Taking photo in C++/CX with Windows Phone 8.1 - windows-phone-8.1

Question

I am working in C++/CX (in Visual Studio 2013) on an app for Windows phone 8.1 systems. I test my app on a Nokia Lumia 930. My app must take photos to do some image processing on them. Therefore I would like to have a byte* or char* or unsigned char* to to whatever I want. So I tried to use ::Windows::Media::Capture::MediaCapture::CapturePhotoToStreamAsync to get the content of the photo into a stream and then with a ::Windows::Storage::Streams::DataReader get the actual bytes of the photo. But I have been unsuccessful. More precisely the problem is here in the code that follows.
IRandomAccessStream ^ras = ref new InMemoryRandomAccessStream();
IAsyncAction ^ac = cap->CapturePhotoToStreamAsync(ImageEncodingProperties::CreateBmp(),ras);
ac->Completed = ref new AsyncActionCompletedHandler(
[=] (IAsyncAction ^async_op,AsyncStatus status) mutable
{
debug->Text = L"finished";
});
where cap is a managed pointer to a MediaCapture which seems to be correctly initialized.
But the debug TextBlock never shows finished. And when I get the status of ac it seems to be blocked on Started forever, it never gets to Error or Completed. I do not understand why. So for now I implemented a dirty workaround that uses ::Windows::Media::Capture::MediaCapture::CapturePhotoToStorageFileAsync. But storing the photo in a bitmap on a file then reading it back to get the image back in memory is not satisfactory at all.
I have found a lot on taking photos with Windows Phone 8.1, but they are all in C# and copy-pasting those solutions by replacing the '.' by '::' does not work. I mean it is (at least for me) not easy at all to adapt C# code to C++ code.
So my questions are :
Is there a quick and/or clean way of getting a good old C pointer to the pixels of the image?
Why do CapturePhotoToStreamAsync block with status Started?
Thank you for your answers and your time.

Answer 1

Take a look at the basic camera sample app on the Microsoft Github page: https://github.com/Microsoft/Windows-universal-samples/tree/master/Samples/CameraStarterKit
There's a lot you need to do before you can take a picture (initialize, configure, start preview, etc.) and the sample will walk you through it.
Here's a shortened snippet from the sample I linked above:
/// <summary>
/// Takes a photo to a StorageFile and adds rotation metadata to it
/// </summary>
/// <returns></returns>
task<void> MainPage::TakePhotoAsync()
{
auto inputStream = ref new Streams::InMemoryRandomAccessStream();
// Take the picture
WriteLine("Taking photo...");
return create_task(_mediaCapture->CapturePhotoToStreamAsync(Windows::Media::MediaProperties::ImageEncodingProperties::CreateJpeg(), inputStream))
.then([this, inputStream]()
{
WriteLine("Photo taken!");
auto photoOrientation = ConvertOrientationToPhotoOrientation(GetCameraOrientation());
return ReencodeAndSavePhotoAsync(inputStream, photoOrientation);
}).then([this](task<void> previousTask)
{
try
{
previousTask.get();
}
catch (Exception^ ex)
{
WriteException(ex);
}
});
}