Mega Code Archive
How to set properties without triggering an event
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//Some components will trigger OnChange, OnClick, etc. events
//even if a property is changed programmatically,
//not by the user.
unit Unit1;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls,Menus,ComCtrls;
type
TForm1 = class(TForm)
CheckBox1: TCheckBox;
Button1: TButton;
procedure CheckBox1Click(Sender: TObject);
procedure Button1Click(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;
var
Form1: TForm1;
implementation
{$R *.dfm}
//Here are some examples how to avoid these events.
procedure SetCheckBox(C: TCheckBox; V: Boolean);
var
N: TNotifyEvent;
begin
with C do
begin
N:= OnClick;
OnClick:= nil;
Checked:= V;
OnClick:= N;
end;
end;
procedure SetMenuCheck(C: TMenuItem; V: Boolean);
var
N: TNotifyEvent;
begin
with C do
begin
N:= OnClick;
OnClick:= nil;
Checked:= V;
OnClick:= N;
end;
end;
procedure TrackPos(C: TTrackBar; V: Integer);
var
N: TNotifyEvent;
begin
with C do
begin
N:= OnChange;
OnChange:= nil;
Position:= V;
OnChange:= N;
end;
end;
procedure TForm1.CheckBox1Click(Sender: TObject);
begin
Showmessage('Clicked');
end;
//Test:
procedure TForm1.Button1Click(Sender: TObject);
begin
SetCheckBox(CheckBox1, True);
end;
end.
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