Effect parameter: briefly show value in parameter name widget

src/effects/effectparameterslotbase.cpp

@@ -71,5 +71,6 @@ void EffectParameterSlotBase::onEffectMetaParameterChanged(double parameter, boo
 void EffectParameterSlotBase::slotValueChanged(double v) {
     if (m_pEffectParameter) {
         m_pEffectParameter->setValue(v);
+        emit valueChanged(v);
     }
 }

src/effects/effectparameterslotbase.h

@@ -55,6 +55,7 @@ class EffectParameterSlotBase : public QObject {
   signals:
     // Signal that indicates that the EffectParameterSlotBase has been updated.
     void updated();
+    void valueChanged(double v);
 
   public slots:
     // Solely for handling control changes

src/widget/weffectparameternamebase.cpp

@@ -9,13 +9,22 @@
 
 namespace {
 const QString kMimeTextDelimiter = QStringLiteral("\n");
+// for rounding the value display to 2 decimals
+constexpr int kValDecimals = 100;
 } // anonymous namespace
 
 WEffectParameterNameBase::WEffectParameterNameBase(
         QWidget* pParent, EffectsManager* pEffectsManager)
-        : WLabel(pParent), m_pEffectsManager(pEffectsManager) {
+        : WLabel(pParent),
+          m_pEffectsManager(pEffectsManager),
+          m_text("") {
     setAcceptDrops(true);
     parameterUpdated();
+    // When the parameter value changed it is display briefly.
+    // Set up the timer that restores the parameter name.
+    m_displayNameResetTimer.setSingleShot(true);
+    m_displayNameResetTimer.setInterval(800);
+    m_displayNameResetTimer.callOnTimeout(this, [this]() { setText(m_text); });
 }
 
 void WEffectParameterNameBase::setEffectParameterSlot(
@@ -33,17 +42,33 @@ void WEffectParameterNameBase::setEffectParameterSlot(
 void WEffectParameterNameBase::parameterUpdated() {
     if (m_pParameterSlot) {
         if (!m_pParameterSlot->shortName().isEmpty()) {
-            setText(m_pParameterSlot->shortName());
+            m_text = m_pParameterSlot->shortName();
         } else {
-            setText(m_pParameterSlot->name());
+            m_text = m_pParameterSlot->name();
         }
         setBaseTooltip(QString("%1\n%2").arg(
                 m_pParameterSlot->name(),
                 m_pParameterSlot->description()));
+        // Make connection to show parameter value instead of name briefly
+        // after value has changed.
+        if (m_pParameterSlot->parameterType() == EffectParameterType::Knob) {
+            connect(m_pParameterSlot.data(),
+                    &EffectParameterSlotBase::valueChanged,
+                    this,
+                    &WEffectParameterNameBase::showNewValue);
+        }
     } else {
-        setText(kNoEffectString);
+        m_text = kNoEffectString;
         setBaseTooltip(tr("No effect loaded."));
     }
+    setText(m_text);
+}
+
+void WEffectParameterNameBase::showNewValue(double newValue) {
+    double newValRounded =
+            std::ceil(newValue * kValDecimals) / kValDecimals;
+    setText(QString::number(newValRounded));
+    m_displayNameResetTimer.start();
 }
 
 void WEffectParameterNameBase::mousePressEvent(QMouseEvent* event) {

src/widget/weffectparameternamebase.h

@@ -1,6 +1,7 @@
 #pragma once
 
 #include <QDomNode>
+#include <QTimer>
 
 #include "effects/effectparameterslotbase.h"
 #include "skin/legacy/skincontext.h"
@@ -21,6 +22,7 @@ class WEffectParameterNameBase : public WLabel {
 
   protected slots:
     void parameterUpdated();
+    void showNewValue(double v);
 
   protected:
     void setEffectParameterSlot(EffectParameterSlotBasePointer pEffectKnobParameterSlot);
@@ -31,4 +33,6 @@ class WEffectParameterNameBase : public WLabel {
 
   private:
     const QString mimeTextIdentifier() const;
+    QString m_text;
+    QTimer m_displayNameResetTimer;
 };