Rgui.exe 4.2.0 does not receive characters via the Windows API's PostMessage function

Dear Jose,

On 5/15/22 01:31, jcfaria wrote:

Dear Tomas,

I am very grateful for your attention!

I've been reading some things about the GraphApp 
toolkit(http://enchantia.com/software/graphapp/) that is being used 
in the development of new versions of Rgui.

Really, if it's a matter of choice, the problems I reported cannot be 
considered a "bug". It's up to us - GUI and IDE application 
developers - to adapt to the new features.

I'm studying how to get around the problem, but I still haven't found 
a simple way.

The solution you proposed (code below) ran fine here in all versions 
of Rgui I have installed, but it's working only for very simple 
strings, like the one I tested. When testing the needs close to the 
real I found some problems.

For example, when sending the string below:
- char *s = "(s <- c('?', 'b', 'c', '?'))";

Rgui receives:

9s ,- c9'', 'b', 'c', ''00

Error: unexpected symbol in "9s"

#include <windows.h>
#include <stdio.h>
#include <string.h>

int main(int argc, char **argv) {
?? HWND hw;
?? int i, res;

?? printf("Getting Rgui window...\n");
?? hw = FindWindow(NULL, "R Console (64-bit)");

?? printf("Got window: %x\n", hw);
?? if (hw == NULL) {
???? printf("Could not get Rgui window: %x\n", GetLastError());
???? return 2;
?? }

?? //Samples to send:
// char *s = "sd";
?? char *s = "(s <- c('?', 'b', 'c', '?'))";

?? for(i = 0; i < strlen(s); i++) {
???? res = PostMessage(hw, WM_KEYDOWN, VkKeyScan(s[i]), 0);
???? printf("Sending char %c: %d.\n", s[i], res);
?? }

?? res = PostMessage(hw, WM_KEYDOWN, VK_RETURN, 0);
?? printf("Sending return: %d\n.", res);
?? return 0;
}

The idea of Tinn-R communicating with Rgui.exe is to take advantage 
of the great stability of Rgui. Since communication with Rterm is 
done via pipe.

I believe that developing a new interface using the resources of the 
R.dll library, as proposed, is outside the simple purposes of the 
Tinn-R project.

Any help in this regard is welcome.

If embedding R seems too involved, and the hack above doesn't work 
well enough, perhaps you could use SendInput() (also mentioned in the 
blog post [1] below as a more correct way to inject input as 
WM_KEYDOWN).? This is an example:

---

#include <windows.h>
#include <stdio.h>

int main(int argc, char **argv) {
? HWND hw, ow;
? int i, res;

? hw = FindWindow(NULL, "R Console (64-bit)");
? if (hw == NULL) {
??? printf("Could not get Rgui window: %x\n", GetLastError());
??? return 2;
? }

? ow = GetForegroundWindow();
? if (ow == NULL)
??? printf("Foreground window is NULL\n");

? if (!SetForegroundWindow(hw))
??? printf("Could not set Rgui as foreground window\n");

? char *sd = "sd";
? for(i = 0; i < strlen(sd); i++) {
??? INPUT input;

??? ZeroMemory(&input, sizeof(INPUT));
??? input.type = INPUT_KEYBOARD;
??? input.ki.dwFlags = KEYEVENTF_UNICODE;
??? input.ki.wScan = (unsigned) sd[i];
??? res = SendInput(1, &input, sizeof(INPUT));

??? printf("Sending char %c (%x): %d.\n", sd[i], sd[i], res);
? }

? {
??? INPUT input[2];

??? ZeroMemory(input, 2*sizeof(INPUT));
??? input[0].type = input[1].type = INPUT_KEYBOARD;
??? input[1].ki.dwFlags = KEYEVENTF_KEYUP;
??? input[0].ki.wVk = input[1].ki.wVk = VK_RETURN;
??? res = SendInput(2, input, sizeof(INPUT));
??? printf("Sending return: %d.\n", res);
? }

? if (!SetForegroundWindow(ow))
??? printf("Could not set the original window as foreground");

? return 0;
}

---

This example works for me with R 4.1.3 and with R-devel 82368. It 
doesn't work with R 4.2.0 (see a related thread about Dasher on this 
list).

Best
Tomas

Best,
///\\\///\\\///\\\///\\\///\\\///\\\///\\\///\\\///\\\///\\\
Jose Claudio Faria
UESC/DCET/Brasil
joseclaudio.faria at gmail.com
Telefones:
55(73)3680.5545 - UESC
55(73)99966.9100 - VIVO
///\\\///\\\///\\\///\\\///\\\///\\\///\\\///\\\///\\\///\\\
If you have software to deal with statistics, you have arms,
if you have good software, you have arms and legs,
if you have software like R, you have arms, legs and wings...
the height of your flight depends only on you.

------ Mensagem original ------
De: "Tomas Kalibera" <tomas.kalibera at gmail.com>
Para: "jcfaria" <joseclaudio.faria at gmail.com>; "Duncan Murdoch" 
<murdoch.duncan at gmail.com>; r-devel at r-project.org
Enviado(s): 11/05/2022 13:32:23
Assunto: Re: [Rd] Rgui.exe 4.2.0 does not receive characters via the 
Windows API's PostMessage function

On 5/11/22 15:39, Tomas Kalibera wrote:

On 5/11/22 08:15, Tomas Kalibera wrote:

On 5/11/22 03:02, jcfaria wrote:

Dear Tomas,
I've tried, but I don't have the necessary C/C++ programming 
skills to fulfill your request.

Maybe someone can help us by transcribing the little code in 
object Pascal that I sent to C/C++.

If a small executable, made in Object Pascal, can help in your 
debug, I can provide.

Dear Jose,

no problem, I can try out with the Pascal code.
Is there a free compiler I can use to build and run it?

Actually I can reproduce it in a C program doing the same thing.

The primary cause is that Rgui is using GraphApp Unicode windows on 
systems running in a multi-byte locale, which affects most systems 
since R 4.2 because of the switch to UTF-8. While Unicode windows 
have been used even in older versions of R, it was only on systems 
then running in a multi-byte locale, and apparently this hasn't 
been reported.

When I modify R-devel to use non-Unicode GraphApp windows, the 
message sending works again. I will have a closer look, thanks for 
the report.

I had a closer look and this doesn't really seem to be a bug in R to 
me. For Unicode Windows, GraphApp uses WM_IME_COMPOSITION messages 
to read the keys instead of WM_CHAR, which it uses for non-Unicode 
windows. This is internal functionality of Rgui and a legitimate 
choice. Rgui cannot simply handle both messages in Unicode windows, 
because the characters would be doubled (if you see an easy, elegant 
change to Rgui that would mimic the previous behavior, let me know). 
This is certainly not a documented interface for Rgui, so I am 
afraid you would have to change something in your application.

I read that using PostMessage to simulate keyboard input is 
considered wrong, see [1], and then one should instead use SendInput 
(which then requires bringing the window to the foreground), if at 
all simulating keyboard input. Maybe one could create a better 
working solution that way, or using some automation library.

As a quick hack, I found that [2] happens to be working on my 
system, but again relying on the current implementation of Rgui 
(simply you send WM_KEYDOWN also for the characters other than the 
newline/return). It seems to be working also with R 4.1 for me.

The usual way for GUIs/front-ends is to "embed" R, to link it as a 
DLL. Rgui itself does it and also external applications such as 
RStudio. Typically you would want to have a thin layer application 
embedding R and make your GUI communicate with that, but switching 
to that from sending the messages would require some work.

Best
Tomas

[1] https://devblogs.microsoft.com/oldnewthing/20050530-11/?p=35513

[2]
#include <windows.h>
#include <stdio.h>
#include <string.h>

int main(int argc, char **argv) {
? HWND hw;
? int i, res;

? printf("Getting Rgui window...\n");
? hw = FindWindow(NULL, "R Console (64-bit)");

? printf("Got window: %x\n", hw);
? if (hw == NULL) {
??? printf("Could not get Rgui window: %x\n", GetLastError());
??? return 2;
? }

? char *sd = "sd";
? for(i = 0; i < strlen(sd); i++) {
??? res = PostMessage(hw, WM_KEYDOWN, VkKeyScan(sd[i]), 0);
??? printf("Sending char %c: %d.\n", sd[i], res);
? }

? res = PostMessage(hw, WM_KEYDOWN, VK_RETURN, 0);
? printf("Sending return: %d\n.", res);
? return 0;
}

For reference, to reproduce I ran

Rgui --sdi

and used this C example:

#include <windows.h>
#include <stdio.h>
#include <string.h>

int main(int argc, char **argv) {
? HWND hw;
? int i, res;

? printf("Getting Rgui window...\n");
? hw = FindWindow(NULL, "R Console (64-bit)");

? printf("Got window: %x\n", hw);
? if (hw == NULL) {
??? printf("Could not get Rgui window: %x\n", GetLastError());
??? return 2;
? }

? char *sd = "sd";
? for(i = 0; i < strlen(sd); i++) {
??? res = PostMessage(hw, WM_CHAR, (unsigned int) sd[i], 0);
??? printf("Sending char %c: %d.\n", sd[i], res);
? }

? res = PostMessage(hw, WM_KEYDOWN, VK_RETURN, 0);
? printf("Sending return: %d\n.", res);
? return 0;
}

Best
Tomas

Thanks
Tomas

Grateful for the attention,,
///\\\///\\\///\\\///\\\///\\\///\\\///\\\///\\\///\\\///\\\
Jose Claudio Faria
UESC/DCET/Brasil
joseclaudio.faria at gmail.com
Telefones:
55(73)3680.5545 - UESC
55(73)99966.9100 - VIVO
///\\\///\\\///\\\///\\\///\\\///\\\///\\\///\\\///\\\///\\\
If you have software to deal with statistics, you have arms,
if you have good software, you have arms and legs,
if you have software like R, you have arms, legs and wings...
the height of your flight depends only on you.

------ Mensagem original ------
De: "Tomas Kalibera" <tomas.kalibera at gmail.com>
Para: "jcfaria" <joseclaudio.faria at gmail.com>; "Duncan Murdoch" 
<murdoch.duncan at gmail.com>; r-devel at r-project.org
Enviado(s): 06/05/2022 04:24:44
Assunto: Re: [Rd] Rgui.exe 4.2.0 does not receive characters via 
the Windows API's PostMessage function

On 5/6/22 07:03, jcfaria wrote:

Dear Duncan,
I believe the problem is of a different nature.
I get TRUE 3 times running the code below:

procedure TfMain.btnPasteClick(Sender: TObject);
var
? i: integer;
? sTmp: string;
? hBN: HWND;
? j: bool;

begin
? hBN:= FindWindowA(nil,
??????????????????? 'R Console (64-bit)');

? sTmp:= 'sd';

? for i:= 1 to Length(sTmp) do begin
??? j:= PostMessage(hBN,
??????????????????? WM_CHAR,
??????????????????? Ord(sTmp[i]),
??????????????????? 0);

??? ShowMessage(BoolToStr(j,
????????????????????????? True));
? end;

? j:= PostMessage(hBN,
????????????? WM_KEYDOWN,
????????????? VK_RETURN, 0);

? ShowMessage(BoolToStr(j,
??????????????????????? True));
end;

That is, Rgui is receiving the message of the characters (via 
PostMessage), but it is blocking because it does not show them 
in the console.
The only thing Rgui blames is Carriage Return, as it adds an 
additional prompt with each run.

I can't provide a good guess what impacted your use, but if you 
could give me a full example, ideally in C, which can be 
compiled with Rtools42 (so gcc, MinGW) and I can edit/recompile, 
and works with R 4.1, I am happy to help debugging on 4.2.

Rgui now uses GraphApp Unicode windows on systems where it 
didn't before, because it uses UTF-8 also on systems it didn't 
before (on systems that would use a single-byte locale in R 
4.1). These Unicode windows are a different code path and there 
may be bugs not reported previously, including processing inputs 
(recently I fixed handling of accents, for example). Otherwise 
indeed R now uses UTF-8 as native encoding and UCRT as the C 
runtime.

Best
Tomas

Best,
///\\\///\\\///\\\///\\\///\\\///\\\///\\\///\\\///\\\///\\\
Jose Claudio Faria
UESC/DCET/Brasil
joseclaudio.faria at gmail.com
Telefones:
55(73)3680.5545 - UESC
55(73)99966.9100 - VIVO
///\\\///\\\///\\\///\\\///\\\///\\\///\\\///\\\///\\\///\\\
If you have software to deal with statistics, you have arms,
if you have good software, you have arms and legs,
if you have software like R, you have arms, legs and wings...
the height of your flight depends only on you.

------ Mensagem original ------
De: "Duncan Murdoch" <murdoch.duncan at gmail.com>
Para: "jcfaria" <joseclaudio.faria at gmail.com>; 
r-devel at r-project.org
Enviado(s): 05/05/2022 13:17:53
Assunto: Re: [Rd] Rgui.exe 4.2.0 does not receive characters 
via the Windows API's PostMessage function

On 05/05/2022 11:17 a.m., jcfaria wrote:

Hello,

Rgui.exe 4.2.0 does not receive characters via the Windows API's
PostMessage function.

The Tinn-R project sends messages to Rgui.exe (SDI mode) via 
the Windows
API's PostMessage function.
A simplification of the code (in object Pascal) can be seen 
below.

procedure TfMain.btnPasteClick(Sender: TObject);
var
??? i: integer;
??? sTmp: WideString;
??? hBN: HWND;

begin
??? hBN:= FindWindowA(nil,
????????????????????? 'R Console (64-bit)');

??? sTmp:= 'sd';

??? for i:= 1 to Length(sTmp) do begin
????? PostMessage(hBN,
????????????????? WM_CHAR,
????????????????? Ord(sTmp[i]),
????????????????? 0);
??? end;

??? PostMessage(hBN,
??????????????? WM_KEYDOWN,
??????????????? VK_RETURN, 0);
end;

This code has always worked fine for all versions of Rgui.exe 
with the
exception of the last one released, ie 4.2.0.

We've been trying to get around the problem on the Object 
Pascal side,
but without success so far.

Does anyone connected to the compilation of Rqui.exe know 
what the
problem is?

It could be that the new build enforces Windows security more 
stringently.? More details are described in the answer to this 
question: https://stackoverflow.com/a/40139498/2554330, but at 
a minimum you should be checking the return value from 
PostMessage.

Duncan Murdoch

Best,
///\\\///\\\///\\\///\\\///\\\///\\\///\\\///\\\///\\\///\\\
Jose Claudio Faria
UESC/DCET/Brasil
joseclaudio.faria at gmail.com
Telefones:
55(73)3680.5545 - UESC
55(73)99966.9100 - VIVO
///\\\///\\\///\\\///\\\///\\\///\\\///\\\///\\\///\\\///\\\
If you have software to deal with statistics, you have arms,
if you have good software, you have arms and legs,
if you have software like R, you have arms, legs and wings...
the height of your flight depends only on you.

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