Introduce knobDoubleClicked for KnobEventHandler

Signed-off-by: falkTX <falktx@falktx.com>

dgl/EventHandlers.hpp

@@ -113,6 +113,7 @@ public:
         virtual void knobDragStarted(SubWidget* widget) = 0;
         virtual void knobDragFinished(SubWidget* widget) = 0;
         virtual void knobValueChanged(SubWidget* widget, float value) = 0;
+        virtual void knobDoubleClicked(SubWidget*) {};
     };
 
     explicit KnobEventHandler(SubWidget* self);

dgl/Widget.hpp

@@ -64,7 +64,7 @@ public:
         uint mod;
         /** Event flags. @see EventFlag */
         uint flags;
-        /** Event timestamp (if any). */
+        /** Event timestamp in milliseconds (if any). */
         uint time;
 
         /** Constructor for default/null values */

dgl/src/EventHandlers.cpp

@@ -288,6 +288,7 @@ struct KnobEventHandler::PrivateData {
 
     double lastX;
     double lastY;
+    uint lastClickTime;
 
     PrivateData(KnobEventHandler* const s, SubWidget* const w)
         : self(s),
@@ -305,7 +306,8 @@ struct KnobEventHandler::PrivateData {
           orientation(Vertical),
           state(kKnobStateDefault),
           lastX(0.0),
-          lastY(0.0) {}
+          lastY(0.0),
+          lastClickTime(0) {}
 
     PrivateData(KnobEventHandler* const s, SubWidget* const w, PrivateData* const other)
         : self(s),
@@ -323,7 +325,8 @@ struct KnobEventHandler::PrivateData {
           orientation(other->orientation),
           state(kKnobStateDefault),
           lastX(0.0),
-          lastY(0.0) {}
+          lastY(0.0),
+          lastClickTime(0) {}
 
     void assignFrom(PrivateData* const other)
     {
@@ -341,6 +344,7 @@ struct KnobEventHandler::PrivateData {
         state        = kKnobStateDefault;
         lastX        = 0.0;
         lastY        = 0.0;
+        lastClickTime = 0;
     }
 
     inline float logscale(const float v) const
@@ -374,9 +378,21 @@ struct KnobEventHandler::PrivateData {
                 return true;
             }
 
-            state |= kKnobStateDragging;
             lastX = ev.pos.getX();
             lastY = ev.pos.getY();
+
+            if (lastClickTime > 0 && ev.time > lastClickTime && ev.time - lastClickTime <= 300)
+            {
+                lastClickTime = 0;
+
+                if (callback != nullptr)
+                    callback->knobDoubleClicked(widget);
+
+                return true;
+            }
+
+            lastClickTime = ev.time;
+            state |= kKnobStateDragging;
             widget->repaint();
 
             if (callback != nullptr)