Too much calls paint method

Question

I created a test component

unit Control1;

interface

uses
  System.SysUtils, System.Classes, FMX.Types, FMX.Controls;

type
  TTestComp = class(TControl)
  private
    i: integer;
  protected
    procedure Paint; override;
  public
    constructor Create(AOwner: TComponent); override;
  published
    property Width;
    property Height;
  end;

procedure Register;

implementation

procedure Register;
begin
  RegisterComponents('Test', [TTestComp]);
end;

{ TTestComp }

constructor TTestComp.Create(AOwner: TComponent);
begin
  inherited Create(AOwner);
  i := 0;
end;

procedure TTestComp.Paint;
begin
  inherited;
  inc(i);
  canvas.BeginScene;
  canvas.Fill.Color := $FF000000;
  canvas.FillRect(localrect, 0, 0, [], 1);
  canvas.Fill.Color := $FFFFFFFF;
  canvas.FillText(localrect, IntToStr(i), false, 1, [], TTextAlign.Center);
  canvas.EndScene;
end;

end.

Here is the problem:

Component is drawing in top-left corner
Too much paint method calls when resizing form.

Just resized form.

I have a lot of components, built according to this principle. And when I change the size of the form, they begin to lag (Low FPS).

Standard components (TButton and etc.) work fine

How have determined that Paint is called too many times? How many times should it be called and how many times is or called? — David Heffernan, Jun 27 '16 at 13:52
@DavidHeffernan look at the Paint procedure in my method. It's increases var "I" each time it repainting. — Vlad Romanovsky, Jun 27 '16 at 14:13
That addresses how many times it is called. How can you determine how many times is **should** be called, and why is that number too great. — David Heffernan, Jun 27 '16 at 14:30

score 0 · Answer 1 · answered Jun 27 '16 at 14:21

1.Component is drawing in top-left corner

Your component is drawing exactly where it is placed (Position property). If you don't assign any values to Position.X and Position.Y the default values 0 is used for both.

2.Too much paint method calls when resizing form.

When you resize the form all components are re-painted, also f.ex. buttons. In a test with 81 of your controls I did not realize any lagging (but I assume your actual controls do some more painting than this example control).

Too much calls paint method

1 Answers1