使用WIC将Direct2D绘制的图形保存为文件

从Windows Vista开始引入的WIC(Windows Imaging Component)组件以面向对象的方式处理位图，并且很适合与Direct2D配合使用。

可以将Direct2D绘制的图像使用WIC保存为位图文件。

以下代码演示如何将Direct2D绘制的带有透明背景色的图像保存到png位图文件：

CComPtr<IWICImagingFactory> spWicImagingFactory;

IFR(Direct2DHelper::CreateWICImagingFactory(&spWicImagingFactory));

CComPtr<IWICBitmap> spWicBitmap;

CComPtr<ID2D1RenderTarget> spBitmapRT;

CRect rc;

GetClientRect(&rc);

int width = rc.Width(), height = rc.Height();

        

IFR(spWicImagingFactory->CreateBitmap(

    width,

    height,

    //GUID_WICPixelFormat32bppBGR,

    GUID_WICPixelFormat32bppPBGRA,

    WICBitmapCacheOnLoad,

    &spWicBitmap));

D2D1_PIXEL_FORMAT pixelFormat = PixelFormat(

    DXGI_FORMAT_B8G8R8A8_UNORM,

    D2D1_ALPHA_MODE_PREMULTIPLIED);

IFR(m_spD2dFactory->CreateWicBitmapRenderTarget(

    spWicBitmap,

    RenderTargetProperties(),

    //RenderTargetProperties(D2D1_RENDER_TARGET_TYPE_DEFAULT,pixelFormat),

    &spBitmapRT));

CComPtr<ID2D1SolidColorBrush> spSolidBrush;

IFR(spBitmapRT->CreateSolidColorBrush(ColorF(ColorF::Pink),&spSolidBrush));

//Drawing...

spBitmapRT->BeginDraw();

spBitmapRT->Clear(ColorF(ColorF::White,0));

D2D1_ELLIPSE ellipse = Ellipse(Point2F(width/2,height/2),width/2-50,height/2-50);

spBitmapRT->FillEllipse(ellipse,spSolidBrush);

spBitmapRT->EndDraw();

CComPtr<IWICStream> spStream;

IFR(spWicImagingFactory->CreateStream(&spStream));

LPCTSTR fileName = _T("output.png");

IFR(spStream->InitializeFromFilename(fileName,GENERIC_WRITE));

CComPtr<IWICBitmapEncoder> spBitmapEncoder;

CComPtr<IWICBitmapFrameEncode> spFrameEncode;

IFR(spWicImagingFactory->CreateEncoder(GUID_ContainerFormatPng,NULL,&spBitmapEncoder));

IFR(spBitmapEncoder->Initialize(spStream,WICBitmapEncoderNoCache));

IFR(spBitmapEncoder->CreateNewFrame(&spFrameEncode,NULL));

IFR(spFrameEncode->Initialize(NULL));

IFR(spFrameEncode->SetSize(width,height));

WICPixelFormatGUID format = GUID_WICPixelFormatDontCare;

IFR(spFrameEncode->SetPixelFormat(&format));

IFR(spFrameEncode->WriteSource(spWicBitmap,NULL));

IFR(spFrameEncode->Commit());

IFR(spBitmapEncoder->Commit());