WinRT API WIndows::System::Launcher::LaunchFileAsync() usage from C++ - c++

Question

I'm trying to launch an image using WinRT API WIndows::System::Launcher::LaunchFileAsync().
Code snippet is as follows:
RoInitialize(RO_INIT_MULTITHREADED);
String^ imagePath = ref new String(L"C:\\Users\\GoodMan\\Pictures\\wood.png");
auto file = Storage::StorageFile::GetFileFromPathAsync(imagePath);
Windows::System::Launcher::LaunchFileAsync(file);
I'm getting this error from the LaunchFileAsync() API:
error C2665: 'Windows::System::Launcher::LaunchFileAsync' : none of
the 2 overloads could convert all the argument types
Can I please get help how to solve this. I'm very new to WinRT C++ coding .

Answer 1

The method GetFileFromPathAsync does not return a StorageFile, but it returns IAsyncOperation<StorageFile>^. What you have to do is convert the latter to the former, as follows:
using namespace concurrency;
String^ imagePath = ref new String(L"C:\\Users\\GoodMan\\Pictures\\wood.png");
auto task = create_task(Windows::Storage::StorageFile::GetFileFromPathAsync(imagePath));
task.then([this](Windows::Storage::StorageFile^ file)
{
Windows::System::Launcher::LaunchFileAsync(file);
});
Generally all Windows Store app framework methods that end in Async will return either an IAsyncOperation, or a task. These methods are what are known as asynchronous methods, and require some special handling. See this article for more info: Asynchronous programming in C++ .
So now everything is great, correct? Well, not quite. There is another issue with your code. It is that when you run the code above, you will get an access-denied error. The reason is that Windows Store Apps are sandboxed, and you cannot generally access just any file on the filesystem.
You are in luck, though, because you are trying to access a file in your Pictures folder. The Pictures folder is a special folder that Windows Store apps have access to. You can get at it using the KnownFolders class:
using namespace concurrency;
Windows::Storage::StorageFolder^ pictures =
Windows::Storage::KnownFolders::PicturesLibrary;
auto task = create_task(pictures->GetFileAsync("wood.png"));
task.then([this](Windows::Storage::StorageFile^ file)
{
Windows::System::Launcher::LaunchFileAsync(file);
});
Note that in order to access the Pictures folder your application has to declare it in the project manifest. To do so, double click on the Package.appmanifest file in the project "tree" in Visual Studio, and select the Capabilities tab. Then under Capabilities, check Pictures Library.