Leaderboard

domeniu - gratuit hosting - gratuit blog - gratuiti Pãsãrici

Author: bubzuru An important concept in Windows programming is the concept of an object handle. Many functions return a handle to an object that the function created or loaded from a resource. Internally, Windows keeps track of all of these handles, and the handle serves as the link through the operating system between the object and the application. There are several ways to obtain the handle of a window. I) FindWindow Syntax: FindWindow(lpClassName: PChar; {a pointer to a null-terminated class name string} lpWindowName: PChar {a pointer to a null-terminated window name string} ): HWND; {returns a handle to a window} 1. The FindWindow function retrieves the handle to the top-level window whose class name and window name match the specified strings. This function does not search child windows. If the function succeeds, the return value is the handle to the window that has the specified class name and window name. If the function fails, the return value is 0. Examples : Get the handle of Notepad by its Classname: procedure TForm1.Button1Click(Sender: TObject); var hNotepadWindow: HWND; begin hNotepadWindow := FindWindow('notepad', nil); end; Get the handle of Winword by its Classname and hide it/show it after 2 Sec.: Code: procedure TForm1.Button1Click(Sender: TObject); var hWordWindow: HWND; begin hWordWindow := FindWindow ('OpusApp', nil); ShowWindow(hWordWindow, SW_HIDE); Sleep(2000); ShowWindow(hWordWindow, SW_SHOW); end; Get the handle of Internet Explorer and minimize/close all its windows: procedure TForm1.Button1Click(Sender: TObject); var hIExplorer: HWND; begin hIExplorer := FindWindow('IEFrame', nil); if hIExplorer <> 0 then begin // Minimize IE: SendMessage(hIExplorer, WM_SYSCOMMAND, SC_MINIMIZE, 0); // Close IE: SendMessage(hIExplorer, WM_SYSCOMMAND, SC_CLOSE, 0); end; end; II) GetWindow FindWindowByTitle returns the handle of a window that contains a certain "WindowTitle". function FindWindowByTitle(WindowTitle: string): Hwnd; var NextHandle: Hwnd; NextTitle: array[0..260] of char; begin // Get the first window NextHandle := GetWindow(Application.Handle, GW_HWNDFIRST); while NextHandle > 0 do begin // retrieve its text GetWindowText(NextHandle, NextTitle, 255); if Pos(WindowTitle, StrPas(NextTitle)) <> 0 then begin Result := NextHandle; Exit; end else // Get the next window NextHandle := GetWindow(NextHandle, GW_HWNDNEXT); end; Result := 0; end; Example how to search for a window that contains the word "notepad" and maximize it. procedure TForm1.Button1Click(Sender: TObject); var h: hwnd; begin h := FindWindowByTitle('notepad'); if h <> 0 then // if we found notepad ShowWindow(h, SW_MAXIMIZE) else ShowMessage('not found.'); end; III. FindWindowEx {Syntax:} FindWindowEx(Parent: HWND; {a handle to a parent window} Child: HWND; {a handle to a child window} ClassName: PChar; {a pointer to a null-terminated class name string} WindowName: PChar {a pointer to a null-terminated window name string} ): HWND; {returns a handle to a window} Description: FindWindowEx retrieves the handle of the window with the specified class name and window name. Unlike FindWindow, this function searches child windows, starting with the one following the given child window. Example to find a TButton (Child Window) on a TForm procedure TForm1.Button1Click(Sender: TObject); var FoundWindow: HWND; WindowText: array[0..255] of char; begin {Find a TButton child window} FoundWindow := FindWindowEx(Form1.Handle, 0, 'TButton', nil); {Get its text} GetWindowText(FoundWindow, WindowText, 255); {Display it} label1.Caption := 'FindWindowEx found window handle ' + IntToStr(FoundWindow) + ': ' + WindowText; end; Example to search for Edit field nr. x in another application and send a text to it function FindControlByNumber(hApp: HWND; ControlClassName: string; ControlNr: Word = 1): HWND; var i: Word; hControl: HWND; begin Result := 0; if IsWindow(hApp) then begin Dec(ControlNr); hControl := 0; for i := 0 to ControlNr do begin hControl := FindWindowEx(hApp, hControl, PChar(ControlClassName), nil); if hControl = 0 then Exit; end; end; Result := hControl; end; procedure SetEditText(hApp: HWND; EditClassName, AText: string; EditNr: Integer); var hEdit: HWND; begin // Search for the 2. Edit Field in a application hEdit := FindControlByNumber(FindWindow('Write_Here_Class_Of_App', nil), 'Edit', 2); if hEdit <> 0 then // Test: Send a "Hello" to the Edit Field SendMessage(hEdit, WM_SETTEXT, 0, Integer(PChar('Hello'))); end; IV) EnumWindows // Syntax: EnumWindows(lpEnumFunc: TFNWndEnumProc; {the address of the enumeration callback function} lParam: LPARAM {a 32-bit application-defined value} ): BOOL; {returns TRUE or FALSE} The EnumWindows function enumerates all top-level windows on the screen by passing the handle of each window, in turn, to an application-defined callback function. EnumWindows continues until the last top-level window is enumerated or the callback function returns FALSE. Callback Syntax: EnumWindowsProc(hWnd: HWND; {a handle to a top-level window} lParam: LPARAM {the application-defined data} ): BOOL; {returns TRUE or FALSE} Example how to list all Top-Level Windows in a Listbox. function EnumWindowsProc(wHandle: HWND; lb: TListBox): Bool; stdcall; export; var Title, ClassName: array[0..255] of char; begin Result := True; GetWindowText(wHandle, Title, 255); GetClassName(wHandle, ClassName, 255); if IsWindowVisible(wHandle) then lb.Items.Add(string(Title) + '-' + string(ClassName)); end; procedure TForm1.Button1Click(Sender: TObject); begin EnumWindows(@EnumWindowsProc, Integer(Listbox1)); end; V) EnumChildWindows //Syntax: EnumerateChildWindows(hWnd: HWND;{a handle to a top-level window} lParam: LPARAM): {a 32-bit application-defined value} BOOL; stdcall; {returns TRUE or FALSE} Description : The EnumChildWindows function enumerates the child windows that belong to the specified parent window by passing the handle of each child window, in turn, to an application-defined callback function. EnumChildWindows continues until the last child window is enumerated or the callback function returns False. Here is an example that lists the controls on a TPrintDialog function EnumProc(wnd: HWND; Lines: TStrings): BOOL; stdcall; var buf, Caption: array[0..255] of char; begin Result := True; GetClassName(wnd, buf, SizeOf(buf) - 1); SendMessage(wnd, WM_GETTEXT, 256, Integer(@Caption)); Lines.Add(Format('ID: %d, ClassName: %s, Caption: %s', [GetDlgCtrlID(wnd), buf, Caption])); end; procedure TForm1.PrintDialog1Show(Sender: TObject); begin Memo1.Clear; EnumChildWindows(printdialog1.Handle, @EnumProc, Integer(memo1.Lines)); end; VI) EnumThreadWindows // Syntax: EnumThreadWindows(dwThreadId: DWORD; {the thread identification number} lpfn: TFNWndEnumProc; {the address of the enumeration callback function} lParam: LPARAM {a 32-bit application-defined value} ): BOOL; {returns TRUE or FALSE} Description This function enumerates all of the nonchild windows associated with the specified thread. Each window handle associated with the specified thread is passed to an application-defined callback function. This function will continue until all of the windows are enumerated or the callback function returns False. Syntax of the Callback function: EnumThreadWndProc(hWnd: HWND; {a handle to a window} lParam: LPARAM {the application-defined data} ): BOOL; function EnumerateThreadWindows(Wnd: HWND; Data: lParam): BOOL; var WindowText: array[0..255] of char; // holds the text of the window begin { Get the text from the window } GetWindowText(Wnd, WindowText, 255); { Display it in the listbox} Form1.ListBox1.Items.Add(WindowText); { Continue the enumeration } Result := True; end; procedure TForm1.Button1Click(Sender: TObject); begin { Clear the listbox } ListBox1.Items.Clear; { Enumerate all windows that belong to the current thread } EnumThreadWindows(GetCurrentThreadID, @EnumerateThreadWindows, 0); end;