組合交換鏈程式代碼範例
這些程式代碼範例使用 Windows 實作連結庫 （WIL） 。 安裝 WIL 的便利方式是移至 Visual Studio，按兩下 [專案>管理 NuGet 套件...]>在搜尋方塊中瀏覽、輸入或貼上 Microsoft.Windows.ImplementationLibrary，選取搜尋結果中的專案，然後按兩下 [安裝] 以安裝該專案的套件。
範例 1 - 在支援組合交換鏈 API 的系統上建立簡報管理員
如前所述，組合交換鏈 API 需要支持的驅動程式才能運作。 下列範例說明如果系統支援 API，您的應用程式如何建立簡報管理員。 這示範為 TryCreate-style 函式，只有在支援 API 時，才會傳回簡報管理員。 此函式也會示範如何正確建立 Direct3D 裝置來備份簡報管理員。
C++ 範例
bool TryCreatePresentationManager(
_In_ bool requestDirectPresentation,
_Out_ ID3D11Device** ppD3DDevice,
_Outptr_opt_result_maybenull_ IPresentationManager **ppPresentationManager)
{
// Null the presentation manager and Direct3D device initially
*ppD3DDevice = nullptr;
*ppPresentationManager = nullptr;
// Direct3D device creation flags. The composition swapchain API requires that applications disable internal
// driver threading optimizations, as these optimizations are incompatible with the
// composition swapchain API. If this flag is not present, then the API will fail the call to create the
// presentation factory.
UINT deviceCreationFlags =
D3D11_CREATE_DEVICE_BGRA_SUPPORT |
D3D11_CREATE_DEVICE_SINGLETHREADED |
D3D11_CREATE_DEVICE_PREVENT_INTERNAL_THREADING_OPTIMIZATIONS;
// Create the Direct3D device.
com_ptr_failfast<ID3D11DeviceContext> d3dDeviceContext;
FAIL_FAST_IF_FAILED(D3D11CreateDevice(
nullptr, // No adapter
D3D_DRIVER_TYPE_HARDWARE, // Hardware device
nullptr, // No module
deviceCreationFlags, // Device creation flags
nullptr, 0, // Highest available feature level
D3D11_SDK_VERSION, // API version
ppD3DDevice, // Resulting interface pointer
nullptr, // Actual feature level
&d3dDeviceContext)); // Device context
// Call the composition swapchain API export to create the presentation factory.
com_ptr_failfast<IPresentationFactory> presentationFactory;
FAIL_FAST_IF_FAILED(CreatePresentationFactory(
(*ppD3DDevice),
IID_PPV_ARGS(&presentationFactory)));
// Determine whether the system is capable of supporting the composition swapchain API based
// on the capability that's reported by the presentation factory. If your application
// wants direct presentation (that is, presentation without the need for DWM to
// compose, using MPO or iflip), then we query for direct presentation support.
bool isSupportedOnSystem;
if (requestDirectPresentation)
{
isSupportedOnSystem = presentationFactory->IsPresentationSupportedWithIndependentFlip();
}
else
{
isSupportedOnSystem = presentationFactory->IsPresentationSupported();
}
// Create the presentation manager if it is supported on the current system.
if (isSupportedOnSystem)
{
FAIL_FAST_IF_FAILED(presentationFactory->CreatePresentationManager(ppPresentationManager));
}
return isSupportedOnSystem;
}
範例 2 - 建立簡報管理員和簡報介面
下列範例說明您的應用程式如何建立簡報管理員和簡報介面，以系結至可視化樹狀結構中的視覺效果。 後續範例將示範如何將簡報介面系結至 DirectComposition 和 Windows.UI.Composition 可視化樹狀結構。
C++ 範例 （DCompositionGetTargetStatistics）
bool MakePresentationManagerAndPresentationSurface(
_Out_ ID3D11Device** ppD3dDevice,
_Out_ IPresentationManager** ppPresentationManager,
_Out_ IPresentationSurface** ppPresentationSurface,
_Out_ unique_handle& compositionSurfaceHandle)
{
// Null the output pointers initially.
*ppD3dDevice = nullptr;
*ppPresentationManager = nullptr;
*ppPresentationSurface = nullptr;
compositionSurfaceHandle.reset();
com_ptr_failfast<IPresentationManager> presentationManager;
com_ptr_failfast<IPresentationSurface> presentationSurface;
com_ptr_failfast<ID3D11Device> d3d11Device;
// Call the function we defined previously to create a Direct3D device and presentation manager, if
// the system supports it.
if (TryCreatePresentationManager(
true, // Request presentation with independent flip.
&d3d11Device,
&presentationManager) == false)
{
// Return 'false' out of the call if the composition swapchain API is unsupported. Assume the caller
// will handle this somehow, such as by falling back to DXGI.
return false;
}
// Use DirectComposition to create a composition surface handle.
FAIL_FAST_IF_FAILED(DCompositionCreateSurfaceHandle(
COMPOSITIONOBJECT_ALL_ACCESS,
nullptr,
compositionSurfaceHandle.addressof()));
// Create presentation surface bound to the composition surface handle.
FAIL_FAST_IF_FAILED(presentationManager->CreatePresentationSurface(
compositionSurfaceHandle.get(),
presentationSurface.addressof()));
// Return the Direct3D device, presentation manager, and presentation surface to the caller for future
// use.
*ppD3dDevice = d3d11Device.detach();
*ppPresentationManager = presentationManager.detach();
*ppPresentationSurface = presentationSurface.detach();
// Return 'true' out of the call if the composition swapchain API is supported and we were able to
// create a presentation manager.
return true;
}
範例 3- 將簡報介面系結至 Windows.UI.Composition 介面筆刷
下列範例說明您的應用程式如何將組合介面控點系結至簡報介面，如上述範例中所建立，系結至 Windows.UI.Composition （WinComp） 表面筆刷，然後該筆筆刷可以系結至應用程式可視化樹狀結構中的 Sprite 視覺效果。
C++ 範例
void BindPresentationSurfaceHandleToWinCompTree(
_In_ ICompositor * pCompositor,
_In_ ISpriteVisual * pVisualToBindTo, // The sprite visual we want to bind to.
_In_ unique_handle& compositionSurfaceHandle)
{
// QI an interop compositor from the passed compositor.
com_ptr_failfast<ICompositorInterop> compositorInterop;
FAIL_FAST_IF_FAILED(pCompositor->QueryInterface(IID_PPV_ARGS(&compositorInterop)));
// Create a composition surface for the presentation surface's composition surface handle.
com_ptr_failfast<ICompositionSurface> compositionSurface;
FAIL_FAST_IF_FAILED(compositorInterop->CreateCompositionSurfaceForHandle(
compositionSurfaceHandle.get(),
&compositionSurface));
// Create a composition surface brush, and bind the surface to it.
com_ptr_failfast<ICompositionSurfaceBrush> surfaceBrush;
FAIL_FAST_IF_FAILED(pCompositor->CreateSurfaceBrush(&surfaceBrush));
FAIL_FAST_IF_FAILED(surfaceBrush->put_Surface(compositionSurface.get()));
// Bind the brush to the visual.
auto brush = surfaceBrush.query<ICompositionBrush>();
FAIL_FAST_IF_FAILED(pVisualToBindTo->put_Brush(brush.get()));
}
範例 4 — 將簡報介面系結至 DirectComposition 視覺效果
下列範例說明您的應用程式如何將簡報介面系結至可視化樹狀結構中的 DirectComposition （DComp） 視覺效果。
C++ 範例
void BindPresentationSurfaceHandleToDCompTree(
_In_ IDCompositionDevice* pDCompDevice,
_In_ IDCompositionVisual* pVisualToBindTo,
_In_ unique_handle& compositionSurfaceHandle) // The composition surface handle that was
// passed to CreatePresentationSurface.
{
// Create a DComp surface to wrap the presentation surface.
com_ptr_failfast<IUnknown> dcompSurface;
FAIL_FAST_IF_FAILED(pDCompDevice->CreateSurfaceFromHandle(
compositionSurfaceHandle.get(),
&dcompSurface));
// Bind the presentation surface to the visual.
FAIL_FAST_IF_FAILED(pVisualToBindTo->SetContent(dcompSurface.get()));
}
範例 5 - 在簡報介面上設定 Alpha 模式和色彩空間
下列範例說明您的應用程式如何在簡報介面上設定 Alpha 模式和色彩空間。 Alpha 模式描述是否應該解譯紋理中的 Alpha 色板，以及其方式。 色彩空間描述紋理像素所參考的色彩空間。
這類所有屬性更新都會在應用程式的下一個簡報中生效，並且與屬於該簡報一部分的任何緩衝區更新一起以不可部分完成的方式生效。 如果應用程式想要的話，也可能是存在，完全不會更新任何緩衝區，而是只包含屬性更新。 任何未在特定簡報上更新其緩衝區的簡報介面，都會系結至它們之前系結至該簡報之前所系結的任何緩衝區。
C++ 範例
void SetAlphaModeAndColorSpace(
_In_ IPresentationSurface* pPresentationSurface)
{
// Set alpha mode.
FAIL_FAST_IF_FAILED(pPresentationSurface->SetAlphaMode(DXGI_ALPHA_MODE_IGNORE));
// Set color space to full RGB.
FAIL_FAST_IF_FAILED(pPresentationSurface->SetColorSpace(DXGI_COLOR_SPACE_RGB_FULL_G22_NONE_P709));
}
範例 6 — 在簡報介面上設定信箱邊界
下列範例說明您的應用程式如何在簡報介面上指定信箱邊界。 Letterboxing 可用來填滿表面內容本身以外的指定區域，以說明內容與顯示裝置之間的不同外觀比例。 其中一個很好的範例是，在 為寬螢幕影院格式化電影的計算機上觀看時，通常會在內容上方和下方看到黑條 。 組合交換鏈 API 可讓您指定在這類情況下轉譯信箱的邊界。
目前，信箱區域一律會填滿不透明的黑色。
做為可視化樹狀結構內容，呈現介面存在於主視覺效果的座標空間中。 使用信箱呈現時，視覺效果座標空間的原點會對應至信箱的左上方。 也就是說，緩衝區本身存在視覺效果座標空間的位移。 界限會計算為緩衝區的大小加上信箱大小。
下列說明視覺座標空間中存在緩衝區和信箱的位置，以及界限的計算方式。
最後，如果套用至簡報介面的轉換隨附位移，則緩衝區或信箱未涵蓋的區域會被視為超出內容界限，並被視為透明，這類似於任何其他可視化樹狀結構內容在內容界限外處理的方式。
信箱和轉換互動
為了提供一致的信箱邊界大小，不論您的應用程式套用到緩衝區以填滿某些內容區域，DWM 會嘗試以一致的大小轉譯邊界，而不論縮放比例為何，但考慮到已套用至簡報介面的轉換結果。
換句話說，在套用簡報介面的轉換之前，會以技術方式套用信箱邊界，但會補償可能屬於該轉換的任何縮放比例。 也就是說，表示介面的轉換會解構為兩個元件，也就是調整的轉換部分，以及轉換的其餘部分。
例如，使用 100px 信箱邊界，且沒有套用至簡報介面的轉換，產生的緩衝區會轉譯而不縮放比例，而信箱邊界會是 100px 寬。
另一個範例是，在簡報介面上套用 100px 信箱邊界，以及套用 2 倍的縮放比例轉換，產生的緩衝區會以 2 倍小數位數轉譯，而螢幕上看到的信箱邊界仍會以 100px 為單位。
另一個範例是，使用 45 度旋轉轉換，產生的信箱邊界會顯示 100px，而信箱邊界會隨著緩衝區旋轉。
另一個範例是縮放 2 倍和旋轉 45 度轉換，影像會旋轉和縮放，而信箱邊界也會是 100px 寬，並以緩衝區旋轉。
如果無法明確地從應用程式套用至簡報介面的轉換擷取縮放轉換，例如產生的 X 或 Y 尺規為 0，則會使用套用整個轉換來轉譯信箱邊界，而且我們不會嘗試補償縮放比例。
C++ 範例
void SetContentLayoutAndFill(
_In_ IPresentationSurface* pPresentationSurface)
{
// Set layout properties. Each layout property is described below.
// The source RECT describes the area from the bound buffer that will be sampled from. The
// RECT is in source texture coordinates. Below we indicate that we'll sample from a
// 100x100 area on the source texture.
RECT sourceRect;
sourceRect.left = 0;
sourceRect.top = 0;
sourceRect.right = 100;
sourceRect.bottom = 100;
FAIL_FAST_IF_FAILED(pPresentationSurface->SetSourceRect(&sourceRect));
// The presentation transform defines how the source rect will be transformed when
// rendering the buffer. In this case, we indicate we want to scale it 2x in both
// width and height, and we also want to offset it 50 pixels to the right.
PresentationTransform transform = { 0 };
transform.M11 = 2.0f; // X scale 2x
transform.M22 = 2.0f; // Y scale 2x
transform.M31 = 50.0f; // X offset 50px
FAIL_FAST_IF_FAILED(pPresentationSurface->SetTransform(&transform));
// The letterboxing parameters describe how to letterbox the content. Letterboxing
// is commonly used to fill area not covered by video/surface content when scaling to
// an aspect ratio that doesn't match the aspect ratio of the surface itself. For
// example, when viewing content formatted for the theater on a 1080p home screen, one
// can typically see black "bars" on the top and bottom of the video, covering the space
// on screen that wasn't covered by the video due to the differing aspect ratios of the
// content and the display device. The composition swapchain API allows the user to specify
// letterboxing margins, which describe the number of pixels to surround the surface
// content with on screen. In this case, surround the top and bottom of our content with
// 100 pixel tall letterboxing.
FAIL_FAST_IF_FAILED(pPresentationSurface->SetLetterboxingMargins(
0.0f,
100.0f,
0.0f,
100.0f));
}
範例 7 — 在簡報介面上設定內容限制
下列範例說明您的應用程式如何防止其他應用程式讀取簡報介面的內容，例如 PrintScreen、DDA、Capture API 等技術，以取得受保護的內容。 它也會示範如何將簡報介面的顯示限制為只有單一 DXGI 輸出。
如果內容回寫已停用，則當您的應用程式嘗試回寫時，擷取的影像將會包含不透明的黑色來取代簡報介面。 如果簡報介面受限於 IDXGIOutput，則所有其他輸出上會顯示為不透明的黑色。
C++ 範例
void SetContentRestrictions(
_In_ IPresentationSurface* pPresentationSurface,
_In_ IDXGIOutput* pOutputToRestrictTo)
{
// Disable readback of the surface via printscreen, bitblt, etc.
FAIL_FAST_IF_FAILED(pPresentationSurface->SetDisableReadback(true));
// Restrict display of surface to only the passed output.
FAIL_FAST_IF_FAILED(pPresentationSurface->RestrictToOutput(pOutputToRestrictTo));
}
範例 8 - 將簡報緩衝區新增至簡報管理員
下列範例說明您的應用程式如何配置一組 Direct3D 紋理，並將其新增至簡報管理員，以做為簡報緩衝區使用，以呈現給簡報介面。
如前所述，在可註冊紋理的簡報管理員數目方面沒有任何限制。 不過，在大部分的一般使用案例中，紋理只會註冊到單一簡報管理員。
另請注意，由於 API 在簡報管理員中將紋理註冊為簡報緩衝區時接受共用緩衝區作為貨幣，而且 DXGI 可以為單一 texture2D 建立多個共用緩衝區，因此在技術上，您的應用程式可以針對單一紋理建立多個共用緩衝區句柄，並同時向簡報管理員註冊它們。 基本上，加入相同緩衝區的效果不止一次。 不建議這麼做，因為它會中斷簡報管理員所提供的同步處理機制，因為以唯一方式追蹤的兩個簡報緩衝區實際上會對應到相同的紋理。 由於這是進階 API，而且因為實作在發生此案例時偵測此案例實際上相當困難，因此 API 不會嘗試驗證此案例。
C++ 範例
void AddBuffersToPresentationManager(
_In_ ID3D11Device* pD3D11Device, // The backing Direct3D device
_In_ IPresentationManager* pPresentationManager, // Previously-made presentation manager
_In_ UINT bufferWidth, // The width of the buffers to add
_In_ UINT bufferHeight, // The height of the buffers to add
_In_ UINT numberOfBuffersToAdd, // The number of buffers to add to the presentation manager
_Out_ vector<com_ptr_failfast<ID3D11Texture2D>>& textures, // Array of textures returned
_Out_ vector<com_ptr_failfast<IPresentationBuffer>>& presentationBuffers) // Array of presentation buffers returned
{
// Clear the returned vectors initially.
textures.clear();
presentationBuffers.clear();
// Add the desired buffers to the presentation manager.
for (UINT i = 0; i < numberOfBuffersToAdd; i++)
{
com_ptr_failfast<ID3D11Texture2D> texture;
com_ptr_failfast<IPresentationBuffer> presentationBuffer;
// Call our helper to make a new buffer of the desired type.
AddNewPresentationBuffer(
pD3D11Device,
pPresentationManager,
bufferWidth,
bufferHeight,
&texture,
&presentationBuffer);
// Track our buffers in our own set of vectors.
textures.push_back(texture);
presentationBuffers.push_back(presentationBuffer);
}
}
void AddNewPresentationBuffer(
_In_ ID3D11Device* pD3D11Device,
_In_ IPresentationManager* pPresentationManager,
_In_ UINT bufferWidth,
_In_ UINT bufferHeight,
_Out_ ID3D11Texture2D** ppTexture2D,
_Out_ IPresentationBuffer** ppPresentationBuffer)
{
com_ptr_failfast<ID3D11Texture2D> texture2D;
unique_handle sharedResourceHandle;
// Create a shared Direct3D texture and handle with the passed attributes.
MakeD3D11Texture(
pD3D11Device,
bufferWidth,
bufferHeight,
&texture2D,
out_param(sharedResourceHandle));
// Add the texture2D to the presentation manager, and get back a presentation buffer.
com_ptr_failfast<IPresentationBuffer> presentationBuffer;
FAIL_FAST_IF_FAILED(pPresentationManager->AddBufferFromSharedHandle(
sharedResourceHandle.get(),
&presentationBuffer));
// Return back the texture and buffer presentation buffer.
*ppTexture2D = texture2D.detach();
*ppPresentationBuffer = presentationBuffer.detach();
}
void MakeD3D11Texture(
_In_ ID3D11Device* pD3D11Device,
_In_ UINT textureWidth,
_In_ UINT textureHeight,
_Out_ ID3D11Texture2D** ppTexture2D,
_Out_ HANDLE* sharedResourceHandle)
{
D3D11_TEXTURE2D_DESC textureDesc = {};
// Width and height can be anything within max texture size of the adapter backing the Direct3D
// device.
textureDesc.Width = textureWidth;
textureDesc.Height = textureHeight;
// MipLevels and ArraySize must be 1.
textureDesc.MipLevels = 1;
textureDesc.ArraySize = 1;
// Format can be one of the following:
// DXGI_FORMAT_B8G8R8A8_UNORM
// DXGI_FORMAT_R8G8B8A8_UNORM
// DXGI_FORMAT_R16G16B16A16_FLOAT
// DXGI_FORMAT_R10G10B10A2_UNORM
// DXGI_FORMAT_NV12
// DXGI_FORMAT_YUY2
// DXGI_FORMAT_420_OPAQUE
// For this
textureDesc.Format = DXGI_FORMAT_B8G8R8A8_UNORM;
// SampleDesc count and quality must be 1 and 0 respectively.
textureDesc.SampleDesc.Count = 1;
textureDesc.SampleDesc.Quality = 0;
// Usage must be D3D11_USAGE_DEFAULT.
textureDesc.Usage = D3D11_USAGE_DEFAULT;
// BindFlags must include D3D11_BIND_SHADER_RESOURCE for RGB textures, and D3D11_BIND_DECODER
// for YUV textures. For RGB textures, it is likely your application will want to specify
// D3D11_BIND_RENDER_TARGET in order to render to it.
textureDesc.BindFlags =
D3D11_BIND_SHADER_RESOURCE |
D3D11_BIND_RENDER_TARGET;
// MiscFlags should include D3D11_RESOURCE_MISC_SHARED and D3D11_RESOURCE_MISC_SHARED_NTHANDLE,
// and might also include D3D11_RESOURCE_MISC_SHARED_DISPLAYABLE if your application wishes to
// qualify for MPO and iflip. If D3D11_RESOURCE_MISC_SHARED_DISPLAYABLE is not provided, then the
// content will not qualify for MPO or iflip, but can still be composed by DWM
textureDesc.MiscFlags =
D3D11_RESOURCE_MISC_SHARED |
D3D11_RESOURCE_MISC_SHARED_NTHANDLE |
D3D11_RESOURCE_MISC_SHARED_DISPLAYABLE;
// CPUAccessFlags must be 0.
textureDesc.CPUAccessFlags = 0;
// Use Direct3D to create a texture 2D matching the desired attributes.
com_ptr_failfast<ID3D11Texture2D> texture2D;
FAIL_FAST_IF_FAILED(pD3D11Device->CreateTexture2D(&textureDesc, nullptr, &texture2D));
// Create a shared handle for the texture2D.
unique_handle sharedBufferHandle;
auto dxgiResource = texture2D.query<IDXGIResource1>();
FAIL_FAST_IF_FAILED(dxgiResource->CreateSharedHandle(
nullptr,
GENERIC_ALL,
nullptr,
&sharedBufferHandle));
// Return the handle to the caller.
*ppTexture2D = texture2D.detach();
*sharedResourceHandle = sharedBufferHandle.release();
}
範例 9 — 從簡報管理員移除簡報緩衝區，以及物件存留期
從簡報管理員移除簡報緩衝區就像將 IPresentationBuffer 對象發行至 0 refcount 一樣簡單。 不過，發生這種情況時，不一定表示可以釋放簡報緩衝區。 在某些情況下，緩衝區可能仍在使用中，例如在螢幕上顯示該簡報緩衝區，或有未處理的呈現參考它。
簡言之，簡報管理員會追蹤應用程式直接和間接使用每個緩衝區的方式。 它會持續追蹤顯示哪些緩衝區、呈現的未處理和參考緩衝區，而且它會在內部追蹤所有此狀態，以確保緩衝區不會真正釋放/取消註冊，直到它真正不再使用為止。
思考緩衝區存留期的好方法是，如果您的應用程式釋放 IPresentationBuffer，它會告訴 API，它不會再在未來任何呼叫中使用該緩衝區。 組合交換鏈 API 將會追蹤此狀況，以及使用緩衝區的任何其他方式，而且只有在完全安全的情況下，才會完全釋放緩衝區。
簡言之，您的應用程式在完成時應該釋放 IPresentationBuffer ，並知道組合交換鏈 API 也會在所有其他用途完成時完全釋放緩衝區。
以下是上述概念的圖例。
在此範例中，我們有一個具有兩個簡報緩衝區的簡報管理員。 緩衝區 1 有三個參考讓它保持運作。
- 您的應用程式會保存 參考它的 IPresentationBuffer 。
- API 內部會將其儲存為簡報介面的目前系結緩衝區，因為它是應用程式所系結的最後一個緩衝區，然後呈現它。
- 目前佇列中也有一個未處理的現成，打算在簡報介面上顯示緩衝區 1。
緩衝區 1 會在其對應的 Direct3D 紋理配置上額外持有參考。 您的應用程式也有參考該配置的ID3D11Texture2D。
緩衝區 2 沒有來自應用程式端的未完成參考，它所參考的紋理配置也不會維持運作，但緩衝區 2 會保持運作，因為它是目前在螢幕上呈現介面所顯示的內容。 處理 Present 1 並改為在螢幕上顯示緩衝區 1 時，緩衝區 2 將不會再有參考，而且會釋出它，進而在其 Direct3D 紋理2D 配置上釋放其參考。
C++ 範例
void ReleasePresentationManagerBuffersExample(
_In_ ID3D11Device* pD3D11Device,
_In_ IPresentationManager* pPresentationManager)
{
com_ptr_failfast<ID3D11Texture2D> texture2D;
com_ptr_failfast<IPresentationBuffer> newBuffer;
// Create a new texture/presentation buffer.
AddNewPresentationBuffer(
pD3D11Device,
pPresentationManager,
200, // Buffer width
200, // Buffer height
&texture2D,
&newBuffer);
// Release the IPresentationBuffer. This indicates that we have no more intention to use it
// from the application side. However, if we have any presents outstanding that reference
// the buffer, it will be kept alive internally and released when all outstanding presents
// have been retired.
newBuffer.reset();
// When the presentation buffer is truly released internally, it will in turn release its
// reference on the texture2D which it corresponds to. Your application must also release
// its own references to the texture2D for it to be released.
texture2D.reset();
}
範例 10 — 調整簡報管理員中的緩衝區大小
下列範例說明您的應用程式如何執行 簡報緩衝區的大小 。 例如，如果電影串流服務正在串流 480p，但決定將格式切換為 1080p，因為網路頻寬很高，則它會想要將其緩衝區從 480p 重新配置至 1080p，使其可以開始呈現 1080p 內容。
在 DXGI 中，這稱為 重設大小 作業。 DXGI 會以不可部分完成的方式重新配置所有緩衝區，成本高昂，而且可以在螢幕上產生問題。 這裡的範例說明如何在組合交換鏈 API 中，以 DXGI 進行不可部分完成的大小調整。 稍後的範例將示範如何以錯開的方式重設大小、跨多個簡報的重新配置間距，達到比不可部分完成的交換鏈重設大小更好的效能。
C++ 範例
void ResizePresentationManagerBuffersExample(
_In_ ID3D11Device* pD3D11Device,
_In_ IPresentationManager* pPresentationManager) // Previously-made presentation manager.
{
// Vectors representing the IPresentationBuffer and ID3D11Texture2D collections.
vector<com_ptr_failfast<ID3D11Texture2D>> textures;
vector<com_ptr_failfast<IPresentationBuffer>> presentationBuffers;
// Add 6 50x50 buffers to the presentation manager. See previous example for definition of
// this function.
AddBuffersToPresentationManager(
pD3D11Device,
pPresentationManager,
50, // Buffer width
50, // Buffer height
6, // Number of buffers
textures,
presentationBuffers);
// Release all the buffers we just added. The presentation buffers internally will be released
// when any other references are also removed (outstanding presents, display references, etc.).
textures.clear();
presentationBuffers.clear();
// Add 6 new 100x100 buffers to the presentation manager to replace the
// old ones we just removed.
AddBuffersToPresentationManager(
pD3D11Device,
pPresentationManager,
100, // Buffer width
100, // Buffer height
6, // Number of buffers
textures,
presentationBuffers);
}
範例 11 - 使用緩衝區可用的事件同步處理簡報，以及處理簡報管理員遺失的事件
如果您的應用程式會發出與先前簡報中使用的簡報緩衝區相關的簡報，則您必須確定上一個簡報已完成，以便轉譯並再次呈現簡報緩衝區。 組合交換鏈 API 提供幾種不同的機制來加速此同步處理。 最簡單的是簡報緩衝區的可用事件，這是當緩衝區可供使用時發出訊號的 NT 事件對象（也就是說，所有先前的簡報都已進入淘汰或已淘汰狀態），否則為未簽署狀態。 此範例說明如何使用緩衝區可用的事件來挑選可用的緩衝區來呈現。 它也說明如何接聽 裝置遺失 的錯誤，這些錯誤在道德上相當於 DXGI 裝置遺失，而且需要重新整理簡報管理員。
簡報管理員遺失錯誤
如果簡報管理員在內部遇到無法復原的錯誤，可能會遺失。 您的應用程式必須終結遺失的簡報管理員，並建立要改用的新簡報管理員。 當簡報管理員遺失時，它將會停止接受進一步的簡報。 任何在遺失的簡報管理員上呼叫 Present 的嘗試都會傳回 PRESENTATION_ERROR_LOST。 不過，所有其他方法都會正常運作。 這是為了確保您的應用程式只需要檢查 目前呼叫上的PRESENTATION_ERROR_LOST ，而且不需要預測/處理每個 API 呼叫上的遺失錯誤。 如果您的應用程式想要在目前呼叫外部檢查或收到通知，則可以使用 IPresentationManager：：GetLostEvent 所傳回的遺失事件。
目前佇列和時間
簡報管理員所發出的簡報可以指定目標的特定時間。 這個目標時間是系統嘗試顯示目前的理想時間。 由於螢幕會以有限的步調更新，所以目前不太可能在指定的時間精確顯示，但它會顯示為盡可能接近時間。
此目標時間是系統相對時間，或系統自開啟以來一直以數百奈秒為單位執行的時間。 計算目前時間的簡單方式是查詢目前的 QueryPerformanceCounter （QPC） 值、將其除以系統的 QPC 頻率，並將它乘以 10,000,000。 除了四捨五入和有效位數限制之外，這會以適用的單位計算目前時間。 系統也可以藉由呼叫 MfGetSystemTime 或 QueryInterruptTimePrecise 來取得目前的時間。
一旦知道目前時間，您的應用程式通常會發出目前時間的遞增位移。
不論目標時間為何，簡報一律會依佇列順序處理。 即使目前的目標時間早於上一個存在，在處理上一個存在之前，它將不會處理。 這基本上意謂著任何不以某個時間為目標的目前專案，都會覆寫上一個存在之前的時間。 這也表示，如果您的應用程式想要儘早發出簡報，則它根本無法設定目標時間（在此情況下，目標時間會維持在最後一個存在的時間），或設定目標時間 0。 兩者都會有相同的效果。 如果您的應用程式不想等候先前的簡報完成，以便進行新的簡報，則必須取消先前的簡報。 未來的範例說明如何執行這項操作。
T=3s：目前 1、2、3 全部就緒，而 3 是最後一個禮物，獲勝。 T=4s：目前 4、5、6 全部就緒，而 6 是最後一個禮物，獲勝。
上圖說明目前佇列中未完成的簡報範例。 目前 1 個目標時間為 3s。 因此，在 3 到 3 點之前，不會進行任何禮物。 不過，目前 2 實際上也會以較早的時間、2s 和目前 3 個目標 3 為目標。 因此，在時間 3s， present 1， 2， and 3 將全部完成， 而現在 3 將實際生效。 之後，下一個現成 4,4 將會滿足於 4，但立即由以 0 為目標的 Present 5 覆寫，而 Present 6 則沒有設定目標時間。 5 和 6 有效儘早生效。
C++ 範例
bool SimpleEventSynchronizationExample(
_In_ ID3D11Device* pD3D11Device,
_In_ IPresentationManager* pPresentationManager,
_In_ IPresentationSurface* pPresentationSurface,
_In_ vector<com_ptr_failfast<ID3D11Texture2D>>& textures,
_In_ vector<com_ptr_failfast<IPresentationBuffer>>& presentationBuffers)
{
// Track a time we'll be presenting to below. Default to the current time, then increment by
// 1/10th of a second every present.
SystemInterruptTime presentTime;
QueryInterruptTimePrecise(&presentTime.value);
// Build an array of events that we can wait on to perform various actions in our work loop.
vector<unique_event> waitEvents;
// The lost event will be the first event in our list. This is an event that signifies that
// something went wrong in the system (due to extreme conditions such as memory pressure, or
// driver issues) that indicate that the presentation manager has been lost, and should no
// longer be used, and instead should be recreated.
unique_event lostEvent;
pPresentationManager->GetLostEvent(&lostEvent);
waitEvents.emplace_back(std::move(lostEvent));
// Add each buffer's available event to the list of events we will be waiting on.
for (UINT bufferIndex = 0; bufferIndex < presentationBuffers.size(); bufferIndex++)
{
unique_event availableEvent;
presentationBuffers[bufferIndex]->GetAvailableEvent(&availableEvent);
waitEvents.emplace_back(std::move(availableEvent));
}
// Iterate for 120 presents.
constexpr UINT numberOfPresents = 120;
for (UINT onPresent = 0; onPresent < numberOfPresents; onPresent++)
{
// Advance our present time 1/10th of a second in the future. Note the API accepts
// time in 100ns units, or 1/1e7 of a second, meaning that 1 million units correspond to
// 1/10th of a second.
presentTime.value += 1'000'000;
// Wait for the lost event or an available buffer. Since WaitForMultipleObjects prioritizes
// lower-indexed events, it is recommended to put any higher importance events (like the
// lost event) first, and then follow up with buffer available events.
DWORD waitResult = WaitForMultipleObjects(
static_cast<UINT>(waitEvents.size()),
reinterpret_cast<HANDLE*>(waitEvents.data()),
FALSE,
INFINITE);
// Failfast if the wait hit an error.
FAIL_FAST_IF((waitResult - WAIT_OBJECT_0) >= waitEvents.size());
// Our lost event was the first event in the array. If this is signaled, the caller
// should recreate the presentation manager. This is very similar to how Direct3D devices
// can be lost. Assume our caller knows to handle this return value appropriately.
if (waitResult == WAIT_OBJECT_0)
{
return false;
}
// Otherwise, compute the buffer corresponding to the available event that was signaled.
UINT bufferIndex = waitResult - (WAIT_OBJECT_0 + 1);
// Draw red to that buffer
DrawColorToSurface(
pD3D11Device,
textures[bufferIndex],
1.0f, // red
0.0f, // green
0.0f); // blue
// Bind the presentation buffer to the presentation surface. Changes in this binding will take
// effect on the next present, and the binding persists across presents. That is, any number
// of subsequent presents will imply this binding until it is changed. It is completely fine
// to only update buffers for a subset of the presentation surfaces owned by a presentation
// manager on a given present - the implication is that it simply didn't update.
//
// Similarly, note that if your application were to call SetBuffer on the same presentation
// surface multiple times without calling present, this is fine. The policy is last writer
// wins.
//
// Your application may present without first binding a presentation surface to a buffer.
// The result will be that presentation surface will simply have no content on screen,
// similar to how DComp and WinComp surfaces appear in a tree before they are rendered to.
// In that case system content will show through where the buffer would have been.
//
// Your application may also set a 'null' buffer binding after previously having bound a
// buffer and present - the end result is the same as if your application had presented
// without ever having set the content.
pPresentationSurface->SetBuffer(presentationBuffers[bufferIndex].get());
// Present at the targeted time. Note that a present can target only a single time. If an
// application wants to updates two buffers at two different times, then it must present
// two times.
//
// Presents are always processed in queue order. A present will not take effect before any
// previous present in the queue, even if it targets an earlier time. In such a case, when
// the previous present is processed, the next present will also be processed immediately,
// and override that previous present.
//
// For this reason, if your application wishes to present "now" or "early as possible", then
// it can simply present, without setting a target time. The implied target time will be 0,
// and the new present will override the previous present.
//
// If your application wants to present truly "now", and not wait for previous presents in the
// queue to be processed, then it will need to cancel previous presents. A future example
// demonstrates how to do this.
//
// Your application will receive PRESENTATION_ERROR_LOST if it attempts to Present a lost
// presentation manager. This is the only call that will return such an error. A lost
// presentation manager functions normally in every other case, so applications need only
// to handle this error at the time they call Present.
pPresentationManager->SetTargetTime(presentTime);
HRESULT hrPresent = pPresentationManager->Present();
if (hrPresent == PRESENTATION_ERROR_LOST)
{
// Our presentation manager has been lost. Return 'false' to the caller to indicate that
// the presentation manager should be recreated.
return false;
}
else
{
FAIL_FAST_IF_FAILED(hrPresent);
}
}
return true;
}
void DrawColorToSurface(
_In_ ID3D11Device* pD3D11Device,
_In_ const com_ptr_failfast<ID3D11Texture2D>& texture2D,
_In_ float redValue,
_In_ float greenValue,
_In_ float blueValue)
{
com_ptr_failfast<ID3D11DeviceContext> D3DDeviceContext;
com_ptr_failfast<ID3D11RenderTargetView> renderTargetView;
// Get the immediate context from the D3D11 device.
pD3D11Device->GetImmediateContext(&D3DDeviceContext);
// Create a render target view of the passed texture.
auto resource = texture2D.query<ID3D11Resource>();
FAIL_FAST_IF_FAILED(pD3D11Device->CreateRenderTargetView(
resource.get(),
nullptr,
renderTargetView.addressof()));
// Clear the texture with the specified color.
float clearColor[4] = { redValue, greenValue, blueValue, 1.0f }; // red, green, blue, alpha
D3DDeviceContext->ClearRenderTargetView(renderTargetView.get(), clearColor);
}
範例 12 — 進階同步處理 — 使用目前的同步處理柵欄將工作流程節流至未處理的目前佇列大小，以及處理簡報管理員遺失的事件
下列範例說明您的應用程式如何提交大量的禮物供未來使用，然後睡眠到目前仍未完成的簡報數目下降到特定數量為止。 Windows Media Foundation 這類架構會以這種方式節流，以將發生的 CPU 喚醒數目降到最低，同時仍然確保目前的佇列不會耗盡（這可防止順暢播放，並造成問題）。 這會影響在簡報工作流程期間將 CPU 電源使用量降至最低。 您的應用程式會將簡報數目上限排入佇列（根據已配置的簡報緩衝區數目），然後睡眠到目前佇列耗盡之前，以重新填入佇列。
C++ 範例
bool FenceSynchronizationExample(
_In_ ID3D11Device* pD3D11Device,
_In_ IPresentationManager* pPresentationManager,
_In_ IPresentationSurface* pPresentationSurface,
_In_ vector<com_ptr_failfast<ID3D11Texture2D>>& textures,
_In_ vector<com_ptr_failfast<IPresentationBuffer>>& presentationBuffers)
{
// Track a time we'll be presenting to below. Default to the current time, then increment by
// 1/10th of a second every present.
SystemInterruptTime presentTime;
QueryInterruptTimePrecise(&presentTime.value);
// Get present retiring fence.
com_ptr_failfast<ID3D11Fence> presentRetiringFence;
FAIL_FAST_IF_FAILED(pPresentationManager->GetPresentRetiringFence(
IID_PPV_ARGS(&presentRetiringFence)));
// Get the lost event to query before presentation.
unique_event lostEvent;
pPresentationManager->GetLostEvent(&lostEvent);
// Create an event to synchronize to our queue depth with. We'll use Direct3D to signal this event
// when our synchronization fence indicates reaching a specific present.
unique_event presentQueueSyncEvent;
presentQueueSyncEvent.create(EventOptions::ManualReset);
// Cycle the present queue 10 times.
constexpr UINT numberOfPresentRefillCycles = 10;
for (UINT onRefillCycle = 0; onRefillCycle < numberOfPresentRefillCycles; onRefillCycle++)
{
// Fill up presents for all presentation buffers. We compare the presentation manager's
// next present ID to the present confirmed fence's value to figure out how
// far ahead we are. We stop when we've issued presents for all buffers.
while ((pPresentationManager->GetNextPresentId() -
presentRetiringFence->GetCompletedValue()) < presentationBuffers.size())
{
// Present buffers in cyclical pattern. We can figure out the current buffer to
// present by taking the modulo of the next present ID by the number of buffers. Note that the
// first present of a presentation manager always has a present ID of 1 and increments by 1 on
// each subsequent present. A present ID of 0 is conceptually meant to indicate that "no
// presents have taken place yet".
UINT bufferIndex = static_cast<UINT>(
pPresentationManager->GetNextPresentId() % presentationBuffers.size());
// Assert that the passed buffer is tracked as available for presentation. Because we throttle
// based on the total number of buffers, this should always be true.
NT_ASSERT(presentationBuffers[bufferIndex]->IsAvailable());
// Advance our present time 1/10th of a second in the future.
presentTime.value += 1'000'000;
// Draw red to the texture.
DrawColorToSurface(
pD3D11Device,
textures[bufferIndex],
1.0f, // red
0.0f, // green
0.0f); // blue
// Bind the presentation buffer to the presentation surface.
pPresentationSurface->SetBuffer(presentationBuffers[bufferIndex].get());
// Present at the targeted time.
pPresentationManager->SetTargetTime(presentTime);
HRESULT hrPresent = pPresentationManager->Present();
if (hrPresent == PRESENTATION_ERROR_LOST)
{
// Our presentation manager has been lost. Return 'false' to the caller to indicate that
// the presentation manager should be recreated.
return false;
}
else
{
FAIL_FAST_IF_FAILED(hrPresent);
}
};
// Now that the buffer is full, go to sleep until the present queue has been drained to
// the desired queue depth. To figure out the appropriate present to wake on, we subtract
// the desired wake queue depth from the presentation manager's last present ID. We
// use Direct3D's SetEventOnCompletion to signal our wait event when that particular present
// is retiring, and then wait on that event. Note that the semantic of SetEventOnCompletion
// is such that even if we happen to call it after the fence has already reached the
// requested value, the event will be set immediately.
constexpr UINT wakeOnQueueDepth = 2;
presentQueueSyncEvent.ResetEvent();
FAIL_FAST_IF_FAILED(presentRetiringFence->SetEventOnCompletion(
pPresentationManager->GetNextPresentId() - 1 - wakeOnQueueDepth,
presentQueueSyncEvent.get()));
HANDLE waitHandles[] = { lostEvent.get(), presentQueueSyncEvent.get() };
DWORD waitResult = WaitForMultipleObjects(
ARRAYSIZE(waitHandles),
waitHandles,
FALSE,
INFINITE);
// Failfast if we hit an error during our wait.
FAIL_FAST_IF((waitResult - WAIT_OBJECT_0) >= ARRAYSIZE(waitHandles));
if (waitResult == WAIT_OBJECT_0)
{
// The lost event was signaled - return 'false' to the caller to indicate that
// the presentation manager was lost.
return false;
}
// Iterate into another refill cycle.
}
return true;
}
範例 13 — VSync 中斷和硬體翻轉佇列支援
此 API 並引進了稱為 硬體翻轉佇列的新格式翻轉佇列 管理，基本上允許 GPU 硬體完全獨立於 CPU 管理簡報。 其主要優點是電源效率。 當 CPU 不需要參與簡報程式時，繪製的電力較少。
讓 GPU 句柄獨立呈現的缺點是，當顯示簡報時，CPU 狀態無法立即反映。 組合交換鏈 API 概念，例如緩衝區可用的事件、同步處理柵欄，以及目前的統計數據將不會立即更新。 相反地，GPU 只會定期重新整理顯示目前狀態的CPU狀態。 這表示對於目前狀態的應用程式意見反應會產生延遲。
您的應用程式通常會在顯示某些簡報時小心，但不在意其他簡報。 例如，如果您的應用程式發出10個簡報，它可能會決定它想要知道第8個何時顯示，因此它可以再次開始重新填入目前的佇列。 在此情況下，唯一真正想要的意見反應是 8 日。 當顯示 1-7 或 9 時，它不打算執行任何動作。
是否呈現更新 CPU 狀態取決於 GPU 硬體是否設定為在顯示該狀態時產生 VSync 中斷。 如果 CPU 尚未作用中，則此 VSync 中斷會喚醒 CPU，而 CPU 接著會執行特殊的核心層級程式代碼，以在 GPU 上上次檢查以來發生的簡報上自行更新，進而更新緩衝可用事件、目前淘汰的柵欄和目前的統計數據等意見反應機制。
若要讓應用程式明確指出哪些簡報應該發出 VSync 中斷，簡報管理員會公開 IPresentationManager：：ForceVSyncInterrupt 方法，指定後續簡報是否應該發出 VSync 中斷。 此設定會套用至所有未來的簡報，直到變更為止，這與 IPresentationManager：：SetTargetTime 和 IPresentationManager：：SetPreferredPresentDuration 類似。
如果在特定存在時啟用此設定，則硬體會在顯示存在時立即通知 CPU，使用更多電源，但確保當存在時立即通知 CPU，以便讓應用程式儘快回應。 如果在特定簡報上停用此設定，則當顯示目前時，系統將允許延遲更新 CPU—省電，但延遲意見反應。
您的應用程式通常不會強制任何簡報的 VSync 中斷，但它想要同步處理的簡報除外。 在上述範例中，由於您的應用程式想要在顯示第8個簡報時喚醒以重新填入其目前佇列，因此它會要求顯示8個訊號的VSync中斷，但呈現1-7且目前9則不會。
根據預設，如果您的應用程式未設定此設定，則簡報管理員一律會在顯示每個簡報時發出 VSync 中斷訊號。 對電源使用不關心或不知道硬體翻轉佇列支援的應用程式根本無法呼叫 ForceVSyncInterrupt，而且保證會因此正確同步處理。 瞭解硬體翻轉佇列支援的應用程式可以明確控制此設定，以改善電源效率。
下圖描述與 VSync 中斷設定相關的 API 行為。
C++ 範例
bool ForceVSyncInterruptPresentsExample(
_In_ ID3D11Device* pD3D11Device,
_In_ IPresentationManager* pPresentationManager,
_In_ IPresentationSurface* pPresentationSurface,
_In_ vector<com_ptr_failfast<ID3D11Texture2D>>& textures,
_In_ vector<com_ptr_failfast<IPresentationBuffer>>& presentationBuffers)
{
// Track a time we'll be presenting to below. Default to the current time, then increment by
// 1/10th of a second every present.
SystemInterruptTime presentTime;
QueryInterruptTimePrecise(&presentTime.value);
// Get present retiring fence.
com_ptr_failfast<ID3D11Fence> presentRetiringFence;
FAIL_FAST_IF_FAILED(pPresentationManager->GetPresentRetiringFence(
IID_PPV_ARGS(&presentRetiringFence)));
// Get the lost event to query before presentation.
unique_event lostEvent;
pPresentationManager->GetLostEvent(&lostEvent);
// Create an event to synchronize to our queue depth with. We will use Direct3D to signal this event
// when our synchronization fence indicates reaching a specific present.
unique_event presentQueueSyncEvent;
presentQueueSyncEvent.create(EventOptions::ManualReset);
// Issue 10 presents, and wake when the present queue is 2 entries deep (which happens when
// present 7 is retiring).
constexpr UINT wakeOnQueueDepth = 2;
constexpr UINT numberOfPresents = 10;
const UINT presentIdToWakeOn = numberOfPresents - 1 - wakeOnQueueDepth;
while (pPresentationManager->GetNextPresentId() <= numberOfPresents)
{
UINT bufferIndex = static_cast<UINT>(
pPresentationManager->GetNextPresentId() % presentationBuffers.size());
// Advance our present time 1/10th of a second in the future.
presentTime.value += 1'000'000;
// Draw red to the texture.
DrawColorToSurface(
pD3D11Device,
textures[bufferIndex],
1.0f, // red
0.0f, // green
0.0f); // blue
// Bind the presentation buffer to the presentation surface.
pPresentationSurface->SetBuffer(presentationBuffers[bufferIndex].get());
// Present at the targeted time.
pPresentationManager->SetTargetTime(presentTime);
// If this present is not going to retire the present that we want to wake on when it is shown, then
// we don't need immediate updates to buffer available events, present retiring fence, or present
// statistics. As such, we can mark it as not requiring a VSync interrupt, to allow for greater
// power efficiency on machines with hardware flip queue support.
bool forceVSyncInterrupt = (pPresentationManager->GetNextPresentId() == (presentIdToWakeOn + 1));
pPresentationManager->ForceVSyncInterrupt(forceVSyncInterrupt);
HRESULT hrPresent = pPresentationManager->Present();
if (hrPresent == PRESENTATION_ERROR_LOST)
{
// Our presentation manager has been lost. Return 'false' to the caller to indicate that
// the presentation manager should be recreated.
return false;
}
else
{
FAIL_FAST_IF_FAILED(hrPresent);
}
}
// Now that the buffer is full, go to sleep until presentIdToWakeOn has begun retiring. We
// configured the subsequent present to force a VSync interrupt when it is shown, which will ensure
// this wait is completed immediately.
presentQueueSyncEvent.ResetEvent();
FAIL_FAST_IF_FAILED(presentRetiringFence->SetEventOnCompletion(
presentIdToWakeOn,
presentQueueSyncEvent.get()));
HANDLE waitHandles[] = { lostEvent.get(), presentQueueSyncEvent.get() };
DWORD waitResult = WaitForMultipleObjects(
ARRAYSIZE(waitHandles),
waitHandles,
FALSE,
INFINITE);
// Failfast if we hit an error during our wait.
FAIL_FAST_IF((waitResult - WAIT_OBJECT_0) >= ARRAYSIZE(waitHandles));
if (waitResult == WAIT_OBJECT_0)
{
// The lost event was signaled - return 'false' to the caller to indicate that
// the presentation manager was lost.
return false;
}
return true;
}
範例 14 - 取消會呈現未來排程
將未來深度排入佇列的媒體應用程式可能會決定取消先前發行的簡報。 例如，如果您的應用程式正在播放視訊，未來會發出大量的畫面格，而使用者決定暫停視訊播放。 在此情況下，您的應用程式會想要堅持目前的框架，並取消任何尚未排入佇列的未來畫面格。 如果媒體應用程式決定將播放移至影片中的不同點，也可能會發生此情況。 在此情況下，您的應用程式會想要取消尚未排入影片中舊位置佇列的所有簡報，並將這些簡報取代為新位置的簡報。 在此情況下，取消先前的簡報之後，您的應用程式可以在未來發出新的簡報，以對應影片中的新點。
C++ 範例
void PresentCancelExample(
_In_ IPresentationManager* pPresentationManager,
_In_ UINT64 firstPresentIDToCancelFrom)
{
// Assume we've issued a number of presents in the future. Something happened in the app, and
// we want to cancel the issued presents that occur after a specified time or present ID. This
// may happen, for example, when the user pauses playback from inside a media application. The
// application will want to cancel all presents posted targeting beyond the pause time. The
// cancel will apply to all previously posted presents whose present IDs are at least
// 'firstPresentIDToCancelFrom'. Note that Present IDs are always unique, and never recycled,
// so even if a present is canceled, no subsequent present will ever reuse its present ID.
//
// Also note that if some presents we attempt to cancel can't be canceled because they've
// already started queueing, then no error will be returned, they simply won't be canceled as
// requested. Cancelation takes a "best effort" approach.
FAIL_FAST_IF_FAILED(pPresentationManager->CancelPresentsFrom(firstPresentIDToCancelFrom));
// In the case where the media application scrubbed to a different position in the video, it may now
// choose to issue new presents to replace the ones canceled. This is not illustrated here, but
// previous examples that demonstrate presentation show how this may be achieved.
}
範例 15 — 交錯緩衝區重設大小作業，以改善效能
此範例說明您的應用程式如何交錯緩衝區大小，以改善 DXGI 的效能。 回想上一個重設大小範例，其中電影串流服務用戶端想要將播放解析度從 720p 變更為 1080p。 在 DXGI 中，應用程式會在 DXGI 交換鏈上執行重設大小作業，這會以不可部分完成的方式擲回所有先前的緩衝區，並一次重新配置所有新的 1080p 緩衝區，並將其新增至交換鏈。 這種不可部分完成的緩衝區重設大小成本很高，而且可能會花費很長的時間並造成問題。 新的 API 可更精細地控制個別的簡報緩衝區。 因此，您可以重新配置緩衝區，並逐一取代多個簡報，以隨著時間分割工作負載。 這對任何一個存在的影響較小，而且不太可能造成故障。 基本上，對於具有 n 個簡報緩衝區的簡報管理員，針對 『n』 簡報，您的應用程式可以移除舊大小的舊簡報緩衝區、在新的大小配置新的簡報緩衝區，並加以呈現。 在 'n' 出現之後，所有緩衝區都會處於新的大小。
C++ 範例
bool StaggeredResizeExample(
_In_ ID3D11Device* pD3D11Device,
_In_ IPresentationManager* pPresentationManager,
_In_ IPresentationSurface* pPresentationSurface,
_In_ vector<com_ptr_failfast<ID3D11Texture2D>> textures,
_In_ vector<com_ptr_failfast<IPresentationBuffer>> presentationBuffers)
{
// Track a time we'll be presenting to below. Default to the current time, then increment by
// 1/10th of a second every present.
SystemInterruptTime presentTime;
QueryInterruptTimePrecise(&presentTime.value);
// Assume textures/presentationBuffers vector contains 10 100x100 buffers, and we want to resize
// our swapchain to 200x200. Instead of reallocating 10 200x200 buffers all at once,
// like DXGI does today, we can stagger the reallocation across multiple presents. For
// each present, we can allocate one buffer at the new size, and replace one old buffer
// at the old size with the new one at the new size. After 10 presents, we will have
// reallocated all our buffers, and we will have done so in a manner that's much less
// likely to produce delays or glitches.
constexpr UINT numberOfBuffers = 10;
for (UINT bufferIndex = 0; bufferIndex < numberOfBuffers; bufferIndex++)
{
// Advance our present time 1/10th of a second in the future.
presentTime.value += 1'000'000;
// Release the old texture/presentation buffer at the presented index.
auto& replacedTexture = textures[bufferIndex];
auto& replacedPresentationBuffer = presentationBuffers[bufferIndex];
replacedTexture.reset();
replacedPresentationBuffer.reset();
// Create a new texture/presentation buffer in its place.
AddNewPresentationBuffer(
pD3D11Device,
pPresentationManager,
200, // Buffer width
200, // Buffer height
&replacedTexture,
&replacedPresentationBuffer);
// Draw red to the new texture.
DrawColorToSurface(
pD3D11Device,
replacedTexture,
1.0f, // red
0.0f, // green
0.0f); // blue
// Bind the presentation buffer to the presentation surface.
pPresentationSurface->SetBuffer(replacedPresentationBuffer.get());
// Present at the targeted time.
pPresentationManager->SetTargetTime(presentTime);
HRESULT hrPresent = pPresentationManager->Present();
if (hrPresent == PRESENTATION_ERROR_LOST)
{
// Our presentation manager has been lost. Return 'false' to the caller to indicate that
// the presentation manager should be recreated.
return false;
}
else
{
FAIL_FAST_IF_FAILED(hrPresent);
}
}
return true;
}
範例 16 — 讀取和處理目前的統計數據
API 會報告所提交之每個簡報的統計數據。 概括而言，目前的統計數據是一種意見反應機制，描述系統處理或顯示特定簡報的方式。 您的應用程式可以註冊以接收不同類型的統計數據，而 API 本身的統計數據基礎結構是可擴充的，因此未來可以新增更多類型的統計數據。 此 API 描述如何讀取統計數據，並描述目前定義的統計數據類型，以及他們在高階傳達的資訊。
C++ 範例
// This is an identifier we'll assign to our presentation surface that will be used to reference that
// presentation surface in statistics. This is to avoid referring to a presentation surface by pointer
// in a statistics structure, which has unclear refcounting and lifetime semantics.
static constexpr UINT_PTR myPresentedContentTag = 12345;
bool StatisticsExample(
_In_ ID3D11Device* pD3D11Device,
_In_ IPresentationManager* pPresentationManager,
_In_ IPresentationSurface* pPresentationSurface,
_In_ vector<com_ptr_failfast<ID3D11Texture2D>>& textures,
_In_ vector<com_ptr_failfast<IPresentationBuffer>>& presentationBuffers)
{
// Track a time we'll be presenting to below. Default to the current time, then increment by
// 1/10th of a second every present.
SystemInterruptTime presentTime;
QueryInterruptTimePrecise(&presentTime.value);
// Register to receive 3 types of statistics.
FAIL_FAST_IF_FAILED(pPresentationManager->EnablePresentStatisticsKind(
PresentStatisticsKind_CompositionFrame,
true));
FAIL_FAST_IF_FAILED(pPresentationManager->EnablePresentStatisticsKind(
PresentStatisticsKind_PresentStatus,
true));
FAIL_FAST_IF_FAILED(pPresentationManager->EnablePresentStatisticsKind(
PresentStatisticsKind_IndependentFlipFrame,
true));
// Stats come back referencing specific presentation surfaces. We assign 'tags' to presentation
// surfaces in the API that statistics will use to reference the presentation surface in a
// statistic.
pPresentationSurface->SetTag(myPresentedContentTag);
// Build an array of events that we can wait on.
vector<unique_event> waitEvents;
// The lost event will be the first event in our list. This is an event that signifies that
// something went wrong in the system (due to extreme conditions like memory pressure, or
// driver issues) that indicate that the presentation manager has been lost, and should no
// longer be used, and instead should be recreated.
unique_event lostEvent;
FAIL_FAST_IF_FAILED(pPresentationManager->GetLostEvent(&lostEvent));
waitEvents.emplace_back(std::move(lostEvent));
// The statistics event will be the second event in our list. This event will be signaled
// by the presentation manager when there are statistics to read back.
unique_event statisticsEvent;
FAIL_FAST_IF_FAILED(pPresentationManager->GetPresentStatisticsAvailableEvent(&statisticsEvent));
waitEvents.emplace_back(std::move(statisticsEvent));
// Add each buffer's available event to the list of events we will be waiting on.
for (UINT bufferIndex = 0; bufferIndex < presentationBuffers.size(); bufferIndex++)
{
unique_event availableEvent;
presentationBuffers[bufferIndex]->GetAvailableEvent(&availableEvent);
waitEvents.emplace_back(std::move(availableEvent));
}
// Iterate our workflow 120 times.
constexpr UINT iterationCount = 120;
for (UINT i = 0; i < iterationCount; i++)
{
// Wait for an event to be signaled.
DWORD waitResult = WaitForMultipleObjects(
static_cast<UINT>(waitEvents.size()),
reinterpret_cast<HANDLE*>(waitEvents.data()),
FALSE,
INFINITE);
// Failfast if the wait hit an error.
FAIL_FAST_IF((waitResult - WAIT_OBJECT_0) >= waitEvents.size());
// Our lost event was the first event in the array. If this is signaled, then the caller
// should recreate the presentation manager. This is very similar to how Direct3D devices
// can be lost. Assume our caller knows to handle this return value appropriately.
if (waitResult == WAIT_OBJECT_0)
{
return false;
}
// The second event in the array is the statistics event. If this event is signaled,
// read and process our statistics.
if (waitResult == (WAIT_OBJECT_0 + 1))
{
StatisticsExample_ProcessStatistics(pPresentationManager);
}
// Otherwise, the event corresponds to a buffer available event that is signaled.
// Compute the buffer for the available event that was signaled and present a
// frame.
else
{
DWORD bufferIndex = waitResult - (WAIT_OBJECT_0 + 2);
// Draw red to the texture.
DrawColorToSurface(
pD3D11Device,
textures[bufferIndex],
1.0f, // red
0.0f, // green
0.0f); // blue
// Bind the texture to the presentation surface.
pPresentationSurface->SetBuffer(presentationBuffers[bufferIndex].get());
// Advance our present time 1/10th of a second in the future.
presentTime.value += 1'000'000;
// Present at the targeted time.
pPresentationManager->SetTargetTime(presentTime);
HRESULT hrPresent = pPresentationManager->Present();
if (hrPresent == PRESENTATION_ERROR_LOST)
{
// Our presentation manager has been lost. Return 'false' to the caller to indicate that
// the presentation manager should be recreated.
return false;
}
else
{
FAIL_FAST_IF_FAILED(hrPresent);
}
}
}
return true;
}
void StatisticsExample_ProcessStatistics(
_In_ IPresentationManager* pPresentationManager)
{
// Dequeue a single present statistics item. This will return the item
// and pop it off the queue of statistics.
com_ptr_failfast<IPresentStatistics> presentStatisticsItem;
pPresentationManager->GetNextPresentStatistics(&presentStatisticsItem);
// Read back the present ID this corresponds to.
UINT64 presentId = presentStatisticsItem->GetPresentId();
UNREFERENCED_PARAMETER(presentId);
// Switch on the type of statistic this item corresponds to.
switch (presentStatisticsItem->GetKind())
{
case PresentStatisticsKind_PresentStatus:
{
// Present status statistics describe whether a given present was queued for display,
// skipped due to some future present being a better candidate to display on a given
// frame, or canceled via the API.
auto presentStatusStatistics = presentStatisticsItem.query<IPresentStatusStatistics>();
// Read back the status
PresentStatus status = presentStatusStatistics->GetPresentStatus();
UNREFERENCED_PARAMETER(status);
// Possible values for status:
// PresentStatus_Queued
// PresentStatus_Skipped
// PresentStatus_Canceled;
// Depending on the status returned, your application can adjust their workflow
// accordingly. For example, if your application sees that a large percentage of their
// presents are skipped, it means they are presenting more frames than the system can
// display. In such a case, your application might decided to lower the rate at which
// you present frames.
}
break;
case PresentStatisticsKind_CompositionFrame:
{
// Composition frame statistics describe how a given present was used in a DWM frame.
// It includes information such as which monitors displayed the present, whether the
// present was composed or directly scanned out via an MPO plane, and rendering
// properties such as what transforms were applied to the rendering. Composition
// frame statistics are not issued for iflip presents - only for presents issued by the
// compositor. iflip presents have their own type of statistic (described next).
auto compositionFrameStatistics =
presentStatisticsItem.query<ICompositionFramePresentStatistics>();
// Stats should come back for the present statistics item that we tagged earlier.
NT_ASSERT(compositionFrameStatistics->GetContentTag() == myPresentedContentTag);
// The composition frame ID indicates the DWM frame ID that the present was used
// in.
CompositionFrameId frameId = compositionFrameStatistics->GetCompositionFrameId();
// Get the display instance array to indicate which displays showed the present. Each
// instance of the presentation surface will have an entry in this array. For example,
// if your application adds the same presentation surface to four different visuals in the
// visual tree, then each instance in the tree will have an entry in the display instance
// array. Similarly, if the presentation surface shows up on multiple monitors, then each
// monitor instance will be accounted for in the display instance array that is
// returned.
//
// Note that the pointer returned from GetDisplayInstanceArray is valid for the
// lifetime of the ICompositionFramePresentStatistics. Your application must not attempt
// to read this pointer after the ICompositionFramePresentStatistics has been released
// to a refcount of 0.
UINT displayInstanceArrayCount;
const CompositionFrameDisplayInstance* pDisplayInstances;
compositionFrameStatistics->GetDisplayInstanceArray(
&displayInstanceArrayCount,
&pDisplayInstances);
for (UINT i = 0; i < displayInstanceArrayCount; i++)
{
const auto& displayInstance = pDisplayInstances[i];
// The following are fields that are available in a display instance.
// The LUID, VidPnSource, and unique ID of the output and its owning
// adapter. The unique ID will be bumped when a LUID/VidPnSource is
// recycled. Applications should use the unique ID to determine when
// this happens so that they don't try and correlate stats from one
// monitor with another.
displayInstance.outputAdapterLUID;
displayInstance.outputVidPnSourceId;
displayInstance.outputUniqueId;
// The instanceKind field indicates how the present was used. It
// indicates that the present was composed (rendered to DWM's backbuffer),
// scanned out (via MPO/DFlip) or composed to an intermediate buffer by DWM
// for effects.
displayInstance.instanceKind;
// The finalTransform field indicates the transform at which the present was
// shown in world space. It will include all ancestor visual transforms and
// can be used to know how it was rendered in the global visual tree.
displayInstance.finalTransform;
// The requiredCrossAdapterCopy field indicates whether or not we needed to
// copy your application's buffer to a different adapter in order to display
// it. Applications should use this to determine whether or not they should
// reallocate their buffers onto a different adapter for better performance.
displayInstance.requiredCrossAdapterCopy;
// The colorSpace field indicates the colorSpace of the output that the
// present was rendered to.
displayInstance.colorSpace;
// For example, if your application sees that the finalTransform is scaling your
// content by 2x, you might elect to pre-render that scale into your presentation
// surface, and then add a 1/2 scale. At which point, the finalTransform should
// be 1x, and some MPO hardware will be more likely to MPO a presentation surface
// with a 1x scale applied, since some hardware has a maximum they are able to
// scale in an MPO plane. Similarly, if your application's content is being scaled
// down on screen, you may wish to simply render its content at a
// smaller scale to conserve resources, and apply an enlargement transform.
}
// Additionally, we can use the CompositionFrameId reported by the statistic
// to query timing-related information about that specific frame via the new
// composition timing API, such as when that frame showed up on screen.
// Note this is achieved using a separate API from the composition swapchain API, but
// using the composition frame ID reported in the composition swapchain API to
// properly specify which frame your application wants timing information from.
COMPOSITION_FRAME_TARGET_STATS frameTargetStats;
COMPOSITION_TARGET_STATS targetStats[4];
frameTargetStats.targetCount = ARRAYSIZE(targetStats);
frameTargetStats.targetStats = targetStats;
// Specify the frameId that we got from stats in order to pass to the call
// below and retrieve timing information about that frame.
frameTargetStats.frameId = frameId;
FAIL_FAST_IF_FAILED(DCompositionGetTargetStatistics(1, &frameTargetStats));
// If the frameTargetStats comes back with a 0 frameId, it means the frame isn't
// part of statistics. This might mean that it has expired out of
// DCompositionGetTargetStatistics history, but that call keeps a history buffer
// roughly equivalent to ~5 seconds worth of frame history, so if your application
// is processing statistics from the presentation manager relatively regularly,
// by all accounts it shouldn't worry about DCompositionGetTargetStatistics
// history expiring. The more likely scenario when this occurs is that it's too
// early, and that this frame isn't part of statistics YET. In that case, your application
// should defer processing for this frame, and try again later. For the purposes
// if sample brevity, we don't bother trying again here. A good method to use would
// be to add this present info to a list of presents that we haven't gotten target
// statistics for yet, and try again for all presents in that list any time we get
// a new PresentStatisticsKind_CompositionFrame for a future frame.
if (frameTargetStats.frameId == frameId)
{
// The targetCount will represent the count of outputs the given frame
// applied to.
frameTargetStats.targetCount;
// The targetTime corresponds to the wall clock QPC time DWM was
// targeting for the frame.
frameTargetStats.targetTime;
for (UINT i = 0; i < frameTargetStats.targetCount; i++)
{
const auto& targetStat = frameTargetStats.targetStats[i];
// The present time corresponds to the targeted present time of the composition
// frame.
targetStat.presentTime;
// The target ID corresponds to the LUID/VidPnSourceId/Unique ID for the given
// target.
targetStat.targetId;
// The completedStats convey information about the time a compositor frame was
// completed, which marks the time any of its associated composition swapchain API
// presents entered the displayed state. In particular, your application might wish
// to use the 'time' to know if a present showed at a time it expected.
targetStat.completedStats.presentCount;
targetStat.completedStats.refreshCount;
targetStat.completedStats.time;
// There is various other timing statistics information conveyed by
// DCompositionGetTargetStatistics.
}
}
}
break;
case PresentStatisticsKind_IndependentFlipFrame:
{
// Independent flip frame statistics describe a present that was shown via
// independent flip.
auto independentFlipFrameStatistics =
presentStatisticsItem.query<IIndependentFlipFramePresentStatistics>();
// Stats should come back for the present statistics item that we tagged earlier.
NT_ASSERT(independentFlipFrameStatistics->GetContentTag() == myPresentedContentTag);
// The driver-approved present duration describes the custom present duration that was
// approved by the driver and applied during the present. This is how, for example, media
// will know whether or not they got 24hz mode for their content if they requested it.
independentFlipFrameStatistics->GetPresentDuration();
// The displayed time is the time the present was confirmed to have been shown
// on screen.
independentFlipFrameStatistics->GetDisplayedTime();
// The adapter LUID/VidpnSource ID describe the output on which the present took
// place. Unlike the composition statistic above, we don't report a unique ID here
// because a monitor recycle would kick the presentation out of iflip.
independentFlipFrameStatistics->GetOutputAdapterLUID();
independentFlipFrameStatistics->GetOutputVidPnSourceId();
}
break;
}
}
範例 17 -- 使用抽象層，從您的應用程式使用新的組合交換鏈 API 或 DXGI 來呈現
假設新組合交換鏈 API 的系統/驅動程式需求較高，您的應用程式可能會想要在不支援新 API 的情況下使用 DXGI。 幸運的是，引進抽象層相當容易，該層會利用任何 API 可供執行簡報。 下列範例說明如何達成此目的。
C++ 範例
// A base class presentation provider. We'll provide implementations using both DXGI and the new
// composition swapchain API, which the example will use based on what's supported.
class PresentationProvider
{
public:
virtual void GetBackBuffer(
_Out_ ID3D11Texture2D** ppBackBuffer) = 0;
virtual void Present(
_In_ SystemInterruptTime presentationTime) = 0;
virtual bool ReadStatistics(
_Out_ UINT* pPresentCount,
_Out_ UINT64* pSyncQPCTime) = 0;
virtual ID3D11Device* GetD3D11DeviceNoRef()
{
return m_d3dDevice.get();
}
protected:
com_ptr_failfast<ID3D11Device> m_d3dDevice;
};
// An implementation of PresentationProvider using a DXGI swapchain to provide presentation
// functionality.
class DXGIProvider :
public PresentationProvider
{
public:
DXGIProvider(
_In_ UINT width,
_In_ UINT height,
_In_ UINT bufferCount)
{
com_ptr_failfast<IDXGIAdapter> dxgiAdapter;
com_ptr_failfast<IDXGIFactory7> dxgiFactory;
com_ptr_failfast<IDXGISwapChain1> dxgiSwapchain;
com_ptr_failfast<ID3D11DeviceContext> d3dDeviceContext;
// Direct3D device creation flags.
UINT deviceCreationFlags =
D3D11_CREATE_DEVICE_BGRA_SUPPORT |
D3D11_CREATE_DEVICE_SINGLETHREADED;
// Create the Direct3D device.
FAIL_FAST_IF_FAILED(D3D11CreateDevice(
nullptr, // No adapter
D3D_DRIVER_TYPE_HARDWARE, // Hardware device
nullptr, // No module
deviceCreationFlags, // Device creation flags
nullptr, 0, // Highest available feature level
D3D11_SDK_VERSION, // API version
&m_d3dDevice, // Resulting interface pointer
nullptr, // Actual feature level
&d3dDeviceContext)); // Device context
// Make our way from the Direct3D device to the DXGI factory.
auto dxgiDevice = m_d3dDevice.query<IDXGIDevice>();
FAIL_FAST_IF_FAILED(dxgiDevice->GetParent(IID_PPV_ARGS(&dxgiAdapter)));
FAIL_FAST_IF_FAILED(dxgiAdapter->GetParent(IID_PPV_ARGS(&dxgiFactory)));
// Create a swapchain matching the desired parameters.
DXGI_SWAP_CHAIN_DESC1 desc = {};
desc.Width = width;
desc.Height = height;
desc.Format = DXGI_FORMAT_B8G8R8A8_UNORM;
desc.BufferUsage = DXGI_USAGE_RENDER_TARGET_OUTPUT;
desc.SampleDesc.Count = 1;
desc.SampleDesc.Quality = 0;
desc.BufferCount = bufferCount;
desc.Scaling = DXGI_SCALING_STRETCH;
desc.SwapEffect = DXGI_SWAP_EFFECT_FLIP_SEQUENTIAL;
desc.AlphaMode = DXGI_ALPHA_MODE_PREMULTIPLIED;
FAIL_FAST_IF_FAILED(dxgiFactory->CreateSwapChainForComposition(
m_d3dDevice.get(),
&desc,
nullptr,
&dxgiSwapchain));
// Store the swapchain.
dxgiSwapchain.query_to(&m_swapchain);
}
void GetBackBuffer(
_Out_ ID3D11Texture2D** ppBackBuffer) override
{
// Get the backbuffer directly from the swapchain.
FAIL_FAST_IF_FAILED(m_swapchain->GetBuffer(
m_swapchain->GetCurrentBackBufferIndex(),
IID_PPV_ARGS(ppBackBuffer)));
}
void Present(
_In_ SystemInterruptTime presentationTime) override
{
// Convert the passed presentation time to a present interval. The implementation is
// not provided here, as there's a great deal of complexity around computing this
// most accurately, but it essentially boils down to taking the time from now and
// figuring out the number of vblanks that corresponds to that time duration.
UINT vblankIntervals = ComputePresentIntervalFromTime(presentationTime);
// Issue a present to the swapchain. If we wanted to allow for a time to be specified,
// code here could convert the time to a present duration, which could be passed here.
FAIL_FAST_IF_FAILED(m_swapchain->Present(vblankIntervals, 0));
}
bool ReadStatistics(
_Out_ UINT* pPresentCount,
_Out_ UINT64* pSyncQPCTime) override
{
// Zero our output parameters initially.
*pPresentCount = 0;
*pSyncQPCTime = 0;
// Grab frame statistics from the swapchain.
DXGI_FRAME_STATISTICS frameStatistics;
FAIL_FAST_IF_FAILED(m_swapchain->GetFrameStatistics(&frameStatistics));
// If the statistics have changed since our last read, then return the new information
// to the caller.
bool hasNewStats = false;
if (frameStatistics.PresentCount > m_lastPresentCount)
{
m_lastPresentCount = frameStatistics.PresentCount;
hasNewStats = true;
*pPresentCount = frameStatistics.PresentCount;
*pSyncQPCTime = frameStatistics.SyncQPCTime.QuadPart;
}
return hasNewStats;
}
private:
com_ptr_failfast<IDXGISwapChain4> m_swapchain;
UINT m_lastPresentCount = 0;
};
// An implementation of PresentationProvider using the composition swapchain API to provide
// presentation functionality.
class PresentationAPIProvider :
public PresentationProvider
{
public:
PresentationAPIProvider(
_In_ UINT width,
_In_ UINT height,
_In_ UINT bufferCount)
{
// Create the presentation manager and presentation surface using the function defined in a
// previous example.
MakePresentationManagerAndPresentationSurface(
&m_d3dDevice,
&m_presentationManager,
&m_presentationSurface,
m_presentationSurfaceHandle);
// Register for present statistics.
FAIL_FAST_IF_FAILED(m_presentationManager->EnablePresentStatisticsKind(
PresentStatisticsKind_CompositionFrame,
true));
// Get the statistics event from the presentation manager.
FAIL_FAST_IF_FAILED(m_presentationManager->GetPresentStatisticsAvailableEvent(
&m_statisticsAvailableEvent));
// Create and register the specified number of presentation buffers.
for (UINT i = 0; i < bufferCount; i++)
{
com_ptr_failfast<ID3D11Texture2D> texture;
com_ptr_failfast<IPresentationBuffer> presentationBuffer;
AddNewPresentationBuffer(
m_d3dDevice.get(),
m_presentationManager.get(),
width,
height,
&texture,
&presentationBuffer);
// Add the new presentation buffer and texture to our array.
m_textures.push_back(texture);
m_presentationBuffers.push_back(presentationBuffer);
// Store the available event for the presentation buffer.
unique_event availableEvent;
FAIL_FAST_IF_FAILED(presentationBuffer->GetAvailableEvent(&availableEvent));
m_bufferAvailableEvents.emplace_back(std::move(availableEvent));
}
}
void GetBackBuffer(
_Out_ ID3D11Texture2D** ppBackBuffer) override
{
// Query an available backbuffer using our available events.
DWORD waitIndex = WaitForMultipleObjects(
static_cast<UINT>(m_bufferAvailableEvents.size()),
reinterpret_cast<HANDLE*>(m_bufferAvailableEvents.data()),
FALSE,
INFINITE);
UINT bufferIndex = waitIndex - WAIT_OBJECT_0;
// Set the backbuffer to be the next presentation buffer.
FAIL_FAST_IF_FAILED(m_presentationSurface->SetBuffer(m_presentationBuffers[bufferIndex].get()));
// Return the backbuffer to the caller.
m_textures[bufferIndex].query_to(ppBackBuffer);
}
void Present(
_In_ SystemInterruptTime presentationTime) override
{
// Present at the targeted time.
m_presentationManager->SetTargetTime(presentationTime);
HRESULT hrPresent = m_presentationManager->Present();
if (hrPresent == PRESENTATION_ERROR_LOST)
{
// Our presentation manager has been lost. See previous examples regarding how to handle this.
return;
}
else
{
FAIL_FAST_IF_FAILED(hrPresent);
}
}
bool ReadStatistics(
_Out_ UINT* pPresentCount,
_Out_ UINT64* pSyncQPCTime) override
{
// Zero our out parameters initially.
*pPresentCount = 0;
*pSyncQPCTime = 0;
bool hasNewStats = false;
// Peek at the statistics available event state to see if we've got new statistics.
while (WaitForSingleObject(m_statisticsAvailableEvent.get(), 0) == WAIT_OBJECT_0)
{
// Pop a statistics item to process.
com_ptr_failfast<IPresentStatistics> statisticsItem;
FAIL_FAST_IF_FAILED(m_presentationManager->GetNextPresentStatistics(
&statisticsItem));
// If this is a composition frame stat, process it.
if (statisticsItem->GetKind() == PresentStatisticsKind_CompositionFrame)
{
// We've got new stats to report.
hasNewStats = true;
// Convert to composition frame statistic item.
auto frameStatisticsItem = statisticsItem.query<ICompositionFramePresentStatistics>();
// Query DirectComposition's target statistics API to determine the completed time.
COMPOSITION_FRAME_TARGET_STATS frameTargetStats;
COMPOSITION_TARGET_STATS targetStats[4];
frameTargetStats.targetCount = ARRAYSIZE(targetStats);
frameTargetStats.targetStats = targetStats;
// Specify the frameId we got from stats in order to pass to the call
// below and retrieve timing information about that frame.
frameTargetStats.frameId = frameStatisticsItem->GetCompositionFrameId();
FAIL_FAST_IF_FAILED(DCompositionGetTargetStatistics(1, &frameTargetStats));
// Return the statistics information for the first target.
*pPresentCount = static_cast<UINT>(frameStatisticsItem->GetPresentId());
*pSyncQPCTime = frameTargetStats.targetStats[0].completedStats.time;
// Note that there's a much richer variety of statistics information in the new
// API that can be used to infer much more than is possible with DXGI frame
// statistics.
}
}
return hasNewStats;
}
static bool IsSupportedOnSystem()
{
// Direct3D device creation flags. The composition swapchain API requires that applications disable internal
// driver threading optimizations, as these optimizations break synchronization of the API.
// If this flag isn't present, then the API will fail the call to create the presentation factory.
UINT deviceCreationFlags =
D3D11_CREATE_DEVICE_BGRA_SUPPORT |
D3D11_CREATE_DEVICE_SINGLETHREADED |
D3D11_CREATE_DEVICE_PREVENT_INTERNAL_THREADING_OPTIMIZATIONS;
// Create the Direct3D device.
com_ptr_failfast<ID3D11Device> d3dDevice;
com_ptr_failfast<ID3D11DeviceContext> d3dDeviceContext;
FAIL_FAST_IF_FAILED(D3D11CreateDevice(
nullptr, // No adapter
D3D_DRIVER_TYPE_HARDWARE, // Hardware device
nullptr, // No module
deviceCreationFlags, // Device creation flags
nullptr, 0, // Highest available feature level
D3D11_SDK_VERSION, // API version
&d3dDevice, // Resulting interface pointer
nullptr, // Actual feature level
&d3dDeviceContext)); // Device context
// Call the composition swapchain API export to create the presentation factory.
com_ptr_failfast<IPresentationFactory> presentationFactory;
FAIL_FAST_IF_FAILED(CreatePresentationFactory(
d3dDevice.get(),
IID_PPV_ARGS(&presentationFactory)));
// Now determine whether the system is capable of supporting the composition swapchain API based
// on the capability that's reported by the presentation factory.
return presentationFactory->IsPresentationSupported();
}
private:
com_ptr_failfast<IPresentationManager> m_presentationManager;
com_ptr_failfast<IPresentationSurface> m_presentationSurface;
vector<com_ptr_failfast<ID3D11Texture2D>> m_textures;
vector<com_ptr_failfast<IPresentationBuffer>> m_presentationBuffers;
vector<unique_event> m_bufferAvailableEvents;
unique_handle m_presentationSurfaceHandle;
unique_event m_statisticsAvailableEvent;
};
void DXGIOrPresentationAPIExample()
{
// Get the current system time. We'll base our 'PresentAt' time on this result.
SystemInterruptTime currentTime;
QueryInterruptTimePrecise(¤tTime.value);
// Track a time we'll be presenting at below. Default to the current time, then increment by
// 1/10th of a second every present.
auto presentTime = currentTime;
// Allocate a presentation provider using the composition swapchain API if it is supported;
// otherwise fall back to DXGI.
unique_ptr<PresentationProvider> presentationProvider;
if (PresentationAPIProvider::IsSupportedOnSystem())
{
presentationProvider = std::make_unique<PresentationAPIProvider>(
500, // Buffer width
500, // Buffer height
6); // Number of buffers
}
else
{
// System doesn't support the composition swapchain API. Fall back to DXGI.
presentationProvider = std::make_unique<DXGIProvider>(
500, // Buffer width
500, // Buffer height
6); // Number of buffers
}
// Present 50 times.
constexpr UINT numPresents = 50;
for (UINT i = 0; i < 50; i++)
{
// Advance our present time 1/10th of a second in the future.
presentTime.value += 1'000'000;
// Call the presentation provider to get a backbuffer to render to.
com_ptr_failfast<ID3D11Texture2D> backBuffer;
presentationProvider->GetBackBuffer(&backBuffer);
// Render to the backbuffer.
DrawColorToSurface(
presentationProvider->GetD3D11DeviceNoRef(),
backBuffer,
1.0f, // red
0.0f, // green
0.0f); // blue
// Present the backbuffer.
presentationProvider->Present(presentTime);
// Process statistics.
bool hasNewStats;
UINT64 presentTime;
UINT presentCount;
hasNewStats = presentationProvider->ReadStatistics(
&presentCount,
&presentTime);
if (hasNewStats)
{
// Process these statistics however your application wishes.
}
}
}
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