Add ability to shift-click to reset sliders.

Fixes #69

dgl/ImageWidgets.hpp

@@ -180,6 +180,7 @@ public:
 
     float getValue() const noexcept;
     void setValue(float value, bool sendCallback = false) noexcept;
+    void setDefault(float def) noexcept;
 
     void setStartPos(const Point<int>& startPos) noexcept;
     void setStartPos(int x, int y) noexcept;
@@ -203,7 +204,9 @@ private:
     float fMaximum;
     float fStep;
     float fValue;
+    float fValueDef;
     float fValueTmp;
+    bool  fUsingDefault;
 
     bool fDragging;
     bool fInverted;

dgl/src/ImageWidgets.cpp

@@ -649,7 +649,9 @@ ImageSlider::ImageSlider(Window& parent, const Image& image) noexcept
       fMaximum(1.0f),
       fStep(0.0f),
       fValue(0.5f),
+      fValueDef(fValue),
       fValueTmp(fValue),
+      fUsingDefault(false),
       fDragging(false),
       fInverted(false),
       fValueIsSet(false),
@@ -670,7 +672,9 @@ ImageSlider::ImageSlider(Widget* widget, const Image& image) noexcept
       fMaximum(1.0f),
       fStep(0.0f),
       fValue(0.5f),
+      fValueDef(fValue),
       fValueTmp(fValue),
+      fUsingDefault(false),
       fDragging(false),
       fInverted(false),
       fValueIsSet(false),
@@ -743,6 +747,12 @@ void ImageSlider::setInverted(bool inverted) noexcept
     repaint();
 }
 
+void ImageSlider::setDefault(float value) noexcept
+{
+    fValueDef = value;
+    fUsingDefault = true;
+}
+
 void ImageSlider::setRange(float min, float max) noexcept
 {
     fMinimum = min;
@@ -830,6 +840,13 @@ bool ImageSlider::onMouse(const MouseEvent& ev)
         if (! fSliderArea.contains(ev.pos))
             return false;
 
+        if ((ev.mod & kModifierShift) != 0 && fUsingDefault)
+        {
+            setValue(fValueDef, true);
+            fValueTmp = fValue;
+            return true;
+        }
+
         float vper;
         const int x = ev.pos.getX();
         const int y = ev.pos.getY();