Fix ICairoShim interface: replace volatile with virtual

engine/cairoShim.h

@@ -17,41 +17,42 @@ namespace minsky
   class ICairoShim
   {
   public:
-    volatile void moveTo(double x, double y)=0;
-    volatile void lineTo(double x, double y)=0;
-    volatile void relMoveTo(double x, double y)=0;
-    volatile void relLineTo(double x, double y)=0;
-    volatile void arc(double x, double y, double radius, double start, double end)=0;
+    virtual ~ICairoShim() = default;
+    virtual void moveTo(double x, double y)=0;
+    virtual void lineTo(double x, double y)=0;
+    virtual void relMoveTo(double x, double y)=0;
+    virtual void relLineTo(double x, double y)=0;
+    virtual void arc(double x, double y, double radius, double start, double end)=0;
 
-    volatile void setLineWidth(double)=0;
+    virtual void setLineWidth(double)=0;
 
     // paths
-    volatile void newPath()=0;
-    volatile void closePath()=0;
-    volatile void fill()=0;
-    volatile void clip()=0;
-    volatile void stroke()=0;
-    volatile void strokePreserve()=0;
+    virtual void newPath()=0;
+    virtual void closePath()=0;
+    virtual void fill()=0;
+    virtual void clip()=0;
+    virtual void stroke()=0;
+    virtual void strokePreserve()=0;
 
     // sources
-    volatile void setSourceRGB(double r, double g, double b)=0;
-    volatile void setSourceRGBA(double r, double g, double b, double a)=0;
+    virtual void setSourceRGB(double r, double g, double b)=0;
+    virtual void setSourceRGBA(double r, double g, double b, double a)=0;
 
     // text. Argument is in UTF8 encoding
-    volatile void showText(const std::string&)=0;
-    volatile void setTextExtents(const std::string&)=0;
-    volatile double textWidth() const=0;
-    volatile double textHeight() const=0;
+    virtual void showText(const std::string&)=0;
+    virtual void setTextExtents(const std::string&)=0;
+    virtual double textWidth() const=0;
+    virtual double textHeight() const=0;
 
     // matrix transformation
-    volatile void identityMatrix()=0;
-    volatile void translate(double x, double y)=0;
-    volatile void scale(double sx, double sy)=0;
-    volatile void rotate(double angle)=0; ///< angle in radians
+    virtual void identityMatrix()=0;
+    virtual void translate(double x, double y)=0;
+    virtual void scale(double sx, double sy)=0;
+    virtual void rotate(double angle)=0; ///< angle in radians
 
     // context manipulation
-    volatile void save()=0;
-    volatile void restore()=0;
+    virtual void save()=0;
+    virtual void restore()=0;
 
   };