使用 DirectX 和 Direct2D 組合原生交互操作
Windows.UI.Composition API 提供 ICompositorInterop、ICompositionDrawingSurfaceInterop 和 ICompositionGraphicsDeviceInterop 原生交互操作介面，可讓內容直接移至撰寫器。
原生交互操作是以 DirectX 紋理支援的介面物件為基礎。 介面是從稱為 CompositionGraphicsDevice 的處理站物件建立。 此物件是由基礎 Direct2D 或 Direct3D 裝置物件所支援，其用來為介面配置視訊記憶體。 組合 API 永遠不會建立基礎 DirectX 裝置。 應用程式必須負責建立一個基礎裝置物件，並將其傳遞至 CompositionGraphicsDevice 物件。 應用程式一次可能會建立一個以上的 CompositionGraphicsDevice 物件，而且可能會使用相同的 DirectX 裝置來做為多個 CompositionGraphicsDevice 物件的轉譯裝置。
建立介面
每個 CompositionGraphicsDevice 都可作為介面處理站。 每個介面都是以初始大小建立 (可能是0,0)，但沒有有效的像素。 處於初始狀態的介面可能會立即在視覺化樹狀結構被取用，例如，透過 CompositionSurfaceBrush 和 SpriteVisual，但在其初始狀態中，介面對螢幕輸出沒有作用。 此介面就所有用途而言，目前都是完全透明的，即使指定的透明度模式為「不透明」也一樣。
有時候，DirectX 裝置可能會轉譯為無法使用。 有許多原因，可能會使這種情況發生，例如應用程式將無效的引數傳遞至特定 DirectX API，或是系統重設了圖形介面卡，又或者驅動程式經過更新。 Direct3D 具有一個 API，如果因為任何原因而遺失裝置，應用程式就可使用這個 API 以非同步方式進行探索。 當 DirectX 裝置遺失時，應用程式必須捨棄它、建立新的裝置，並將它傳遞給先前與錯誤 DirectX 裝置相關聯的任何 CompositionGraphicsDevice 物件。
將像素載入介面
若要將像素載入介面，應用程式必須呼叫 BeginDraw 方法，此方法會根據應用程式要求的內容，傳回代表紋理或 Direct2D 內容的 DirectX 介面。 然後，應用程式必須將像素轉譯或上傳至該紋理。 當應用程式完成時，它必須呼叫 EndDraw 方法。 只有此時，新的像素才可供組合使用，但在下次認可視覺化樹狀結構的所有變更之前，它們仍不會顯示在畫面上。 如果在呼叫 EndDraw 之前認可視覺化樹狀結構，則在畫面上看不到進行中的更新，而且介面會繼續顯示它在 BeginDraw 之前具有的內容。 呼叫 EndDraw 時，BeginDraw 所傳回的紋理或 Direct2D 內容指標會失效。 應用程式絕對不該在 EndDraw 呼叫之後快取該指標。
對於任何指定的 CompositionGraphicsDevice，應用程式一次只能在一個介面上呼叫 BeginDraw。 在呼叫 BeginDraw 之後，應用程式必須先在該介面上呼叫 EndDraw，才能在另一個介面上呼叫 BeginDraw。 由於 API 是敏捷式架構，如果應用程式想要從多個背景工作執行緒執行轉譯，則應用程式會負責同步處理這些呼叫。 如果應用程式想要中斷轉譯一個介面並暫時切換到另一個介面，應用程式可能會使用 SuspendDraw 方法。 這可讓另一個 BeginDraw 成功，但不會讓第一個介面更新提供給畫面上的組合使用。 這可讓應用程式以交易方式執行多個更新。 暫停介面之後，應用程式可以藉由呼叫 ResumeDraw 方法來繼續更新，或者可以宣告更新是藉由呼叫 EndDraw 來完成。 這表示任何指定的 CompositionGraphicsDevice 一次只能主動更新一個介面。 每個圖形裝置都會彼此獨立來保留此狀態，因此如果應用程式屬於不同的圖形裝置，就可能會同時轉譯為兩個介面。 不過，這會排除這兩個介面的視訊記憶體而無法成為集區，因此記憶體效率較低。
如果應用程式執行不正確的作業 (例如傳遞無效的引數，或是先在一個介面上呼叫 BeginDraw 後又在另一個介面上呼叫 EndDraw)，則 BeginDraw、SuspendDraw、ResumeDraw 和 EndDraw 方法會傳回失敗。 這些類型的失敗代表應用程式有錯誤，因此，應該會以快速檢錯來處理它們。 如果基礎 DirectX 裝置遺失，BeginDraw 也可能傳回失敗。 此失敗並不嚴重，因為應用程式可以重新建立其 DirectX 裝置，然後再試一次。 因此，應用程式應該只要略過轉譯，即可處理裝置遺失。 如果 BeginDraw 因任何原因而失敗，應用程式也應該不會呼叫 EndDraw，因為從開始就永遠不會成功。
捲動
基於效能考慮，當應用程式呼叫 BeginDraw 時，傳回紋理的內容不保證就是先前的介面內容。 應用程式必須假設內容是隨機的，因此，應用程式必須確定所有像素都已處理過，方法是在轉譯之前清除介面，或是繪製足夠的不透明內容來覆蓋整個更新的矩形。 這一點，加上紋理指標只在 BeginDraw 和 EndDraw 呼叫之間有效的事實，使得應用程式不可能從介面複製先前的內容。 基於這個理由，我們提供 Scroll 方法，讓應用程式能夠執行相同介面的像素複製。
C++/WinRT 使用範例
下列程式碼範例說明交互操作案例。 此範例結合了 Windows Composition 的 Windows 執行階段型介面區提供的類型，以及 Interop 標頭提供的類型，還有使用以 COM 為基礎的 DirectWrite 和 Direct2D API 來轉譯文字的程式碼。 此範例會使用 BeginDraw 和 EndDraw，讓這些技術之間可以順暢地交互操作。 此範例會使用 DirectWrite 來配置文字，然後使用 Direct2D 來轉譯文字。 組合圖形裝置會在初始化的時間直接接受 Direct2D 裝置。 這可讓 BeginDraw 傳回 ID2D1DeviceContext 介面指標，比起讓應用程式在每個繪圖作業上建立 Direct2D 內容來包裝傳回的 ID3D11Texture2D 介面，這樣做會更有效率。
若要試用下列 C++/WinRT 程式碼範例，請先在 Visual Studio 中建立新的 核心應用程式 (C++/WinRT) 專案 (若要了解需求，請參閱 C++/WinRT 的 Visual Studio 支援)。 將 pch.h 與 App.cpp 原始碼檔案的內容替換為以下列出的程式碼，然後建置並執行。 應用程式會在透明背景上以黑色文字呈現字串 “Hello, World!”。
// pch.h
#pragma once
#include <windows.h>
#include <D2d1_1.h>
#include <D3d11_4.h>
#include <Dwrite.h>
#include <Windows.Graphics.DirectX.Direct3D11.interop.h>
#include <Windows.ui.composition.interop.h>
#include <unknwn.h>
#include <winrt/Windows.ApplicationModel.Core.h>
#include <winrt/Windows.Foundation.h>
#include <winrt/Windows.Graphics.DirectX.h>
#include <winrt/Windows.Graphics.DirectX.Direct3D11.h>
#include <winrt/Windows.UI.Composition.h>
#include <winrt/Windows.UI.Core.h>
#include <winrt/Windows.UI.Input.h>
// App.cpp
//*********************************************************
//
// Copyright (c) Microsoft. All rights reserved.
// This code is licensed under the MIT License (MIT).
// THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
// IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
// TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH
// THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
//*********************************************************
#include "pch.h"
using namespace winrt;
using namespace winrt::Windows::ApplicationModel::Core;
using namespace winrt::Windows::Foundation;
using namespace winrt::Windows::Foundation::Numerics;
using namespace winrt::Windows::Graphics::DirectX;
using namespace winrt::Windows::Graphics::DirectX::Direct3D11;
using namespace winrt::Windows::UI;
using namespace winrt::Windows::UI::Composition;
using namespace winrt::Windows::UI::Core;
namespace abi
{
using namespace ABI::Windows::Foundation;
using namespace ABI::Windows::Graphics::DirectX;
using namespace ABI::Windows::UI::Composition;
}
// An app-provided helper to render lines of text.
struct SampleText
{
SampleText(winrt::com_ptr<::IDWriteTextLayout> const& text, CompositionGraphicsDevice const& compositionGraphicsDevice) :
m_text(text),
m_compositionGraphicsDevice(compositionGraphicsDevice)
{
// Create the surface just big enough to hold the formatted text block.
DWRITE_TEXT_METRICS metrics;
winrt::check_hresult(m_text->GetMetrics(&metrics));
winrt::Windows::Foundation::Size surfaceSize{ metrics.width, metrics.height };
CompositionDrawingSurface drawingSurface{ m_compositionGraphicsDevice.CreateDrawingSurface(
surfaceSize,
DirectXPixelFormat::B8G8R8A8UIntNormalized,
DirectXAlphaMode::Premultiplied) };
// Cache the interop pointer, since that's what we always use.
m_drawingSurfaceInterop = drawingSurface.as<abi::ICompositionDrawingSurfaceInterop>();
// Draw the text
DrawText();
// If the rendering device is lost, the application will recreate and replace it. We then
// own redrawing our pixels.
m_deviceReplacedEventToken = m_compositionGraphicsDevice.RenderingDeviceReplaced(
[this](CompositionGraphicsDevice const&, RenderingDeviceReplacedEventArgs const&)
{
// Draw the text again.
DrawText();
return S_OK;
});
}
~SampleText()
{
m_compositionGraphicsDevice.RenderingDeviceReplaced(m_deviceReplacedEventToken);
}
// Return the underlying surface to the caller.
auto Surface()
{
// To the caller, the fact that we have a drawing surface is an implementation detail.
// Return the base interface instead.
return m_drawingSurfaceInterop.as<ICompositionSurface>();
}
private:
// The text to draw.
winrt::com_ptr<::IDWriteTextLayout> m_text;
// The composition surface that we use in the visual tree.
winrt::com_ptr<abi::ICompositionDrawingSurfaceInterop> m_drawingSurfaceInterop;
// The device that owns the surface.
CompositionGraphicsDevice m_compositionGraphicsDevice{ nullptr };
//winrt::com_ptr<abi::ICompositionGraphicsDevice> m_compositionGraphicsDevice2;
// For managing our event notifier.
winrt::event_token m_deviceReplacedEventToken;
// We may detect device loss on BeginDraw calls. This helper handles this condition or other
// errors.
bool CheckForDeviceRemoved(HRESULT hr)
{
if (hr == S_OK)
{
// Everything is fine: go ahead and draw.
return true;
}
if (hr == DXGI_ERROR_DEVICE_REMOVED)
{
// We can't draw at this time, but this failure is recoverable. Just skip drawing for
// now. We will be asked to draw again once the Direct3D device is recreated.
return false;
}
// Any other error is unexpected and, therefore, fatal.
winrt::check_hresult(hr);
return true;
}
// Renders the text into our composition surface
void DrawText()
{
// Begin our update of the surface pixels. If this is our first update, we are required
// to specify the entire surface, which nullptr is shorthand for (but, as it works out,
// any time we make an update we touch the entire surface, so we always pass nullptr).
winrt::com_ptr<::ID2D1DeviceContext> d2dDeviceContext;
POINT offset;
if (CheckForDeviceRemoved(m_drawingSurfaceInterop->BeginDraw(nullptr,
__uuidof(ID2D1DeviceContext), d2dDeviceContext.put_void(), &offset)))
{
d2dDeviceContext->Clear(D2D1::ColorF(D2D1::ColorF::Black, 0.f));
// Create a solid color brush for the text. A more sophisticated application might want
// to cache and reuse a brush across all text elements instead, taking care to recreate
// it in the event of device removed.
winrt::com_ptr<::ID2D1SolidColorBrush> brush;
winrt::check_hresult(d2dDeviceContext->CreateSolidColorBrush(
D2D1::ColorF(D2D1::ColorF::Black, 1.0f), brush.put()));
// Draw the line of text at the specified offset, which corresponds to the top-left
// corner of our drawing surface. Notice we don't call BeginDraw on the D2D device
// context; this has already been done for us by the composition API.
d2dDeviceContext->DrawTextLayout(D2D1::Point2F((float)offset.x, (float)offset.y), m_text.get(),
brush.get());
// Our update is done. EndDraw never indicates rendering device removed, so any
// failure here is unexpected and, therefore, fatal.
winrt::check_hresult(m_drawingSurfaceInterop->EndDraw());
}
}
};
struct DeviceLostEventArgs
{
DeviceLostEventArgs(IDirect3DDevice const& device) : m_device(device) {}
IDirect3DDevice Device() { return m_device; }
static DeviceLostEventArgs Create(IDirect3DDevice const& device) { return DeviceLostEventArgs{ device }; }
private:
IDirect3DDevice m_device;
};
struct DeviceLostHelper
{
DeviceLostHelper() = default;
~DeviceLostHelper()
{
StopWatchingCurrentDevice();
m_onDeviceLostHandler = nullptr;
}
IDirect3DDevice CurrentlyWatchedDevice() { return m_device; }
void WatchDevice(winrt::com_ptr<::IDXGIDevice> const& dxgiDevice)
{
// If we're currently listening to a device, then stop.
StopWatchingCurrentDevice();
// Set the current device to the new device.
m_device = nullptr;
winrt::check_hresult(::CreateDirect3D11DeviceFromDXGIDevice(dxgiDevice.get(), reinterpret_cast<::IInspectable**>(winrt::put_abi(m_device))));
// Get the DXGI Device.
m_dxgiDevice = dxgiDevice;
// QI For the ID3D11Device4 interface.
winrt::com_ptr<::ID3D11Device4> d3dDevice{ m_dxgiDevice.as<::ID3D11Device4>() };
// Create a wait struct.
m_onDeviceLostHandler = nullptr;
m_onDeviceLostHandler = ::CreateThreadpoolWait(DeviceLostHelper::OnDeviceLost, (PVOID)this, nullptr);
// Create a handle and a cookie.
m_eventHandle.attach(::CreateEvent(nullptr, false, false, nullptr));
winrt::check_bool(bool{ m_eventHandle });
m_cookie = 0;
// Register for device lost.
::SetThreadpoolWait(m_onDeviceLostHandler, m_eventHandle.get(), nullptr);
winrt::check_hresult(d3dDevice->RegisterDeviceRemovedEvent(m_eventHandle.get(), &m_cookie));
}
void StopWatchingCurrentDevice()
{
if (m_dxgiDevice)
{
// QI For the ID3D11Device4 interface.
auto d3dDevice{ m_dxgiDevice.as<::ID3D11Device4>() };
// Unregister from the device lost event.
::CloseThreadpoolWait(m_onDeviceLostHandler);
d3dDevice->UnregisterDeviceRemoved(m_cookie);
// Clear member variables.
m_onDeviceLostHandler = nullptr;
m_eventHandle.close();
m_cookie = 0;
m_device = nullptr;
}
}
void DeviceLost(winrt::delegate<DeviceLostHelper const*, DeviceLostEventArgs const&> const& handler)
{
m_deviceLost = handler;
}
winrt::delegate<DeviceLostHelper const*, DeviceLostEventArgs const&> m_deviceLost;
private:
void RaiseDeviceLostEvent(IDirect3DDevice const& oldDevice)
{
m_deviceLost(this, DeviceLostEventArgs::Create(oldDevice));
}
static void CALLBACK OnDeviceLost(PTP_CALLBACK_INSTANCE /* instance */, PVOID context, PTP_WAIT /* wait */, TP_WAIT_RESULT /* waitResult */)
{
auto deviceLostHelper = reinterpret_cast<DeviceLostHelper*>(context);
auto oldDevice = deviceLostHelper->m_device;
deviceLostHelper->StopWatchingCurrentDevice();
deviceLostHelper->RaiseDeviceLostEvent(oldDevice);
}
private:
IDirect3DDevice m_device;
winrt::com_ptr<::IDXGIDevice> m_dxgiDevice;
PTP_WAIT m_onDeviceLostHandler{ nullptr };
winrt::handle m_eventHandle;
DWORD m_cookie{ 0 };
};
struct SampleApp : implements<SampleApp, IFrameworkViewSource, IFrameworkView>
{
IFrameworkView CreateView()
{
return *this;
}
void Initialize(CoreApplicationView const&)
{
}
// Run once when the application starts up
void Initialize()
{
// Create a Direct2D device.
CreateDirect2DDevice();
// To create a composition graphics device, we need to QI for another interface
winrt::com_ptr<abi::ICompositorInterop> compositorInterop{ m_compositor.as<abi::ICompositorInterop>() };
// Create a graphics device backed by our D3D device
winrt::com_ptr<abi::ICompositionGraphicsDevice> compositionGraphicsDeviceIface;
winrt::check_hresult(compositorInterop->CreateGraphicsDevice(
m_d2dDevice.get(),
compositionGraphicsDeviceIface.put()));
m_compositionGraphicsDevice = compositionGraphicsDeviceIface.as<CompositionGraphicsDevice>();
}
void Load(hstring const&)
{
}
void Uninitialize()
{
}
void Run()
{
CoreWindow window = CoreWindow::GetForCurrentThread();
window.Activate();
CoreDispatcher dispatcher = window.Dispatcher();
dispatcher.ProcessEvents(CoreProcessEventsOption::ProcessUntilQuit);
}
void SetWindow(CoreWindow const& window)
{
m_compositor = Compositor{};
m_target = m_compositor.CreateTargetForCurrentView();
ContainerVisual root = m_compositor.CreateContainerVisual();
m_target.Root(root);
Initialize();
winrt::check_hresult(
::DWriteCreateFactory(
DWRITE_FACTORY_TYPE_SHARED,
__uuidof(m_dWriteFactory),
reinterpret_cast<::IUnknown**>(m_dWriteFactory.put())
)
);
winrt::check_hresult(
m_dWriteFactory->CreateTextFormat(
L"Segoe UI",
nullptr,
DWRITE_FONT_WEIGHT_REGULAR,
DWRITE_FONT_STYLE_NORMAL,
DWRITE_FONT_STRETCH_NORMAL,
36.f,
L"en-US",
m_textFormat.put()
)
);
Rect windowBounds{ window.Bounds() };
std::wstring text{ L"Hello, World!" };
winrt::check_hresult(
m_dWriteFactory->CreateTextLayout(
text.c_str(),
(uint32_t)text.size(),
m_textFormat.get(),
windowBounds.Width,
windowBounds.Height,
m_textLayout.put()
)
);
Visual textVisual{ CreateVisualFromTextLayout(m_textLayout) };
textVisual.Size({ windowBounds.Width, windowBounds.Height });
root.Children().InsertAtTop(textVisual);
}
// Called when Direct3D signals the device lost event.
void OnDirect3DDeviceLost(DeviceLostHelper const* /* sender */, DeviceLostEventArgs const& /* args */)
{
// Create a new Direct2D device.
CreateDirect2DDevice();
// Restore our composition graphics device to good health.
winrt::com_ptr<abi::ICompositionGraphicsDeviceInterop> compositionGraphicsDeviceInterop{ m_compositionGraphicsDevice.as<abi::ICompositionGraphicsDeviceInterop>() };
winrt::check_hresult(compositionGraphicsDeviceInterop->SetRenderingDevice(m_d2dDevice.get()));
}
// Create a surface that is asynchronously filled with an image
ICompositionSurface CreateSurfaceFromTextLayout(winrt::com_ptr<::IDWriteTextLayout> const& text)
{
// Create our wrapper object that will handle downloading and decoding the image (assume
// throwing new here).
SampleText textSurface{ text, m_compositionGraphicsDevice };
// The caller is only interested in the underlying surface.
return textSurface.Surface();
}
// Create a visual that holds an image.
Visual CreateVisualFromTextLayout(winrt::com_ptr<::IDWriteTextLayout> const& text)
{
// Create a sprite visual
SpriteVisual spriteVisual{ m_compositor.CreateSpriteVisual() };
// The sprite visual needs a brush to hold the image.
CompositionSurfaceBrush surfaceBrush{
m_compositor.CreateSurfaceBrush(CreateSurfaceFromTextLayout(text))
};
// Associate the brush with the visual.
CompositionBrush brush{ surfaceBrush.as<CompositionBrush>() };
spriteVisual.Brush(brush);
// Return the visual to the caller as an IVisual.
return spriteVisual;
}
private:
CompositionTarget m_target{ nullptr };
Compositor m_compositor{ nullptr };
winrt::com_ptr<::ID2D1Device> m_d2dDevice;
winrt::com_ptr<::IDXGIDevice> m_dxgiDevice;
//winrt::com_ptr<abi::ICompositionGraphicsDevice> m_compositionGraphicsDevice;
CompositionGraphicsDevice m_compositionGraphicsDevice{ nullptr };
std::vector<SampleText> m_textSurfaces;
DeviceLostHelper m_deviceLostHelper;
winrt::com_ptr<::IDWriteFactory> m_dWriteFactory;
winrt::com_ptr<::IDWriteTextFormat> m_textFormat;
winrt::com_ptr<::IDWriteTextLayout> m_textLayout;
// This helper creates a Direct2D device, and registers for a device loss
// notification on the underlying Direct3D device. When that notification is
// raised, the OnDirect3DDeviceLost method is called.
void CreateDirect2DDevice()
{
uint32_t createDeviceFlags = D3D11_CREATE_DEVICE_BGRA_SUPPORT;
// Array with DirectX hardware feature levels in order of preference.
D3D_FEATURE_LEVEL featureLevels[] =
{
D3D_FEATURE_LEVEL_11_1,
D3D_FEATURE_LEVEL_11_0,
D3D_FEATURE_LEVEL_10_1,
D3D_FEATURE_LEVEL_10_0,
D3D_FEATURE_LEVEL_9_3,
D3D_FEATURE_LEVEL_9_2,
D3D_FEATURE_LEVEL_9_1
};
// Create the Direct3D 11 API device object and a corresponding context.
winrt::com_ptr<::ID3D11Device> d3DDevice;
winrt::com_ptr<::ID3D11DeviceContext> d3DImmediateContext;
D3D_FEATURE_LEVEL d3dFeatureLevel{ D3D_FEATURE_LEVEL_9_1 };
winrt::check_hresult(
::D3D11CreateDevice(
nullptr, // Default adapter.
D3D_DRIVER_TYPE_HARDWARE,
0, // Not asking for a software driver, so not passing a module to one.
createDeviceFlags, // Set debug and Direct2D compatibility flags.
featureLevels,
ARRAYSIZE(featureLevels),
D3D11_SDK_VERSION,
d3DDevice.put(),
&d3dFeatureLevel,
d3DImmediateContext.put()
)
);
// Initialize Direct2D resources.
D2D1_FACTORY_OPTIONS d2d1FactoryOptions{ D2D1_DEBUG_LEVEL_NONE };
// Initialize the Direct2D Factory.
winrt::com_ptr<::ID2D1Factory1> d2D1Factory;
winrt::check_hresult(
::D2D1CreateFactory(
D2D1_FACTORY_TYPE_SINGLE_THREADED,
__uuidof(d2D1Factory),
&d2d1FactoryOptions,
d2D1Factory.put_void()
)
);
// Create the Direct2D device object.
// Obtain the underlying DXGI device of the Direct3D device.
m_dxgiDevice = d3DDevice.as<::IDXGIDevice>();
m_d2dDevice = nullptr;
winrt::check_hresult(
d2D1Factory->CreateDevice(m_dxgiDevice.get(), m_d2dDevice.put())
);
m_deviceLostHelper.WatchDevice(m_dxgiDevice);
m_deviceLostHelper.DeviceLost({ this, &SampleApp::OnDirect3DDeviceLost });
}
};
int __stdcall wWinMain(HINSTANCE, HINSTANCE, PWSTR, int)
{
CoreApplication::Run(winrt::make<SampleApp>());
}
C++/CX 使用範例
注意
此程式碼範例可協助您維護 C++/CX 應用程式。 但我們建議您將 C++/WinRT 用於新的應用程式。 C++/WinRT 是完全標準現代的 Windows 執行階段 (WinRT) API 的 C++17 語言投影，僅實作為標頭檔案式程式庫，以及設計用來提供您現代化 Windows API 的第一級存取。
以下的 C++/CX 程式碼範例，會省略範例的 DirectWrite 和 Direct2D 部分。
//------------------------------------------------------------------------------
//
// Copyright (C) Microsoft. All rights reserved.
//
//------------------------------------------------------------------------------
#include "stdafx.h"
using namespace Microsoft::WRL;
using namespace Windows::Foundation;
using namespace Windows::Graphics::DirectX;
using namespace Windows::UI::Composition;
// This is an app-provided helper to render lines of text
class SampleText
{
private:
// The text to draw
ComPtr<IDWriteTextLayout> _text;
// The composition surface that we use in the visual tree
ComPtr<ICompositionDrawingSurfaceInterop> _drawingSurfaceInterop;
// The device that owns the surface
ComPtr<ICompositionGraphicsDevice> _compositionGraphicsDevice;
// For managing our event notifier
EventRegistrationToken _deviceReplacedEventToken;
public:
SampleText(IDWriteTextLayout* text, ICompositionGraphicsDevice* compositionGraphicsDevice) :
_text(text),
_compositionGraphicsDevice(compositionGraphicsDevice)
{
// Create the surface just big enough to hold the formatted text block.
DWRITE_TEXT_METRICS metrics;
FailFastOnFailure(text->GetMetrics(&metrics));
Windows::Foundation::Size surfaceSize = { metrics.width, metrics.height };
ComPtr<ICompositionDrawingSurface> drawingSurface;
FailFastOnFailure(_compositionGraphicsDevice->CreateDrawingSurface(
surfaceSize,
DirectXPixelFormat::DirectXPixelFormat_B8G8R8A8UIntNormalized,
DirectXAlphaMode::DirectXAlphaMode_Ignore,
&drawingSurface));
// Cache the interop pointer, since that's what we always use.
FailFastOnFailure(drawingSurface.As(&_drawingSurfaceInterop));
// Draw the text
DrawText();
// If the rendering device is lost, the application will recreate and replace it. We then
// own redrawing our pixels.
FailFastOnFailure(_compositionGraphicsDevice->add_RenderingDeviceReplaced(
Callback<RenderingDeviceReplacedEventHandler>([this](
ICompositionGraphicsDevice* source, IRenderingDeviceReplacedEventArgs* args)
-> HRESULT
{
// Draw the text again
DrawText();
return S_OK;
}).Get(),
&_deviceReplacedEventToken));
}
~SampleText()
{
FailFastOnFailure(_compositionGraphicsDevice->remove_RenderingDeviceReplaced(
_deviceReplacedEventToken));
}
// Return the underlying surface to the caller
ComPtr<ICompositionSurface> get_Surface()
{
// To the caller, the fact that we have a drawing surface is an implementation detail.
// Return the base interface instead
ComPtr<ICompositionSurface> surface;
FailFastOnFailure(_drawingSurfaceInterop.As(&surface));
return surface;
}
private:
// We may detect device loss on BeginDraw calls. This helper handles this condition or other
// errors.
bool CheckForDeviceRemoved(HRESULT hr)
{
if (SUCCEEDED(hr))
{
// Everything is fine -- go ahead and draw
return true;
}
else if (hr == DXGI_ERROR_DEVICE_REMOVED)
{
// We can't draw at this time, but this failure is recoverable. Just skip drawing for
// now. We will be asked to draw again once the Direct3D device is recreated
return false;
}
else
{
// Any other error is unexpected and, therefore, fatal
FailFast();
}
}
// Renders the text into our composition surface
void DrawText()
{
// Begin our update of the surface pixels. If this is our first update, we are required
// to specify the entire surface, which nullptr is shorthand for (but, as it works out,
// any time we make an update we touch the entire surface, so we always pass nullptr).
ComPtr<ID2D1DeviceContext> d2dDeviceContext;
POINT offset;
if (CheckForDeviceRemoved(_drawingSurfaceInterop->BeginDraw(nullptr,
__uuidof(ID2D1DeviceContext), &d2dDeviceContext, &offset)))
{
// Create a solid color brush for the text. A more sophisticated application might want
// to cache and reuse a brush across all text elements instead, taking care to recreate
// it in the event of device removed.
ComPtr<ID2D1SolidColorBrush> brush;
FailFastOnFailure(d2dDeviceContext->CreateSolidColorBrush(
D2D1::ColorF(D2D1::ColorF::Black, 1.0f), &brush));
// Draw the line of text at the specified offset, which corresponds to the top-left
// corner of our drawing surface. Notice we don't call BeginDraw on the D2D device
// context; this has already been done for us by the composition API.
d2dDeviceContext->DrawTextLayout(D2D1::Point2F(offset.x, offset.y), _text.Get(),
brush.Get());
// Our update is done. EndDraw never indicates rendering device removed, so any
// failure here is unexpected and, therefore, fatal.
FailFastOnFailure(_drawingSurfaceInterop->EndDraw());
}
}
};
class SampleApp
{
ComPtr<ICompositor> _compositor;
ComPtr<ID2D1Device> _d2dDevice;
ComPtr<ICompositionGraphicsDevice> _compositionGraphicsDevice;
std::vector<ComPtr<SampleText>> _textSurfaces;
public:
// Run once when the application starts up
void Initialize(ICompositor* compositor)
{
// Cache the compositor (created outside of this method)
_compositor = compositor;
// Create a Direct2D device (helper implementation not shown here)
FailFastOnFailure(CreateDirect2DDevice(&_d2dDevice));
// To create a composition graphics device, we need to QI for another interface
ComPtr<ICompositorInterop> compositorInterop;
FailFastOnFailure(_compositor.As(&compositorInterop));
// Create a graphics device backed by our D3D device
FailFastOnFailure(compositorInterop->CreateGraphicsDevice(
_d2dDevice.Get(),
&_compositionGraphicsDevice));
}
// Called when Direct3D signals the device lost event
void OnDirect3DDeviceLost()
{
// Create a new device
FailFastOnFailure(CreateDirect2DDevice(_d2dDevice.ReleaseAndGetAddressOf()));
// Restore our composition graphics device to good health
ComPtr<ICompositionGraphicsDeviceInterop> compositionGraphicsDeviceInterop;
FailFastOnFailure(_compositionGraphicsDevice.As(&compositionGraphicsDeviceInterop));
FailFastOnFailure(compositionGraphicsDeviceInterop->SetRenderingDevice(_d2dDevice.Get()));
}
// Create a surface that is asynchronously filled with an image
ComPtr<ICompositionSurface> CreateSurfaceFromTextLayout(IDWriteTextLayout* text)
{
// Create our wrapper object that will handle downloading and decoding the image (assume
// throwing new here)
SampleText* textSurface = new SampleText(text, _compositionGraphicsDevice.Get());
// Keep our image alive
_textSurfaces.push_back(textSurface);
// The caller is only interested in the underlying surface
return textSurface->get_Surface();
}
// Create a visual that holds an image
ComPtr<IVisual> CreateVisualFromTextLayout(IDWriteTextLayout* text)
{
// Create a sprite visual
ComPtr<ISpriteVisual> spriteVisual;
FailFastOnFailure(_compositor->CreateSpriteVisual(&spriteVisual));
// The sprite visual needs a brush to hold the image
ComPtr<ICompositionSurfaceBrush> surfaceBrush;
FailFastOnFailure(_compositor->CreateSurfaceBrushWithSurface(
CreateSurfaceFromTextLayout(text).Get(),
&surfaceBrush));
// Associate the brush with the visual
ComPtr<ICompositionBrush> brush;
FailFastOnFailure(surfaceBrush.As(&brush));
FailFastOnFailure(spriteVisual->put_Brush(brush.Get()));
// Return the visual to the caller as the base class
ComPtr<IVisual> visual;
FailFastOnFailure(spriteVisual.As(&visual));
return visual;
}
private:
// This helper (implementation not shown here) creates a Direct2D device and registers
// for a device loss notification on the underlying Direct3D device. When that notification is
// raised, assume the OnDirect3DDeviceLost method is called.
HRESULT CreateDirect2DDevice(ID2D1Device** ppDevice);
};