error message of "Path does not exist" seems cannot be deprecated or covered. Any way that I can revise the virtual folder to return the correct path ?
Update: I tried IFileDialog, I copied the code from the MSDN sample, code, and add breakpoints to see what will happen. However,
// Show the dialog
hr = pfd->Show(NULL);//the breakpoint is added here
if (SUCCEEDED(hr))
{
// Obtain the result once the user clicks
// the 'Open' button.
// The result is an IShellItem object.
IShellItem *psiResult;
hr = pfd->GetResult(&psiResult);
if (SUCCEEDED(hr))
{
//do something
}
}
When I click "Open" button, the error message box of "Path does not exist, check the path and try again" still show up. And it never comes out of pfd->Show(NULL) after I click Open" button.
Based on the comments in the sample code, it should come out of hr = pfd->Show(NULL); and reach to the next line.but the error message happens inside the hr = pfd->Show(NULL);.
Update:
In the IFileDialog, I tried
hr = pfd->GetOptions(&dwFlags);
if (SUCCEEDED(hr))
{
hr = pfd->SetOptions(dwFlags | FOS_ALLNONSTORAGEITEMS);
if (SUCCEEDED(hr))
{
// Show the dialog
hr = pfd->Show(NULL);
if (SUCCEEDED(hr))
{
// Obtain the result once the user clicks
// the 'Open' button.
// The result is an IShellItem object.
IShellItem *psiResult;
hr = pfd->GetResult(&psiResult);
if (SUCCEEDED(hr))
{
// We are just going to print out the
// name of the file for sample sake.
PWSTR pszFilePath = NULL;
hr = psiResult->GetDisplayName(SIGDN_FILESYSPATH,
&pszFilePath);
if (SUCCEEDED(hr))
{
TaskDialog(NULL,
NULL,
L"CommonFileDialogApp",
pszFilePath,
NULL,
TDCBF_OK_BUTTON,
TD_INFORMATION_ICON,
NULL);
CoTaskMemFree(pszFilePath);
}
psiResult->Release();
}
}
}
I also tried
hr = pfd->SetOptions(dwFlags);//delete FOS_FORCEFILESYSTEM
And tried
DWORD dwFlags = 0;
if (SUCCEEDED(hr))
{
// overwrite options completely
hr = pfd->SetOptions(dwFlags | FOS_ALLNONSTORAGEITEMS);
I also tried to return the whole name in namespace extension code:
WCHAR szDisplayName[MAX_PATH];
if (shgdnFlags & SHGDN_INFOLDER)
{
// This form of the display name needs to be handled by ParseDisplayName.
hr = _GetName(pidl, szDisplayName, ARRAYSIZE(szDisplayName));
}
else
{
PWSTR pszThisFolder;// = L"Computer\\Jerry";
hr = SHGetNameFromIDList(m_pidl, (shgdnFlags & SHGDN_FORADDRESSBAR) ? SIGDN_DESKTOPABSOLUTEEDITING : SIGDN_DESKTOPABSOLUTEPARSING, &pszThisFolder);
if (SUCCEEDED(hr))
{
StringCchCopy(szDisplayName, ARRAYSIZE(szDisplayName), pszThisFolder);
StringCchCat(szDisplayName, ARRAYSIZE(szDisplayName), L"\\");
WCHAR szName[MAX_PATH];
hr = _GetName(pidl, szName, ARRAYSIZE(szName));
if (SUCCEEDED(hr))
{
StringCchCat(szDisplayName, ARRAYSIZE(szDisplayName), szName);
}
CoTaskMemFree(pszThisFolder);
}
}
if (SUCCEEDED(hr))
{
hr = StringToStrRet(szDisplayName, pName);
}
But the result is:
Update:
hr = pfd->SetOptions(dwFlags | FOS_ALLNONSTORAGEITEMS | FOS_NOVALIDATE);
This works for me!!
With the help of #RemyLebeau, I did some tests in my code. Finally, I found the working solution for me:
I copied the code from MSDN for IFileDialog: https://msdn.microsoft.com/en-us/library/windows/desktop/bb776913.aspx#file_types
and then revise it a little bit:
HRESULT BasicFileOpen()
{
// CoCreate the File Open Dialog object.
IFileDialog *pfd = NULL;
HRESULT hr = CoCreateInstance(CLSID_FileOpenDialog,
NULL,
CLSCTX_INPROC_SERVER,
IID_PPV_ARGS(&pfd));
if (SUCCEEDED(hr))
{
// Create an event handling object, and hook it up to the dialog.
IFileDialogEvents *pfde = NULL;
hr = CDialogEventHandler_CreateInstance(IID_PPV_ARGS(&pfde));
if (SUCCEEDED(hr))
{
// Hook up the event handler.
DWORD dwCookie;
hr = pfd->Advise(pfde, &dwCookie);
if (SUCCEEDED(hr))
{
// Set the options on the dialog.
DWORD dwFlags = 0;
if (SUCCEEDED(hr))
{
// the default flag is FOS_PATHMUSTEXIST and FOS_FILEMUSTEXIST, so I set overwrite it with these two flags.
hr = pfd->SetOptions(dwFlags | FOS_ALLNONSTORAGEITEMS | FOS_NOVALIDATE);
if (SUCCEEDED(hr))
{
// Show the dialog
hr = pfd->Show(NULL);
if (SUCCEEDED(hr))
{
// Obtain the result once the user clicks
// the 'Open' button.
// The result is an IShellItem object.
IShellItem *psiResult;
hr = pfd->GetResult(&psiResult);
if (SUCCEEDED(hr))
{
// We are just going to print out the
// name of the file for sample sake.
PWSTR pszFilePath = NULL;
hr = psiResult->GetDisplayName(SIGDN_FILESYSPATH,
&pszFilePath);
if (SUCCEEDED(hr))
{
TaskDialog(NULL,
NULL,
L"CommonFileDialogApp",
pszFilePath,
NULL,
TDCBF_OK_BUTTON,
TD_INFORMATION_ICON,
NULL);
CoTaskMemFree(pszFilePath);
}
psiResult->Release();
}
}
}
}
// Unhook the event handler.
pfd->Unadvise(dwCookie);
}
pfde->Release();
}
pfd->Release();
}
return hr;
}
The key point is to overwrite the options by SetOptions. Based on the MSDN:https://msdn.microsoft.com/en-us/library/windows/desktop/dn457282(v=vs.85).aspx ,
FOS_PATHMUSTEXIST
The item returned must be in an existing folder. This is a default value.
FOS_FILEMUSTEXIST
The item returned must exist. This is a default value for the Open dialog.
These flags are default values which prevent it returns.
So I set it to :
hr = pfd->SetOptions(dwFlags | FOS_ALLNONSTORAGEITEMS | FOS_NOVALIDATE);
These flags mean:
FOS_NOVALIDATE
Do not check for situations that would prevent an application from opening the selected file, such as sharing violations or access denied errors.
and
FOS_ALLNONSTORAGEITEMS
Enables the user to choose any item in the Shell namespace, not just those with SFGAO_STREAM or SFAGO_FILESYSTEM attributes. This flag cannot be combined with FOS_FORCEFILESYSTEM.
Then it finally works!
After looking at a very similar question and seeing almost identical code, I've decided to ask this question separately. I want to show a video preview of the webcam's video stream to the default window DirectShow uses, and I also want the ability to "take a picture" of the video stream at any given moment.
I started with the DirectShow examples on MSDN, as well as the AMCap sample code, and have something I believe should should the preview part, but does not. I've found no examples of grabbing an image from the video stream except using SampleGrabber, which is deprecated and therefore I am trying not to use it.
Below is my code, line for line. Note that most of the code in EnumerateCameras is commented out. That code would've been for attaching to another window, which I don't want to do. In the MSDN documentation, it explicitly states that the VMR_7 creates its own window to display the video stream. I get no errors in my app, but this window never appears.
My question then is this: What am I doing wrong? Alternatively, if you know of a simple example of what I am trying to do, link me to it. AMCap is not a simple example, for reference.
NOTE: InitalizeVMR is for running in windowless state, which is my ultimate goal (integrating into a DirectX game). For now, however, i just want it to run in the simplest mode possible.
EDIT: The first portion of this question, that is previewing the camera stream, is solved. I am now just looking for an alternative to the deprecated SampleGrabber class so I can snap a photo at any moment and save it to a file.
EDIT: After looking for almost an hour on google, the general concensus seems to be that you HAVE to use ISampleGrabber. Please let me know if you find anything different.
Testing code (main.cpp):
CWebcam* camera = new CWebcam();
HRESULT hr = CoInitializeEx(NULL, COINIT_MULTITHREADED);
MessageBox(NULL, L"text", L"caption", NULL);
if (SUCCEEDED(hr))
{
camera->Create();
camera->EnumerateCameras();
camera->StartCamera();
}
int d;
cin >> d;
Webcam.cpp:
#include "Webcam.h"
CWebcam::CWebcam() {
HRESULT hr = CoInitializeEx(NULL, COINIT_MULTITHREADED);
//m_pTexInst = nullptr;
//m_pTexRes = nullptr;
}
CWebcam::~CWebcam() {
CoUninitialize();
m_pDeviceMonikers->Release();
m_pMediaController->Release();
}
BOOL CWebcam::Create() {
InitCaptureGraphBuilder(&m_pFilterGraph, &m_pCaptureGraph);
hr = m_pFilterGraph->QueryInterface(IID_IMediaControl, (void **)&m_pMediaController);
return TRUE;
}
void CWebcam::Destroy() {
}
void CWebcam::EnumerateCameras() {
HRESULT hr = EnumerateDevices(CLSID_VideoInputDeviceCategory, &m_pDeviceMonikers);
if (SUCCEEDED(hr))
{
//DisplayDeviceInformation(m_pDeviceMonikers);
//m_pDeviceMonikers->Release();
IMoniker *pMoniker = NULL;
if(m_pDeviceMonikers->Next(1, &pMoniker, NULL) == S_OK)
{
hr = pMoniker->BindToObject(0, 0, IID_IBaseFilter, (void**)&m_pCameraFilter);
if (SUCCEEDED(hr))
{
hr = m_pFilterGraph->AddFilter(m_pCameraFilter, L"Capture Filter");
}
}
// connect the output pin to the video renderer
if(SUCCEEDED(hr))
{
hr = m_pCaptureGraph->RenderStream(&PIN_CATEGORY_PREVIEW, &MEDIATYPE_Video,
m_pCameraFilter, NULL, NULL);
}
//InitializeVMR(hwnd, m_pFilterGraph, &m_pVMRControl, 1, FALSE);
//get the video window that will be displayed from the filter graph
IVideoWindow *pVideoWindow = NULL;
hr = m_pFilterGraph->QueryInterface(IID_IVideoWindow, (void **)&pVideoWindow);
/*if(hr != NOERROR)
{
printf("This graph cannot preview properly");
}
else
{
//get the video stream configurations
hr = m_pCaptureGraph->FindInterface(&PIN_CATEGORY_CAPTURE,
&MEDIATYPE_Video, m_pCameraFilter,
IID_IAMStreamConfig, (void **)&m_pVideoStreamConfig);
//Find out if this is a DV stream
AM_MEDIA_TYPE *pMediaTypeDV;
//fake window handle
HWND window = NULL;
if(m_pVideoStreamConfig && SUCCEEDED(m_pVideoStreamConfig->GetFormat(&pMediaTypeDV)))
{
if(pMediaTypeDV->formattype == FORMAT_DvInfo)
{
// in this case we want to set the size of the parent window to that of
// current DV resolution.
// We get that resolution from the IVideoWindow.
IBasicVideo* pBasivVideo;
// If we got here, gcap.pVW is not NULL
//ASSERT(pVideoWindow != NULL);
hr = pVideoWindow->QueryInterface(IID_IBasicVideo, (void**)&pBasivVideo);
/*if(SUCCEEDED(hr))
{
HRESULT hr1, hr2;
long lWidth, lHeight;
hr1 = pBasivVideo->get_VideoHeight(&lHeight);
hr2 = pBasivVideo->get_VideoWidth(&lWidth);
if(SUCCEEDED(hr1) && SUCCEEDED(hr2))
{
ResizeWindow(lWidth, abs(lHeight));
}
}
}
}
RECT rc;
pVideoWindow->put_Owner((OAHWND)window); // We own the window now
pVideoWindow->put_WindowStyle(WS_CHILD); // you are now a child
GetClientRect(window, &rc);
pVideoWindow->SetWindowPosition(0, 0, rc.right, rc.bottom); // be this big
pVideoWindow->put_Visible(OATRUE);
}*/
}
}
BOOL CWebcam::StartCamera() {
if(m_bIsStreaming == FALSE)
{
m_bIsStreaming = TRUE;
hr = m_pMediaController->Run();
if(FAILED(hr))
{
// stop parts that ran
m_pMediaController->Stop();
return FALSE;
}
return TRUE;
}
return FALSE;
}
void CWebcam::EndCamera() {
if(m_bIsStreaming)
{
hr = m_pMediaController->Stop();
m_bIsStreaming = FALSE;
//invalidate client rect as well so that it must redraw
}
}
BOOL CWebcam::CaptureToTexture() {
return TRUE;
}
HRESULT CWebcam::InitCaptureGraphBuilder(
IGraphBuilder **ppGraph, // Receives the pointer.
ICaptureGraphBuilder2 **ppBuild // Receives the pointer.
)
{
if (!ppGraph || !ppBuild)
{
return E_POINTER;
}
IGraphBuilder *pGraph = NULL;
ICaptureGraphBuilder2 *pBuild = NULL;
// Create the Capture Graph Builder.
HRESULT hr = CoCreateInstance(CLSID_CaptureGraphBuilder2, NULL,
CLSCTX_INPROC_SERVER, IID_ICaptureGraphBuilder2, (void**)&pBuild );
if (SUCCEEDED(hr))
{
// Create the Filter Graph Manager.
hr = CoCreateInstance(CLSID_FilterGraph, 0, CLSCTX_INPROC_SERVER,
IID_IGraphBuilder, (void**)&pGraph);
if (SUCCEEDED(hr))
{
// Initialize the Capture Graph Builder.
pBuild->SetFiltergraph(pGraph);
// Return both interface pointers to the caller.
*ppBuild = pBuild;
*ppGraph = pGraph; // The caller must release both interfaces.
return S_OK;
}
else
{
pBuild->Release();
}
}
return hr; // Failed
}
HRESULT CWebcam::EnumerateDevices(REFGUID category, IEnumMoniker **ppEnum)
{
// Create the System Device Enumerator.
ICreateDevEnum *pSystemDeviceEnumerator;
HRESULT hr = CoCreateInstance(CLSID_SystemDeviceEnum, NULL,
CLSCTX_INPROC_SERVER, IID_PPV_ARGS(&pSystemDeviceEnumerator));
if (SUCCEEDED(hr))
{
// Create an enumerator for the category.
hr = pSystemDeviceEnumerator->CreateClassEnumerator(category, ppEnum, 0);
if (hr == S_FALSE)
{
hr = VFW_E_NOT_FOUND; // The category is empty. Treat as an error.
}
pSystemDeviceEnumerator->Release();
}
return hr;
}
void CWebcam::DisplayDeviceInformation(IEnumMoniker *pEnum)
{
IMoniker *pMoniker = NULL;
int counter = 0;
while (pEnum->Next(1, &pMoniker, NULL) == S_OK)
{
IPropertyBag *pPropBag;
HRESULT hr = pMoniker->BindToStorage(0, 0, IID_PPV_ARGS(&pPropBag));
if (FAILED(hr))
{
pMoniker->Release();
continue;
}
VARIANT var;
VariantInit(&var);
// Get description or friendly name.
hr = pPropBag->Read(L"Description", &var, 0);
if (FAILED(hr))
{
hr = pPropBag->Read(L"FriendlyName", &var, 0);
}
if (SUCCEEDED(hr))
{
printf("%d: %S\n", counter, var.bstrVal);
VariantClear(&var);
}
hr = pPropBag->Write(L"FriendlyName", &var);
// WaveInID applies only to audio capture devices.
hr = pPropBag->Read(L"WaveInID", &var, 0);
if (SUCCEEDED(hr))
{
printf("%d: WaveIn ID: %d\n", counter, var.lVal);
VariantClear(&var);
}
hr = pPropBag->Read(L"DevicePath", &var, 0);
if (SUCCEEDED(hr))
{
// The device path is not intended for display.
printf("%d: Device path: %S\n", counter, var.bstrVal);
VariantClear(&var);
}
pPropBag->Release();
pMoniker->Release();
counter++;
}
}
HRESULT CWebcam::InitializeVMR(
HWND hwndApp, // Application window.
IGraphBuilder* pFG, // Pointer to the Filter Graph Manager.
IVMRWindowlessControl** ppWc, // Receives the interface.
DWORD dwNumStreams, // Number of streams to use.
BOOL fBlendAppImage // Are we alpha-blending a bitmap?
)
{
IBaseFilter* pVmr = NULL;
IVMRWindowlessControl* pWc = NULL;
*ppWc = NULL;
// Create the VMR and add it to the filter graph.
HRESULT hr = CoCreateInstance(CLSID_VideoMixingRenderer, NULL,
CLSCTX_INPROC, IID_IBaseFilter, (void**)&pVmr);
if (FAILED(hr))
{
return hr;
}
hr = pFG->AddFilter(pVmr, L"Video Mixing Renderer");
if (FAILED(hr))
{
pVmr->Release();
return hr;
}
// Set the rendering mode and number of streams.
IVMRFilterConfig* pConfig;
hr = pVmr->QueryInterface(IID_IVMRFilterConfig, (void**)&pConfig);
if (SUCCEEDED(hr))
{
pConfig->SetRenderingMode(VMRMode_Windowless);
// Set the VMR-7 to mixing mode if you want more than one video
// stream, or you want to mix a static bitmap over the video.
// (The VMR-9 defaults to mixing mode with four inputs.)
if (dwNumStreams > 1 || fBlendAppImage)
{
pConfig->SetNumberOfStreams(dwNumStreams);
}
pConfig->Release();
hr = pVmr->QueryInterface(IID_IVMRWindowlessControl, (void**)&pWc);
if (SUCCEEDED(hr))
{
pWc->SetVideoClippingWindow(hwndApp);
*ppWc = pWc; // The caller must release this interface.
}
}
pVmr->Release();
// Now the VMR can be connected to other filters.
return hr;
}
In windowless mode VMR would not create separate window. Since you started initialization for widnowless mode, you have to follow SetVideoClippingWindow with IVMRWindowlessControl::SetVideoPosition call to provide position within the window, see VMR Windowless Mode on MSDN.
Another sample code snippet for you: http://www.assembla.com/code/roatl-utilities/subversion/nodes/trunk/FullScreenWindowlessVmrSample01/MainDialog.h#ln188
So we have a simple C++ win32 console app. All we want is to print list of web cameras and other video capture devices that are avaliable. We want to use windows apis as much as possible - no external libs - after all - all we want is to print out a a list - not to fly onto the moon!) How to do such thing?
My own reserch:
I found this official msdn sample but I still do not get how to output device list onto screen=( (sorry - I am new to C++)
... some more reserch...
In one of simpliest ms samples on topic found this
HRESULT OnInitDialog(HWND hwnd, ChooseDeviceParam *pParam)
{
HRESULT hr = S_OK;
HWND hList = GetDlgItem(hwnd, IDC_DEVICE_LIST);
// Display a list of the devices.
for (DWORD i = 0; i < pParam->count; i++)
{
WCHAR *szFriendlyName = NULL;
hr = pParam->ppDevices[i]->GetAllocatedString(
MF_DEVSOURCE_ATTRIBUTE_FRIENDLY_NAME,
&szFriendlyName,
NULL
);
if (FAILED(hr))
{
break;
}
int index = ListBox_AddString(hList, szFriendlyName);
ListBox_SetItemData(hList, index, i);
CoTaskMemFree(szFriendlyName);
}
looks like it should do the job but I do not get how to include this into simple command line app so to output data...
also from this series:
How to get a list of video capture devices on linux? and special details on getting cameras NAMES with correct, tested answers
How to get a list of video capture devices on Mac OS? with correct, not yet tested by my answers
How to get a list of video capture devices on windows? with correct, tested answers
How to get a list video capture devices NAMES using Qt (crossplatform)?
From the examples shown, copy the following code into dev.c. Then open the command line with all the SDK variables set. At the command line link to ole32.lib and oleaut32.lib. It will then show you all the devices.
cl dev.c ole32.lib oleaut32.lib
dev.exe will give out the list on the command line.
#include <windows.h>
#include <dshow.h>
#pragma comment(lib, "strmiids")
HRESULT EnumerateDevices(REFGUID category, IEnumMoniker **ppEnum)
{
// Create the System Device Enumerator.
ICreateDevEnum *pDevEnum;
HRESULT hr = CoCreateInstance(CLSID_SystemDeviceEnum, NULL,
CLSCTX_INPROC_SERVER, IID_PPV_ARGS(&pDevEnum));
if (SUCCEEDED(hr))
{
// Create an enumerator for the category.
hr = pDevEnum->CreateClassEnumerator(category, ppEnum, 0);
if (hr == S_FALSE)
{
hr = VFW_E_NOT_FOUND; // The category is empty. Treat as an error.
}
pDevEnum->Release();
}
return hr;
}
void DisplayDeviceInformation(IEnumMoniker *pEnum)
{
IMoniker *pMoniker = NULL;
while (pEnum->Next(1, &pMoniker, NULL) == S_OK)
{
IPropertyBag *pPropBag;
HRESULT hr = pMoniker->BindToStorage(0, 0, IID_PPV_ARGS(&pPropBag));
if (FAILED(hr))
{
pMoniker->Release();
continue;
}
VARIANT var;
VariantInit(&var);
// Get description or friendly name.
hr = pPropBag->Read(L"Description", &var, 0);
if (FAILED(hr))
{
hr = pPropBag->Read(L"FriendlyName", &var, 0);
}
if (SUCCEEDED(hr))
{
printf("%S\n", var.bstrVal);
VariantClear(&var);
}
hr = pPropBag->Write(L"FriendlyName", &var);
// WaveInID applies only to audio capture devices.
hr = pPropBag->Read(L"WaveInID", &var, 0);
if (SUCCEEDED(hr))
{
printf("WaveIn ID: %d\n", var.lVal);
VariantClear(&var);
}
hr = pPropBag->Read(L"DevicePath", &var, 0);
if (SUCCEEDED(hr))
{
// The device path is not intended for display.
printf("Device path: %S\n", var.bstrVal);
VariantClear(&var);
}
pPropBag->Release();
pMoniker->Release();
}
}
void main()
{
HRESULT hr = CoInitializeEx(NULL, COINIT_MULTITHREADED);
if (SUCCEEDED(hr))
{
IEnumMoniker *pEnum;
hr = EnumerateDevices(CLSID_VideoInputDeviceCategory, &pEnum);
if (SUCCEEDED(hr))
{
DisplayDeviceInformation(pEnum);
pEnum->Release();
}
hr = EnumerateDevices(CLSID_AudioInputDeviceCategory, &pEnum);
if (SUCCEEDED(hr))
{
DisplayDeviceInformation(pEnum);
pEnum->Release();
}
CoUninitialize();
}
}
How to let user select a video recording device (web-cam) with OpenCV?
the answer isnt opencv specific
Here is C++ code to list connected webcams on a windows machine without any additional libraries
/* List connected webcams on windows machine
Build: g++ cameralist.cpp -lstrmiids -lole32 -loleaut32
microsoft docs https://learn.microsoft.com/en-us/windows/win32/directshow/using-the-system-device-enumerator
*/
#include <windows.h>
#include <dshow.h>
HRESULT EnumerateDevices(REFGUID category, IEnumMoniker **ppEnum)
{
// Create the System Device Enumerator.
HRESULT hr;
ICreateDevEnum *pDevEnum = NULL;
hr = CoCreateInstance(CLSID_SystemDeviceEnum, NULL, CLSCTX_INPROC_SERVER,
IID_ICreateDevEnum, (void **)&pDevEnum);
if (SUCCEEDED(hr))
{
// Create an enumerator for the category.
hr = pDevEnum->CreateClassEnumerator(category, ppEnum, 0);
if (hr == S_FALSE)
{
hr = VFW_E_NOT_FOUND; // The category is empty. Treat as an error.
}
pDevEnum->Release();
}
return hr;
}
void DisplayDeviceInformation(IEnumMoniker *pEnum)
{
IMoniker *pMoniker = NULL;
while (pEnum->Next(1, &pMoniker, NULL) == S_OK)
{
IPropertyBag *pPropBag;
HRESULT hr = pMoniker->BindToStorage(0, 0, IID_PPV_ARGS(&pPropBag));
if (FAILED(hr))
{
pMoniker->Release();
continue;
}
VARIANT var;
VariantInit(&var);
// Get description or friendly name.
hr = pPropBag->Read(L"Description", &var, 0);
if (FAILED(hr))
{
hr = pPropBag->Read(L"FriendlyName", &var, 0);
}
if (SUCCEEDED(hr))
{
printf("%S\n", var.bstrVal);
VariantClear(&var);
}
hr = pPropBag->Write(L"FriendlyName", &var);
hr = pPropBag->Read(L"DevicePath", &var, 0);
if (SUCCEEDED(hr))
{
// The device path is not intended for display.
printf("Device path: %S\n", var.bstrVal);
VariantClear(&var);
}
pPropBag->Release();
pMoniker->Release();
}
}
int main()
{
HRESULT hr = CoInitializeEx(NULL, COINIT_MULTITHREADED);
if (SUCCEEDED(hr))
{
IEnumMoniker *pEnum;
hr = EnumerateDevices(CLSID_VideoInputDeviceCategory, &pEnum);
if (SUCCEEDED(hr))
{
DisplayDeviceInformation(pEnum);
pEnum->Release();
}
CoUninitialize();
}
return 0;
}