The following example shows how to enumerate and select ltmmPlay object renderers.
// define helper macros for using interfaces under C
#ifndef COBJMACROS
#define COBJMACROS
#endif
#include "ltmm.h"
#include "resource.h"
#include "tchar.h"
#include "stdio.h"
HINSTANCE g_hInstance; // application instance handle
IltmmPlay* g_pPlay; // convert object's interface pointer
//
// BuildRendererList
// fills a listbox to match the contents of the collection
//
// pRenderers = renderer collection's interface pointer
// hwndListBox = listbox window handle
//
void BuildRendererList(IltmmRenderers* pRenderers, HWND hwndListBox)
{
long i;
long count;
int selected = -1;
// reset the listbox contents
SendMessage(hwndListBox, LB_RESETCONTENT, 0, 0);
// get the collection's item count
IltmmRenderers_get_Count(pRenderers, &count);
for(i = 0; i < count; i++)
{
IltmmRenderer* pRenderer;
BSTR bstr;
TCHAR sz[256];
int index;
VARIANT_BOOL f;
// retrieve collection item
IltmmRenderers_Item(pRenderers, i, &pRenderer);
// get displayable name
IltmmRenderer_get_FriendlyName(pRenderer, &bstr);
// convert from unicode
_stprintf(sz, _T("%ls"), bstr);
// free name
SysFreeString(bstr);
// add the name to the listbox
index = SendMessage(hwndListBox, LB_ADDSTRING, 0, (LPARAM) (LPCTSTR) sz);
// associate the listbox item with the collection item index
SendMessage(hwndListBox, LB_SETITEMDATA, index, i);
// remember this listbox item, if it is selected in the collection
IltmmRenderer_get_Selected(pRenderer, &f);
if(f)
selected = i;
// free the collection item
IUnknown_Release(pRenderer);
}
// select the appropriate listbox item
for(i = 0; i < count; i++)
{
if(selected == (long) SendMessage(hwndListBox, LB_GETITEMDATA, i, 0))
{
SendMessage(hwndListBox, LB_SETCURSEL, i, 0);
break;
}
}
}
//
// RendererSelectionChanged
// called to reflect changes in the listbox selection
//
// pRenderers = renderer collection's interface pointer
// hwndListBox = listbox window handle
//
void RendererSelectionChanged(IltmmRenderers* pRenderers, HWND hwndListBox)
{
int index;
long item;
int i;
int count;
HRESULT hr;
// get the index of current listbox selection
index = (int) SendMessage(hwndListBox, LB_GETCURSEL, 0, 0);
if(index < 0)
{
// clear selection
IltmmRenderers_put_Selection(pRenderers, -1);
}
else
{
// get the collection item index
item = (long) SendMessage(hwndListBox, LB_GETITEMDATA, index, 0);
// select the item
#ifdef _DEBUG
{
IltmmRenderer* pRenderer;
IltmmRenderers_Item(pRenderers, item, &pRenderer);
hr = IltmmRenderer_put_Selected(pRenderer, VARIANT_TRUE);
IUnknown_Release(pRenderer);
}
#else
hr = IltmmRenderers_put_Selection(pRenderers, item);
#endif
// if new selection failed, we need to force the listbox to match the actual selection
if(FAILED(hr))
{
// get the real selection
IltmmRenderers_get_Selection(pRenderers, &item);
// find the matching listbox item
count = (int) SendMessage(hwndListBox, LB_GETCOUNT, 0, 0);
for(i = 0; i < count; i++)
{
if(item == (long) SendMessage(hwndListBox, LB_GETITEMDATA, i, 0))
{
SendMessage(hwndListBox, LB_SETCURSEL, i, 0);
break;
}
}
}
}
}
//
// RefreshRendererList
// called when to completely rebuild the collection
//
// pRenderers = renderer collection's interface pointer
// hwndListBox = listbox window handle
//
void RefreshRendererList(IltmmRenderers* pRenderers, HWND hwndListBox)
{
IltmmRenderer* pRenderer;
long item;
BSTR bstr;
// get the currently selected item
IltmmRenderers_get_Selection(pRenderers, &item);
if(item >= 0)
{
// get it's unique name
IltmmRenderers_Item(pRenderers, item, &pRenderer);
IltmmRenderer_get_Name(pRenderer, &bstr);
IUnknown_Release(pRenderer);
}
else
{
bstr = NULL;
}
// rebuild the collection
IltmmRenderers_Refresh(pRenderers);
if(bstr)
{
// find the previously selected item
IltmmRenderers_Find(pRenderers, bstr, &item);
// make it the current selection
if(item >= 0)
IltmmRenderers_put_Selection(pRenderers, item);
SysFreeString(bstr);
}
// rebuild the listbox
BuildRendererList(pRenderers, hwndListBox);
}
//
// RendererDlgProc
// selects object renderers
//
BOOL CALLBACK RendererDlgProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
IltmmRenderers* pRenderers;
lParam = lParam ;
switch (msg)
{
case WM_INITDIALOG:
// initialize the audio renderer listbox
IltmmPlay_get_AudioRenderers(g_pPlay, &pRenderers);
BuildRendererList(pRenderers, GetDlgItem(hwnd, IDC_AUDIODEVICES));
IUnknown_Release(pRenderers);
return TRUE;
break;
case WM_COMMAND:
switch(LOWORD(wParam))
{
case IDC_REFRESHAUDIODEVICES:
// refresh the audio renderer listbox
IltmmPlay_get_AudioRenderers(g_pPlay, &pRenderers);
RefreshRendererList(pRenderers, GetDlgItem(hwnd, IDC_AUDIODEVICES));
IUnknown_Release(pRenderers);
return TRUE;
break;
case IDC_AUDIODEVICES:
if(HIWORD(wParam) == LBN_SELCHANGE)
{
// select the audio renderer
IltmmPlay_get_AudioRenderers(g_pPlay, &pRenderers);
RendererSelectionChanged(pRenderers, GetDlgItem(hwnd, IDC_AUDIODEVICES));
IUnknown_Release(pRenderers);
}
break;
case IDOK:
EndDialog(hwnd, IDOK);
return TRUE;
break;
}
break;
}
return FALSE;
}
void SelectingltmmPlayObjectRenderers_Example ( HINSTANCE hInstance /*application instance handle*/ )
{
HRESULT hr;
g_hInstance = hInstance;
// initialize COM library
hr = CoInitialize(NULL);
if(FAILED(hr))
goto error;
// create the play object
hr = CoCreateInstance(&CLSID_ltmmPlay, NULL, CLSCTX_INPROC_SERVER, &IID_IltmmPlay, (void**) &g_pPlay);
if(FAILED(hr))
goto error;
DialogBox(g_hInstance, (LPCTSTR)IDD_DEVICEDLG, NULL, RendererDlgProc);
error:
// cleanup
if(g_pPlay)
IUnknown_Release(g_pPlay);
CoUninitialize();
}
Help Collections
Raster .NET | C API | C++ Class Library | HTML5 JavaScript
Document .NET | C API | C++ Class Library | HTML5 JavaScript
Medical .NET | C API | C++ Class Library | HTML5 JavaScript
Medical Web Viewer .NET
Multimedia
Direct Show .NET | C API | Filters
Media Foundation .NET | C API | Transforms
Supported Platforms
.NET, Java, Android, and iOS/macOS Assemblies
Imaging, Medical, and Document
C API/C++ Class Libraries
Imaging, Medical, and Document
HTML5 JavaScript Libraries
Imaging, Medical, and Document
Your email has been sent to support! Someone should be in touch! If your matter is urgent please come back into chat.
Chat Hours:
Monday - Friday, 8:30am to 6pm ET
Thank you for your feedback!
Please fill out the form again to start a new chat.
All agents are currently offline.
Chat Hours:
Monday - Friday
8:30AM - 6PM EST
To contact us please fill out this form and we will contact you via email.