MidiOutPort.FromIdAsync(String) 方法

定義

命名空間:

Windows.Devices.Midi

為指定的裝置建立 MidiOutPort 物件。

public:
 static IAsyncOperation<IMidiOutPort ^> ^ FromIdAsync(Platform::String ^ deviceId);

/// [Windows.Foundation.Metadata.RemoteAsync]
 static IAsyncOperation<IMidiOutPort> FromIdAsync(winrt::hstring const& deviceId);

[Windows.Foundation.Metadata.RemoteAsync]
public static IAsyncOperation<IMidiOutPort> FromIdAsync(string deviceId);

function fromIdAsync(deviceId)

Public Shared Function FromIdAsync (deviceId As String) As IAsyncOperation(Of IMidiOutPort)

參數

deviceId

String

Platform::String

winrt::hstring

裝置識別碼，可藉由列舉系統 Windows.Devices.Enumeration.DeviceInformation.FindAllAsync上的裝置來取得。

傳回

IAsyncOperation<IMidiOutPort>

非同步作業。 完成時， IAsyncOperation.GetResults 會傳回 MidiOutPort 物件。

屬性

RemoteAsyncAttribute

範例

// Opens the default MIDI output device.
private async Task<IMidiOutPort> OpenDefaultMidiOut()
{
    IMidiOutPort midiOut = null;

    string midiOutQueryString = MidiOutPort.GetDeviceSelector();
    DeviceInformationCollection midiOutDevices = await DeviceInformation.FindAllAsync(midiOutQueryString);
    int selectedMidiDevice = 0;

    if (0 == midiOutDevices.Count)
    {
        Debug.WriteLine("No Midi output devices");
        return null;
    }
    // If there are > 1 MIDI out devices, pick the first non-integrated one.
    else if (2 <= midiOutDevices.Count)
    {
        for (int midiDeviceIdx = 0; midiDeviceIdx < midiOutDevices.Count; midiDeviceIdx++)
        {
            if (false == MidiSynthesizer.IsSynthesizer(midiOutDevices[midiDeviceIdx]))
            {
                selectedMidiDevice = midiDeviceIdx;
                break;
            }
        }
    }

    midiOut = await MidiOutPort.FromIdAsync(midiOutDevices[selectedMidiDevice].Id);

    return midiOut;
}

// Opens the default MIDI output device.
winrt::Windows::Foundation::IAsyncOperation<IMidiOutPort> OpenDefaultMidiOut()
{
    IMidiOutPort midiOut{ nullptr };

    winrt::hstring midiOutQueryString{ MidiOutPort::GetDeviceSelector() };
    DeviceInformationCollection midiOutDevices{ co_await DeviceInformation::FindAllAsync(midiOutQueryString) };
    uint32_t selectedMidiDevice{ 0 };

    if (0 == midiOutDevices.Size())
    {
        // No Midi output devices.
        co_return midiOut;
    }
    // If there are > 1 MIDI out devices, pick the first non-integrated one.
    else if (2 <= midiOutDevices.Size())
    {
        for (uint32_t midiDeviceIdx = 0; midiDeviceIdx < midiOutDevices.Size(); midiDeviceIdx++)
        {
            if (false == MidiSynthesizer::IsSynthesizer(midiOutDevices.GetAt(midiDeviceIdx)))
            {
                selectedMidiDevice = midiDeviceIdx;
                break;
            }
        }
    }

    midiOut = co_await MidiOutPort::FromIdAsync(midiOutDevices.GetAt(selectedMidiDevice).Id());

    co_return midiOut;
}

備註

若要列舉系統上的 MidiOutPort 物件，請將 GetDeviceSelector 所提供的查詢字串傳遞至 Windows.Devices.Enumeration.DeviceInformation.FindAllAsync。

嘗試建立 MidiInPort 的建議時間是在任何類型的應用程式啟用或使用者互動上。 如果 MidiInPort 上的函式呼叫失敗，或從 MidiInPort 收到的訊息無效，請勿嘗試立即重新建立埠。