Mega Code Archive
Finding distance between two points
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Question:
How can I find the distance between two points?
Answer:
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(Pt1 : TPoint;
Pt2 : TPoint) : Double;
var
dx : LongInt;
dy : LongInt;
begin
dx:= pt1.x - pt2.x;
dy:= pt1.y - pt2.y;
Result := Sqrt((Dx * Dx) + (Dy * Dy));
end;
procedure TForm1.FormMouseMove(Sender: TObject; Shift:
TShiftState; X, Y: Integer);
var
Pt1 : TPoint;
Pt2 : TPoint;
Dist : Double;
begin
Pt1.x := Form1.Width div 2;
Pt1.y := Form1.Height div 2;
Pt2.x := x;
Pt2.y := y;
Dist := Distance(Pt1, Pt2);
Form1.Caption := IntToStr(Pt2.x - Pt1.x) + #32 +
IntToStr(Pt1.y - Pt2.y) + ' = ' +
FloatToStr(Dist);
end;
procedure TForm1.FormPaint(Sender: TObject);
begin
Form1.Canvas.MoveTo(Form1.Width div 2,
0);
Form1.Canvas.LineTo(Form1.Width div 2,
Form1.Height);
Form1.Canvas.MoveTo(0,
Form1.Height div 2);
Form1.Canvas.LineTo(Form1.Width,
Form1.Height div 2);
end;
procedure TForm1.FormResize(Sender: TObject);
begin
Invalidate;
end;
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