C++, XAML and DirectX - Better together - Sridhar Poduri Program Manager Microsoft
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C++, XAML and DirectX – Better together Sridhar Poduri Program Manager Microsoft
Agenda 1. Overview of the Windows Runtime Library 2. Overview of the C++ Component Extensions 3. XAML and DirectX
WRL
Why use WRL
WinRT Concepts
WinRT Object Event
Reference counted Delegate used as Event callback
Implements IInspectable Server advertises events
Instantiated through factory Client creates delegate and registers it to receive events
WeakReference support
Misc
Delegate Reference count management
Callback Asynchronous operations
Interface with method
Delegate instance is WinRT objectWRL Classes
WinRT Object Event
RuntimeClass EventSource
InspectableClass Callback
ActivatableClass
ActivationFactory
Misc
ComPtr, WeakPtr
Delegate AsyncBase
Callback And many moreComPtr activationFactory;
HRESULT hr = GetActivationFactory(
HString::MakeReference(RuntimeClass_Windows_Foundation_Uri).Get(),
&activationFactory
);
// Error handling
ComPtr uriActivationFactory;
hr = activationFactory.As(&uriActivationFactory);
// Error handling
ComPtr 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 handlingComPtr timerFactory;
HRESULT hr = GetActivationFactory(
Wrappers::HString::MakeReference(RuntimeClass_Windows_System_Threading_ThreadPoolTimer).Ge
t(),
&timerFactory
);
// Error handling
TimeSpan delay;
delay.Duration = 200;
ComPtr timer;
hr = timerFactory->CreateTimer(
Callback(
[](IThreadPoolTimer* timer) -> HRESULT {
// Perform some action in separate thread
return S_OK;
}
).Get(), delay, &timer
);H^T
“It’s not okay to call me a carrot”
A hat is a pointer to a pointer to an array of function pointers
aka: Pointer to vptr to vtable
Calculator::ICalculator vtable
&Calculator::QueryInterface
ref class Calculator
&Calculator::AddRef
IStorageCell vtable * vfptr1
&Calculator::Release
ICalculator^ calc ICalculator vtable * vfptr2
&Calculator::GetIids
int _storage
&Calculator::GetRuntimeClassName
int _refcount
&Calculator::GetTrustLevel
&Calculator::AddH^T
“It’s not okay to call me a carrot”
•A hat is a pointer to a pointer to an array of function pointers
aka: Pointer to vptr to vtable
•^ provides automatic reference counting
•Similar to ComPtr
•Adds ability to use casting.Review: Your Modern-style UI framework • Built in and custom controls • Layout, styling, databinding • Media, animation, drawing • Design-time tools A focus on performance • Leveraging hardware • Independent animations • Fast rendering and composition
Review: Your graphics solution Everything in Windows 8 is built around DirectX: hardware to OS to UI frameworks Control vs. Complexity A tradeoff between difficulty and power of lower level APIs More work to align with Modern UI style guidelines
Demo XAML
The Best of Both Worlds
Complex 2D/3D graphics, text
Image effectsWhen do you want UI + Graphics? Example scenarios: Visual design, modeling, creativity Complex image processing Large documents, maps Simulations Games
Interop Functionality Integration Easy composition of XAML + DirectX using familiar XAML model All functionality of both XAML and DirectX Performance Low-latency input and interactivity Incremental rendering for both XAML and DirectX content Low overhead: retained-mode XAML and immediate-mode DirectX together C++ Only XAML code-behind can be managed, but interop DirectX is C++ only (without CX wrappers) Query for native interfaces of XAML WinRT types to access interop methods
3.1 Why use DirectX in your XAML app?
XAML is the first Windows UI platform that includes fully integrated and high-performance DirectX interop
What is XAML for? XAML is focused on building great UI Provides a set of controls and drawing primitives, backed by a rich object model From Rectangle primitives to complex GridViews Accessible in XAML or code behind Properties can be animated, databound
What is DirectX for? DirectX provides a powerful set of graphics functionality • Flexibility, scalability, and high performance • Lowest-level graphics API for applications - “All the way to the metal” – Direct3D – Direct2D – WIC (Windows Imaging Component) – DirectWrite – DirectComposition – DirectManipulation – We built all of XAML on top of DirectX! – DirectComposition in Win 8.1
XAML + DirectX
Windows Store app using XAML (C++, C#, VB)
DirectX interop in XAML
provides developers the Windows Runtime / C++
best of both worlds C++
• UI and controls? Use XAML
• Custom graphics, image editing, XAML Framework
games? Use DirectX
Direct Direct Direct Theme
Media App Input
3D 2D Write & PVL
Windows 8 subsystemMany great applications that you use are built with DirectX interop: • OneNote: custom display canvas • FreshPaint: custom-rendered painting • Bing Maps app • PDF Reader • Games!
3.2 DirectX interop options in XAML
DirectX interop options in XAML: a) Use a DirectX surface as a XAML brush: • SurfaceImageSource • VirtualSurfaceImageSource b) Tightly integrate into compositor, low latency presentation: • SwapChainPanel (Windows 8.1) • SwapChainBackgroundPanel
DirectX interop options in XAML SurfaceImageSource and VirtualSurfaceImageSource
SurfaceImageSource
Derives from XAML ImageSource Object
• Think of it as a dynamically updatable DependencyObject
D2D/D3D bitmap ImageSource
• Just like a BitmapImage, it can fill any XAML SurfaceImageSource
element
ImageBrush^ brush = ref new
Begin/Draw/End update model ImageBrush();
• Application provides D3D device
brush->ImageSource = ref new
• XAML provides a surface to draw to with SurfaceImageSource(300, 300);
D2D/D3D
Ellipse1->Fill = brush;
• XAML retains that surface in the treeSurfaceImageSource
interface ISurfaceImageSourceNative : IUnknown
{
SetDevice(IDXGIDevice *pDevice);
BeginDraw( These methods must
RECT updateRect, be called from the
IDXGISurface** ppSurface, XAML UI thread
POINT* pOffset
);
EndDraw();
};How can I use SurfaceImageSource? 1. Create a SurfaceImageSource 2. Create a D3D device and set it on the SurfaceImageSource 3. Set the SurfaceImageSource on a XAML element’s ImageBrush 4. Call BeginDraw 5. Draw to the returned IDXGISurface with Direct2D or Direct3D 6. Call EndDraw when you’re done drawing
Demo SurfaceImageSource
VirtualSurfaceImageSource
For very large surfaces that are too Object
DependencyObject
large to fit in video memory as a single ImageSource
texture SurfaceImageSource
VirtualSurfaceImageSource
• Larger than 1 screen size
• Virtualization via tiles
• Automatically manages tile cache
• XAML requests tiles from the app when they
XAML
come into view DirectX
• Use for mapping scenarios, large document
canvasesVirtualSurfaceImageSource
interface IVirtualSurfaceImageSourceNative: ISurfaceImageSourceNative
{
RegisterForUpdatesNeeded(IVirtualSurfaceUpdatesCallbackNative *pCallback);
GetUpdateRects(RECT *pUpdates, DWORD count);
GetUpdateRectCount(DWORD *pCount);
Invalidate(RECT updateRect);
};
interface IVirtualSurfaceUpdatesCallbackNative: IUnknown
{
UpdatesNeeded();
};How can I use VirtualSurfaceImageSource?
1. Implement IVirtualSurfaceImageSourceCallbackNative interface
2. Call RegisterForUpdatesNeeded on VSIS
3. In UpdatesNeeded callback, call GetUpdateRectCount and
GetUpdateRects
4. Render the update rectangles (using BeginDraw/EndDraw method as
per SurfaceImageSource)DirectX interop options in XAML SwapChainBackgroundPanel, SwapChainPanel
DirectX
SwapChainBackgroundPanel Allows full screen DirectX content to be used as a background in a XAML app • Low latency presentation controlled by app • Games, FreshPaint • Can render a swap chain on a background Designed for a specific scenario • Must be background element • Must be full-window sized
New for 8.1 - SwapChainPanel Benefits over SwapChainBackgroundPanel • Z-order limitations removed (same for WebView)! • Composable like any other XAML element • Any sized swap chain allowed • Can use more than one simultaneously • Size changed notification to redraw content crisply
SwapChainPanel/SwapChainBackgroundPanel
interface ISwapChainBackgroundPanelNative: IUnknown
{
SetSwapChain(IDXGISwapChain *pSwapChain);
};
interface ISwapChainPanelNative: IUnknown
{
SetSwapChain(IDXGISwapChain *pSwapChain);
};
(Look familiar?)Demo SwapChainBackgroundPanel
When should I use DirectX interop APIs? SurfaceImageSource or VirtualSurfaceImageSource when: • You want your content to integrate tightly with the XAML tree (e.g. ScrollViewer) • Your DirectX content isn’t being updated too frequently – Discrete updates, not continuous updates – The XAML framework can still manipulate its position etc. – Max update frequency is UI thread frame rate SwapChainPanel or SwapChainBackgroundPanel when: • Your content is updating quickly (e.g. games, ink) • You want the lowest presentation latency possible
You can use XAML and DirectX together to create great apps and games Use both swap chain-style and surface-style interop, depending on application needs XAML + DirectX + independent input allows for responsive, custom rendering in XAML apps You can target both Windows 8 and Windows Phone 8 apps.
Resources
Samples
• SwapChainPanel - http://code.msdn.microsoft.com/windowsapps/XAML-SwapChainPanel-
00cb688b
• SurfaceImageSource - http://code.msdn.microsoft.com/windowsapps/XAML-
SurfaceImageSource-85773f74
http://msdn.microsoft.com/en-us/library/windows/apps/hh825871.aspx
http://channel9.msdn.com/coding4fun/articles/Getting-started-with-
Cinder-for-Windows-Store-Apps
http://isocpp.org/std/the-committee
http://dx.codeplex.com
http://bit.ly/14pyw5T http://bit.ly/16Jryep
http://bit.ly/1bzRVqW
http://visualstudiogallery.msdn.microsoft.com/4100e9a9-2af1-44b0-af37-29bb32ee2c03Contact: sridhar.poduri@microsoft.com http://twitter.com/sridharpoduri http://sridharpoduri.com
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