Add "offset" to SliderTextCtrl widget

This parameter adds an offset to the value before calculating the
logarithm to tweak the scaling of the slider.

Signed-off-by: Max Maisel <max.maisel@posteo.de>

src/ShuttleGui.cpp

@@ -618,7 +618,7 @@ wxSlider * ShuttleGuiBase::AddSlider(
 
 SliderTextCtrl* ShuttleGuiBase::AddSliderTextCtrl(
    const TranslatableString &Prompt, double pos, double Max, double Min,
-   int precision, double* value, double scale)
+   int precision, double* value, double scale, double offset)
 {
    HandleOptionality( Prompt );
    AddPrompt( Prompt );
@@ -627,7 +627,7 @@ SliderTextCtrl* ShuttleGuiBase::AddSliderTextCtrl(
       return wxDynamicCast(wxWindow::FindWindowById( miId, mpDlg), SliderTextCtrl);
    SliderTextCtrl * pSlider;
    mpWind = pSlider = safenew SliderTextCtrl(GetParent(), miId,
-      pos, Min, Max, precision, scale, wxDefaultPosition, wxDefaultSize,
+      pos, Min, Max, precision, scale, offset, wxDefaultPosition, wxDefaultSize,
       GetStyle( SliderTextCtrl::HORIZONTAL ),
       value
    );

src/ShuttleGui.h

@@ -267,7 +267,7 @@ public:
 
    SliderTextCtrl* AddSliderTextCtrl(
       const TranslatableString &Prompt, double pos, double Max, double Min = 0,
-      int precision = 2, double* value = NULL, double scale = 0);
+      int precision = 2, double* value = NULL, double scale = 0, double offset = 0);
 
    // Pass the same initValue to the sequence of calls to AddRadioButton and
    // AddRadioButtonToGroup.

src/widgets/SliderTextCtrl.cpp

@@ -29,7 +29,8 @@ wxDEFINE_EVENT(cEVT_SLIDERTEXT, wxCommandEvent);
 
 SliderTextCtrl::SliderTextCtrl(wxWindow *parent, wxWindowID winid,
    double value, double min, double max, int precision, double scale,
-   const wxPoint& pos, const wxSize& size, long style, double* varValue)
+   double offset, const wxPoint& pos, const wxSize& size, long style,
+   double* varValue)
    : wxPanelWrapper(parent, winid, pos, size, wxWS_EX_VALIDATE_RECURSIVELY)
 {
    m_log = style & LOG;
@@ -38,6 +39,7 @@ SliderTextCtrl::SliderTextCtrl(wxWindow *parent, wxWindowID winid,
    m_min = min;
    m_max = max;
    m_zero = -std::numeric_limits<double>::infinity();
+   m_offset = offset;
 
    if(m_int)
    {
@@ -62,13 +64,13 @@ SliderTextCtrl::SliderTextCtrl(wxWindow *parent, wxWindowID winid,
          min = m_zero;
       }
       else
-         min = log10(min);
+         min = log10(min + m_offset);
 
       if(value <= 0.0)
          value = m_zero;
       else
-         value = log10(value);
-      max = log10(max);
+         value = log10(value + m_offset);
+      max = log10(max + m_offset);
    }
 
    m_sizer = safenew wxBoxSizer(
@@ -118,7 +120,7 @@ void SliderTextCtrl::OnTextChange(wxCommandEvent& event)
       if(m_value == 0.0)
          value = m_zero;
       else
-         value = log10(m_value);
+         value = log10(m_value + m_offset);
    }
    m_slider->SetValue(round(value * m_scale));
    event.SetEventType(cEVT_SLIDERTEXT);
@@ -134,7 +136,7 @@ void SliderTextCtrl::OnSlider(wxCommandEvent& event)
          m_value = 0.0;
       else
       {
-         m_value = pow(10.0, m_value);
+         m_value = pow(10.0, m_value) - m_offset;
          m_value = std::max(m_min, m_value);
          m_value = std::min(m_max, m_value);
       }

src/widgets/SliderTextCtrl.h

@@ -37,7 +37,8 @@ class SliderTextCtrl : public wxPanelWrapper
 
       SliderTextCtrl(wxWindow *parent, wxWindowID winid,
          double value, double min, double max, int precision = 2,
-         double scale = 0, const wxPoint& pos = wxDefaultPosition,
+         double scale = 0, double offset = 0,
+         const wxPoint& pos = wxDefaultPosition,
          const wxSize& size = wxDefaultSize, long style = HORIZONTAL,
          double* varValue = NULL);
 
@@ -69,6 +70,7 @@ class SliderTextCtrl : public wxPanelWrapper
       double m_min;
       double m_max;
       double m_zero;
+      double m_offset;
       wxString m_format;
 
       DECLARE_EVENT_TABLE()