Add fine tune for STF slider

stfslider.cpp

@@ -21,6 +21,8 @@ STFSlider::STFSlider(QWidget *parent) : QWidget(parent)
     m_midPoint = 0.5;
     m_whitePoint = 1;
     m_grabbed = -1;
+    m_fineTune = false;
+    setToolTip(tr("Press Shift for fine tuning"));
 }
 
 float STFSlider::blackPoint() const
@@ -94,20 +96,34 @@ void STFSlider::mouseMoveEvent(QMouseEvent *event)
     else
         unsetCursor();
 
+    qreal x = (qreal)event->x()/width();
+    if(event->modifiers() & Qt::ShiftModifier && !m_fineTune)
+    {
+        m_fineTune = true;
+        m_fineTuneX = x;
+    }
+    if(!(event->modifiers() & Qt::ShiftModifier) && m_fineTune)
+        m_fineTune = false;
+
+    if(m_fineTune)
+    {
+        x = m_fineTuneX + (x - m_fineTuneX) * 0.2;
+    }
+
     switch(m_grabbed)
     {
     case 0:
-        m_blackPoint = clamp((qreal)event->x()/width());
+        m_blackPoint = clamp(x);
         m_whitePoint = std::max(m_whitePoint, m_blackPoint);
         QToolTip::showText(event->globalPos(), QString::number(m_blackPoint), this);
         break;
     case 1:
-        m_midPoint = ((qreal)event->x()/width() - m_blackPoint) / (m_whitePoint - m_blackPoint);
+        m_midPoint = (x - m_blackPoint) / (m_whitePoint - m_blackPoint);
         m_midPoint = clamp(m_midPoint);
         QToolTip::showText(event->globalPos(), QString::number(m_midPoint), this);
         break;
     case 2:
-        m_whitePoint = clamp((qreal)event->x()/width());
+        m_whitePoint = clamp(x);
         m_blackPoint = std::min(m_blackPoint, m_whitePoint);
         QToolTip::showText(event->globalPos(), QString::number(m_whitePoint), this);
         break;
@@ -121,6 +137,12 @@ void STFSlider::mouseMoveEvent(QMouseEvent *event)
 
 void STFSlider::mousePressEvent(QMouseEvent *event)
 {
+    if(event->modifiers() & Qt::ShiftModifier)
+    {
+        m_fineTune = true;
+        m_fineTuneX = (qreal)event->x()/width();
+    }
+
     if(std::abs((m_blackPoint + (m_whitePoint - m_blackPoint) * m_midPoint)*width() - event->x()) < 5)
         m_grabbed = 1;
     else if(std::abs(m_blackPoint*width() - event->x()) < 5)
@@ -134,5 +156,6 @@ void STFSlider::mousePressEvent(QMouseEvent *event)
 void STFSlider::mouseReleaseEvent(QMouseEvent *)
 {
     m_grabbed = -1;
+    m_fineTune = false;
     emit paramChanged(m_blackPoint, midPoint(), m_whitePoint);
 }

stfslider.h

@@ -11,6 +11,8 @@ class STFSlider : public QWidget
     float m_midPoint;
     float m_whitePoint;
     int m_grabbed;
+    bool m_fineTune;
+    float m_fineTuneX;
 public:
     explicit STFSlider(QWidget *parent = nullptr);
     float blackPoint() const;