WRLSridhar Madhugiri, Software Design EngineerLukasz Chodorski, Software Design EngineerMicrosoft Corporation

AgendaWRL OverviewWRL ClassesConsuming WinRTProject templateDemo

WRL Overview

WRLTemplate based implementationConsume and Author WinRT objectsException FreeWorks at ABI levelDeveloped specifically for WinRT

Why use WRLPorting COM components to MetroNo exceptions requirementInterop with Com No C++ extensions requirementFine grained control

WRL Classes

Winrt ConceptsWinRT ObjectReference countedImplements IInspectableInstantiated through factoryWeakReference support

DelegateCallbackInterface with methodDelegate instance is WinRT object

EventDelegate used as Event callbackServer advertises eventsClient creates delegate and registers it to receive events

MiscReference count managementAsynchronous operations

WRL ClassesWinRT ObjectRuntimeClassInspectableClassActivatableClassActivationFactory

DelegateCallback

EventEventSourceCallback

MiscComPtr, WeakPtrAsyncBaseAnd many more

Consuming WinRT

ComPtr, HStringComPtr<IActivationFactory> activationFactory;HRESULT hr = GetActivationFactory(

HString::MakeReference(RuntimeClass_Windows_Foundation_Uri).Get(), &activationFactory

);// Error handling

ComPtr<IUriRuntimeClassFactory> uriActivationFactory;hr = activationFactory.As(&uriActivationFactory);// Error handling

ComPtr<IUriRuntimeClass> uri;

hr = uriActivationFactory->CreateUri(HString::MakeReference(L"http://www.microsoft.com").Get(),&uri

);// Error handling

Wrappers::HString domainName;hr = uri->get_Domain(domainName.GetAddressOf());// Error handling

DelegateComPtr<IThreadPoolTimerStatics> timerFactory;    HRESULT hr = GetActivationFactory(

Wrappers::HString::MakeReference(RuntimeClass_Windows_System_Threading_ThreadPoolTimer).Get(), &timerFactory

);       // Error handling TimeSpan delay;delay.Duration = 200; ComPtr<IThreadPoolTimer> timer;hr = timerFactory->CreateTimer(

Callback<ITimerElapsedHandler>([](IThreadPoolTimer* timer) -> HRESULT {

              // Perform some action in separate thread              return S_OK;

       }).Get(), delay, &timer

);

WRL Project Template

Available in Online template gallerySelect Online/Templates/C++/WRL Class Library in New project dialogDoes not work with Beta

Template generated filesProject file with correct settingsIDL file with one interface and one runtimeclassSource files that implement the interface and runtime classBroiler plate code to implement standard exports

Project template

demoDefault WRL project

Project filesProject settingsPreprocessor Define• WINAPI_FAMILY=WINAPI_PARTITION_AP

PMIDL setting to generate WinMDCustom build step for mdmerge

IDLnamespaceruntimeclass, interfaceexclusiveto, activatable

Module.cppBroilerplate codeWires exports to WRL activation infrastructure

WRLClassLibrary1.cppRuntimeClass• Template parameters - interfaces for

Object• Implements- AddRef, Release, QI, GetIids• WeakReference support

InspectableClass• Implements – GetRuntimeclassName,

GetTrustLevel

ActivatableClass• Associates default Activation factory with

class• Wires factory to WRL activation

infrastructure

demoAdd method

IDLAdd method to interface

CPPImplement method in class__stdcall important

Add Method

demoAdd event

IDLDelegate definition – keyword delegate• MIDL creates an interface with method that matches delegate signatureAdd eventadd and eventremove methods to interface• Name of both methods should be same• Fixed signature

CPPEventSource templated on delegate interface as member of classAdd methods corresponding to eventadd and eventremove methods in interface• Delegate represented by its interface name• eventadd function has add_ prefix and eventremove has remove_ prefix• In the implementation of add/remove call Add/Remove on EventSource• Invoke event by calling InvokeAll on EventSource

Add Event

demoAdd non default constructor

IDLDefine constructor factory interface• Add one or more constructor methods, exclusiveto attribute• Out/retval parameter type has to match type specified with exclusivetoSpecify factory interface as parameter to activatable attribute on runtimeclass

CPP

Add Custom Constructor

Implement RuntimeClassInitialize• Two phase construction• Default constructor cannot fail• Parameters same as the ones on

constructor interface method

Add factory class• Template on Constructor interface• Implement constructor interface

methods• MakeAndInitialize

• instantiates class & calls RuntimeClassInitialize

Use ActivitableClassWithFactory• Similar to ActivitableClass

ConclusionFairly easy to useExceptions cannot cross ABI boundaryTedious

© 2012 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.