Delphi: Minimize application to systray - windows

Question

I want to minimize a Delphi application to the systray instead of the task bar.
The necessary steps seem to be the following:
Create icon which should then be displayed in the systray.
When the user clicks the [-] to minimize the application, do the following:
Hide the form.
Add the icon (step #1) to the systray.
Hide/delete the application's entry in the task bar.
When the user double-clicks the application's icon in the systray, do the following:
Show the form.
Un-minimize the application again and bring it to the front.
If "WindowState" is "WS_Minimized" set to "WS_Normal".
Hide/delete the application's icon in the systray.
When the user terminates the application, do the following:
Hide/delete the application's icon in the systray.
That's it. Right?
How could one implement this in Delphi?
I've found the following code but I don't know why it works. It doesn't follow my steps described above ...
unit uMinimizeToTray;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls, ShellApi;
const WM_NOTIFYICON = WM_USER+333;
type
TMinimizeToTray = class(TForm)
procedure FormCreate(Sender: TObject);
procedure FormClose(Sender: TObject; var Action: TCloseAction);
procedure CMClickIcon(var msg: TMessage); message WM_NOTIFYICON;
private
{ Private-Deklarationen }
public
{ Public-Deklarationen }
end;
var
MinimizeToTray: TMinimizeToTray;
implementation
{$R *.dfm}
procedure TMinimizeToTray.CMClickIcon(var msg: TMessage);
begin
if msg.lparam = WM_LBUTTONDBLCLK then Show;
end;
procedure TMinimizeToTray.FormCreate(Sender: TObject);
VAR tnid: TNotifyIconData;
HMainIcon: HICON;
begin
HMainIcon := LoadIcon(MainInstance, 'MAINICON');
Shell_NotifyIcon(NIM_DELETE, #tnid);
tnid.cbSize := sizeof(TNotifyIconData);
tnid.Wnd := handle;
tnid.uID := 123;
tnid.uFlags := NIF_MESSAGE or NIF_ICON or NIF_TIP;
tnid.uCallbackMessage := WM_NOTIFYICON;
tnid.hIcon := HMainIcon;
tnid.szTip := 'Tooltip';
Shell_NotifyIcon(NIM_ADD, #tnid);
end;
procedure TMinimizeToTray.FormClose(Sender: TObject; var Action: TCloseAction);
begin
Action := caNone;
Hide;
end;
end.

Answer 1

If it still works, it's probably easiest to use JVCL's TJvTrayIcon to handle it automatically.

Answer 2

I would recommend using CoolTrayIcon. The author has already worked out all the issues involved with tray icons. Its free with source and examples and very debugged.
http://subsimple.com/delphi.asp

Answer 3

Instead of Application.BringToFront; use SetforegroundWindow(Application.Handle);

Answer 4

In the following text I'll be referring to the step numbers mentioned in the question:
The following solution is without any additional components. It's very easy to implement.
Step #1:
Just use the application's main icon (see following code).
Step #2:
procedure TForm1.ApplicationEvents1Minimize(Sender: TObject);
begin
Shell_NotifyIcon(NIM_ADD, #TrayIconData);
Form1.Hide;
end;
Step #3:
procedure TForm1.TrayMessage(var Msg: TMessage);
begin
if Msg.lParam = WM_LBUTTONDOWN then begin
Form1.Show;
Form1.WindowState := wsNormal;
Application.BringToFront;
Shell_NotifyIcon(NIM_DELETE, #TrayIconData);
end;
end;
Step #4:
procedure TForm1.FormDestroy(Sender: TObject);
begin
Shell_NotifyIcon(NIM_DELETE, #TrayIconData);
end;
Necessary code in interface part:
uses
[...], ShellApi;
const
WM_ICONTRAY = WM_USER + 1;
type
TForm1 = class(TForm)
[...]
procedure TrayMessage(var Msg: TMessage); message WM_ICONTRAY;
end;
The only problem: The application can be minimized to the systray only once. The next time you want to minimize it, nothing will happen. Why?
Source: delphi.about.com