C++/CX如何从缓冲区和缓冲区计数创建BitmapImage
我将mediaCapture与AddEffectsAsync一起使用，以便在相机上设置MFT。使用该MFT，我能够从MFT中返回每一帧的数据。现在，位图以Nokia::Ghraphics::Imaging::Bitmap类的形式出现。在下面的代码中，我从缓冲区中获取缓冲区的大小，并将其发送到我的应用程序：
void TransformImage_NV12(
const D2D_RECT_U &rcDest,
_Inout_updates_(_Inexpressible_(2 * lDestStride * dwHeightInPixels)) BYTE *pDest,
_In_ LONG lDestStride,
_In_reads_(_Inexpressible_(2 * lSrcStride * dwHeightInPixels)) const BYTE *pSrc,
_In_ LONG lSrcStride,
_In_ DWORD dwWidthInPixels,
_In_ DWORD dwHeightInPixels,
IVector<IImageProvider^>^ providers)
{
auto size = Windows::Foundation::Size(dwWidthInPixels, dwHeightInPixels);
auto totalbytes = (int)dwHeightInPixels * (int)dwWidthInPixels * 3 / 2;
Nokia::Graphics::Imaging::Bitmap^ m_BitmapToProcess = AsBitmapNV12(pSrc, (unsigned int)size.Width, (unsigned int)size.Height);
BitmapImageSource^ source = ref new BitmapImageSource(m_BitmapToProcess);
auto first = providers->GetAt(0);
((IImageConsumer^)first)->Source = source;
auto last = providers->GetAt(providers->Size - 1);
BitmapRenderer^ renderer = ref new BitmapRenderer(last, ColorMode::Yuv420Sp);
auto renderOp = renderer->RenderAsync();
auto renderTask = create_task(renderOp);
renderTask.then([pDest, totalbytes](Nokia::Graphics::Imaging::Bitmap^ bitmap)
{
auto count = bitmap->Buffers->Length;
unsigned char* data = FromIBuffer(bitmap->Buffers[0]->Buffer);
CMFTWrapper::FrameData = data;
CMFTWrapper::count = count;
SetEvent(CMFTWrapper::FrameEvent());
CopyMemory(pDest, data, totalbytes);
}).wait();
}为此，我在应用程序中调用了一个回调函数：
void VideoCapturerSampleCallback(struct LmiVideoCapturer_* capturer, const LmiVideoFrame* videoFrame, LmiVoidPtr userData)
{
App2::MainPage^ ctx = context;
Windows::ApplicationModel::Core::CoreApplication::MainView->CoreWindow->Dispatcher->RunAsync(Windows::UI::Core::CoreDispatcherPriority::Normal, ref new Windows::UI::Core::DispatchedHandler([ctx]()
{
Windows::UI::Xaml::Media::Imaging::BitmapImage^ bitmapImage =
ref new Windows::UI::Xaml::Media::Imaging::BitmapImage();
//TODO will need to create it from the buffer
media->Source = bitmapImage;
}));
}在这里，我可以通过使用CMFTWrapper类访问缓冲区和MFT中的计数，我已经在这个类中保存了数据。我的问题是，如何在我创建的bitmapImage中加载这些数据？我找到了一些代码，告诉我如何构建aa bitmapImage，但其中大部分是用C#编写的，我需要使用C++/cx
回答 2
Stack Overflow用户
发布于 2015-01-17 06:56:30
您想要使用Windows.UI.Xaml.Media.Imaging.WriteableBitmap。
对于WriteableBitmap，你需要使用IBufferByteAccess (包括robuffer.h来获得这个定义)：
using namespace Microsoft::WRL;
auto xaml_image = ref new WriteableBitmap(width, height);
// Cast PixelBuffer to Object^, then to its underlying IInspectable interface.
Object^ obj = xaml_image->PixelBuffer;
ComPtr<IInspectable> insp(reinterpret_cast<IInspectable*>(obj));
// Query the IBufferByteAccess interface.
ComPtr<IBufferByteAccess> bufferByteAccess;
ThrowIfFailed(insp.As(&bufferByteAccess));
// Get native pointer to the buffer data.
byte* pixels = nullptr;
ThrowIfFailed(bufferByteAccess->Buffer(&pixels));
// TODO: copy image data in BGRA8 format into 'pixels' buffer
// memcpy_s(pixels, xaml_image->PixelBuffer->Capacity, data, width*height*4);
// Set final source
media->Source = xaml_image;Stack Overflow用户
发布于 2015-01-17 19:14:57
编辑的答案，因为我显然没有正确阅读问题。
你看过CameraPreviewImageSource btw了吗？它在幕后使用MF，让你可以处理相机预览流。
顺便说一句，现在有一个更名为Lumia图像SDK的2.0版本。升级nuget包以获取它。
https://stackoverflow.com/questions/27863067
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