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Revision as of 01:19, 22 November 2012 by yan_ (Talk | contribs)

C++ support from Windows Phone 8

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Windows Phone 8 SDK adds two new sets of APIs to develop applications using native code. This article will explain how to use C++ under Windows Phone and some general directions that any C++ developer should know when targeting the platform.

Note.pngNote: This is a community entry in the Windows Phone 8 Wiki Competition 2012Q4


WP Metro Icon DirectX.png
WP Metro Icon WP8.png
Article Metadata
Tested withCompatibility
Platform(s): Windows Phone 8.0
Windows Phone 8
Article
Keywords: windows phone, c++, managed, direct 3D, natif
Created: yan_ (07 Nov 2012)
Last edited: yan_ (22 Nov 2012)

Contents

Introduction

Windows Phone 8 SDK adds two new sets of APIs to develop applications using native code. This article will explain how to use C++ under Windows Phone and some general directions that any C++ developer should know when targeting the platform.

WP api.png

WIndows Phoen 8 SDK API is divided into three part. These APIs are complementary :

  • .Net gives interaction with Windows phone functionality like live tiles, send sms, ...
  • Windows Phone runtime is a intermediate API which gives access to low level functionality like voice Command, voip,...
  • Native code gives access to low level API like socket, Direct X, ...

For more information read :Windows Phone API reference

.Net (C# & VB)

.Net API is the original Windows Phone framework. It lets you to develop GUI with XAML technologies, access principal functionality (live tiles, tasks, send Mail, sms, ...) and XNA. It's actually the most important framework to develop Windows Phone application. To develop with this framework you can use C# or VB. You can find .net reference documentation here :

Note : XNA is always supported, but only to develop Windows Phone 7 application. It's replaced by Direct3D with Windows Phone 8 .

Windows Phone runtime (c# ,VB & C++/CX)

This API have two functionalities :

This API is based on COM-like technology. Like COM is not user-friendly, Microsoft have creatde Visual C++ Language Reference (C++/CX) to Consume this API with C++ and create WinPRT components. This extension adds to C++ managed concept like garbage collector, properties, delegate, event....

To develop in C++ you will always use this extension somewhere because it's your C++ code which is consumed by managed API and not the other way round.

Native (C++)

Visual studio 2012 have a really good support of C++ language and its recent normalization. For windows phone, these links are good entries to find supported features :

C++11 adds a lot of really good concepts and features. Too learn more and update your abilities, you should read this link : Modern C++.

Native API is developed in C++ and divided into libraries :

COM function will gives you access to camera and audio.

Native application

To launch an application, Windows phone need an "entry point" compatible with managed code. To perform it, your "entry point" will be developed with C++/CX and not in C++. C++ main function is replaced by a C++/CX version :

[Platform::MTAThread]
int main(Platform::Array<Platform::String^>^)
{
auto factory= ref new myFactory();
CoreApplication::Run(direct3DApplicationSource);
return 0;
}
ref class myFactory sealed : Windows::ApplicationModel::Core::IFrameworkViewSource
{
public:
virtual Windows::ApplicationModel::Core::IFrameworkView^ CreateView()
{
return ref new myView();
};
};

IFrameworkView is the display provider use to make Direct3D rendering. Interface function are :

void myView::Initialize(CoreApplicationView^ applicationView)
{
applicationView->Activated +=
ref new TypedEventHandler<CoreApplicationView^, IActivatedEventArgs^>(this, &myView::OnActivated);
 
//handle suspending and resuming application states.
CoreApplication::Suspending +=
ref new EventHandler<SuspendingEventArgs^>(this, &myView::OnSuspending);
 
CoreApplication::Resuming +=
ref new EventHandler<Platform::Object^>(this, &myView::OnResuming);
}
  • Load : load and activate external resources. This function is called before Run().
  • SetWindow : sets the current CoreWindow. Use it to handle application display event like close, visibility change, mono-touch event, ...
void myView::SetWindow(CoreWindow^ window)
{
window->VisibilityChanged +=
ref new TypedEventHandler<CoreWindow^, VisibilityChangedEventArgs^>(this, &myView::OnVisibilityChanged);
 
window->Closed +=
ref new TypedEventHandler<CoreWindow^, CoreWindowEventArgs^>(this, &myView::OnWindowClosed);
 
window->PointerPressed +=
ref new TypedEventHandler<CoreWindow^, PointerEventArgs^>(this, &myView::OnPointerPressed);
 
window->PointerMoved +=
ref new TypedEventHandler<CoreWindow^, PointerEventArgs^>(this, &myView::OnPointerMoved);
 
window->PointerReleased +=
ref new TypedEventHandler<CoreWindow^, PointerEventArgs^>(this, &myView::OnPointerReleased);
}
  • Uninitialize : uninitializes ressources.
  • Run : start your view. Your must implement an application event-loop here.
void myView::Run()
{
//reference time.
BasicTimer^ timer = ref new BasicTimer();
 
while (!m_windowClosed)//while application is not closed
{
if (m_windowVisible)// application is visible, update Direct3D rendering
{
timer->Update();
CoreWindow::GetForCurrentThread()->Dispatcher->ProcessEvents(CoreProcessEventsOption::ProcessAllIfPresent);//process current system events
m_renderer->Update(timer->Total, timer->Delta); //update your render from time reference.
m_renderer->Render();// Direct3D rendering
m_renderer->Present(); // This call is synchronized to the display frame rate.
}
else // application is not visible
{
CoreWindow::GetForCurrentThread()->Dispatcher->ProcessEvents(CoreProcessEventsOption::ProcessOneAndAllPending); ;//process current system events and wait new events.
}
}
}

Native application have three importants points:

  • you can only use Direct3D for display data. Native API doesn't have API to build GUI.
  • you must execute system events.
  • You don't have access to .Net functionality. You can't use live tiles, send a SMS, ...

Without .Net functionality, native applications are not so cool and you are limited to Direct3D develop ... But remember, you can develop Windows Phone run time component with C++/CX. So it's possible to encapsulate your c++ Code with C++/CX and use it in managed code :p


Other wiki resources about Direct3D development:

Mixed application

You can develop mixed application where your managed code consume Windows Phone Runtime components. To develop with C++ Code, you must create a Windows Phone Runtime Component which interface C++ part with a public sealed C++/CX class . It's important to readC++ extension documentation to understand its specificities :

  • a C++/CX class/struct is declared with ref keyword
ref class myclass 
{
//...
};
  • Allocation is performed by ref new.
  • C++/CX struct can be use like a POD.
  • Class instance is handled by ^ type ( is known as a "hat"). This type is a reference counting pointer. You class will be destroyed automatically by the Garbage Collector.
myclass ^ myClass = ref new myclass ();
  • Platform::String Class replace std::wstring. C++/CX String are Unicode.
  • C++/CX collections are compliant with STL.
  • Fundamental types are similar.
  • A property is similar to getter/setter in C++.
  • A delegate is a fucntion object. It can reference c++ or managed function.
  • An event is a delegate collection which perform all delegate when event is raised.
  • sealed keyword : a sealed class or a sealed function can't be overridden.

To be consumed by managed code, C++/CX code generate a set of metadata. This generation depend on access modifier :

Modifier Meaning Emitted to metadata?
private The default accessibility. Same meaning as in standard C++. No
protected Same meaning as in standard C++, both within the app or component and in metadata. Yes
public Same meaning as in standard C++. Yes
public protected –or- protected public Protected accessibility in metadata, public within the app or component. Yes
protected private or private protected Not visible in metadata; protected accessibility within the app or component. No
internal or private public The member is public within the app or component, but is not visible in metadata. No

Metadata are generated only for specific C++/CX objects. A C++/CX class can declare C++ object only if the member/function have a private or internal access. Your public Class/Struct must be sealed because Managed code can't override it.

//C++/CX class declaration which can be consumed by managed code
public ref class MyClass sealed
{
private : // C++ object can be used
std::string aString:
std::vector<uint32_t> aFunction();
 
public : //object and function are accessible by managed coe. if a c++ object is used, error is generated.
property Platform::String ^ anotherString;
Windows::Foundation::Collections::IVector<uint32> ^anotherFunction();
//...
};

Public access is very strict, and only specific C++/CX objects can be used  :

These Objects must be defined with these types :

Once your components is referenced by your managed application, you can consumed like other Managed object. It's so possible to bind public properties with XAML and connect to public events.

You can find interesting explanation here : Creating Windows Runtime Components in C++

Warning : Windows phone implement a subset of the Windows 8 C++/CX namespace. Few object are not accessible.

Collections

Windows Phone Runtime API doesn't implement collections class. To transfer collection between managed and native code, a set of collections Interface are defined. These interface have Equivalent in managed. For example IVector besome an IList in C#.

C++/CX collections use C++ parts and can't be consumed directly by managed Code. Like these classes implement a Windows Phone Runtime interface, you can cast these to be consumed through the interface

Windows::Foundation::Collections::IVector<int>^ Class1::GetInts()
{
auto vec = ref new Platform::Collections::Vector<int>();
...
return vec;// implicit cast to Windows Phone Runtime interface. Managed code can consume collection returned.
}


Remarque : STL collection can be converted to its C++/CX equivalent. When you convert a temporary collection, You can use std::move to avoid unnecessary internal copy

Windows::Foundation::Collections::IVector<int>^ Class1::GetInts()
{
st::vector<int> vec;
for(int i = 0; i < 10; i++)
{
vec.push_back(i);
}
// Implicit conversion to IVector
return ref new Platform::Collections::Vector<int>(std::move(vec));
}

Debugger

You can't debug managed code and native code in same times. To selected which debugger you want use :

  1. open project properties
  2. open debug tab and select debugger mode

Debugger selection.png

Direct 3D  : Comming soon

Reference links

Ressources about C++ Direct3D developpement on Windon sPhone  :

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