如何在image中画任意线(50分)

按下鼠标后，任意移动鼠标，在image上出现线条。
最好随鼠标移动实时出现

var
pts:array [0..1] of TPoint;
isDraw : boolean;
procedure TForm1.Image1MouseDown(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
begin
pts[0]:= Point(X, Y);
pts[1]:= Point(X, Y);
isDraw:=true;
end;

procedure TForm1.Image1MouseMove(Sender: TObject; Shift: TShiftState; X,
Y: Integer);
begin
if isDraw then
begin
Canvas.Pen.Style:= psDot;//线型
Canvas.Pen.Color:= clGray;//颜色
Canvas.Pen.Mode := pmNotXor;
Canvas.MoveTo(pts[0].X, pts[0].Y);
Canvas.LineTo(pts[1].X, pts[1].Y);
Canvas.MoveTo(pts[0].X, pts[0].Y);
Canvas.LineTo(X, Y);
pts[1] := Point(X, Y);
Canvas.Pen.Mode := pmCopy;
end;
end;

procedure TForm1.Image1MouseUp(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
begin
// Canvas.Pen.Mode := pmNotXor;
// Canvas.MoveTo(pts[0].X, pts[0].Y);
// Canvas.LineTo(X, Y);
// Canvas.Pen.Mode := pmCopy;
//如果不需要保留线段，则使用上面几句
isDraw:=false;
end;
不好意思，匆匆忙忙没有调试。现更正。

谢谢楼上的程序。
可是我要的是沿鼠标移动轨迹的任意线（就是按住鼠标拖出一条任意线），您给的只是直线啊

考虑用控件拖动，如：shape

哈哈，这个更简单了
var
pt: TPoint;
isDraw : boolean;
procedure TForm1.Image1MouseDown(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
begin
pt:= Point(X, Y);
isDraw:=true;
end;

procedure TForm1.Image1MouseMove(Sender: TObject; Shift: TShiftState; X,
Y: Integer);
begin
if isDraw then
begin
Canvas.Pen.Style:= psSolid;//线型
Canvas.Pen.Color:= clRed;//颜色
Canvas.Pen.Width:=2;//线宽
Canvas.MoveTo(pt.X, pt.Y);
Canvas.LineTo(X, Y);
pt := Point(X, Y);
Canvas.Pen.Mode := pmCopy;
end;
end;

procedure TForm1.Image1MouseUp(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
begin
isDraw:=false;
end;

接受答案了.