Add-a-Minimize-event-to-your-form


            Title: Add a Minimize event to your form
Question: Have you ever wanted, that your form gets an event when it was minimized?
Answer:
Try this extension to the normal form. You can assign a handler to the OnMnimize property and choose from three "automatic" actions built in in the form:
tmNone = Dont minimize the Window
tmWindow = minimize the Window as usual
tmAll = Minimze all windows of the application
Installation: Put the Unit in the library folder of your delphi compiler and import it to your form sourcecode.
Usage: Replace the
type TMyForm = class (TForm) 
of your form with
type TMyForm = class (TMiniForm) 
Thats all. Assign the OnMinimze property at runtime. Example:
procedure TMyForm.MyMinimize (Sender: TObject; var state: TMiniState);
begin
 state:= tmAll; // minimize all windows
end;
procedure TMyForm.FormCreate;
begin
 OnMinimize:= MyMinimize;
end;
//---------------------------------------------------------
unit MiniForm;
interface
uses Windows, Messages, SysUtils, Classes, Graphics, Controls,
 Forms, Dialogs, StdCtrls, ExtCtrls, ComCtrls, Mask, Menus;
// state flags for automatic handling of minimize events
type TMiniState = (tmNone, // dont react to the message
 tmWindow, // minimize the window
 tmAll); // minimze all windows of the app
// the minimize event himself
type TMinimizeEvent = procedure (Sender: TObject;
 var state: TMiniState) of object;
type TMiniForm = class (TForm) // derived from TForm
 private
 FOnMinimize: TMinimizeEvent;
 FOnRestore: TNotifyEvent;
 procedure WMSIZE(Var Msg: TWMSIZE); Message WM_SIZE;
 procedure WinRestore (Sender: TObject);
 public
 constructor Create (AOwner: TComponent); override;
 destructor Destroy; override;
 published
 property OnMinimize: TMinimizeEvent read FOnMinimize
 write FOnminimize;
 end;
implementation
destructor TMiniForm.Destroy;
begin
 inherited
end;
constructor TMiniForm.Create (AOwner: TComponent);
begin
 FOnMinimize:= NIL;
 inherited;
end;
procedure TMiniForm.WMSIZE (VAR msg: TWMSIZE);
// catch the WM_SIZE message to know what happend
var status: TMiniState;
begin
 if msg.SizeType = integer (wsMinimized) THEN BEGIN
 IF Assigned (FOnMinimize) then begin
 status:= tmWindow; // Default action
 FOnMinimize (self, status);
 case status OF
 tmNone: // Tell windows to restore the window immedately
 PostMessage(Handle, WM_SYSCOMMAND, SC_RESTORE, 0);
 tmWindow: ; // All is done by windows and Delphi
 tmAll: // Minimize all windows of the app
 begin
 // Store the OnRestore event
 FOnRestore:= Application.OnRestore;
 // Replace it with own handler
 Application.OnRestore:= WinRestore;
 // Minimize all
 Application.Minimize;
 end;
 end;
 end;
 end;
 inherited; // Call other hanlder of WMSIZE event
end;
procedure TMiniForm.WinRestore (Sender: TObject);
// handles restoring of the windows
begin
 // made Window normal
 WindowState:= wsNormal;
 // Restore other Windows of the app
 Application.Restore;
 // Restore the old Restore handler
 Application.OnRestore:= FOnRestore;
 // Call the restore handler
 IF Assigned (FOnRestore) then FOnRestore (sender);
end;
end.
Forms Delphi
