plasma: pause and unpause PCM draining in mixer applet

because the draining is on 50ms timer and if the visualizer is not visible
there is no point to drain the PCM

Signed-off-by: Ivailo Monev <xakepa10@gmail.com>

plasma/applets/mixer/mixer.cpp

@@ -43,7 +43,7 @@ static const int s_svgiconsize = 256;
 static const QString s_defaultpopupicon = QString::fromLatin1("audio-card");
 static const int s_defaultsoundcard = -1;
 static const int s_alsapollinterval = 250;
-// for butter-smooth visualization the poll interval is very frequent when visualization is enabled
+// for butter-smooth visualization the poll interval is very frequent
 static const int s_alsavisualizerinterval = 50;
 // deciding factor for the visualization samples frequency
 static const int s_alsapcmbuffersize = 256;
@@ -319,6 +319,7 @@ public:
 
     bool setup(const QByteArray &cardname);
     void showVisualizer(const bool show, const uint scale, const QColor &color, const bool icon);
+    void pauseVisualizer(const bool pause);
      // can't be const because Plasma::Svg requires non-const parent
     QIcon mainVolumeIcon();
     Plasma::ToolTipContent toolTipContent() const;
@@ -333,13 +334,15 @@ Q_SIGNALS:
 
 private Q_SLOTS:
     void slotSliderMovedOrChanged(const int value);
-    void slotTimeout();
+    void slotEventsTimeout();
+    void slotVisualizerTimeout();
 
 private:
     QGraphicsLinearLayout* m_layout;
     snd_mixer_t* m_alsamixer;
     snd_pcm_t* m_alsapcm;
-    QTimer* m_timer;
+    QTimer* m_eventstimer;
+    QTimer* m_visualizertimer;
     QGraphicsWidget* m_spacer;
     Plasma::Frame* m_plotterframe;
     MixerPlotter* m_signalplotter;
@@ -355,7 +358,8 @@ MixerTabWidget::MixerTabWidget(const bool isdefault, const QString &alsamixernam
     m_layout(nullptr),
     m_alsamixer(nullptr),
     m_alsapcm(nullptr),
-    m_timer(nullptr),
+    m_eventstimer(nullptr),
+    m_visualizertimer(nullptr),
     m_spacer(nullptr),
     m_plotterframe(nullptr),
     m_signalplotter(nullptr),
@@ -369,17 +373,25 @@ MixerTabWidget::MixerTabWidget(const bool isdefault, const QString &alsamixernam
     m_layout->setContentsMargins(0, 0, 0, 0);
     setLayout(m_layout);
 
-    m_timer = new QTimer(this);
+    m_eventstimer = new QTimer(this);
-    m_timer->setInterval(s_alsapollinterval);
+    m_eventstimer->setInterval(s_alsapollinterval);
     connect(
-        m_timer, SIGNAL(timeout()),
+        m_eventstimer, SIGNAL(timeout()),
-        this, SLOT(slotTimeout())
+        this, SLOT(slotEventsTimeout())
+    );
+
+    m_visualizertimer = new QTimer(this);
+    m_visualizertimer->setInterval(s_alsavisualizerinterval);
+    connect(
+        m_visualizertimer, SIGNAL(timeout()),
+        this, SLOT(slotVisualizerTimeout())
     );
 }
 
 MixerTabWidget::~MixerTabWidget()
 {
-    m_timer->stop();
+    m_eventstimer->stop();
+    m_visualizertimer->stop();
     if (m_alsapcm) {
         snd_pcm_close(m_alsapcm);
     }
@@ -512,7 +524,7 @@ bool MixerTabWidget::setup(const QByteArray &alsacardname)
     m_layout->addItem(m_spacer);
 
     if (hasvalidelement) {
-        m_timer->start();
+        m_eventstimer->start();
     }
 
     adjustSize();
@@ -522,8 +534,8 @@ bool MixerTabWidget::setup(const QByteArray &alsacardname)
 
 void MixerTabWidget::showVisualizer(const bool show, const uint scale, const QColor &color, const bool icon)
 {
-    const bool starttimer = m_timer->isActive();
+    const bool starttimer = m_visualizertimer->isActive();
-    m_timer->stop();
+    m_visualizertimer->stop();
     if (m_alsapcm) {
         snd_pcm_close(m_alsapcm);
         m_alsapcm = nullptr;
@@ -544,9 +556,7 @@ void MixerTabWidget::showVisualizer(const bool show, const uint scale, const QCo
 
     if (!show) {
         if (starttimer) {
-            // the inteval for when there is no visualization is different
+            m_visualizertimer->start();
-            m_timer->setInterval(s_alsapollinterval);
-            m_timer->start();
         }
         m_spacer = kMakeSpacer(this);
         m_layout->addItem(m_spacer);
@@ -615,14 +625,38 @@ void MixerTabWidget::showVisualizer(const bool show, const uint scale, const QCo
         m_signalplotter->addPlot(color);
         plotterframelayout->addItem(m_signalplotter);
         m_layout->addItem(m_plotterframe);
+
+        m_visualizertimer->start();
     } else {
         m_spacer = kMakeSpacer(this);
         m_layout->addItem(m_spacer);
     }
+}
 
-    // if there are no valid elements then snd_pcm_open() will probably fail anyway
+void MixerTabWidget::pauseVisualizer(const bool pause)
-    m_timer->setInterval(s_alsavisualizerinterval);
+{
-    m_timer->start();
+    if (!m_alsapcm) {
+        return;
+    }
+    if (pause) {
+        kDebug() << "Pausing visualizer";
+        m_visualizertimer->stop();
+        const int alsaresult = snd_pcm_drop(m_alsapcm);
+        if (alsaresult != 0) {
+            kWarning() << "Could not drop PCM" << snd_strerror(alsaresult);
+        }
+    } else if (m_signalplotter) {
+        kDebug() << "Unpausing visualizer";
+        int alsaresult = snd_pcm_prepare(m_alsapcm);
+        if (alsaresult != 0) {
+            kWarning() << "Could not prepare PCM" << snd_strerror(alsaresult);
+        }
+        alsaresult = snd_pcm_start(m_alsapcm);
+        if (alsaresult != 0) {
+            kWarning() << "Could not start PCM" << snd_strerror(alsaresult);
+        }
+        m_visualizertimer->start();
+    }
 }
 
 QIcon MixerTabWidget::mainVolumeIcon()
@@ -730,12 +764,15 @@ void MixerTabWidget::slotSliderMovedOrChanged(const int value)
     kWarning() << "Could not find the element" << slider->alsaelementindex;
 }
 
-void MixerTabWidget::slotTimeout()
+void MixerTabWidget::slotEventsTimeout()
 {
     if (Q_LIKELY(m_alsamixer)) {
         snd_mixer_handle_events(m_alsamixer);
     }
+}
 
+void MixerTabWidget::slotVisualizerTimeout()
+{
     if (m_alsapcm) {
         switch (snd_pcm_state(m_alsapcm)) {
             case SND_PCM_STATE_PREPARED:
@@ -809,6 +846,7 @@ public:
     MixerWidget(MixerApplet *mixer);
 
     void showVisualizer(const bool show, const uint scale, const QColor &color, const bool icon);
+    void pauseVisualizer(const bool pause);
     void decreaseVolume();
     void increaseVolume();
 
@@ -921,6 +959,13 @@ void MixerWidget::showVisualizer(const bool show, const uint scale, const QColor
     }
 }
 
+void MixerWidget::pauseVisualizer(const bool pause)
+{
+    foreach (MixerTabWidget *mixertabwidget, m_tabwidgets) {
+        mixertabwidget->pauseVisualizer(pause);
+    }
+}
+
 void MixerWidget::decreaseVolume()
 {
     if (m_tabwidgets.size() < 1) {
@@ -973,8 +1018,6 @@ MixerApplet::MixerApplet(QObject *parent, const QVariantList &args)
     setAspectRatioMode(Plasma::AspectRatioMode::IgnoreAspectRatio);
     setHasConfigurationInterface(true);
     setPopupIcon(kMixerIcon(this, 0));
-
-    m_mixerwidget = new MixerWidget(this);
 }
 
 MixerApplet::~MixerApplet()
@@ -986,6 +1029,7 @@ void MixerApplet::init()
 {
     Plasma::PopupApplet::init();
 
+    m_mixerwidget = new MixerWidget(this);
     slotThemeChanged();
     connect(Plasma::Theme::defaultTheme(), SIGNAL(themeChanged()), this, SLOT(slotThemeChanged()));
 }
@@ -1045,8 +1089,19 @@ QGraphicsWidget* MixerApplet::graphicsWidget()
     return m_mixerwidget;
 }
 
+void MixerApplet::popupEvent(bool show)
+{
+    if (!m_mixerwidget) {
+        return;
+    }
+    m_mixerwidget->pauseVisualizer(!show);
+}
+
 void MixerApplet::wheelEvent(QGraphicsSceneWheelEvent *event)
 {
+    if (!m_mixerwidget) {
+        return;
+    }
     if (event->delta() < 0) {
         m_mixerwidget->decreaseVolume();
     } else {
@@ -1063,6 +1118,7 @@ void MixerApplet::slotVisualizerToggled(bool toggled)
 
 void MixerApplet::slotConfigAccepted()
 {
+    Q_ASSERT(m_mixerwidget != nullptr);
     Q_ASSERT(m_visualizerbox != nullptr);
     Q_ASSERT(m_visualizerscalebox != nullptr);
     Q_ASSERT(m_visualizerbutton != nullptr);
@@ -1082,10 +1138,12 @@ void MixerApplet::slotConfigAccepted()
     configgroup.writeEntry("visualizerIcon", m_visualizericon);
     emit configNeedsSaving();
     m_mixerwidget->showVisualizer(m_showvisualizer, m_visualizerscale, m_visualizercolor, m_visualizericon);
+    m_mixerwidget->pauseVisualizer(isIconified() && !isPopupShowing());
 }
 
 void MixerApplet::slotThemeChanged()
 {
+    Q_ASSERT(m_mixerwidget != nullptr);
     KConfigGroup configgroup = config();
     m_showvisualizer = configgroup.readEntry("showVisualizer", s_showvisualizer);
     m_visualizerscale = configgroup.readEntry("visualizerScale", s_visualizerscale);
@@ -1096,6 +1154,7 @@ void MixerApplet::slotThemeChanged()
     m_visualizericon = configgroup.readEntry("visualizerIcon", s_visualizericon);
 
     m_mixerwidget->showVisualizer(m_showvisualizer, m_visualizerscale, m_visualizercolor, m_visualizericon);
+    m_mixerwidget->pauseVisualizer(isIconified() && !isPopupShowing());
 }
 
 K_EXPORT_PLASMA_APPLET(mixer, MixerApplet)

plasma/applets/mixer/mixer.h

@@ -40,8 +40,9 @@ public:
     // Plasma::Applet reimplementations
     void init() final;
     void createConfigurationInterface(KConfigDialog *parent) final;
-    // Plasma::PopupApplet reimplementation
+    // Plasma::PopupApplet reimplementations
     QGraphicsWidget* graphicsWidget() final;
+    void popupEvent(bool show) final;
     // QGraphicsWidget reimplementation
     void wheelEvent(QGraphicsSceneWheelEvent *event) final;