[Rd] Writing in R // R 4.2.0 on Windows doesn't work with Dasher

[Duncan Murdoch]

On 15/05/2022 10:58 a.m., Ivan Krylov wrote:
> On Sun, 15 May 2022 11:10:49 -0300
> Paulo Barata <pb using infolink.com.br> wrote:
> 
>> I noticed today that R 4.2.0 responds to the "Enter" character of
>> Dasher version 5.0.0 beta in "Direct Entry" mode. An "Enter" in
>> Dasher causes the R prompt to jump to the next line, as an "Enter"
>> should do.
>>
>> No other characters (letters, digits, special characters like + = & ~
>> | # $) are accepted by R 4.2.0 through Dasher.
> 
> This seems to be very similar to the problem discussed here:
> https://stat.ethz.ch/pipermail/r-devel/2022-May/081683.html
> 
> For the record, here's the part of Dasher responsible for "Direct
> Entry" on Windows:
> https://github.com/dasher-project/dasher/blob/0ec7d646dbaadf06b8eebfc11b784738a20e75af/Src/Win32/Widgets/Edit.cpp#L302
> 
> MSDN says:
> 
>>> If KEYEVENTF_UNICODE is specified, SendInput sends a WM_KEYDOWN or
>>> WM_KEYUP message to the foreground thread's message queue with
>>> wParam equal to VK_PACKET. Once GetMessage or PeekMessage obtains
>>> this message, passing the message to TranslateMessage posts a
>>> WM_CHAR message with the Unicode character originally specified by
>>> wScan.
> 
> <https://docs.microsoft.com/en-us/windows/win32/api/winuser/ns-winuser-keybdinput>

As far as I can see, Graphapp never looks for VK_PACKET.

> 
> Previously, Tomas Kalibera has mentioned:
> 
>> For Unicode Windows, GraphApp uses WM_IME_COMPOSITION messages to
>> read the keys instead of WM_CHAR, which it uses for non-Unicode
>> windows.
> 
> I think that for a combination of R >= 4.2 and Dasher, this means an
> impasse. Either Dasher should be taught to send WM_IME_COMPOSITION
> messages to R (?), or R should learn to understand WM_CHAR messages in
> its Unicode windows in addition to WM_IME_COMPOSITION it currently uses.
> 

Another possible solution for Paulo is to use R via some other front end 
besides RGui, e.g. RStudio, but there are other possibilities too.

Duncan Murdoch