WinRT使用direct2d自由旋转图片

速度比GDI+绘制快上N倍。directx绘制真给力！！

WriteableBitmap^ CImagePosterPuzzle::RotateImage(WriteableBitmap^ bitmap,int rotate){    if(bitmap==nullptr) return nullptr;    ID2D1RenderTarget* pRenderTarget = nullptr;    IWICBitmap* pMainBimtap = nullptr;    ID2D1Bitmap* pD2dBitmap = nullptr;    //将WriteableBitmap转为byte[]    int pixelWidth = bitmap->PixelWidth ;    int pixelHeight = bitmap->PixelHeight;    auto pData = ref new Array<byte>(pixelWidth*pixelHeight*4);    auto dataReader = DataReader::FromBuffer(bitmap->PixelBuffer);    dataReader->ReadBytes(pData);    HRESULT hr=S_OK;    rotate%=360;    double radian=rotate*M_PI/180.f;    float cosa=cos(radian);    float sina=sin(radian);    float newWidth= Max(abs(pixelWidth*cosa-pixelHeight*sina),abs(pixelWidth*cosa+pixelHeight*sina));    float newHeight= Max(abs(pixelWidth*sina-pixelHeight*cosa),abs(pixelWidth*sina+pixelHeight*cosa));    hr = m_pWicFractory->CreateBitmap(        newWidth,        newHeight,        GUID_WICPixelFormat32bppPBGRA,        WICBitmapCacheOnDemand,        &pMainBimtap        );    if(SUCCEEDED(hr))    {        hr= m_pD2d1Factory->CreateWicBitmapRenderTarget(            pMainBimtap,            D2D1::RenderTargetProperties(),            &pRenderTarget            );    }    //创建d2d位图    if (SUCCEEDED(hr))    {        hr =pRenderTarget->CreateBitmap(            D2D1::SizeU(pixelWidth,pixelHeight),            pData->Data,            pixelWidth*4,            D2D1::BitmapProperties(D2D1::PixelFormat(DXGI_FORMAT_B8G8R8A8_UNORM,D2D1_ALPHA_MODE_PREMULTIPLIED)),            &pD2dBitmap            );    }    if(SUCCEEDED(hr))    {        pRenderTarget->BeginDraw();        pRenderTarget->Clear(D2D1::ColorF(D2D1::ColorF::White,1.f));        //计算偏移量         D2D1_POINT_2F offset = D2D1::Point2F((newWidth-pixelWidth)/2.f ,(newHeight-pixelHeight)/2.f);        //中心点        D2D1_POINT_2F center= D2D1::Point2F(offset.x+pixelWidth/2,offset.y+pixelHeight/2);        D2D1::Matrix3x2F angle = D2D1::Matrix3x2F::Rotation(rotate,center);        pRenderTarget->SetTransform(angle);        pRenderTarget->DrawBitmap(pD2dBitmap,D2D1::RectF(offset.x,offset.y,pixelWidth+offset.x,pixelHeight+offset.y));        pRenderTarget->EndDraw();        WICRect rcLock = { 0, 0, newWidth, newHeight };        IWICBitmapLock* pLock = nullptr;        pMainBimtap->Lock(&rcLock,WICBitmapLockRead,&pLock);        UINT pcbBufferSize = 0;        byte* ppbData = nullptr;        pLock->GetDataPointer(&pcbBufferSize,&ppbData);        auto bmp=ref new WriteableBitmap(newWidth, newHeight);        byte *pPixels = BufferFromWriteableBitmap(bmp);        memcpy(pPixels, ppbData, pcbBufferSize);        bmp->Invalidate();        DX::SafeRelease(&pLock);        DX::SafeRelease(&pRenderTarget);        DX::SafeRelease(&pMainBimtap);        DX::SafeRelease(&pD2dBitmap);        return bmp;    }    return nullptr;}byte* CImagePosterPuzzle::BufferFromWriteableBitmap(WriteableBitmap^ bitmap){    IUnknown* pUnknown = reinterpret_cast<IUnknown*>(bitmap->PixelBuffer);    IBufferByteAccess* pBufferByteAccess = nullptr;    HRESULT hr = pUnknown->QueryInterface(IID_PPV_ARGS(&pBufferByteAccess));    pUnknown->Release();    byte *pPixels = nullptr;    hr = pBufferByteAccess->Buffer(&pPixels);    return pPixels;}