Question:
How do I get the handle of another application's window and make
that window the active window?
Answer:
Using the Windows API function FindWindow() is the simplest and
most straightforward method of locating a given window provided you
know the exact window caption or class name. If you know only part of
the window's caption (ie: 'Netscape - ' + 'Some Unknown URL', you need
to use the Windows EnumWindows() function to enumerate all the active
windows, then call the Windows API functions GetWindowsText() and
GetClassName to see if you find a match for the window that you are
searching for.
The following example returns the window handle of the first window
enumerated that contains a partial match of the window title and an
exact match of the window's ClassName (if given) and brings that
window to the foreground.
type
PFindWindowStruct = ^TFindWindowStruct;
TFindWindowStruct = record
Caption : string;
ClassName : string;
WindowHandle : THandle;
end;
function EnumWindowsProc(hWindow : hWnd;
lParam : LongInt) : Bool
{$IFDEF Win32} stdcall; {$ELSE} ; export; {$ENDIF}
var
lpBuffer : PChar;
WindowCaptionFound : bool;
ClassNameFound : bool;
begin
GetMem(lpBuffer, 255);
Result := True;
WindowCaptionFound := False;
ClassNameFound := False;
try
if GetWindowText(hWindow, lpBuffer, 255) > 0 then
if Pos(PFindWindowStruct(lParam).Caption, StrPas(lpBuffer)) > 0
then WindowCaptionFound := true;
if PFindWindowStruct(lParam).ClassName = '' then
ClassNameFound := True else
if GetClassName(hWindow, lpBuffer, 255) > 0 then
if Pos(PFindWindowStruct(lParam).ClassName, StrPas(lpBuffer))
> 0 then ClassNameFound := True;
if (WindowCaptionFound and ClassNameFound) then begin
PFindWindowStruct(lParam).WindowHandle := hWindow;
Result := False;
end;
finally
FreeMem(lpBuffer, sizeof(lpBuffer^));
end;
end;
function FindAWindow(Caption : string;
ClassName : string) : THandle;
var
WindowInfo : TFindWindowStruct;
begin
with WindowInfo do begin
Caption := Caption;
ClassName := ClassName;
WindowHandle := 0;
EnumWindows(@EnumWindowsProc, LongInt(@WindowInfo));
FindAWindow := WindowHandle;
end;
end;
procedure TForm1.Button1Click(Sender: TObject);
var
TheWindowHandle : THandle;
begin
TheWindowHandle := FindAWindow('Netscape - ', '');
if TheWindowHandle = 0 then
ShowMessage('Window Not Found!') else
BringWindowToTop(TheWindowHandle);
end;