[DUG] Arc Solved

[Marshland Engineering]

The problem came in with the interpreation

DELPHI The arc traverses the perimeter of an ellipse that is bounded by the points (X1,Y1) and (X2,Y2). The arc is drawn following the perimeter of the ellipse, counterclockwise, from the starting point to the ending point.

Is the arc or the ellipse bounded by (X1Y1)  (X2Y2)? 

It is actually the ellipse.

The solution is quite simple.  (With the help of Jolyon - Thanks )

         xCtr:=DM.tblOperX1.AsFloat;
         yCtr:=DM.tblOperY1.AsFloat;
         if (dm.tblOper['CW']=False) then  begin
            xStart:=DM.tblOperX2.AsFloat;
            yStart:=DM.tblOperY2.AsFloat;
            xEnd:=DM.tblOperX3.AsFloat;
            yEnd:=DM.tblOperY3.AsFloat;
            end
           else begin
            xStart:=DM.tblOperX3.AsFloat;  //Swop start and end 
            yStart:=DM.tblOperY3.AsFloat;
            xEnd:=DM.tblOperX2.AsFloat;
            yEnd:=DM.tblOperY2.AsFloat;
         end;
         rad:=sqrt(sqr(xStart-xCtr)+sqr(yStart-yCtr));
         TopRH:=round((yCtr+rad)*Scale)+Hoffset;
         TopRV:=round((xCtr-rad)*Scale)+Voffset;
         BotLH:=round((yCtr-rad)*Scale)+Hoffset;
         BotLV:=round((xCtr+rad)*Scale)+Voffset;
         StartH:=round(yStart*Scale)+Hoffset;
         StartV:=round(xStart*Scale)+Voffset;
         EndH:=round(yEnd*Scale)+Hoffset;
         EndV:=round(xEnd*Scale)+Voffset;
         fDraw.Canvas.Arc(TopRH,TopRV,BotLH,BotLV,StartH,StartV,EndH,EndV);

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