The following example shows how to tell the distance between two points. In this example, the caption of the form shows the current point and distance from the center of the form. The y coordinates are inverted to show a more natural north orientation where north is directly up.

Example:

funcTion Distance(Pt : TPoint; Pt2 : TPoint) : Double; var dx : LongInt; dy : LongInt; begin dx:= pt .x - pt2.x; dy:= pt .y - pt2.y; Result := Sqrt((Dx * Dx) + (Dy * Dy)); end;

procedure TForm .FormMouseMove(Sender: TObject; Shift: TShiftState; X, Y: Integer); var Pt : TPoint; Pt2 : TPoint; Dist : Double; begin Pt .x := Form .Width div 2; Pt .y := Form .Height div 2; Pt2.x := x; Pt2.y := y; Dist := Distance(Pt , Pt2); Form .Caption := IntToStr(Pt2.x - Pt .x) + #32 + IntToStr(Pt .y - Pt2.y) + ' = ' + FloatToStr(Dist); end; procedure TForm .FormPaint(Sender: TObject); begin Form .Canvas.MoveTo(Form .Width div 2, 0); Form .Canvas.LineTo(Form .Width div 2, Form .Height); Form .Canvas.MoveTo(0, Form .Height div 2); Form .Canvas.LineTo(Form .Width, Form .Height div 2); end;

procedure TForm .FormResize(Sender: TObject); begin Invalidate; end; 7/ 6/98 4:3 :28 PM