Get Current Selected Text? [closed] - string

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i need to get the current select text independently the windows (browser, text editor, games wtc.)
i found this code in stackoverflow, but it aint work.
...
var
Buff: array[0..65535] of char;
...
function CurrentSelectedText: string;
var
hFocus: hWnd;
aStart, aEnd: integer;
begin
//added by andrei, attach input to current thread
AttachThreadInput(GetCurrentThreadId, GetWindowThreadProcessId(GetForegroundWindow), true);
hFocus:= GetFocus;
SendMessage(hFocus, WM_GETTEXT, 65535, integer(#buff));
SendMessage(hFocus, EM_GETSEL, Integer(#aStart), Integer(#aEnd));
result:= Copy(StrPas(Buff), 1+aStart, aEnd-aStart);
end;

Answer 1

There are some possibly significant problems (failing to detach the thread input, not allowing for the foreground window in the current thread, a complete absence of error checking) and a minor improvement (caching thread IDs) that can be made to your code, but in essence it should work.
I implemented this slightly modified version of your code in a TTimer, set to simply retrieve the current focussed window text into a TEdit control every 1/4 second (250 ms), and it worked exactly as expected.
var
buff: array[0..65535] of char;
thisThread: Integer;
focusThread: Integer;
hForeground: HWND;
hFocus: HWND;
a, b: Integer;
attached: Boolean;
begin
hForeground := GetForegroundWindow;
// ** check hForegound is valid
thisThread := GetCurrentThreadID;
focusThread := GetWindowThreadProcessID(hForeground);
// ** check focusThread is valid
attached := thisThread <> focusThread;
if attached then
begin
AttachThreadInput(thisThread, focusThread, TRUE);
// ** check attach was successful
end;
try
hFocus := GetFocus;
// ** check hFocus is valid/not null
SendMessage(hFocus, WM_GETTEXT, 65535, Integer(#buff));
// ** check SendMessage was successful
Edit1.Text := String(#buff);
if SendMessage(hFocus, EM_GETSEL, Integer(#a), Integer(#b)) <> 0 then
Edit1.Text := Copy(Edit1.Text, 1 + a, b - a);
finally
if attached then
AttachThreadInput(thisThread, focusThread, FALSE);
end;
end;
If this code does not work for you then you can (and in any case should) add error checking code at the points that I have indicated with ** comments, to determine why it is not working in your particular case.
Note that you cannot attach a thread to itself, which is taken into account in the above modified code by only attaching (and detaching) if the two threads are different.
The EM_GETSEL Problem:
It is most likely possible that the problem you have is specifically with the attempt to retrieve the Selection range. As indicated by the message number (EM_...) this is a message that only EDIT controls respond to, so if the current foreground window is not an edit control then this will almost certainly fail.
You should DEFINITELY check the success/failure of the SendMessage( .. EM_GETSEL .. ) call, and only extract a range from the window text if you receive a valid response to that message.
I also found that trying to use Copy() directly on a cast version of the buf char array did not work. This surprised me and might bear further investigation, but to avoid whatever problems might lie in this area, simply convert to a string first and then perform your Copy() to extract the range from the string.
In my working example above this is achieved by rather inefficiently assigning the converted buf to the Edit1.Text property and then using Copy() on that Edit1.Text property. In practice you would use an intermediate string variable.
WM_GETTEXT Limitations
In your question you ask for a technique that will work for any window type, including browsers and games. I do not think there is a universal approach that will achieve this, short of a combination of screen capture and OCR. This is because applications such as browsers and games and even some "ordinary applications", implement window classes which render their content independent of any concept of "Window Text", as reported by WM_GETTEXT. e.g. the "Window text" of a browser window is typically the browser/tab caption text, not the HTML content of the page it is currently presenting, which is maintained internally by the browser application.
If an application implements a custom window class to render some arbitrary content, then you have no way to retrieve that content without intimate knowledge of the specific application in question and/or a published mechanism supported by that application to achieve what you want.