Intervals on timeline are now graphically proportional to time:

- intervals are only valid when using key shortcuts
 - using the mouse to select/scroll does not show proper proportions yet

src/common/LinkedObjectPool.hxx

@@ -129,6 +129,12 @@ class LinkedObjectPool
     */
     const_iter next(const_iter i) const { return std::next(i, 1); }
 
+    /**
+      Canonical iterators from C++ STL.
+    */
+    const_iter cbegin() const { return myList.cbegin(); }
+    const_iter cend() const   { return myList.cend();   }
+
     /**
       Answer whether 'current' is at the specified iterator.
     */

src/common/RewindManager.cxx

@@ -344,7 +344,7 @@ IntArray RewindManager::cyclesList() const
   IntArray arr;
 
   uInt64 firstCycle = getFirstCycles();
-  for(auto it = myStateList.first(); it != myStateList.last(); ++it)
+  for(auto it = myStateList.cbegin(); it != myStateList.cend(); ++it)
     arr.push_back(uInt32(it->cycles - firstCycle));
 
   return arr;

src/gui/TimeLineWidget.cxx

@@ -25,13 +25,16 @@
 
 #include "TimeLineWidget.hxx"
 
+// TODO - remove all references to _stepValue__
+//      - fix posToValue to use _stepValue
+
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 TimeLineWidget::TimeLineWidget(GuiObject* boss, const GUI::Font& font,
                                int x, int y, int w, int h,
                                const string& label, int labelWidth, int cmd)
   : ButtonWidget(boss, font, x, y, w, h, label, cmd),
     _value(0),
-    _stepValue(1),
+    _stepValue__(1),
     _valueMin(0),
     _valueMax(100),
     _isDragging(false),
@@ -45,6 +48,8 @@ TimeLineWidget::TimeLineWidget(GuiObject* boss, const GUI::Font& font,
     _labelWidth = _font.getStringWidth(_label);
 
   _w = w + _labelWidth;
+
+  _stepValue.reserve(100);
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
@@ -73,13 +78,24 @@ void TimeLineWidget::setMaxValue(int value)
   _valueMax = value;
 }
 
-#if 0
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-void TimeLineWidget::setStepValue(int value)
+void TimeLineWidget::setStepValues(const IntArray& steps)
 {
-  _stepValue = value;
+  // Try to allocate as infrequently as possible
+  if(steps.size() > _stepValue.capacity())
+    _stepValue.reserve(2 * steps.size());
+  _stepValue.clear();
+
+  double scale = (_w - _labelWidth - 4) / double(steps.back());
+
+  // Skip the very last value; we take care of it outside the end of the loop
+  for(uInt32 i = 0; i < steps.size() - 1; ++i)
+    _stepValue.push_back(int(steps[i] * scale));
+
+  // Due to integer <-> double conversion, the last value is sometimes
+  // slightly less than the maximum value; we assign it manually to fix this
+  _stepValue.push_back(_w - _labelWidth - 4);
 }
-#endif
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 void TimeLineWidget::handleMouseMoved(int x, int y)
@@ -132,13 +148,13 @@ bool TimeLineWidget::handleEvent(Event::Type e)
     case Event::UIDown:
     case Event::UILeft:
     case Event::UIPgDown:
-      setValue(_value - _stepValue);
+      setValue(_value - _stepValue__);
       break;
 
     case Event::UIUp:
     case Event::UIRight:
     case Event::UIPgUp:
-      setValue(_value + _stepValue);
+      setValue(_value + _stepValue__);
       break;
 
     case Event::UIHome:
@@ -196,9 +212,14 @@ int TimeLineWidget::valueToPos(int value)
 {
   if(value < _valueMin)      value = _valueMin;
   else if(value > _valueMax) value = _valueMax;
-  int range = std::max(_valueMax - _valueMin, 1);  // don't divide by zero
 
-  return ((_w - _labelWidth - 4) * (value - _valueMin) / range);
+  int real = _stepValue[BSPF::clamp(value, _valueMin, _valueMax)];
+#if 0
+  int range = std::max(_valueMax - _valueMin, 1);  // don't divide by zero
+  int actual = ((_w - _labelWidth - 4) * (value - _valueMin) / range);
+cerr << "i=" << value << " real=" << real << endl << "actual=" << actual << endl << endl;
+#endif
+  return real;
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
@@ -207,5 +228,5 @@ int TimeLineWidget::posToValue(int pos)
   int value = (pos) * (_valueMax - _valueMin) / (_w - _labelWidth - 4) + _valueMin;
 
   // Scale the position to the correct interval (according to step value)
-  return value - (value % _stepValue);
+  return value - (value % _stepValue__);
 }

src/gui/TimeLineWidget.hxx

@@ -34,10 +34,12 @@ class TimeLineWidget : public ButtonWidget
     int  getMinValue() const      { return _valueMin; }
     void setMaxValue(int value);
     int  getMaxValue() const      { return _valueMax; }
-#if 0
+
-    void setStepValue(int value);
+    /**
-    int  getStepValue() const     { return _stepValue; }
+      Steps are not necessarily linear in a timeline, so we need info
-#endif
+      on each interval instead.
+    */
+    void setStepValues(const IntArray& steps);
 
   protected:
     void handleMouseMoved(int x, int y) override;
@@ -52,11 +54,13 @@ class TimeLineWidget : public ButtonWidget
     int posToValue(int pos);
 
   protected:
-    int  _value, _stepValue;
+    int  _value, _stepValue__;
     int  _valueMin, _valueMax;
     bool _isDragging;
     int  _labelWidth;
 
+    IntArray _stepValue;
+
   private:
     // Following constructors and assignment operators not supported
     TimeLineWidget() = delete;

src/gui/TimeMachineDialog.cxx

@@ -192,6 +192,7 @@ TimeMachineDialog::TimeMachineDialog(OSystem& osystem, DialogContainer& parent,
                tl_y = ypos + (myCurrentIdxWidget->getHeight() - tl_h) / 2,
                tl_w = myLastIdxWidget->getAbsX() - tl_x - 8;
   myTimeline = new TimeLineWidget(this, font, tl_x, tl_y, tl_w, tl_h, "", 0, kTimeline);
+  myTimeline->setMinValue(0);
   ypos += rowHeight;
 
   // Add time info
@@ -252,8 +253,9 @@ void TimeMachineDialog::loadConfig()
   RewindManager& r = instance().state().rewindManager();
   IntArray cycles = r.cyclesList();
 
-  // Set range for timeline
+  // Set range and intervals for timeline
-  myTimeline->setMaxValue(std::max(Int32(cycles.size()), 1));
+  myTimeline->setMaxValue(cycles.size() - 1);
+  myTimeline->setStepValues(cycles);
 
   // Enable blending (only once is necessary)
   if(!surface().attributes().blending)