Delphi: How do you control multiple alike objects? - delphi

Question

Say that I have five TRectangle objects, and a function is going to pass a parameter in to make one of them blink.
I know how to control one object like the following code:
procedure TForm1.TimerTimer(Sender: TObject);
begin
if rect1.Visible then
rect1.Visible := false
else
rect1.Visible := true;
end;
procedure TForm1.Blink_Square;
begin
Timer := TTimer.Create(nil);
Timer.OnTimer := TimerTimer;
rect1.Fill.Color := TAlphacolors.Red;
rect1.fill.Kind := TBrushKind.bkSolid;
rect1.Stroke.Thickness := 1;
rect1.Stroke.Color := Talphacolors.Darkgray;
Timer.Interval := 500;
Timer.Enabled := True;
end;
But I really wonder if there is a way that I can use the blink square repeatedly like having a procedure as procedure TForm1.Blink_Square(rec_number: integer); And we can call Blink_Square(5); to make rect5 blink.
Thanks in Advance

Answer 1

You can store your objects in an array or list, then use your procedure parameter to index into it.
var
Blinks: array[1..5] of record
Rectangle: TRectangle;
Timer: TTimer;
end;
procedure TForm1.FormCreate(Sender: TObject);
begin
Blinks[1].Rectangle := Rect1;
Blinks[1].Timer := nil;
Blinks[2].Rectangle := Rect2;
Blinks[2].Timer := nil;
Blinks[3].Rectangle := Rect3;
Blinks[3].Timer := nil;
Blinks[4].Rectangle := Rect4;
Blinks[4].Timer := nil;
Blinks[5].Rectangle := Rect5;
Blinks[5].Timer := nil;
end;
procedure TForm1.TimerTimer(Sender: TObject);
var
Timer: TTimer;
begin
Timer := TTimer(Sender);
Blinks[Timer.Tag].Visible := not Blinks[Timer.Tag].Visible;
end;
procedure TForm1.Blink_Square(Number: Integer);
begin
Blinks[Number].Rectangle.Fill.Color := TAlphacolors.Red;
Blinks[Number].Rectangle.fill.Kind := TBrushKind.bkSolid;
Blinks[Number].Rectangle.Stroke.Thickness := 1;
Blinks[Number].Rectangle.Stroke.Color := Talphacolors.Darkgray;
if Blinks[Number].Timer = nil then
begin
Blinks[Number].Timer := TTimer.Create(Self);
Blinks[Number].Timer.OnTimer := TimerTimer;
Blinks[Number].Timer.Interval := 500;
Blinks[Number].Timer.Tag := Number;
Blinks[Number].Timer.Enabled := True;
end;
end;
Alternatively:
var
Rects: array[1..5] of TRectangle;
procedure TForm1.FormCreate(Sender: TObject);
begin
Rects[1] := Rect1;
Rects[2] := Rect2;
Rects[3] := Rect3;
Rects[4] := Rect4;
Rects[5] := Rect5;
end;
procedure TForm1.TimerTimer(Sender: TObject);
begin
TRectangle(Sender).Visible := not TRectangle(Sender).Visible;
end;
procedure TForm1.Blink_Square(Number: Integer);
var
Rec: TRectangle;
Timer: TTimer;
M: TNotifyEvent;
begin
Rec := Rects[Number];
Rec.Fill.Color := TAlphacolors.Red;
Rec.fill.Kind := TBrushKind.bkSolid;
Rec.Stroke.Thickness := 1;
Rec.Stroke.Color := Talphacolors.Darkgray;
if Rec.Tag = 0 then
begin
M := TimerTimer;
TMethod(M).Data := Rec;
Timer := TTimer.Create(Rec);
Timer.OnTimer := M;
Timer.Interval := 500;
Timer.Enabled := True;
Rec.Tag := NativeInt(Timer);
end;
end;