在设备上移动内容
WPD 应用程序完成的另一个常见操作是将内容从设备上的一个位置传输到另一个位置。
内容移动操作是使用下表中所述的接口完成的。
| 接口 | 说明 |
|---|---|
| IPortableDeviceContent 接口 | 提供对特定于内容的方法的访问。 |
| IPortableDevicePropVariantCollection 接口 | 提供对特定于属性的方法的访问。 |
示例应用程序的 ContentTransfer.cpp 模块中的 MoveContentAlreadyOnDevice 函数演示了应用程序如何将内容从一个位置移动到另一个位置。
MoveContentAlreadyOnDevice 函数完成的第一个任务是查询设备驱动程序以查看它是否支持内容移动。 这是通过调用 SupportsCommand 帮助程序函数并将WPD_COMMAND_OBJECT_MANAGEMENT_MOVE_OBJECTS作为第二个参数传递来实现的。
HRESULT hr = S_OK;
WCHAR wszSelection[81] = {0};
WCHAR wszDestinationFolderObjectID[81] = {0};
CComPtr<IPortableDeviceContent> pContent;
CComPtr<IPortableDevicePropVariantCollection> pObjectsToMove;
CComPtr<IPortableDevicePropVariantCollection> pObjectsFailedToMove;
if (SupportsCommand(pDevice, WPD_COMMAND_OBJECT_MANAGEMENT_MOVE_OBJECTS) == FALSE)
{
printf("! This device does not support the move operation (i.e. The WPD_COMMAND_OBJECT_MANAGEMENT_MOVE_OBJECTS command)\n");
return;
}
下一步需要提示用户输入两个对象标识符。 第一个是将要移动的内容的标识符。 第二个是应用程序应将此内容移动到的位置的标识符。
HRESULT hr = S_OK;
WCHAR wszSelection[81] = {0};
WCHAR wszDestinationFolderObjectID[81] = {0};
CComPtr<IPortableDeviceContent> pContent;
CComPtr<IPortableDevicePropVariantCollection> pObjectsToMove;
CComPtr<IPortableDevicePropVariantCollection> pObjectsFailedToMove;
printf("Enter the identifer of the object you wish to move.\n>");
hr = StringCbGetsW(wszSelection,sizeof(wszSelection));
if (FAILED(hr))
{
printf("An invalid object identifier was specified, aborting content moving\n");
}
// Prompt user to enter an object identifier on the device to move.
printf("Enter the identifer of the object you wish to move '%ws' to.\n>", wszSelection);
hr = StringCbGetsW(wszDestinationFolderObjectID,sizeof(wszDestinationFolderObjectID));
if (FAILED(hr))
{
printf("An invalid object identifier was specified, aborting content moving\n");
}
接下来，该示例检索用于访问 IPortableDeviceContent：：Move 方法的 IPortableDeviceContent 对象。
HRESULT hr = S_OK;
WCHAR wszSelection[81] = {0};
WCHAR wszDestinationFolderObjectID[81] = {0};
CComPtr<IPortableDeviceContent> pContent;
CComPtr<IPortableDevicePropVariantCollection> pObjectsToMove;
CComPtr<IPortableDevicePropVariantCollection> pObjectsFailedToMove;
if (SUCCEEDED(hr))
{
hr = pDevice->Content(&pContent);
if (FAILED(hr))
{
printf("! Failed to get IPortableDeviceContent from IPortableDevice, hr = 0x%lx\n",hr);
}
}
最后，移动内容。 此过程涉及以下内容：
- 创建 一个 IPortableDevicePropVariantCollection 对象，该对象接收要移动的对象的 PROPVARIANT 结构。
- 将 PROPVARIANT 添加到 IPortableDevicePropVariantCollection 对象。
- 调用 IPortableDeviceContent：：Move 方法。
HRESULT hr = S_OK;
WCHAR wszSelection[81] = {0};
WCHAR wszDestinationFolderObjectID[81] = {0};
CComPtr<IPortableDeviceContent> pContent;
CComPtr<IPortableDevicePropVariantCollection> pObjectsToMove;
CComPtr<IPortableDevicePropVariantCollection> pObjectsFailedToMove;
if (SUCCEEDED(hr))
{
hr = CoCreateInstance(CLSID_PortableDevicePropVariantCollection,
NULL,
CLSCTX_INPROC_SERVER,
IID_IPortableDevicePropVariantCollection,
(VOID**) &pObjectsToMove);
if (SUCCEEDED(hr))
{
if (pObjectsToMove != NULL)
{
PROPVARIANT pv = {0};
PropVariantInit(&pv);
// Initialize a PROPVARIANT structure with the object identifier string
// that the user selected above. Notice we are allocating memory for the
// LPWSTR value. This memory will be freed when PropVariantClear() is
// called below.
pv.vt = VT_LPWSTR;
pv.pwszVal = AtlAllocTaskWideString(wszSelection);
if (pv.pwszVal != NULL)
{
// Add the object identifier to the objects-to-move list
// (We are only moving 1 in this example)
hr = pObjectsToMove->Add(&pv);
if (SUCCEEDED(hr))
{
// Attempt to move the object on the device
hr = pContent->Move(pObjectsToMove, // Object(s) to move
wszDestinationFolderObjectID, // Folder to move to
NULL); // Object(s) that failed to delete (we are only moving 1, so we can pass NULL here)
if (SUCCEEDED(hr))
{
// An S_OK return lets the caller know that the deletion was successful
if (hr == S_OK)
{
printf("The object '%ws' was moved on the device.\n", wszSelection);
}
// An S_FALSE return lets the caller know that the move failed.
// The caller should check the returned IPortableDevicePropVariantCollection
// for a list of object identifiers that failed to be moved.
else
{
printf("The object '%ws' failed to be moved on the device.\n", wszSelection);
}
}
else
{
printf("! Failed to move an object on the device, hr = 0x%lx\n",hr);
}
}
else
{
printf("! Failed to move an object on the device because we could no add the object identifier string to the IPortableDevicePropVariantCollection, hr = 0x%lx\n",hr);
}
}
else
{
hr = E_OUTOFMEMORY;
printf("! Failed to move an object on the device because we could no allocate memory for the object identifier string, hr = 0x%lx\n",hr);
}
// Free any allocated values in the PROPVARIANT before exiting
PropVariantClear(&pv);
}
else
{
printf("! Failed to move an object from the device because we were returned a NULL IPortableDevicePropVariantCollection interface pointer, hr = 0x%lx\n",hr);
}
}
else
{
printf("! Failed to CoCreateInstance CLSID_PortableDevicePropVariantCollection, hr = 0x%lx\n",hr);
}
}
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