Fixed adding a line to wxGraphicsPath with GDI+ renderer.

When current point is not yet set then wxGraphicsPath::AddLineToPoint() should behave as MoveToPoint().

See #17525

interface/wx/graphics.h

@@ -79,10 +79,14 @@ public:
 
     /**
         Adds a straight line from the current point to (@a x,@a y).
+        If current point is not yet set before the call to AddLineToPoint()
+        this function will behave as MoveToPoint().
     */
     virtual void AddLineToPoint(wxDouble x, wxDouble y);
     /**
         Adds a straight line from the current point to @a p.
+        If current point is not yet set before the call to AddLineToPoint()
+        this function will behave as MoveToPoint().
     */
     void AddLineToPoint(const wxPoint2DDouble& p);
 
@@ -108,7 +112,7 @@ public:
         Appends a rounded rectangle as a new closed subpath.
         If @a radius equals 0 this function will behave as AddRectangle(),
         otherwise after this call the current point will be at
-        (@a x+@a w, @a y + @a h/2).
+        (@a x+@a w, @a y+@a h/2).
     */
     virtual void AddRoundedRectangle(wxDouble x, wxDouble y, wxDouble w,
                                      wxDouble h, wxDouble radius);

src/msw/graphics.cpp

@@ -1220,7 +1220,14 @@ void wxGDIPlusPathData::AddLineToPoint( wxDouble x , wxDouble y )
     }
     else
     {
-        m_path->GetLastPoint(&start);
+        Status st = m_path->GetLastPoint(&start);
+        // If current point is not yet set then
+        // this function should behave as MoveToPoint.
+        if ( st != Ok )
+        {
+            MoveToPoint(x, y);
+            return;
+        }
     }
     m_path->AddLine(start.X, start.Y, (REAL)x, (REAL)y);
 }