Re: Cygwin fails to utilize Unicode replacement character

[Corinna Vinschen <corinna-cygwin at cygwin dot com>]

On Sep  3 20:20, Thomas Wolff wrote:
> Am 03.09.2018 um 19:56 schrieb Thomas Wolff:
> > Am 03.09.2018 um 19:16 schrieb Corinna Vinschen:
> > > On Sep  3 18:34, Thomas Wolff wrote:
> > > > Am 03.09.2018 um 16:59 schrieb Corinna Vinschen:
> > > > > On Sep  3 14:46, Corinna Vinschen wrote:
> > > > > > On Sep  2 05:51, Steven Penny wrote:
> > > > > > > On Sun, 2 Sep 2018 10:07:10, Thomas Wolff wrote:
> > > > > > > > Actually, the width problem I suggested in my
> > > > > > > > other response (and even
> > > > > > > > referring to the wrong character) does not apply as mintty enforces
> > > > > > > > proper width in that case.
> > > > > > > > Also, even with fonts that do not provide the
> > > > > > > > glyph, you will usually
> > > > > > > > still see it by the Windows font fallback mechanism.
> > > > > > > > Shall I make it configurable?
> > > > > > > your call - here are the possible resolutions - in
> > > > > > > order of my preference:
> > > > > > > 
> > > > > > > 1. Change the default to U+FFFD with no option
> > > > > > > 2. Change the default to U+FFFD with option to change
> > > > > > > 3. Leave default as is with option to change
> > > > > > Ideally we could check if the current font supports a visual
> > > > > > representation of 0xfffd and if not, fall back to 0x2592.
> > > > > > 
> > > > > > Not sure how feasible that is, but it doesn't seem to be overly
> > > > > > complicated.  I'm just looking into a solution for the Cygwin
> > > > > > console.
> > > > > Only, I can't get this working.  In theory the GDI function
> > > > > GetGlyphIndicesW is supposed to allow checking if a certain character
> > > > > exists.  But I'm getting a weird result.  This code:
> > > > > 
> > > > >     static const wchar_t replacement_char[2] =
> > > > >       {
> > > > >         0xfffd, /* REPLACEMENT CHARACTER */
> > > > >         0x2592  /* MEDIUM SHADE */
> > > > >       };
> > > > >     HWND cwnd = GetConsoleWindow ();
> > > > >     HDC cdc = GetDC (cwnd);
> > > > >     int rp_idx = 0;
> > > > >     WORD gi = 0;
> > > > >     DWORD ret = GetGlyphIndicesW (cdc, replacement_char, 1, &gi,
> > > > > GGI_MARK_NONEXISTING_GLYPHS);
> > > > >     if (ret != GDI_ERROR && gi == 0xffff)
> > > > >       rp_idx = 1;
> > > > > 
> > > > > always sets rp_idx to 1 when called from inside the Cygwin DLL,
> > > > > independently of the actual console font.  And, here's the
> > > > > really weird
> > > > > thing, it always sets rp_idx to 0 when called directly from an
> > > > > application, likewise independently of the actual console font.
> > > > > 
> > > > > Does anybody have an idea what I'm doing wrong?
> > > > This works in mintty, just uploaded a patch. Maybe somehow the
> > > > GetConsole
> > > > "dc" does not support this usage?
> > > ¯\_(ツ)_/¯
> > Dito; hold on, sorry, your code does *not* work inside mintty.
> > Mine looks a bit different and I thought to have manually verified it's
> > functionally equivalent, but indeed there must be something fishy...
> You still need to
>   SelectObject(cdc, f);
> where f is the HFONT of the font you want to check.
> To compare, you may check out function win_check_glyphs in file wintext.c in
> mintty.

Thanks but I don't know how to get a HFONT for the current console font.

In the meantime I figured out why my GetCurrentConsoleFontEx call
failed with error 87:

When looking again I realized there's a member called cbSize.  The MSDN
docs neglect to tell that the cbSize member has to be primed with
sizeof(CONSOLE_FONT_INFOEX).  As soon as I tried that, the function
succeeded.

Well, it's a start.  I now have the actual font name.  No idea how to
get a HFONT from there, though.  From what I can tell ATM, I'd have to
call CreateFont to get a new HFONT and then destroy it again after
usage.  This looks pretty wasteful.


Thanks,
Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Maintainer                 cygwin AT cygwin DOT com
Red Hat

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