Spring cleaning: Apply clang-tidy to src/widget.

Using LLVM 3.8.0:

$ clang-tidy --fix --checks="*,-llvm-header-guard,-readability-implicit-bool-cast,-readability-else-after-return,-google-readability-todo" $(git ls src/widget | xargs) -- (flags to compile)

107 files changed, 501 insertions, 533 deletions

diff --git a/src/widget/controlwidgetconnection.cpp b/src/widget/controlwidgetconnection.cpp
index 022659052e..5186c9288e 100644
--- a/src/widget/controlwidgetconnection.cpp
+++ b/src/widget/controlwidgetconnection.cpp
@@ -15,11 +15,10 @@ ControlWidgetConnection::ControlWidgetConnection(WBaseWidget* pBaseWidget,
     m_pControl->connectValueChanged(SLOT(slotControlValueChanged(double)));
 }
 
-ControlWidgetConnection::~ControlWidgetConnection() {
-}
+ControlWidgetConnection::~ControlWidgetConnection() = default;
 
 void ControlWidgetConnection::setControlParameter(double parameter) {
-    if (m_pValueTransformer != NULL) {
+    if (m_pValueTransformer != nullptr) {
         parameter = m_pValueTransformer->transformInverse(parameter);
     }
     m_pControl->setParameter(parameter);
@@ -27,7 +26,7 @@ void ControlWidgetConnection::setControlParameter(double parameter) {
 
 double ControlWidgetConnection::getControlParameter() const {
     double parameter = m_pControl->getParameter();
-    if (m_pValueTransformer != NULL) {
+    if (m_pValueTransformer != nullptr) {
         parameter = m_pValueTransformer->transform(parameter);
     }
     return parameter;
@@ -35,7 +34,7 @@ double ControlWidgetConnection::getControlParameter() const {
 
 double ControlWidgetConnection::getControlParameterForValue(double value) const {
     double parameter = m_pControl->getParameterForValue(value);
-    if (m_pValueTransformer != NULL) {
+    if (m_pValueTransformer != nullptr) {
         parameter = m_pValueTransformer->transform(parameter);
     }
     return parameter;
@@ -51,8 +50,7 @@ ControlParameterWidgetConnection::ControlParameterWidgetConnection(WBaseWidget*
           m_emitOption(emitOption) {
 }
 
-ControlParameterWidgetConnection::~ControlParameterWidgetConnection() {
-}
+ControlParameterWidgetConnection::~ControlParameterWidgetConnection() = default;
 
 void ControlParameterWidgetConnection::Init() {
     slotControlValueChanged(m_pControl->get());
@@ -107,8 +105,7 @@ ControlWidgetPropertyConnection::ControlWidgetPropertyConnection(WBaseWidget* pB
     slotControlValueChanged(m_pControl->get());
 }
 
-ControlWidgetPropertyConnection::~ControlWidgetPropertyConnection() {
-}
+ControlWidgetPropertyConnection::~ControlWidgetPropertyConnection() = default;
 
 QString ControlWidgetPropertyConnection::toDebugString() const {
     const ConfigKey& key = getKey();
diff --git a/src/widget/controlwidgetconnection.h b/src/widget/controlwidgetconnection.h
index 4954c096c9..adb4f6d7b2 100644
--- a/src/widget/controlwidgetconnection.h
+++ b/src/widget/controlwidgetconnection.h
@@ -18,7 +18,7 @@ class ControlWidgetConnection : public QObject {
     ControlWidgetConnection(WBaseWidget* pBaseWidget,
                             const ConfigKey& key,
                             ValueTransformer* pTransformer);
-    virtual ~ControlWidgetConnection();
+    ~ControlWidgetConnection() override;
 
     double getControlParameter() const;
     double getControlParameterForValue(double value) const;
@@ -33,7 +33,7 @@ class ControlWidgetConnection : public QObject {
     virtual void slotControlValueChanged(double v) = 0;
 
   protected:
-    void setControlParameter(double v);
+    void setControlParameter(double parameter);
 
     WBaseWidget* m_pWidget;
 
@@ -100,11 +100,11 @@ class ControlParameterWidgetConnection : public ControlWidgetConnection {
                                      ValueTransformer* pTransformer,
                                      DirectionOption directionOption,
                                      EmitOption emitOption);
-    virtual ~ControlParameterWidgetConnection();
+    ~ControlParameterWidgetConnection() override;
 
     void Init();
 
-    QString toDebugString() const;
+    QString toDebugString() const override;
 
     int getDirectionOption() const { return m_directionOption; };
     int getEmitOption() const { return m_emitOption; };
@@ -118,7 +118,7 @@ class ControlParameterWidgetConnection : public ControlWidgetConnection {
     void setControlParameterUp(double v);
 
   private slots:
-    virtual void slotControlValueChanged(double v);
+    void slotControlValueChanged(double value) override;
 
   private:
     DirectionOption m_directionOption;
@@ -131,13 +131,13 @@ class ControlWidgetPropertyConnection : public ControlWidgetConnection {
     ControlWidgetPropertyConnection(WBaseWidget* pBaseWidget,
                                     const ConfigKey& key,
                                     ValueTransformer* pTransformer,
-                                    const QString& property);
-    virtual ~ControlWidgetPropertyConnection();
+                                    const QString& propertyName);
+    ~ControlWidgetPropertyConnection() override;
 
-    QString toDebugString() const;
+    QString toDebugString() const override;
 
   private slots:
-    virtual void slotControlValueChanged(double v);
+    void slotControlValueChanged(double v) override;
 
   private:
     QByteArray m_propertyName;
diff --git a/src/widget/effectwidgetutils.h b/src/widget/effectwidgetutils.h
index f14b7ad9e5..77d13fe966 100644
--- a/src/widget/effectwidgetutils.h
+++ b/src/widget/effectwidgetutils.h
@@ -12,7 +12,7 @@ class EffectWidgetUtils {
             const QDomNode& node,
             const SkinContext& context,
             EffectsManager* pEffectsManager) {
-        if (pEffectsManager == NULL) {
+        if (pEffectsManager == nullptr) {
             return EffectRackPointer();
         }
 
@@ -116,7 +116,7 @@ class EffectWidgetUtils {
     }
 
   private:
-    EffectWidgetUtils() {};
+    EffectWidgetUtils() = default;;
 };
 
 #endif /* EFFECTWIDGETUTILS_H */
diff --git a/src/widget/hexspinbox.cpp b/src/widget/hexspinbox.cpp
index 0272fc15f5..0035ffcee0 100644
--- a/src/widget/hexspinbox.cpp
+++ b/src/widget/hexspinbox.cpp
@@ -5,8 +5,7 @@ HexSpinBox::HexSpinBox(QWidget* pParent)
     setRange(0, 255);
 }
 
-HexSpinBox::~HexSpinBox() {
-}
+HexSpinBox::~HexSpinBox() = default;
 
 QString HexSpinBox::textFromValue(int value) const {
     // Construct a hex string formatted like 0xFF.
@@ -21,6 +20,6 @@ int HexSpinBox::valueFromText(const QString& text) const {
 
 QValidator::State HexSpinBox::validate(QString& input, int& pos) const {
     const QRegExp regExp("^0(x|X)[0-9A-Fa-f]+");
-    QRegExpValidator validator(regExp, NULL);
+    QRegExpValidator validator(regExp, nullptr);
     return validator.validate(input, pos);
 }
diff --git a/src/widget/hexspinbox.h b/src/widget/hexspinbox.h
index aaa11ebf7c..64dd1b0feb 100644
--- a/src/widget/hexspinbox.h
+++ b/src/widget/hexspinbox.h
@@ -6,13 +6,13 @@
 
 class HexSpinBox : public QSpinBox {
   public:
-    HexSpinBox(QWidget *parent);
-    virtual ~HexSpinBox();
+    explicit HexSpinBox(QWidget *pParent);
+    ~HexSpinBox() override;
 
   protected:
-    QString textFromValue(int value) const;
-    int valueFromText(const QString& text) const;
-    QValidator::State validate(QString& input, int& pos) const;
+    QString textFromValue(int value) const override;
+    int valueFromText(const QString& text) const override;
+    QValidator::State validate(QString& input, int& pos) const override;
 };
 
 #endif /* HEXSPINBOX_H */
diff --git a/src/widget/slidereventhandler.h b/src/widget/slidereventhandler.h
index adefad3f18..a456ca0cf3 100644
--- a/src/widget/slidereventhandler.h
+++ b/src/widget/slidereventhandler.h
@@ -105,7 +105,7 @@ class SliderEventHandler {
 
     void wheelEvent(T* pWidget, QWheelEvent* e) {
         // For legacy (MIDI) reasons this is tuned to 127.
-        double wheelAdjustment = ((QWheelEvent *)e)->delta() / (120.0 * 127.0);
+        double wheelAdjustment = (e)->delta() / (120.0 * 127.0);
         double newParameter = pWidget->getControlParameter() + wheelAdjustment;
 
         // Clamp to [0.0, 1.0]