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Categories / Delphi / System
 

Build a multi screen emulator

{** Building a multi screen emulator *** I want to present a simple multi-screen emulator written in Delphi. It consists in a little Form placing in the bottom-right corner of the screen, right above the traybar, which consists of 5 buttons. At the beginning the first button is down; then, when I press another button, a new fresh desktop is opened. In this new desktop I can open other programs and so on with the other buttons. When I go back to one of the buttons, I will see only the applications opened in that contest without the others. The trick is to make the following steps just before pressing another button: 1)Get the handles of all the visible windows (except for Desktop, Taskbar and the application itself) 2)Hiding all the windows detecting at step 1). After pressing the button we must: 1)Show all the windows whose handles we got when we left the button itself by pressing another. Of course if a button is pressed for the first time we have no handles so we will have a new fresh desktop. I want to retrieve the handles of all the visible windows: the key is a call to the “EnumWindows” procedure passing as a parameter a callback function called for example “EnumWindowsProc”. This callback function must be of the following type: } function EnumWindowsProc(hWnd: HWND; lParam: LPARAM): Bool; // The EnumWindows function is of type: BOOL EnumWindows( WNDENUMPROC lpEnumFunc, // pointer to callback function LPARAM lParam // application-defined value ); { I will call EnumWindows(@EnumWindowsProc, 0); The “EnumWindows” function loop over all windows (visible or invisible): for each window there is a call to the callback function “EnumWindowsProc” wich must be implemented. The first param “hWnd” is the handle of the current window. A possible implementation of the “EnumWindowsProc” function may be the inserting of every handle in a list. According to our target we must insert in a list the handle of the following windows: 1)Visible windows //(IsWindowVisible(hwnd) = True) 2)Not my application window //var processed: DWORD; //GetWindowThreadProcessID( hwnd, @processID ); //processID <> GetCurrentProcessID 3)Not the taskbar window //hWnd <> FindWindow('Shell_TrayWnd', Nil) 4)Not the desktop window //hWnd <> FindWindow('Progman', Nil) } // This is the code: unit ProcessView; interface uses Windows, Dialogs, SysUtils, Classes, ShellAPI, TLHelp32, Forms; var HandleList: TStringList; function EnumWindowsProc(hWnd: HWND; lParam: lParam): Bool; stdcall; procedure GetProcessList; implementation procedure GetProcessList; var i: integer; begin HandleList.Clear; EnumWindows(@EnumWindowsProc, 0); end; function EnumWindowsProc(hWnd: HWND; lParam: lParam): Bool; var processID: DWORD; begin GetWindowThreadProcessID(hwnd, @processID); if processID <> GetCurrentProcessID then if (hWnd <> FindWindow('Shell_TrayWnd', nil)) and (hWnd <> FindWindow('Progman', nil)) then if IsWindowVisible(hwnd) then begin HandleList.Add(IntToStr(HWnd)); Result := True; end; end; initialization HandleList := TStringList.Create; finalization HandleList.Free; end. { In the main program I used a variable named Monitors of type “array of TstringList” whose dimension is given by the number of buttons (different monitors available) to keep in memory all the hanldes associated with every button. Another variable named CurrentMonitor keeps in memory the index of the actual monitor (the caption of the button). This is the code: } unit Unit1; interface uses Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs, ProcessView, StdCtrls, Buttons, abfComponents, Menus, ImgList, AppEvnts, TrayIcon; type TForm1 = class(TForm) //these are the buttons (1..5) to switch from a monitor to another /// SpeedButton1: TSpeedButton; SpeedButton2: TSpeedButton; SpeedButton3: TSpeedButton; SpeedButton4: TSpeedButton; SpeedButton5: TSpeedButton; /////////////////////////////////////////////////////////////////////// ImageList1: TImageList; //ImageList connected to the Popup menu PopupMenu1: TPopupMenu; //popup menu displayed by the trayicon //PopupMenu Items/////// ShowApplication: TMenuItem; //Show the form HideApplication: TMenuItem; //Hide the form N1: TMenuItem; // - CloseApplication: TMenuItem; //Close the application //////////////////////////////// TrayIcon1: TTrayIcon; //my TrayIcon component; you can use yours procedure SpeedButton1Click(Sender: TObject); procedure FormCreate(Sender: TObject); procedure FormDestroy(Sender: TObject); procedure FormClose(Sender: TObject; var Action: TCloseAction); procedure FormShow(Sender: TObject); procedure ShowApplicationClick(Sender: TObject); //click on ShowApplication (TMenuItem) procedure HideApplicationClick(Sender: TObject); //click on HideApplication (TMenuItem) procedure FormCloseQuery(Sender: TObject; var CanClose: Boolean); procedure CloseApplicationClick(Sender: TObject); //click on CloseApplication (TMenuItem) private { Private declarations } Monitors: array[1..5] of TStringList; CurrentMonitor: Integer; public { Public declarations } end; var Form1: TForm1; implementation {$R *.DFM} procedure TForm1.SpeedButton1Click(Sender: TObject); var i: integer; Rect: TRect; begin // GetProcessList; Monitors[CurrentMonitor].Assign(HandleList); for i := 0 to HandleList.Count - 1 do begin ShowWindow(StrToInt(HandleList.Strings[i]), SW_HIDE); end; CurrentMonitor := StrToInt((Sender as TSpeedButton).Caption); for i := 0 to Monitors[CurrentMonitor].Count - 1 do begin ShowWindow(StrToInt(Monitors[CurrentMonitor].Strings[i]), SW_SHOW); end; end; procedure TForm1.FormCreate(Sender: TObject); var i: integer; begin // ShowWindow(Application.Handle, SW_HIDE); SetWindowLong(Application.Handle, GWL_EXSTYLE, GetWindowLong(Application.Handle, GWL_EXSTYLE) and not WS_EX_APPWINDOW or WS_EX_TOOLWINDOW); ShowWindow(Application.Handle, SW_SHOW); CurrentMonitor := 1; for i := Low(Monitors) to High(Monitors) do Monitors[i] := TStringList.Create; end; procedure TForm1.FormDestroy(Sender: TObject); var i: integer; begin // for i := Low(Monitors) to High(Monitors) do Monitors[i].Free; end; procedure TForm1.FormClose(Sender: TObject; var Action: TCloseAction); var i, j: integer; begin for i := Low(Monitors) to High(Monitors) do begin for j := 0 to Monitors[i].Count - 1 do begin ShowWindow(StrToInt(Monitors[i].Strings[j]), SW_SHOW); end; end; end; procedure TForm1.FormShow(Sender: TObject); begin // Height := 61; Width := 173; Top := Screen.Height - Height - 30; Left := Screen.Width - Width; end; procedure TForm1.ShowApplicationClick(Sender: TObject); begin // Application.MainForm.Show; end; procedure TForm1.HideApplicationClick(Sender: TObject); begin // Application.MainForm.Hide; end; procedure TForm1.FormCloseQuery(Sender: TObject; var CanClose: Boolean); begin // if MessageDlg('Do you want to close Monitors?', mtConfirmation, [mbOK, mbCancel], 0) = mrCancel then CanClose := False; end; procedure TForm1.CloseApplicationClick(Sender: TObject); begin Close; end; end. { In order to prevent multiple instances of the application I inserted some lines of code inside the project source; this is the modified source: } program Project1; uses Forms, Windows, Unit1 in 'Unit1.pas' {Form1}; {$R *.RES} var atom: integer; begin if GlobalFindAtom('Monitors_Procedure_Atom') = 0 then atom := GlobalAddAtom('Monitors_Procedure_Atom') else Exit; Application.Initialize; Application.CreateForm(TForm1, Form1); Application.Run; GlobalDeleteAtom(atom); end. { The GlobalAddAtom function adds a character string to the global atom table and returns a unique value (an atom) identifying the string. The GlobalFindAtom function searches the global atom table for the specified character string and retrieves the global atom associated with that string. If I have already run the programm then the GlobalFindAtom function returns a value <> 0 because the atom is already present: in this case I abort the execution of the program. Instead, if the GlobalFindAtom function returns 0 then this is the first time I run the program, so I create the atom. At the end I delete the atom. In order to remove the button on the taskbar I inserted the following code inside the OnCreate event of the form: } {...} ShowWindow( Application.handle, SW_HIDE ); SetWindowLong( Application.handle, GWL_EXSTYLE, GetWindowLong( application.handle, GWL_EXSTYLE ) and not WS_EX_APPWINDOW or WS_EX_TOOLWINDOW); ShowWindow( Application.handle, SW_SHOW ); {...} { In order to have a tray icon in the traybar (wich display a menu containing showing, hiding and closing of the form), I used a component (TTrayIcon), I built a year ago; this is the source: } unit TrayIcon; interface uses Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs, ShellAPI, extctrls, Menus; const WM_SYSTEM_TRAY_NOTIFY = WM_USER + 1; type TTrayIconMessage =(imClick, imDoubleClick, imMouseDown, imMouseUp, imLeftClickUp, imLeftDoubleClick, imRightClickUp, imRightDoubleClick, imNone); type TTrayIcon = class(TComponent) private { Private declarations } FData: TNotifyIconData; FIsClicked: Boolean; FIcon: TIcon; FIconList: TImageList; FPopupMenu: TPopupMenu; FTimer: TTimer; FHint: string; FIconIndex: integer; FVisible: Boolean; FHide: Boolean; FAnimate: Boolean; FAppRestore: TTrayIconMessage; FPopupMenuShow: TTrayIconMessage; FApplicationHook: TWindowHook; FOnMinimize: TNotifyEvent; FOnRestore: TNotifyEvent; FOnMouseMove: TMouseMoveEvent; FOnMouseExit: TMouseMoveEvent; FOnMouseEnter: TMouseMoveEvent; FOnClick: TNotifyEvent; FOnDblClick: TNotifyEvent; FOnMouseDown: TMouseEvent; FOnMouseUp: TMouseEvent; FOnAnimate: TNotifyEvent; FOnCreate: TNotifyEvent; FOnDestroy: TNotifyEvent; FOnActivate: TNotifyEvent; FOnDeactivate: TNotifyEvent; procedure SetHint(Hint: string); procedure SetHide(Value: Boolean); function GetAnimateInterval: integer; procedure SetAnimateInterval(Value: integer); function GetAnimate: Boolean; procedure SetAnimate(Value: Boolean); procedure EndSession; function ShiftState: TShiftState; protected { Protected declarations } procedure SetVisible(Value: Boolean); virtual; procedure DoMessage(var Message: TMessage);virtual; procedure DoClick; virtual; procedure DoDblClick; virtual; procedure DoMouseMove(Shift: TShiftState; X: integer; Y: integer); virtual; procedure DoMouseDown(Button: TMouseButton; Shift: TShiftState; X: integer; Y: integer); virtual; procedure DoMouseUp(Button: TMouseButton; Shift: TShiftState; X: integer; Y: integer); virtual; procedure DoOnAnimate(Sender: TObject); virtual; procedure Notification(AComponent: TComponent; Operation: TOperation); override; function ApplicationHookProc(var Message: TMessage): Boolean; procedure Loaded(); override; property Data: TNotifyIconData read FData; public { Public declarations } constructor Create(Owner: TComponent); override; destructor Destroy; override; procedure Minimize(); virtual; procedure Restore(); virtual; procedure Update(); virtual; procedure ShowMenu(); virtual; procedure SetIconIndex(Value: integer); virtual; procedure SetDefaultIcon(); virtual; function GetHandle():HWND; published { Published declarations } property Visible: Boolean read FVisible write SetVisible default false; property Hint: string read FHint write SetHint; property PopupMenu: TPopupMenu read FPopupMenu write FPopupMenu; property Hide: Boolean read FHide write SetHide; property RestoreOn: TTrayIconMessage read FAppRestore write FAppRestore; property PopupMenuOn: TTrayIconMessage read FPopupMenuShow write FPopupMenuShow; property Icons: TImageList read FIconList write FIconList; property IconIndex: integer read FIconIndex write SetIconIndex default 0; property AnimateInterval: integer read GetAnimateInterval write SetAnimateInterval default 1000; property Animate: Boolean read GetAnimate write SetAnimate default false; property Handle: HWND read GetHandle; // Events property OnMinimize: TNotifyEvent read FOnMinimize write FOnMinimize; property OnRestore: TNotifyEvent read FOnRestore write FOnRestore; property OnClick: TNotifyEvent read FOnClick write FOnClick; property OnMouseEnter: TMouseMoveEvent read FOnMouseEnter write FOnMouseEnter; property OnMouseExit: TMouseMoveEvent read FOnMouseExit write FOnMouseExit; property OnMouseMove: TMouseMoveEvent read FOnMouseMove write FOnMouseMove; property OnMouseUp:TMouseEvent read FOnMouseUp write FOnMouseUp; property OnMouseDown: TMouseEvent read FOnMouseDown write FOnMouseDown; property OnAnimate: TNotifyEvent read FOnAnimate write FOnAnimate; property OnCreate: TNotifyEvent read FOnCreate write FOnCreate; property OnDestroy: TNotifyEvent read FOnDestroy write FOnDestroy; property OnActivate: TNotifyEvent read FOnActivate write FOnActivate; property OnDeactivate: TNotifyEvent read FOnDeactivate write FOnDeactivate; end; procedure Register; implementation procedure Register; begin RegisterComponents('Carlo Pasolini', [TTrayIcon]); end; constructor TTrayIcon.Create(Owner: TComponent); begin inherited; FIcon := TIcon.Create(); FTimer := TTimer.Create(nil); FIconIndex := 0; FIcon.Assign(Application.Icon); FAppRestore := imDoubleClick; FOnAnimate := DoOnAnimate; FPopupMenuShow := imNone; FVisible := false; FHide := true; FTimer.Enabled := false; FTimer.OnTimer := OnAnimate; FTimer.Interval := 1000; if not (csDesigning in ComponentState) then begin FillChar(FData, sizeof(TNotifyIconData), #0); // memset(&FData, 0, sizeof(TNotifyIconData)); FData.cbSize := sizeof(TNotifyIconData); FData.Wnd := AllocateHWnd(DoMessage); FData.uID := UINT(Self); FData.hIcon := FIcon.Handle; FData.uFlags := NIF_ICON or NIF_MESSAGE; FData.uCallbackMessage := WM_SYSTEM_TRAY_NOTIFY; FApplicationHook := ApplicationHookProc; Update; end; end; //--------------------------------------------------------------------------- destructor TTrayIcon.Destroy(); begin if not (csDesigning in ComponentState) then begin Shell_NotifyIcon(NIM_DELETE, @FData); //booh forse @FData DeallocateHWnd(FData.Wnd); end; if (Assigned(FIcon)) then FIcon.Free; if (Assigned(FTimer)) then FTimer.Free; inherited; end; //--------------------------------------------------------------------------- procedure TTrayIcon.Notification(AComponent: TComponent; Operation: TOperation); begin inherited Notification(AComponent, Operation); if Operation = opRemove then begin if (AComponent = FIconList) then FIconList := nil else if (AComponent = FPopupMenu) then FPopupMenu := nil; end; end; //--------------------------------------------------------------------------- procedure TTrayIcon.Loaded(); begin inherited Loaded(); if (not Assigned(FIconList)) then begin FAnimate := false; FIcon.Assign(Application.Icon); end else begin FTimer.Enabled := FAnimate; FIconList.GetIcon(FIconIndex, FIcon); end; Update(); end; //--------------------------------------------------------------------------- procedure TTrayIcon.SetVisible(Value: Boolean); begin FVisible := Value; if not (csDesigning in ComponentState) then begin if FVisible then begin if (not Shell_NotifyIcon(NIM_ADD, @FData)) then raise EOutOfResources.Create('Cannot Create System Shell Notification Icon'); Hide := true; Application.HookMainWindow(FApplicationHook); end else begin if (not Shell_NotifyIcon(NIM_DELETE, @FData)) then raise EOutOfResources.Create('Cannot Remove System Shell Notification Icon'); Hide := false; Application.UnhookMainWindow(FApplicationHook); end; end; end; //--------------------------------------------------------------------------- procedure TTrayIcon.SetHint(Hint: string); begin // The new hint must be different than the previous hint and less than // 64 characters to be modified. 64 is an operating system limit. if ((FHint <> Hint) and (Length(Hint) < 64)) then begin FHint := Hint; StrPLCopy(FData.szTip, Hint, sizeof(FData.szTip) - 1); // If there is no hint then there is no tool tip. if (Length(Hint) <> 0) then FData.uFlags := FData.uFlags or NIF_TIP else FData.uFlags := FData.uFlags and (not NIF_TIP); Update(); end; end; //--------------------------------------------------------------------------- procedure TTrayIcon.SetHide(Value: Boolean); begin FHide := Value; end; //--------------------------------------------------------------------------- function TTrayIcon.GetAnimateInterval(): integer; begin Result := FTimer.Interval; end; //--------------------------------------------------------------------------- procedure TTrayIcon.SetAnimateInterval(Value: integer); begin FTimer.Interval := Value; end; //--------------------------------------------------------------------------- function TTrayIcon.GetAnimate(): Boolean; begin Result := FAnimate; end; //--------------------------------------------------------------------------- procedure TTrayIcon.SetAnimate(Value: Boolean); begin if (Assigned(FIconList) or (csLoading in ComponentState)) then FAnimate := Value; if (Assigned(FIconList) and (not (csDesigning in ComponentState))) then FTimer.Enabled := Value; end; //--------------------------------------------------------------------------- procedure TTrayIcon.EndSession(); begin Shell_NotifyIcon(NIM_DELETE, @FData); end; //--------------------------------------------------------------------------- function TTrayIcon.ShiftState(): TShiftState; var Res: TShiftState; begin Res := []; if (GetKeyState(VK_SHIFT) < 0) then Res := Res + [ssShift]; if (GetKeyState(VK_CONTROL) < 0) then Res := Res + [ssCtrl]; if (GetKeyState(VK_MENU) < 0) then Res := Res + [ssAlt]; Result := Res; end; //--------------------------------------------------------------------------- procedure TTrayIcon.DoMessage(var Message: TMessage); var point: TPoint; shift: TShiftState; begin case (Message.Msg) of //begin WM_QUERYENDSESSION: Message.Result := 1; //break; WM_ENDSESSION: EndSession(); //break; WM_SYSTEM_TRAY_NOTIFY: case (Message.LParam) of //begin WM_MOUSEMOVE: if (Assigned(FOnClick)) then begin shift := ShiftState(); GetCursorPos(point); DoMouseMove(shift, point.x, point.y); end; //break; WM_LBUTTONDOWN: begin shift := ShiftState(); shift := shift + [ssLeft]; GetCursorPos(point); DoMouseDown(mbLeft, shift, point.x, point.y); FIsClicked := true; //break; end; WM_LBUTTONUP: begin shift := ShiftState(); shift := shift + [ssLeft]; GetCursorPos(point); if (Assigned(FOnClick)) then DoClick(); DoMouseUp(mbLeft, shift, point.x, point.y); if (FAppRestore = imLeftClickUp) then Restore(); if (FPopupMenuShow = imLeftClickUp) then ShowMenu(); //break; end; WM_LBUTTONDBLCLK: begin DoDblClick(); if (FAppRestore = imLeftDoubleClick) then Restore(); if (FPopupMenuShow = imLeftDoubleClick) then ShowMenu(); //break; end; WM_RBUTTONDOWN: begin shift := ShiftState(); shift := shift + [ssRight]; GetCursorPos(point); DoMouseDown(mbRight, shift, point.x, point.y); //break; end; WM_RBUTTONUP: begin shift := ShiftState(); shift := shift + [ssRight]; GetCursorPos(point); DoMouseUp(mbRight, shift, point.x, point.y); if (FAppRestore = imRightClickUp) then Restore(); if (FPopupMenuShow = imRightClickUp) then ShowMenu(); //break; end; WM_RBUTTONDBLCLK: begin DoDblClick(); if (FAppRestore = imRightDoubleClick) then Restore(); if (FPopupMenuShow = imRightDoubleClick) then ShowMenu(); //break; end; WM_MBUTTONDOWN: begin shift := ShiftState(); shift := shift + [ssMiddle]; GetCursorPos(point); DoMouseDown(mbMiddle, shift, point.x, point.y); //break; end; WM_MBUTTONUP: begin shift := ShiftState(); shift := shift + [ssMiddle]; GetCursorPos(point); DoMouseUp(mbMiddle, shift, point.x, point.y); //break; end; WM_MBUTTONDBLCLK: DoDblClick(); //break; end; end; inherited Dispatch(Message); end; //--------------------------------------------------------------------------- procedure TTrayIcon.ShowMenu(); var point: TPoint; begin GetCursorPos(point); if (Screen.ActiveForm.Handle <> 0) then SetForegroundWindow(Screen.ActiveForm.Handle); FPopupMenu.Popup(point.x, point.y); end; //--------------------------------------------------------------------------- procedure TTrayIcon.DoClick(); begin if (FAppRestore = imClick) then Restore(); if (FPopupMenuShow = imClick) then ShowMenu(); if (Assigned(FOnClick)) then FOnClick(Self); end; //--------------------------------------------------------------------------- procedure TTrayIcon.DoDblClick(); begin if (FAppRestore = imDoubleClick) then Restore(); if (FPopupMenuShow = imDoubleClick) then ShowMenu(); if (Assigned(FOnDblClick)) then FOnDblClick(Self); end; //--------------------------------------------------------------------------- procedure TTrayIcon.DoMouseMove(Shift: TShiftState; X:integer; Y: integer); begin if (Assigned(FOnMouseMove)) then FOnMouseMove(Self, Shift, X, Y); end; //--------------------------------------------------------------------------- procedure TTrayIcon.DoMouseDown(Button: TMouseButton; Shift: TShiftState; X: integer; Y: integer); begin if (FAppRestore = imMouseDown) then Restore(); if (FPopupMenuShow = imMouseDown) then ShowMenu(); if (Assigned(FOnMouseDown)) then FOnMouseDown(Self, Button, Shift, X, Y); end; //--------------------------------------------------------------------------- procedure TTrayIcon.DoMouseUp(Button: TMouseButton; Shift: TShiftState; X: integer; Y:integer); begin if (FAppRestore = imMouseDown) then Restore(); if (FPopupMenuShow = imMouseDown) then ShowMenu(); if (Assigned(FOnMouseUp)) then FOnMouseUp(Self, Button, Shift, X, Y); end; //--------------------------------------------------------------------------- procedure TTrayIcon.DoOnAnimate(Sender: TObject); begin if (IconIndex < FIconList.Count) then Inc(FIconIndex) else FIconIndex := 0; SetIconIndex(FIconIndex); Update(); end; //--------------------------------------------------------------------------- procedure TTrayIcon.Minimize(); begin Application.Minimize(); ShowWindow(Application.Handle, SW_HIDE); if (Assigned(FOnMinimize)) then FOnMinimize(Self); end; //--------------------------------------------------------------------------- procedure TTrayIcon.Restore(); begin Application.Restore(); ShowWindow(Application.Handle, SW_RESTORE); SetForegroundWindow(Application.Handle); if (Assigned(FOnRestore)) then FOnRestore(Self); end; //--------------------------------------------------------------------------- procedure TTrayIcon.Update(); begin if not (csDesigning in ComponentState) then begin FData.hIcon := FIcon.Handle; if (Visible = true) then Shell_NotifyIcon(NIM_MODIFY, @FData); end; end; //--------------------------------------------------------------------------- procedure TTrayIcon.SetIconIndex(Value: integer); begin FIconIndex := Value; if (Assigned(FIconList)) then FIconList.GetIcon(FIconIndex, FIcon); Update(); end; //--------------------------------------------------------------------------- function TTrayIcon.ApplicationHookProc(var Message: TMessage): Boolean; begin if (Message.Msg = WM_SYSCOMMAND) then begin if (Message.WParam = SC_MINIMIZE) then Minimize(); if (Message.WParam = SC_RESTORE) then Restore(); end; Result:= false; end; //--------------------------------------------------------------------------- procedure TTrayIcon.SetDefaultIcon(); begin FIcon.Assign(Application.Icon); Update(); end; //--------------------------------------------------------------------------- function TTrayIcon.GetHandle(): HWND; begin Result := FData.Wnd; end; //--------------------------------------------------------------------------- end.