Re: undo problem for Input Method

[Bram Moolenaar]

Yukihiro Nakadaira wrote:

> I am using GTK2 GUI.  When using Input Method, undo sequence is broken at
> each start of multibyte character.  For example, after insert some multibyte
> characters (A B C),
>   line: A B C
> Do undo
>   line: A B C
> Do undo
>   line: A B
> Do undo
>   line: A
> Do undo
>   line:
> I must undo four times to undo one insert command.
>
> When using Input Method, Left key is added to typeahead buffer by
> mbyte.c:im_correct_cursor().  Then, the Left key command is interpreted and
> later new undo sequence is started.  To avoid this problem, check if
> im_is_preediting() is true in start_arrow().
>
> Thanks.
>
>
> *** edit.c.orig Fri Aug 25 06:14:48 2006
> --- edit.c Fri Aug 25 06:14:55 2006
> ***************
> *** 6026,6031 ****
> --- 6026,6035 ----
>   start_arrow(end_insert_pos)
>       pos_T    *end_insert_pos;    /* can be NULL */
>   {
> + #if defined(FEAT_XIM) && defined(FEAT_GUI_GTK)
> +     if (im_is_preediting())
> + return;    /* XIM is busy, don't break an undo sequence */
> + #endif
>       if (!arrow_used)    /* something has been inserted */
>       {
>   AppendToRedobuff(ESC_STR);

I don't understand why the cursor is moved.  This appears to happen
after inserting characters, thus moving cursor to before these inserted
characters.  Hmm, it appears they are later deleted with the Del key.

I find it a little bit dangerous to simply return from start_arrow().
To make this a bit more strict perhaps the call to start_arrow() in
ins_left() can be skipped when im_is_preediting() returns TRUE?

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[Yukihiro Nakadaira-2]

Bram Moolenaar wrote:
> I don't understand why the cursor is moved.  This appears to happen
> after inserting characters, thus moving cursor to before these inserted
> characters.  Hmm, it appears they are later deleted with the Del key.

Cursor is moved just for displaying.  And also cursor can be positioned
at middle of preedit string.

Those inserted characters are preedit string.  Preedit string is
temporarily inserted to show what is to be inserted (like a Vim's
completion).  It can be edited with Input Method until it is committed.
"commit" means inserting edited string.  When preedit string is changed,
it is deleted and new preedt string is inserted.  When preedit string is
committed, it is deleted and the edited string is inserted really.

> I find it a little bit dangerous to simply return from start_arrow().
> To make this a bit more strict perhaps the call to start_arrow() in
> ins_left() can be skipped when im_is_preediting() returns TRUE?

I agree with you.  I think that im_is_preediting() returns TRUE only
when start_arrow() is called from ins_left().

--
Yukihiro Nakadaira - [hidden email]