Re: gtk_text_buffer_delete ?

[Liam R E Quin]

On Thu, 08 Oct 2015 20:59:21 +0200
Stefan Salewski  wrote:

> I was hoping that it could be possible to simple block input when buffer
> has a maximum length, but I got that not working.

Note that this can give an unpleasant user experience. It might be more helpful 
just to have a count of characters available that becomes negative and changes 
from grey to red (change both lightness and colour, for people who can't 
differentiate black from red) - you see this approach on Web sites quite often. 
Then people can paste a longer text and delete it, or can add a new word and 
then delete a longer one.

Best,

Liam


-- 
Liam Quin - XML Activity Lead, W3C, http://www.w3.org/People/Quin/
Pictures from old books: http://fromoldbooks.org/
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Re: gtk_text_buffer_delete ?

[Pierre Wieser]

> - Original Message -
>> From: "Stefan Salewski" 
>> Sent: Wednesday, October 7, 2015 7:36:05 PM
> 
>> On Wed, 2015-10-07 at 13:14 +0200, Pierre Wieser wrote:
>>> I so connected to the 'changed' signal of the GtkTextBuffer,
>> 
>> Maybe try connecting to insert-text signal -- changed signal may be
>> emitted again when you delete. See
>> 
>> http://stackoverflow.com/questions/2791035/how-do-i-set-buffer-limit-for
>> -gtk-text-view-in-c
> 
> Humm.. I've seen this thread too, but didn't understand the proposed behavior.

Oop's. Sorry ! I've clicked on the bad button !!
Please, do not consider this mail, as I have to worked a bit more on it..
Thanks
Pierre
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Re: gtk_text_buffer_delete ?

[Stefan Salewski]

On Thu, 2015-10-08 at 10:30 +0200, Pierre Wieser wrote:
> Oop's. Sorry ! I've clicked on the bad button !!

Yes, it is sad that this trivial task is so hard, and that no one can
really help.

I was hoping that it could be possible to simple block input when buffer
has a maximum length, but I got that not working.

But deleting works at least.

https://developer.gnome.org/gtk3/stable/GtkTextBuffer.html#GtkTextBuffer
-insert-text

>Note that if your handler runs before the default handler it must not
>invalidate the location iter (or has to revalidate it).

So our callback have to reset the iter!

I did some test in Nim, a change to test my bindings and become some
more comfortable with that language. There we have

discard g_signal_connect_after(buffer, "insert-text", g_callback(clip), nil)

proc clip*(buffer: TextBuffer, iter: TextIter; text: cstring; len: gint; data: 
gpointer) {.cdecl.} =
  const max = 8
  var i, j: TextIterObj
  var cc = buffer.char_count
  if cc > max:
buffer.get_iter_at_offset(i, cc)
j = i # copy iter object
discard j.backward_chars(cc - max)
buffer.delete(j, i)
buffer.get_iter_at_offset(iter[], max) # set iter to valid value again, 
value seems to be arbitray

So the trick is just the last line, reset the iter callback parameter to
a valid value after deletion. It is strange, I have the feeling that the
callback is executed after the new text was already inserted, but in
spite of that gtk complains about invalid iter. Strange. I guess you can
understand the idea of that Nim code. I connected to "insert-text"
signal, so no danger of recursion. I used g_signal_connect_after here,
seems to make more sense when we delete last char. g_signal_connect
works similar, but we seem to get one char more? Maybe Emmanuele Bassi
can comment on this later...
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gtk_text_buffer_delete ?

[Pierre Wieser]

Hello, 

On the application I'm currently working on [1], I want limit the size of the
text entered in a GtkTextBuffer to those saved in the DBMS, so 4096 chars.

I so connected to the 'changed' signal of the GtkTextBuffer, and the handler
is :

static void
on_notes_changed( GtkTextBuffer *buffer, void *empty )
{
static const gchar *thisfn = "my_utils_on_notes_changed";
static const gint MAX_LENGTH = 4096;
static gboolean in = FALSE;
gint count;
GtkTextIter start, end;

/* prevent an infinite recursion */
if( !in ){
count = gtk_text_buffer_get_char_count( buffer );
if( count >= MAX_LENGTH ){
/*
 * this code works, but emit the following Gtk-Warning:
 *
 * Invalid text buffer iterator: either the iterator is
 * uninitialized, or the characters/pixbufs/widgets in 
the
 * buffer have been modified since the iterator was 
created.
 * You must use marks, character numbers, or line 
numbers to
 * preserve a position across buffer modifications.
 * You can apply tags and insert marks without 
invalidating
 * your iterators, but any mutation that affects 
'indexable'
 * buffer contents (contents that can be referred to by 
character
 * offset) will invalidate all outstanding iterators
 */
gtk_text_buffer_get_iter_at_offset( buffer, , 
MAX_LENGTH-1 );
/*gtk_text_iter_backward_char(  );*/
/*gtk_text_buffer_get_iter_at_offset( buffer, , 
count );*/
gtk_text_buffer_get_end_iter( buffer,  );
/*gtk_text_iter_backward_char(  );*/
in = TRUE;
g_debug( "%s: count=%d, start=%d, end=%d",
thisfn, count, 
gtk_text_iter_get_offset(  ), gtk_text_iter_get_offset(  ));
    gtk_text_buffer_delete( buffer, ,  );
in = FALSE;
}
}
}

As stated in the comment, the code works (the size if actually limited to 4095 
chars),
but each execution of gtk_text_buffer_delete() triggers the well-known warning
"Invalid text buffer iterator".

I am a bit stucked here, because I do not understand why this happens, as the 
buffer
is not modified between taking the iters and deleting the content...

Can anyone help me in this matter ?

Thanks in advance.
Regards
Pierre
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Re: gtk_text_buffer_delete ?

[Pierre Wieser]

> On the application I'm currently working on [1], I want limit the size of the
> [...]

I omit the application link, for reference ;)

[1] https://github.com/trychlos/openbook/
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Re: gtk_text_buffer_delete ?

[Jim Charlton]

On 15-10-07 04:14 AM, Pierre Wieser wrote:

Hello,

On the application I'm currently working on [1], I want limit the size of the
text entered in a GtkTextBuffer to those saved in the DBMS, so 4096 chars.

I so connected to the 'changed' signal of the GtkTextBuffer, and the handler
is :

static void
on_notes_changed( GtkTextBuffer *buffer, void *empty )
{
static const gchar *thisfn = "my_utils_on_notes_changed";
static const gint MAX_LENGTH = 4096;
static gboolean in = FALSE;
gint count;
GtkTextIter start, end;

/* prevent an infinite recursion */
if( !in ){
count = gtk_text_buffer_get_char_count( buffer );
if( count >= MAX_LENGTH ){
/*
 * this code works, but emit the following Gtk-Warning:
 *
 * Invalid text buffer iterator: either the iterator is
 * uninitialized, or the characters/pixbufs/widgets in 
the
 * buffer have been modified since the iterator was 
created.
 * You must use marks, character numbers, or line 
numbers to
 * preserve a position across buffer modifications.
 * You can apply tags and insert marks without 
invalidating
 * your iterators, but any mutation that affects 
'indexable'
 * buffer contents (contents that can be referred to by 
character
 * offset) will invalidate all outstanding iterators
 */
gtk_text_buffer_get_iter_at_offset( buffer, , 
MAX_LENGTH-1 );
/*gtk_text_iter_backward_char(  );*/
/*gtk_text_buffer_get_iter_at_offset( buffer, , 
count );*/
gtk_text_buffer_get_end_iter( buffer,  );
/*gtk_text_iter_backward_char(  );*/
in = TRUE;
g_debug( "%s: count=%d, start=%d, end=%d",
thisfn, count, gtk_text_iter_get_offset( 
 ), gtk_text_iter_get_offset(  ));
    gtk_text_buffer_delete( buffer, ,  );
in = FALSE;
}
}
}

As stated in the comment, the code works (the size if actually limited to 4095 
chars),
but each execution of gtk_text_buffer_delete() triggers the well-known warning
"Invalid text buffer iterator".

I am a bit stucked here, because I do not understand why this happens, as the 
buffer
is not modified between taking the iters and deleting the content...

Can anyone help me in this matter ?

Thanks in advance.
Regards
Pierre
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I do not have an answer to the problem as stated, but I have written 
code that achieves the overall purpose of pruning the text buffer.

I work in Gtkmm rather than in GTK3.  Here is a snippet of code.
*
start = tb1_ptr->begin();
end = tb1_ptr->end();
if (end.get_offset() > 254) end.set_offset(254);
text = tb1_ptr->get_text(start, end, FALSE);

where
tb1_ptr = Gtk::TextBuffer::create();
Gtk::TextIter start;
Gtk::TextIter end;
Glib::ustring text;

In your case, rather than using gtk_text_buffer_delete, you would use
gtk_text_iter_get_offset (/|const GtkTextIter 
<https://developer.gnome.org/gtk3/stable/GtkTextIter.html> *iter|/);

and
gtk_text_iter_set_offset (/|GtkTextIter 
<https://developer.gnome.org/gtk3/stable/GtkTextIter.html> *iter|/, 
/|gint 
<https://developer.gnome.org/glib/unstable/glib-Basic-Types.html#gint> 
char_offset|/);


to limit the text buffer to your desired length.

Hope this helps...   Jim...




text = tb1_ptr->get_text(start, end, FALSE);
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Re: gtk_text_buffer_delete ?

[Stefan Salewski]

On Wed, 2015-10-07 at 13:14 +0200, Pierre Wieser wrote:
> Hello, 
> 
> On the application I'm currently working on [1], I want limit the size
> of the
> text entered in a GtkTextBuffer to those saved in the DBMS, so 4096
> chars.

Seen that:

http://www.gtkforums.com/viewtopic.php?t=1012

Very similar to your solution, but I think that was GTK2, and your is
GTK3.

No other idea, sorry.
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Re: gtk_text_buffer_delete ?

[Stefan Salewski]

On Wed, 2015-10-07 at 13:14 +0200, Pierre Wieser wrote:
> I so connected to the 'changed' signal of the GtkTextBuffer,

Maybe try connecting to insert-text signal -- changed signal may be
emitted again when you delete. See

http://stackoverflow.com/questions/2791035/how-do-i-set-buffer-limit-for
-gtk-text-view-in-c
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Re: gtk_text_buffer_delete ?

[Pierre Wieser]

On Wed, 2015-10-07 at 15:05 +0200, Stefan Salewski wrote:

> On Wed, 2015-10-07 at 13:14 +0200, Pierre Wieser wrote:
>> Hello, 
>> 
>> On the application I'm currently working on [1], I want limit the size
>> of the
>> text entered in a GtkTextBuffer to those saved in the DBMS, so 4096
>> chars.
>
> Seen that:
>
> http://www.gtkforums.com/viewtopic.php?t=1012
>
> Very similar to your solution, but I think that was GTK2, and your is
> GTK3.

Hi Stefan,

Thanks for your interest, but the thread you point to is actually the one
on which I based my own code.
I do not think that GTK2 vs GTK3 is a point in this matter, do you ?

> No other idea, sorry.

And Google has not been my friend further...
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