IAudioEffectsChangedNotificationClient：：OnAudioEffectsChanged 方法 (audioclient.h)

当音频效果列表更改或启用效果所需的资源发生更改时，即当关联AUDIO_EFFECT的 canSetState 字段的值发生更改时，由系统调用。

语法

HRESULT OnAudioEffectsChanged();

返回值

HRESULT。

注解

通过调用 IAudioEffectsManager：：RegisterAudioEffectsChangedNotificationCallback 注册回调接口。

示例

下面的代码示例演示了一个实现 IAudioEffectsChangedNotificationClient 的类，以便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