Building Windows Runtime Components in C++

1. Building Windows Runtime Components in C++ Harry Pierson Program Manager, Windows Runtime Experience Team Microsoft Corporation

2. What is the “Windows Runtime”? The new API surface area in Windows 8 that’s available to C++, JavaScript, C# and Visual Basic.

3. Windows 8 Platform Metro style Apps Desktop Apps HTML JavaScript HTML / CSS XAML View JavaScript (Chakra) C C++ C# VB Model Controller C# VB C C++ WinRT APIs Devices & Printing Communication & Data Graphics & Media System Services .NET / SL Internet Explorer Win32 Application Model Windows Core OS Services Core

4. What is the “Windows Runtime”? The new API surface area in Windows 8 that’s available to C++, JavaScript, C# and Visual Basic. The low-level system infrastructure that enables language projection of APIs.

5. You can leverage the Windows Runtime in order to build your own APIs that project into C++, JavaScript, C# and VB.

6. Language Projection

7. WinRT Component Authoring Choices • C# / VB • C++/CX • C++ with WRL

8. C++ WinRT Components Reasons

9. C++ Hybrid App Scenarios • HTML/JS Front End • C#/VBFront End • C++ Front End • C++ WinRT Components • C++ WinRT Components • C#/VB WinRT Components

10. demo Building C++/cx WinRTComponents

11. WinRT is a marshaling boundary. Favor course-grained APIs over fine-grained.

12. Marshaling Example: Array vs. Vector //marshals entire array at once void ArraySample(constArray<int>^ ints) { for(auto x = 0u; x < ints->Length; x++) { autovalue = ints[x]; } } //marshals each call to Size and GetAt separately voidVectorSample(IVectorView<int>^ ints) { for(auto x = 0u; x < ints->Size; x++) { autovalue = ints->GetAt(x); } }

13. WinRT only provides async methods for all potentially long running operations.Favor async methods and use PPL to implement them.

14. Async Example IAsyncOperation<int>^ CalculateAnswer() { returnconcurrency::create_async([]() -> int { //do long running operation here return42; }); } IAsyncOperation<String^>^ CalculateQuestion() { returncreate_async([]() -> String^ { //do long running operation here returnref new String(L"Whatdo you get if you multiply six by nine?"); }); }

15. WinRT doesn’t allow UI updates from background threads.Use CoreDispatcher to fire events on the correct thread

16. Event Firing Example auto callback = [this](Object^ sender,InvokedHandlerArgs^ e) { this->Ticked(this->currentTick); }; //get window via CoreWindow::GetForCurrentThread window->Dispatcher->Invoke(CoreDispatcherPriority::Normal, ref new InvokedHandler(callback), this, nullptr);

17. Leverage the WinRT Infrastructure of Windows 8Build WinRT Components that can be used in C++, JavaScript, C# & VB apps.Be mindful of threading and marshaling boundaries.

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