* user-ptr as image :data
@ 2019-03-15 19:14 Evgeny Zajcev
2019-03-15 19:41 ` Stefan Monnier
0 siblings, 1 reply; 3+ messages in thread
From: Evgeny Zajcev @ 2019-03-15 19:14 UTC (permalink / raw)
To: emacs-devel
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I'm currently porting (https://github.com/zevlg/ffi-wand.el) nice wand-mode
from SXEmacs to GNU Emacs and I miss feature to specify image `:data' as
user-ptr object.
There is also no possibility to create DATA string in emacs-module, without
string interpretation, because there is only `make_string' method, which
expects given `str' pointer to be null-terminated UTF-8 string.
What is the best approach to create `:data` value for image using user-ptr?
Thanks
--
lg
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^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: user-ptr as image :data
2019-03-15 19:14 Evgeny Zajcev
@ 2019-03-15 19:41 ` Stefan Monnier
0 siblings, 0 replies; 3+ messages in thread
From: Stefan Monnier @ 2019-03-15 19:41 UTC (permalink / raw)
To: emacs-devel
> I'm currently porting (https://github.com/zevlg/ffi-wand.el) nice wand-mode
> from SXEmacs to GNU Emacs and I miss feature to specify image `:data' as
> user-ptr object.
>
> There is also no possibility to create DATA string in emacs-module, without
> string interpretation, because there is only `make_string' method, which
> expects given `str' pointer to be null-terminated UTF-8 string.
Hmm... indeed we don't have any direct way to create a unibyte string.
Can you `M-x report-emacs-bug` to request this new feature?
> What is the best approach to create `:data` value for image using user-ptr?
AFAICT while the string needs to have a NUL byte after its end,
make_string should handle NUL bytes within the string, so the best
option until a new primitive is provided is probably:
1- use make-string on your non-utf-8 binary data.
2- call encode-coding-string on the result (with utf-8 coding system).
It's ugly, hackish, and inefficient, but our decoding+encoding functions
are supposed to always preserve binary contents when no changes took
place (using the chars in the eight-bit charset when needed), so 1+2
should give you a unibyte string which has the exact byte sequence from
which you started.
Stefan
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: user-ptr as image :data
@ 2019-03-15 20:28 Evgeny Zajcev
0 siblings, 0 replies; 3+ messages in thread
From: Evgeny Zajcev @ 2019-03-15 20:28 UTC (permalink / raw)
To: monnier; +Cc: emacs-devel
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> Hmm... indeed we don't have any direct way to create a unibyte string.
> Can you `M-x report-emacs-bug` to request this new feature?
will do
> AFAICT while the string needs to have a NUL byte after its end,
> make_string should handle NUL bytes within the string, so the best
> option until a new primitive is provided is probably:
> 1- use make-string on your non-utf-8 binary data.
> 2- call encode-coding-string on the result (with utf-8 coding system).
This works! very slow, but it works, I'll use this hack for now
thanks
--
lg
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^ permalink raw reply [flat|nested] 3+ messages in thread
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2019-03-15 19:41 ` Stefan Monnier
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