TColorBox bad performance, if style differs from default

[Perpeto 5]

I have a test application, where i only have a TColorBox-Component. If I change the style in any way, it takes ~20ms to initialise. In Delphi11 it's faster than in Delphi12, because Delphi12 has more Colors in "System.UIConsts".

In our "real" application we do have some dialogs with 20 or more coloroboxes, which adds up to 700ms per Dialog only to initialize those colorboxes. 

 

We assume, that the issue is in TCustomColorBox.PopulateList or more preciseley "TCustomColorBox.ColorCallBack".

Does anyone have tips how to speed things up or what i do wrong here?

 

Thanks!

unit colorbox_performance;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Vcl.ExtCtrls;

type
  TForm22 = class(TForm)
    ColorBox1: TColorBox;
    procedure FormShow(Sender: TObject);
  end;

var
  Form22: TForm22;

implementation

uses
  diagnostics;

{$R *.dfm}

{ TForm22 }
procedure TForm22.FormShow(Sender: TObject);
begin
  var StopWatch := TStopwatch.StartNew;
  ColorBox1.Style := ColorBox1.Style - [cbStandardColors];
  ShowMessage(format('%dms', [round(StopWatch.Elapsed.TotalMilliseconds)]));
end;

.

[dwrbudr 8]

If all or most of the comboboxes need to be populated with the same items, then cache the Items of one combobox to a TStringList.

Then use ColorBox1.Items := CachedColorItems instead of setting its Style. On my side it increases the performance from 20ms to 15ms