Implement TouchScreen LongPress on Sliders

1. Add a LongHoldMixin
2. Implement that on slider
3. In touch mode, as a result, you end up with a long hold
   opening the RMB menu

Addresses surge-synthesizer#5802

src/surge-xt/gui/SurgeGUIUtils.cpp

@@ -38,6 +38,12 @@ bool showCursor(SurgeStorage *storage)
     return sc || tm;
 };
 
+bool isTouchMode(SurgeStorage *storage)
+{
+    bool tm = Surge::Storage::getUserDefaultValue(storage, Surge::Storage::TouchMouseMode, false);
+    return tm;
+}
+
 /*
  * We kinda want to know if we are standalone here, but don't have reference to the processor
  * but that's a constant for a process (you can't mix standalone and not) so make it a static

src/surge-xt/gui/SurgeGUIUtils.h

@@ -12,6 +12,7 @@ std::string toOSCaseForMenu(const std::string &menuName);
 
 extern bool showCursor(SurgeStorage *storage);
 extern bool allowKeyboardEdits(SurgeStorage *storage);
+extern bool isTouchMode(SurgeStorage *storage);
 
 bool get_line_intersection(float p0_x, float p0_y, float p1_x, float p1_y, float p2_x, float p2_y,
                            float p3_x, float p3_y, float *i_x, float *i_y);

src/surge-xt/gui/widgets/ModulatableSlider.cpp

@@ -387,6 +387,8 @@ void ModulatableSlider::mouseDrag(const juce::MouseEvent &event)
         return;
     }
 
+    mouseDragLongHold(event);
+
     auto p = mouseDownFloatPosition;
     float distance = event.position.getX() - p.getX();
     if (orientation == ParamConfig::kVertical)
@@ -472,6 +474,7 @@ void ModulatableSlider::mouseDown(const juce::MouseEvent &event)
         return;
     }
 
+    mouseDownLongHold(event);
     valueOnMouseDown = value;
     modValueOnMouseDown = modValue;
     lastDistance = 0.f;
@@ -481,6 +484,7 @@ void ModulatableSlider::mouseDown(const juce::MouseEvent &event)
 
 void ModulatableSlider::mouseMove(const juce::MouseEvent &event)
 {
+    mouseMoveLongHold(event);
     enqueueFutureInfowindow(SurgeGUIEditor::InfoQAction::START, event.position);
 }
 
@@ -499,6 +503,8 @@ void ModulatableSlider::mouseUp(const juce::MouseEvent &event)
         hideInfowindowSoon();
     }
 
+    mouseUpLongHold(event);
+
     if (!Surge::GUI::showCursor(storage))
     {
         juce::Desktop::getInstance().getMainMouseSource().enableUnboundedMouseMovement(false);

src/surge-xt/gui/widgets/ModulatableSlider.h

@@ -31,6 +31,7 @@ namespace Widgets
 {
 struct ModulatableSlider : public juce::Component,
                            public WidgetBaseMixin<ModulatableSlider>,
+                           public LongHoldMixin<ModulatableSlider>,
                            public ModulatableControlInterface
 {
     ModulatableSlider();

src/surge-xt/gui/widgets/WidgetBaseMixin.h

@@ -18,6 +18,7 @@
 
 #include "SkinSupport.h"
 #include "SurgeGUICallbackInterfaces.h"
+#include "SurgeGUIUtils.h"
 
 #include "juce_gui_basics/juce_gui_basics.h"
 
@@ -185,6 +186,75 @@ struct WidgetBaseMixin : public Surge::GUI::SkinConsumingComponent,
         return firstListenerOfType<SurgeGUIEditor>() && e.mods.isMiddleButtonDown();
     }
 };
+
+template <typename T> struct LongHoldMixin
+{
+    LongHoldMixin() {}
+    virtual ~LongHoldMixin()
+    {
+        if (timer && timer->isTimerRunning())
+            timer->stopTimer();
+    }
+    inline T *asT() { return static_cast<T *>(this); }
+
+    static constexpr uint32_t holdDelayTimeInMS = 1000;
+    void onLongHoldWrapper()
+    {
+        if (timer)
+            timer->stopTimer();
+        onLongHold();
+    }
+
+    virtual void onLongHold()
+    {
+        juce::ModifierKeys k{0};
+        asT()->notifyControlModifierClicked(k, true);
+    }
+
+    bool shouldLongHold()
+    {
+        // return true;
+        return GUI::isTouchMode(asT()->storage);
+    }
+
+    juce::Point<float> startingHoldPosition;
+    virtual void mouseDownLongHold(const juce::MouseEvent &e)
+    {
+        if (!shouldLongHold())
+            return;
+
+        startingHoldPosition = e.position.toFloat();
+        if (timer && timer->isTimerRunning())
+            timer->stopTimer();
+        timer = std::make_unique<LHCB>(this);
+        timer->startTimer(holdDelayTimeInMS); // ms
+    }
+    virtual void mouseMoveLongHold(const juce::MouseEvent &e)
+    {
+        if (e.position.getDistanceFrom(startingHoldPosition) > 4)
+            if (timer && timer->isTimerRunning())
+                timer->stopTimer();
+    }
+    virtual void mouseDragLongHold(const juce::MouseEvent &e)
+    {
+        if (e.position.getDistanceFrom(startingHoldPosition) > 1)
+            if (timer && timer->isTimerRunning())
+                timer->stopTimer();
+    }
+    virtual void mouseUpLongHold(const juce::MouseEvent &e)
+    {
+        if (timer && timer->isTimerRunning())
+            timer->stopTimer();
+    }
+
+    struct LHCB : public juce::Timer
+    {
+        LongHoldMixin<T> *that{nullptr};
+        LHCB(LongHoldMixin<T> *t) : that(t) {}
+        void timerCallback() override { that->onLongHoldWrapper(); }
+    };
+    std::unique_ptr<juce::Timer> timer;
+};
 } // namespace Widgets
 } // namespace Surge
 #endif // SURGE_XT_WIDGETBASEMIXIN_H