[Delphi] Get All handles & Management

Here is an example how to get all of paltalks handles we use in our applications, It will get the handles to both “RichEdit20W” used for sending and receiving text and also the Nicklist handle, it will also create a list which can be used to store multiple windows, like “Paltalk room selector”. It uses a generic list with a custom record for storing the handles for easy access. This is only demonstration and I suggest using what you learn here to make your own class and add methods like “GetText”, “SendText” ect.. for each item in your list.

Here is an example how to retrive the data to use…

// Itemindex in this example is the item index of a combobox...

// Returns a String which will be the main room / pm Title
WindowList.Items[ItemIndex].sMain;

// Returns a type Hwnd for the main Room / Pm Window
WindowList.Items[ItemIndex].hMain

// Returns a type Hwnd for the Incooming text
WindowList.Items[ItemIndex].hIncomming

// Returns a type Hwnd for the Outgoing text
WindowList.Items[ItemIndex].hOutgoing

// Returns a type Hwnd for the Nicklist
WindowList.Items[ItemIndex].hNicklist

Sample:
Add the following control to your form and rename them as specified

* 1 x Button – Rename to “btnRefresh”
* 1 x Combobox – Rename to “cbPalWindows”
* 5 x Labels – Rename to “lblTitle”, “lblMainHwnd”, “lblIncomming”, “lblOutgoing”, “lblNicklist”

Code:

{ Record for holding all our paltalk handles }
type
  TWindowInfo = record
    sMain: array [0 .. 255] Of Char;
    hMain: HWND;
    hIncomming: HWND;
    hOutgoing: HWND;
    hNicklist: HWND;
  end;

var
  Form1: TForm1;
  { List for holding all our records }
  WindowList: TList;

implementation

{$R *.dfm}

{ Set all record values to nil }
function ZeroOutWinInfo(rWinInfo: TWindowInfo): TWindowInfo;
begin
  FillChar(rWinInfo.sMain, SizeOf(rWinInfo.sMain), #0);
  rWinInfo.hMain := 0;
  rWinInfo.hIncomming := 0;
  rWinInfo.hOutgoing := 0;
  rWinInfo.hNicklist := 0;
  Result := rWinInfo;
end;

{ Get Window title based on Hwnd }
function GetWindowTitle(HWND: HWND): string;
begin
  SetLength(Result, 255);
  SetLength(Result, GetWindowText(HWND, PChar(Result), 255));
end;

{ Get the Classname based on Hwnd }
function GetWindowClass(HWND: HWND): string;
begin
  SetLength(Result, 255);
  SetLength(Result, GetClassName(HWND, PChar(Result), 255));
end;

{ EnumChildWindows Callback }
function EnumChildProc(aHwnd: HWND; Param: lParam): Boolean; stdcall;
var
  WindowList: TList;
  WindowInfo: TWindowInfo;
begin

  WindowList := TList(Param);

  if IsWindowVisible(aHwnd) = True then
  begin
    WindowInfo := WindowList.Items[Pred(WindowList.Count)];

    case GetDlgCtrlID(aHwnd) of
      202:
        begin
          WindowInfo.hIncomming := aHwnd;
          WindowList.Items[Pred(WindowList.Count)] := WindowInfo;
        end;
      203:
        begin
          WindowInfo.hOutgoing := aHwnd;
          WindowList.Items[Pred(WindowList.Count)] := WindowInfo;
        end;
      1789:
        begin
          WindowInfo.hNicklist := aHwnd;
          WindowList.Items[Pred(WindowList.Count)] := WindowInfo;
        end;
    end;
  end;
  Result := True;
end;

{ EnumWindows Callback }
function EnumWinProc(aHwnd: HWND; Param: lParam): Boolean; stdcall;
var
  WindowList: TList;
  WindowInfo: TWindowInfo;
begin
  WindowList := TList(Param);

  if GetWindowClass(aHwnd) = 'DlgGroupChat Window Class' then
  begin
    WindowInfo := ZeroOutWinInfo(WindowInfo);
    WindowInfo.hMain := aHwnd;
    GetWindowText(aHwnd, WindowInfo.sMain, 255);
    WindowList.Add(WindowInfo);
    EnumChildWindows(aHwnd, @EnumChildProc, Param);
  end;
  Result := True;

end;

{ Update Combobox With Rooms }
procedure TForm1.btnRefreshClick(Sender: TObject);
var
  WindowInfo: TWindowInfo;
begin
  WindowList.Clear;
  cbPalWindows.Clear;
  cbPalWindows.Text := 'Room Selector';
  EnumWindows(@EnumWinProc, lParam(WindowList));
  for WindowInfo in WindowList do
    cbPalWindows.Items.Add(WindowInfo.sMain);
end;

{ On select display our handles for current window }
procedure TForm1.cbPalWindowsSelect(Sender: TObject);
begin
  lblTitle.Caption := 'Title: ' + WindowList.Items[cbPalWindows.ItemIndex].sMain;
  lblMainHwnd.Caption := 'MainHwnd: ' +
    IntToStr(WindowList.Items[cbPalWindows.ItemIndex].hMain);
  lblIncomming.Caption := 'IncommingHwnd: ' +
    IntToStr(WindowList.Items[cbPalWindows.ItemIndex].hIncomming);
  lblOutgoing.Caption := 'OutgoingHwnd: ' +
    IntToStr(WindowList.Items[cbPalWindows.ItemIndex].hOutgoing);
  lblNicklist.Caption := 'NicklistHwnd: ' +
    IntToStr(WindowList.Items[cbPalWindows.ItemIndex].hNicklist);
end;

{ Create WindowList note: add "ReportMemoryLeaksOnShutdown := True;" to projects source }
procedure TForm1.FormCreate(Sender: TObject);
begin
  WindowList := TList.Create;
end;

{ Make sure our data has been disposed of }
procedure TForm1.FormDestroy(Sender: TObject);
begin
  WindowList.Free;
end;

Don’t forget to point your OnClick Event for “btnRefresh” and OnSelect Event for “cbPalWindows” to corresponding Events.

It should look similar to below image
ScreenShot:

Summary:
If you running newer versions of Delphi then I suggest adding “ReportMemoryLeaksOnShutdown := True” to the main project file, This is only a reporting tool to inform you of any leaking memory if you wish to build on to the above example.

While this demo uses Delphi it can also be achieved in the .net language, By using generic list and defining your “Record” a.k.a “Structure” in .net, you can make handling of multiple rooms and handles much easier on your self, Even use this style to create your own classes which will do things with the handles, and the most important thing about this demo is the usage of EnumWindows and EnuChildWindows, we limit the amount of calling to these functions, First we only need to call it once to get all rooms handles and child handles to those rooms. If you wish to update the rooms(incase a room / pm window) is close we only need to validate the top level window(room /pm) and no need to call EnumWindows, because if the top level window handle is valid so must be its child handles(incoming, outgoing and nicklist) We can check this with against our List using a simple call to IsWindow API to see if it returns true or false(http://msdn.microsoft.com/en-us/library/windows/desktop/ms633528(v=vs.85).aspx)

Also the benefits of inheriting all of the functions and procedure of TList makes managing your rooms and handles a lot easier……

AddRange
IndexOf
LastIndexOf
Contains
Remove
Delete
DeleteRange
Extract
TrimExcess
Clear
Insert
InsertRange
Sort
BinarySearch
Reverse
Count
Items
Capacity

And finally here is the Project source incase you still have problems or would like to compile and test this out straight away.
Download Source: