Define a base class that will be useful for several track control sliders

src/tracks/ui/SliderHandle.cpp

@@ -0,0 +1,96 @@
+/**********************************************************************
+
+Audacity: A Digital Audio Editor
+
+SliderHandle.cpp
+
+Paul Licameli
+
+**********************************************************************/
+
+#include "../../Audacity.h"
+#include "SliderHandle.h"
+#include "../../widgets/ASlider.h"
+#include "../../HitTestResult.h"
+#include "../../RefreshCode.h"
+#include "../../TrackPanelMouseEvent.h"
+
+SliderHandle::SliderHandle()
+{
+}
+
+SliderHandle::~SliderHandle()
+{
+}
+
+HitTestPreview SliderHandle::HitPreview()
+{
+   // No special message or cursor
+   return {};
+}
+
+UIHandle::Result SliderHandle::Click
+(const TrackPanelMouseEvent &evt, AudacityProject *)
+{
+   wxMouseEvent &event = evt.event;
+   using namespace RefreshCode;
+   if (!event.Button(wxMOUSE_BTN_LEFT))
+      return Cancelled;
+
+   // Come here for left click or double click
+   mStartingValue = GetValue();
+   mpSlider->Set(mStartingValue);
+   mpSlider->OnMouseEvent(event);
+
+   if (event.ButtonDClick())
+      // Just did a modal dialog in OnMouseEvent
+      // Do not start a drag
+      return RefreshCell | Cancelled;
+   else
+      return RefreshCell;
+}
+
+UIHandle::Result SliderHandle::Drag
+(const TrackPanelMouseEvent &evt, AudacityProject *pProject)
+{
+   wxMouseEvent &event = evt.event;
+   using namespace RefreshCode;
+   mpSlider->OnMouseEvent(event);
+   const float newValue = mpSlider->Get();
+
+   // Make a non-permanent change to the project data:
+   return RefreshCell | SetValue(pProject, newValue);
+}
+
+HitTestPreview SliderHandle::Preview
+(const TrackPanelMouseEvent &, const AudacityProject *)
+{
+   // No special message or cursor
+   return {};
+}
+
+UIHandle::Result SliderHandle::Release
+(const TrackPanelMouseEvent &evt, AudacityProject *pProject,
+ wxWindow *)
+{
+   using namespace RefreshCode;
+   wxMouseEvent &event = evt.event;
+   mpSlider->OnMouseEvent(event);
+   const float newValue = mpSlider->Get();
+
+   Result result = RefreshCell;
+
+   // Commit changes to the project data:
+   result |= SetValue(pProject, newValue);
+   result |= CommitChanges(event, pProject);
+   return result;
+}
+
+UIHandle::Result SliderHandle::Cancel(AudacityProject *pProject)
+{
+   wxMouseEvent event(wxEVT_LEFT_UP);
+   mpSlider->OnMouseEvent(event);
+
+   // Undo un-committed changes to project data:
+   return RefreshCode::RefreshCell | SetValue(pProject, mStartingValue);
+}

src/tracks/ui/SliderHandle.h

@@ -0,0 +1,64 @@
+/**********************************************************************
+
+Audacity: A Digital Audio Editor
+
+SliderHandle.h
+
+Paul Licameli
+
+**********************************************************************/
+
+#ifndef __AUDACITY_SLIDER_HANDLE__
+#define __AUDACITY_SLIDER_HANDLE__
+
+#include "../../UIHandle.h"
+
+class wxMouseEvent;
+class LWSlider;
+class Track;
+
+class SliderHandle /* not final */ : public UIHandle
+{
+   SliderHandle(const SliderHandle&) = delete;
+   SliderHandle &operator=(const SliderHandle&) = delete;
+
+protected:
+   SliderHandle();
+   virtual ~SliderHandle();
+
+   // These new abstract virtuals simplify the duties of further subclasses.
+   // This class will decide whether to refresh the clicked cell for slider state
+   // change.
+   // Subclass can decide to refresh other things and the results will be ORed.
+   virtual float GetValue() = 0;
+   virtual Result SetValue(AudacityProject *pProject, float newValue) = 0;
+   virtual Result CommitChanges
+      (const wxMouseEvent &event, AudacityProject *pProject) = 0;
+
+   // For derived classes to define hit tests
+   static HitTestPreview HitPreview();
+
+   Result Click
+      (const TrackPanelMouseEvent &event, AudacityProject *pProject) override;
+
+   Result Drag
+      (const TrackPanelMouseEvent &event, AudacityProject *pProject) override;
+
+   HitTestPreview Preview
+      (const TrackPanelMouseEvent &event, const AudacityProject *pProject)
+      override;
+
+   Result Release
+      (const TrackPanelMouseEvent &event, AudacityProject *pProject,
+       wxWindow *pParent) override;
+
+   Result Cancel(AudacityProject *pProject) override;
+
+   // Derived track is expected to set these two before Click():
+   Track *mpTrack {};
+   LWSlider *mpSlider {};
+
+   float mStartingValue {};
+};
+
+#endif