IAudioEffectsManager：：RegisterAudioEffectsChangedNotificationCallback 方法 (audioclient.h)

注册 IAudioEffectsChangedNotificationClient 接口。 此回调接口允许应用程序在音频效果列表更改或启用效果更改所需的资源时接收通知，即当关联AUDIO_EFFECT的 canSetState 字段的值发生更改时。

语法

HRESULT RegisterAudioEffectsChangedNotificationCallback(
  IAudioEffectsChangedNotificationClient *client
);

参数

client

要注册 的 IAudioEffectsChangedNotificationClient 接口。

返回值

值	说明
S_OK	成功
AUDCLNT_E_DEVICE_INVALIDATED	关联的音频流已被销毁。

注解

通过调用 UnregisterAudioEffectsChangedNotificationCallback 取消注册回调接口。

示例

下面的代码示例演示了一个类，该类实现 IAudioEffectsChangedNotificationClient 以在音频效果列表更改或启用效果更改所需的资源时接收通知。 在 OnAudioStreamEffectsChanged 回调中，该示例调用 GetAudioEffects 以获取当前效果列表。

class AudioEffectsChangedHandler :
    public winrt::implements<AudioEffectsChangedHandler, IAudioEffectsChangedNotificationClient>
{

    public:
    AudioEffectsChangedHandler(_In_ IAudioClient *client) : m_client(client){}
    STDMETHOD(OnAudioEffectsChanged)()
    {
        OnAudioStreamEffectsChanged(m_client.get());
        return S_OK;
    }
    private:
    wil::com_ptr_nothrow<IAudioClient> m_client;

};

wil::com_ptr_nothrow<IAudioEffectsChangedNotificationClient> g_effectsChangedHandler;

HRESULT RegisterAudioStreamEffectsChangedEvent(_In_ IAudioClient *client)
{
    if (!g_effectsChangedHandler)
    {
        wil::com_ptr_nothrow<IAudioEffectsManager> audioEffectsManager;
        RETURN_IF_FAILED(client->GetService(IID_PPV_ARGS(&audioEffectsManager)));

        // Register for the audio effects changed notification
        g_effectsChangedHandler = winrt::make<AudioEffectsChangedHandler>(client).get();
        RETURN_IF_NULL_ALLOC(g_effectsChangedHandler);

        return audioEffectsManager->RegisterAudioEffectsChangedNotificationCallback(
            g_effectsChangedHandler.get());
    }
    return S_OK;
}

HRESULT UnregisterAudioStreamEffectsChangedEvent(_In_ IAudioClient *client)
{
    if (g_effectsChangedHandler != nullptr)
    {
        wil::com_ptr_nothrow<IAudioEffectsManager> audioEffectsManager;
        RETURN_IF_FAILED(client->GetService(IID_PPV_ARGS(&audioEffectsManager)));

        // Unregister from the audio effects changed notification 
        return audioEffectsManager->UnregisterAudioEffectsChangedNotificationCallback(
            g_effectsChangedHandler.get());
        }

        return S_OK;
}

HRESULT OnAudioStreamEffectsChanged(_In_ IAudioClient *client)
{
    // Re-query the list of effects since there was some change
    wil::com_ptr_nothrow<IAudioEffectsManager> audioEffectsManager;
    RETURN_IF_FAILED(client->GetService(IID_PPV_ARGS(&audioEffectsManager)));
    wil::unique_cotaskmem_array_ptr<AUDIO_EFFECT> effects;
    UINT32 numEffects;
    RETURN_IF_FAILED(audioEffectsManager->GetAudioEffects(&effects, &numEffects));

    for (UINT32 i = 0; i < numEffects; i++)
    {

        // Here the app can check which effects are still enabled, and check if there are new
        // effects that now can be enabled.
        // As an example, the following code enables any effect that can be enabled, if it is not
        // already enabled.
        if (effects[i].canSetState && effects[i].state == AUDIO_EFFECT_STATE_OFF)
        {
            HRESULT hr = audioEffectsManager->SetAudioEffectState(effects[i].id, AUDIO_EFFECT_STATE_ON));
            if (hr == AUDCLNT_E_EFFECT_NOT_AVAILABLE || hr == AUDCLNT_E_EFFECT_STATE_READ_ONLY)
            {
                hr = S_OK;
            }
            RETURN_IF_FAILED(hr);

        }
    }

    return S_OK;
}

要求

要求	值
最低受支持的客户端	Windows 内部版本 22000
标头	audioclient.h

另请参阅

UnregisterAudioEffectsChangedNotificationCallback