[dasher] Refactored computation of polar co-ordinates for auto speed control.

[Patrick Welche <pwelche src gnome org>]

commit 1b88d825b7f894ce98c40a2af78ba6ea762d3028
Author: Alan Lawrence <acl33 inf phy cam ac uk>
Date:   Fri May 15 17:49:54 2009 +0100

    Refactored computation of polar co-ordinates for auto speed control.
---
 ChangeLog                           |    4 ++++
 Src/DasherCore/AutoSpeedControl.cpp |   14 +++-----------
 Src/DasherCore/DasherView.h         |   14 ++++----------
 Src/DasherCore/DasherViewSquare.cpp |   13 +++++++++++++
 Src/DasherCore/DasherViewSquare.h   |   13 +++++++------
 5 files changed, 31 insertions(+), 27 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 67fa3ed..bd3382d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -2,6 +2,10 @@
 
 	* Backport to OS X 10.4 universal binary for PPC.
 	* DasherModel.{h,cpp}: Remove unused Recursive_Push_Node method.
+	* AutoSpeedControl.cpp, DasherView.h, DasherViewSquare.{h,cpp}:
+	Refactored computation of polar co-ordinates for auto speed
+	control.
+
 
 2009-05-14  Patrick Welche  <prlw1 cam ac uk>
 
diff --git a/Src/DasherCore/AutoSpeedControl.cpp b/Src/DasherCore/AutoSpeedControl.cpp
index e0cefe4..b8813e9 100644
--- a/Src/DasherCore/AutoSpeedControl.cpp
+++ b/Src/DasherCore/AutoSpeedControl.cpp
@@ -181,17 +181,9 @@ inline void CAutoSpeedControl::UpdateSigmas(double r, double dFrameRate)
 void CAutoSpeedControl::SpeedControl(myint iDasherX, myint iDasherY, double dFrameRate, CDasherView *pView) {
   if(GetBoolParameter(BP_AUTO_SPEEDCONTROL) && !GetBoolParameter(BP_DASHER_PAUSED)) {
     
-//  Coordinate transforms:    
-    iDasherX = myint(pView->xmap(iDasherX / static_cast < double >(GetLongParameter(LP_MAX_Y))) * GetLongParameter(LP_MAX_Y));
-    iDasherY = myint(pView->ymap(iDasherY));
-
-    myint iDasherOX = myint(pView->xmap(GetLongParameter(LP_OX) / static_cast < double >(GetLongParameter(LP_MAX_Y))) * GetLongParameter(LP_MAX_Y));
-    myint iDasherOY = myint(pView->ymap(GetLongParameter(LP_OY)));
-
-    double x = -(iDasherX - iDasherOX) / double(iDasherOX); //Use normalised coords so min r works 
-    double y = -(iDasherY - iDasherOY) / double(iDasherOY); 
-    double theta = atan2(y, x);
-    double r = sqrt(x * x + y * y);
+//  Coordinate transforms:
+	double r,theta;
+	pView->Dasher2Polar(iDasherX, iDasherY, r, theta);
 
     m_dBitrate = GetLongParameter(LP_MAX_BITRATE) / 100.0; //  stored as long(round(true bitrate * 100))
 
diff --git a/Src/DasherCore/DasherView.h b/Src/DasherCore/DasherView.h
index fca7bd2..041666d 100644
--- a/Src/DasherCore/DasherView.h
+++ b/Src/DasherCore/DasherView.h
@@ -104,21 +104,15 @@ public:
 
   virtual void Dasher2Screen(myint iDasherX, myint iDasherY, screenint & iScreenX, screenint & iScreenY) = 0;
 
+  ///
+  /// Convert Dasher co-ordinates to polar co-ordinates (r,theta), with 0<r<1, 0<theta<2*pi
+  ///
+  virtual void Dasher2Polar(myint iDasherX, myint iDasherY, double &r, double &theta) = 0;
 
   virtual bool IsNodeVisible(myint y1, myint y2) { return true; };
 
   virtual void VisibleRegion( myint &iDasherMinX, myint &iDasherMinY, myint &iDasherMaxX, myint &iDasherMaxY ) = 0;
 
-  /// \todo This function is only public (and in the parent class)
-  /// because of the slightly hacky conversion needed for auto speed
-  /// control. At some point find a way to make this more sensible.
-  virtual double xmap(double x) const = 0;
-
-  /// \todo This function is only public (and in the parent class)
-  /// because of the slightly hacky conversion needed for auto speed
-  /// control. At some point find a way to make this more sensible.
-  virtual double ymap(double x) const = 0;
-
   /// @}
 
   /// Change the screen - must be called if the Screen is replaced or resized
diff --git a/Src/DasherCore/DasherViewSquare.cpp b/Src/DasherCore/DasherViewSquare.cpp
index fd79fd8..a204503 100644
--- a/Src/DasherCore/DasherViewSquare.cpp
+++ b/Src/DasherCore/DasherViewSquare.cpp
@@ -894,6 +894,19 @@ void CDasherViewSquare::Dasher2Screen(myint iDasherX, myint iDasherY, screenint
   }
 }
 
+void CDasherViewSquare::Dasher2Polar(myint iDasherX, myint iDasherY, double &r, double &theta) {
+	iDasherX = myint(xmap(iDasherX / static_cast < double >(GetLongParameter(LP_MAX_Y))) * GetLongParameter(LP_MAX_Y));
+    iDasherY = myint(m_ymap.map(iDasherY));
+	
+    myint iDasherOX = myint(xmap(GetLongParameter(LP_OX) / static_cast < double >(GetLongParameter(LP_MAX_Y))) * GetLongParameter(LP_MAX_Y));
+    myint iDasherOY = myint(m_ymap.map(GetLongParameter(LP_OY)));
+	
+    double x = -(iDasherX - iDasherOX) / double(iDasherOX); //Use normalised coords so min r works 
+    double y = -(iDasherY - iDasherOY) / double(iDasherOY); 
+    theta = atan2(y, x);
+    r = sqrt(x * x + y * y);
+}
+
 void CDasherViewSquare::VisibleRegion( myint &iDasherMinX, myint &iDasherMinY, myint &iDasherMaxX, myint &iDasherMaxY ) {
   // TODO: Change output parameters to pointers and allow NULL to mean
   // 'I don't care'. Need to be slightly careful about this as it will
diff --git a/Src/DasherCore/DasherViewSquare.h b/Src/DasherCore/DasherViewSquare.h
index 60bb9e6..a8a8ad9 100644
--- a/Src/DasherCore/DasherViewSquare.h
+++ b/Src/DasherCore/DasherViewSquare.h
@@ -78,6 +78,11 @@ public:
   ///
   void Dasher2Screen(myint iDasherX, myint iDasherY, screenint & iScreenX, screenint & iScreenY);
 
+  ///
+  /// Convert Dasher co-ordinates to polar co-ordinates (r,theta), with 0<r<1, 0<theta<2*pi
+  ///
+  virtual void Dasher2Polar(myint iDasherX, myint iDasherY, double &r, double &theta);	
+	
   /// 
   /// Return true if a node spanning y1 to y2 is entirely enclosed by
   /// the screen boundary
@@ -89,11 +94,6 @@ public:
   ///
   void VisibleRegion( myint &iDasherMinX, myint &iDasherMinY, myint &iDasherMaxX, myint &iDasherMaxY );
 
-  double xmap(double x) const;
-  double ymap(double x) const {
-    return m_ymap.map( (myint)x );
-  };
-
   /// @}
 
 
@@ -151,7 +151,7 @@ private:
 #endif
 
   // Class definitions
-
+  ///Implements the non-linearity near the extremes of the Y axis
   class Cymap {
   public:
     Cymap(myint iScale);
@@ -162,6 +162,7 @@ private:
     myint m_Y1, m_Y2, m_Y3;
   };
 
+  double xmap(double x) const;
   double xmax(double x, double y) const;
   double ixmap(double x) const;
   inline void Crosshair(myint sx);