擷取裝置支援的轉譯功能
支援轉譯資訊功能類別 (WPD_FUNCTIONAL_CATEGORY_RENDERING_INFORMATION) 的 Windows 可攜式裝置會在查詢時傳回轉譯資訊。 轉譯資訊描述嘗試將內容寫入裝置的應用程式所加總的需求和限制。
ListRenderingCapabilityInformation 函式、SupportsFunctionalCategory 協助程式函式，以及 DeviceCapabilities.cpp 模組中的 ReadProfileInformationProperties 協助程式函式會示範擷取所選裝置的轉譯功能。
您的應用程式可以使用下表所述的介面，擷取裝置支援的轉譯功能。
| 介面 | 描述 |
|---|---|
| IPortableDeviceContent 介面 | 提供 IPortableDeviceProperties 介面的存取權。 |
| IPortableDeviceProperties 介面 | 提供屬性特定方法的存取權。 |
| IPortableDeviceKeyCollection 介面 | 用來儲存指定設定檔的屬性索引鍵。 |
| IPortableDeviceValues 介面 | 用來儲存指定設定檔的屬性值。 |
| IPortableDeviceCapabilities 介面 | 用來儲存指定設定檔的屬性值。 |
| IPortableDevicePropVariantCollection 介面 | 用來儲存指定設定檔的屬性值。 |
| IPortableDeviceValuesCollection 介面 | 用來儲存指定設定檔的屬性值。 |
範例應用程式完成的第一項工作是判斷所選裝置是否能夠列出轉譯功能。 SupportsFunctionalCategory 協助程式函式會呼叫 ListRenderingCapabilityInformation 協助程式函式，並傳遞WPD_FUNCTIONAL_CATEGORY_RENDERING_INFORMATION做為第二個引數，來判斷這是這種情況。
HRESULT hr = S_OK;
CComPtr<IPortableDeviceCapabilities> pCapabilities;
CComPtr<IPortableDevicePropVariantCollection> pRenderingInfoObjects;
CComPtr<IPortableDeviceValuesCollection> pRenderingInfoProfiles;
CAtlStringW strRenderingInfoObjectID;
if (SupportsFunctionalCategory(pDevice, WPD_FUNCTIONAL_CATEGORY_RENDERING_INFORMATION) == FALSE)
{
printf("This device does not support device rendering information to display\n");
return;
}
如果裝置能夠列出轉譯功能，下一個步驟需要擷取 IPortableDeviceCapabilities 物件，並叫用 GetFunctionalObjects 方法來擷取轉譯資訊物件的物件識別碼。
HRESULT hr = S_OK;
CComPtr<IPortableDeviceCapabilities> pCapabilities;
CComPtr<IPortableDevicePropVariantCollection> pRenderingInfoObjects;
CComPtr<IPortableDeviceValuesCollection> pRenderingInfoProfiles;
CAtlStringW strRenderingInfoObjectID;
hr = pDevice->Capabilities(&pCapabilities);
if (FAILED(hr))
{
printf("! Failed to get IPortableDeviceCapabilities from IPortableDevice, hr = 0x%lx\n",hr);
}
// Get the functional object identifier for the rendering information object
if (SUCCEEDED(hr))
{
hr = pCapabilities->GetFunctionalObjects(WPD_FUNCTIONAL_CATEGORY_RENDERING_INFORMATION, &pRenderingInfoObjects);
if (FAILED(hr))
{
printf("! Failed to get functional objects, hr = 0x%lx\n", hr);
}
}
下一個步驟是儲存剛才在字串變數中擷取的轉譯資訊物件識別碼， (strRenderingInfoObjectID) ，然後呼叫 ReadProfileInformationProperties 協助程式函式。 (將 strRenderingInfoObjectID 變數當做第二個引數傳遞至 helper function.)
HRESULT hr = S_OK;
CComPtr<IPortableDeviceCapabilities> pCapabilities;
CComPtr<IPortableDevicePropVariantCollection> pRenderingInfoObjects;
CComPtr<IPortableDeviceValuesCollection> pRenderingInfoProfiles;
CAtlStringW strRenderingInfoObjectID;
if (SUCCEEDED(hr))
{
PROPVARIANT pv = {0};
PropVariantInit(&pv);
hr = pRenderingInfoObjects->GetAt(0, &pv);
if ((SUCCEEDED(hr)) &&
(pv.vt== VT_LPWSTR) )
{
strRenderingInfoObjectID = pv.pwszVal;
}
else
{
printf("! Failed to get first rendering object's identifier, hr = 0x%lx\n", hr);
}
PropVariantClear(&pv);
}
if (SUCCEEDED(hr))
{
hr = ReadProfileInformationProperties(pDevice,
strRenderingInfoObjectID,
&pRenderingInfoProfiles);
// Error output statements are performed by the helper function, so they
// are omitted here.
}
協助程式函式完成的第一個工作之一是擷取 IPortableDeviceContent 物件，該物件會用來存取內容特定的方法。
HRESULT hr = S_OK;
CComPtr<IPortableDeviceValuesCollection> pRenderingInfoProfiles;
CComPtr<IPortableDeviceContent> pContent;
CComPtr<IPortableDeviceProperties> pProperties;
CComPtr<IPortableDeviceKeyCollection> pPropertiesToRead;
CComPtr<IPortableDeviceValues> pObjectProperties;
if (SUCCEEDED(hr))
{
hr = pDevice->Content(&pContent);
if (FAILED(hr))
{
printf("! Failed to get IPortableDeviceContent from IPortableDevice, hr = 0x%lx\n",hr);
}
}
接下來，協助程式函式會擷取 IPortableDeviceProperties 物件，該物件會用來存取屬性特定的方法。
HRESULT hr = S_OK;
CComPtr<IPortableDeviceValuesCollection> pRenderingInfoProfiles;
CComPtr<IPortableDeviceContent> pContent;
CComPtr<IPortableDeviceProperties> pProperties;
CComPtr<IPortableDeviceKeyCollection> pPropertiesToRead;
CComPtr<IPortableDeviceValues> pObjectProperties;
if (SUCCEEDED(hr))
{
hr = pContent->Properties(&pProperties);
if (FAILED(hr))
{
printf("! Failed to get IPortableDeviceProperties from IPortableDevice, hr = 0x%lx\n",hr);
}
}
下一個步驟是建立 IPortableDeviceKeyCollection 物件，其中儲存轉譯資訊的屬性索引鍵。 建立物件之後，會叫用 IPortableDeviceKeyCollection：：Add 方法以新增必要的金鑰。 (必須新增這些索引鍵，才能在後續的步驟中擷取對應的轉譯設定檔。)
HRESULT hr = S_OK;
CComPtr<IPortableDeviceValuesCollection> pRenderingInfoProfiles;
CComPtr<IPortableDeviceContent> pContent;
CComPtr<IPortableDeviceProperties> pProperties;
CComPtr<IPortableDeviceKeyCollection> pPropertiesToRead;
CComPtr<IPortableDeviceValues> pObjectProperties;
hr = CoCreateInstance(CLSID_PortableDeviceKeyCollection,
NULL,
CLSCTX_INPROC_SERVER,
IID_IPortableDeviceKeyCollection,
(VOID**) &pPropertiesToRead);
if (SUCCEEDED(hr))
{
// Populate the IPortableDeviceKeyCollection with the keys we wish to read.
// NOTE: We are not handling any special error cases here so we can proceed with
// adding as many of the target properties as we can.
if (pPropertiesToRead != NULL)
{
HRESULT hrTemp = S_OK;
hrTemp = pPropertiesToRead->Add(WPD_RENDERING_INFORMATION_PROFILES);
if (FAILED(hrTemp))
{
printf("! Failed to add WPD_RENDERING_INFORMATION_PROFILES to IPortableDeviceKeyCollection, hr= 0x%lx\n", hrTemp);
}
}
}
下一個步驟是從設備磁碟機擷取屬性值，方法是呼叫 IPortableDeviceProperties：：GetValues 方法。
HRESULT hr = S_OK;
CComPtr<IPortableDeviceValuesCollection> pRenderingInfoProfiles;
CComPtr<IPortableDeviceContent> pContent;
CComPtr<IPortableDeviceProperties> pProperties;
CComPtr<IPortableDeviceKeyCollection> pPropertiesToRead;
CComPtr<IPortableDeviceValues> pObjectProperties;
if (SUCCEEDED(hr))
{
hr = pProperties->GetValues(wszFunctionalObjectID, // The object whose properties we are reading
pPropertiesToRead, // The properties we want to read
&pObjectProperties); // Driver supplied property values for the specified object
if (FAILED(hr))
{
printf("! Failed to get all properties for object '%ws', hr= 0x%lx\n", wszFunctionalObjectID, hr);
}
}
下一個步驟會擷取轉譯資訊設定檔，並將其儲存在 ppRenderingInfoProfiles 引數中。
HRESULT hr = S_OK;
CComPtr<IPortableDeviceValuesCollection> pRenderingInfoProfiles;
CComPtr<IPortableDeviceContent> pContent;
CComPtr<IPortableDeviceProperties> pProperties;
CComPtr<IPortableDeviceKeyCollection> pPropertiesToRead;
CComPtr<IPortableDeviceValues> pObjectProperties;
if (SUCCEEDED(hr))
{
hr = pObjectProperties->GetIPortableDeviceValuesCollectionValue(WPD_RENDERING_INFORMATION_PROFILES,
&pRenderingInfoProfiles);
if (FAILED(hr))
{
printf("! Failed to get WPD_RENDERING_INFORMATION_PROFILES from rendering information, hr= 0x%lx\n", hr);
}
}
// QueryInterface the interface into the out-going parameters.
if (SUCCEEDED(hr))
{
hr = pRenderingInfoProfiles->QueryInterface(IID_PPV_ARGS(ppRenderingInfoProfiles));
if (FAILED(hr))
{
printf("! Failed to QueryInterface for IPortableDeviceValuesCollection (Rendering information profiles), hr= 0x%lx\n", hr);
}
}
協助程式函式讀取WPD_RENDERING_INFORMATION_PROFILES屬性之後，會顯示轉譯設定檔。 這些設定檔是由 DisplayRenderingProfile 協助程式函式所顯示。
void DisplayRenderingProfile(
IPortableDeviceValues* pProfile)
{
HRESULT hr = S_OK;
if (pProfile == NULL)
{
return;
}
if (SUCCEEDED(hr))
{
DWORD dwTotalBitrate = 0;
DWORD dwChannelCount = 0;
DWORD dwAudioFormatCode = 0;
GUID guidFormat = WPD_OBJECT_FORMAT_UNSPECIFIED;
// Display WPD_MEDIA_TOTAL_BITRATE
hr = pProfile->GetUnsignedIntegerValue(WPD_MEDIA_TOTAL_BITRATE, &dwTotalBitrate);
if (SUCCEEDED(hr))
{
printf("Total Bitrate: %d\n", dwTotalBitrate);
}
// If we fail to read the total bitrate as a single value, then it must be
// a valid value set. (i.e. returning IPortableDeviceValues as the value which
// contains properties describing the valid values for this property.)
if (hr == DISP_E_TYPEMISMATCH)
{
CComPtr<IPortableDeviceValues> pExpectedValues;
hr = pProfile->GetIPortableDeviceValuesValue(WPD_MEDIA_TOTAL_BITRATE, &pExpectedValues);
if (SUCCEEDED(hr))
{
printf("Total Bitrate: ");
DisplayExpectedValues(pExpectedValues);
}
}
// If we are still a failure here, report the error
if (FAILED(hr))
{
printf("! Failed to get WPD_MEDIA_TOTAL_BITRATE from rendering profile, hr = 0x%lx\n",hr);
}
// Display WPD_AUDIO_CHANNEL_COUNT
hr = pProfile->GetUnsignedIntegerValue(WPD_AUDIO_CHANNEL_COUNT, &dwChannelCount);
if (SUCCEEDED(hr))
{
printf("Channel Count: %d\n", dwChannelCount);
}
else
{
printf("! Failed to get WPD_AUDIO_CHANNEL_COUNT from rendering profile, hr = 0x%lx\n",hr);
}
// Display WPD_AUDIO_FORMAT_CODE
hr = pProfile->GetUnsignedIntegerValue(WPD_AUDIO_FORMAT_CODE, &dwAudioFormatCode);
if (SUCCEEDED(hr))
{
printf("Audio Format Code: %d\n", dwAudioFormatCode);
}
else
{
printf("! Failed to get WPD_AUDIO_FORMAT_CODE from rendering profile, hr = 0x%lx\n",hr);
}
// Display WPD_OBJECT_FORMAT
hr = pProfile->GetGuidValue(WPD_OBJECT_FORMAT, &guidFormat);
if (SUCCEEDED(hr))
{
printf("Object Format: %ws\n", (LPWSTR)CComBSTR(guidFormat));
}
else
{
printf("! Failed to get WPD_OBJECT_FORMAT from rendering profile, hr = 0x%lx\n",hr);
}
}
}
請注意，由於轉譯設定檔是靜態的，因此您的應用程式可以選擇讀取設定檔，並將其儲存在本機 (，而不是每次需要資料時存取裝置) 。
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