OpenCV/opencv/samples/wp8/OcvImageManipulation/PhoneXamlDirect3DApp1/PhoneXamlDirect3DApp1Comp/DirectXHelper.h

#pragma once

#include <wrl/client.h>
#include <ppl.h>
#include <ppltasks.h>

namespace DX
{
    inline void ThrowIfFailed(HRESULT hr)
    {
        if (FAILED(hr))
        {
            // Set a breakpoint on this line to catch Win32 API errors.
            throw Platform::Exception::CreateException(hr);
        }
    }

    // Function that reads from a binary file asynchronously.
    inline Concurrency::task<Platform::Array<byte>^> ReadDataAsync(Platform::String^ filename)
    {
        using namespace Windows::Storage;
        using namespace Concurrency;

        auto folder = Windows::ApplicationModel::Package::Current->InstalledLocation;

        return create_task(folder->GetFileAsync(filename)).then([] (StorageFile^ file)
        {
            return file->OpenReadAsync();
        }).then([] (Streams::IRandomAccessStreamWithContentType^ stream)
        {
            unsigned int bufferSize = static_cast<unsigned int>(stream->Size);
            auto fileBuffer = ref new Streams::Buffer(bufferSize);
            return stream->ReadAsync(fileBuffer, bufferSize, Streams::InputStreamOptions::None);
        }).then([] (Streams::IBuffer^ fileBuffer) -> Platform::Array<byte>^
        {
            auto fileData = ref new Platform::Array<byte>(fileBuffer->Length);
            Streams::DataReader::FromBuffer(fileBuffer)->ReadBytes(fileData);
            return fileData;
        });
    }
}