Rework stretch to use just MTF

stfslider.cpp

@@ -3,9 +3,15 @@
 #include <QPainter>
 #include <QPaintEvent>
 
+static float clamp(float x)
+{
+    return std::min(std::max(x, 0.0f), 1.0f);
+}
+
 STFSlider::STFSlider(QWidget *parent) : QWidget(parent)
 {
     setMinimumHeight(15);
+    setMaximumHeight(15);
     setMouseTracking(true);
     m_blackPoint = 0;
     m_midPoint = 0.5;
@@ -13,6 +19,29 @@ STFSlider::STFSlider(QWidget *parent) : QWidget(parent)
     m_grabbed = -1;
 }
 
+float STFSlider::blackPoint() const
+{
+    return m_blackPoint;
+}
+
+float STFSlider::midPoint() const
+{
+    return m_midPoint;
+}
+
+float STFSlider::whitePoint() const
+{
+    return m_whitePoint;
+}
+
+void STFSlider::setMTFParams(float low, float mid, float high)
+{
+    m_blackPoint = clamp(low);
+    m_midPoint = clamp(mid);
+    m_whitePoint = clamp(high);
+    update();
+}
+
 void STFSlider::paintEvent(QPaintEvent *event)
 {
     QPainter painter(this);
@@ -77,7 +106,10 @@ void STFSlider::mouseMoveEvent(QMouseEvent *event)
         break;
     }
     if(m_grabbed >= 0)
-        repaint();
+    {
+        emit paramChanged(m_blackPoint, midPoint(), m_whitePoint);
+        update();
+    }
 }
 
 void STFSlider::mousePressEvent(QMouseEvent *event)
@@ -95,4 +127,5 @@ void STFSlider::mousePressEvent(QMouseEvent *event)
 void STFSlider::mouseReleaseEvent(QMouseEvent *)
 {
     m_grabbed = -1;
+    emit paramChanged(m_blackPoint, midPoint(), m_whitePoint);
 }