Get UWP app local data location

AppDataLocation.cpp

#include "AppDataLocation.h"

#ifdef NEEDS_UWP_APP_DATA_LOCATION
#include <winrt/Windows.Storage.h>
#include <winrt/Windows.Foundation.h>
#endif

QString appDataLocationPath()
{
    static QString path; // calculate it only once and store it here

    if (path.isEmpty())
    {
#ifdef NEEDS_UWP_APP_DATA_LOCATION
        try
        {
            auto localFolder = winrt::Windows::Storage::ApplicationData::Current().LocalFolder();
            std::wstring folderPath = localFolder.Path().c_str();
            path = QString::fromStdWString(folderPath);
        }
        catch (const std::exception& e)
        {
            qWarning() << "Failed to get the UWP AppData path:" << e.what() << "Falling back to QStandardPaths";
            path = QStandardPaths::writableLocation(QStandardPaths::AppDataLocation);
        }
#else
        path = QStandardPaths::writableLocation(QStandardPaths::AppDataLocation);
#endif
    }

    return path;
}

AppDataLocation.h

# For use in Qt 6 Win32 apps, delivered via the Microsoft Store, where app data was previously saved by a Qt 5 UWP app.
# In this scenario, define `NEEDS_UWP_APP_DATA_LOCATION`.

QString appDataLocationPath();

CMakeLists.txt

# If using CMake, you'll need the following snippet. This assumes that the AppDataLocation files
# are in a subdirectory as a library called `AppDataLocationLib`.
# Put this code in the parent folder.
# When you set the CMake cache variable `NEEDS_UWP_APP_DATA_LOCATION` to `ON`, it adds the
# necessary configuration and defines NEEDS_UWP_APP_DATA_LOCATION for C++.

add_subdirectory(AppDataLocation)

option(NEEDS_UWP_APP_DATA_LOCATION "Use UWP app data location for backward compatibility" OFF)
if(NEEDS_UWP_APP_DATA_LOCATION)
    message(STATUS "Applying legacy UWP app data location path, for delivery via the Microsoft Store")

    target_compile_definitions(AppDataLocationLib PRIVATE WINVER=0x0A00 _WIN32_WINNT=0x0A00)
    target_link_libraries(AppDataLocationLib PRIVATE WindowsApp)

    target_compile_definitions(AppDataLocationLib PRIVATE NEEDS_UWP_APP_DATA_LOCATION)
endif()

target_link_libraries(${APP_TARGET}
    PRIVATE
        Qt6::Qml Qt6::Quick
        AppDataLocationLib
        ...
)