Spurious characters in the GtkText widget?

[Sachin Garg <sachin cdacb ernet in>]

Hi all,

Recently, I started using GTK+, so my question might be very basic.
Please bear with me for this long mail.

What I am trying to do is this:

Catch KeyPresses, put them in a buffer, do some processing and then
insert the processed text in a GTKText widget. The processing involves
knowing where a word ends (using the space, tab or newline
characters). If a word ending is found, advance the insertion point
using gtk_text_set_point(), else let the insertion point be at the
beginning of the word, i.e. call gtk_text_set_point() with teh old
position, which is stored in a static variable.

I am enclosing a snippet of what happens.I request u people to make
head-or-tail out of this :)

	KEY_PRESS_EVENT event->keyval: 181: 0xb5 event->length 1
	event->string µ
	INPUT string length 1
	INPUT string :
	0xb5 
	OUTPUT string length 2
	OUTPUT string :
	0x4d 0xc9 
	Widget Text length: 2
	Widget Text: MÉ
	0x4d 0xc9 
	Widget Text Pos: 2
	KLUDGE: Del Status: 0
	KLUDGE: After Delete: Widget Text length: 2
	KLUDGE: After Delete: Widget Text: MÉ
	0x4d 0xc9 

let me explain this:

The key corresponding to 0xb5 (keys have been remapped using xmodmap)
is pressed. The input buffer contains 0xb5, and after
processing the output buffer contains 0x4d 0xc9. These characters are
inserted into the text widget using gtk_text_insert(). After this, the
widget contents length, text and position are queried for using
gtk_text_get_length(), gtk_editable_get_chars() and
gtk_text_get_point() functions.

I will explain the lines starting with "KLUDGE:" later. 

So far, so good.

The problem starts here:

	KEY_PRESS_EVENT event->keyval: 65505: 0xffe1 event->length 0
	event->string

Now this wasn't a key press! Something spurious is happening here! 
event->length is zero, so NO damage done and we carry on: 

	KEY_PRESS_EVENT event->keyval: 197: 0xc5 event->length 1 event->string Å
	INPUT string length 2
	INPUT string :
	0xb5 0xc5 

Now the INPUT buffer contains 2 characters, 

	OUTPUT string length 4
	OUTPUT string :
	0x4d 0xc9 0x76 0xc9 

and the OUTPUT buffer 4 characters

	Widget Text length: 7
	Widget Text: MÉvÉMɵ
	0x4d 0xc9 0x76 0xc9 0x4d 0xc9 0xb5 

BUT, the Widget contains 7 characters. The 3 extra characters, as can
be noticed are the previous 2 in the buffer and the previous key
press. 

	Widget Text Pos: 4

and the point is positioned at 4, where it should be!

	KLUDGE: Del Status: 1
	KLUDGE: After Delete: Widget Text length: 4
	KLUDGE: After Delete: Widget Text: MÉvÉ
	0x4d 0xc9 0x76 0xc9 

This is something I did to prevent cluttering up the display. I simply
delete gtk_text_get_length() - gtk_text_get_point() number of
characters using gtk_text_forward_delete()

Now, carrying on:

	KEY_PRESS_EVENT event->keyval: 218: 0xda event->length 1 event->string Ú
	INPUT string length 3
	INPUT string :
	0xb5 0xc5 0xda 

INPUT buffer: 3 characters,

	OUTPUT string length 5
	OUTPUT string :
	0x4d 0xc9 0x76 0xc9 0xc9 

OUTPUT buffer: 5 characters,

	Widget Text length: 10
	Widget Text: MÉvÉÉMÉvÉÅ
	0x4d 0xc9 0x76 0xc9 0xc9 0x4d 0xc9 0x76 0xc9 0xc5 
	Widget Text Pos: 5

BUT, widget contains 10 characters, insertion point is at location 5. 
The 5 extra characters, as can be noticed are the previous 4 in the
buffer and the previous key press.

May, I add, that since a word ending has *not* been encountered, the
insertion point remains at the old one, i.e. 0.

	KLUDGE: Del Status: 1
	KLUDGE: After Delete: Widget Text length: 5
	KLUDGE: After Delete: Widget Text: MÉvÉÉ
	0x4d 0xc9 0x76 0xc9 0xc9 

Carrying on:

	KEY_PRESS_EVENT event->keyval: 32: 0x20 event->length 1 event->string  
	INPUT string length 4
	INPUT string :
	0xb5 0xc5 0xda 0x20 
	OUTPUT string length 6
	OUTPUT string :
	0x4d 0xc9 0x76 0xc9 0xc9 0x20 
	Widget Text length: 12
	Widget Text: MÉvÉÉ MÉvÉÉÚ
	0x4d 0xc9 0x76 0xc9 0xc9 0x20 0x4d 0xc9 0x76 0xc9 0xc9 0xda 
	Widget Text Pos: 6

BUT, widget contains 12 characters, insertion point is at location 6. 
The 6 extra characters, as can be noticed are the previous 5 in the
buffer and the previous key press.

	KLUDGE: Del Status: 1
	KLUDGE: After Delete: Widget Text length: 6
	KLUDGE: After Delete: Widget Text: MÉvÉÉ 
	0x4d 0xc9 0x76 0xc9 0xc9 0x20 

A space has been received (0x20), and the insertion point moves on to
position 6.
 
	KEY_PRESS_EVENT event->keyval: 186: 0xba event->length 1 event->string º
	INPUT string length 1
	INPUT string :
	0xba 
	OUTPUT string length 2
	OUTPUT string :
	0x56 0xc9 
	Widget Text length: 9
	Widget Text: MÉvÉÉ VÉ 
	0x4d 0xc9 0x76 0xc9 0xc9 0x20 0x56 0xc9 0x20 
	Widget Text Pos: 8
	KLUDGE: Del Status: 1
	KLUDGE: After Delete: Widget Text length: 8
	KLUDGE: After Delete: Widget Text: MÉvÉÉ VÉ
	0x4d 0xc9 0x76 0xc9 0xc9 0x20 0x56 0xc9

BUT, widget contains 9 characters, insertion point is at location 8. 
The 1 extra character, as can be noticed is the previous key press.
 
	KEY_PRESS_EVENT event->keyval: 216: 0xd8 event->length 1 event->string Ø
	INPUT string length 2
	INPUT string :
	0xba 0xd8 
	OUTPUT string length 4
	OUTPUT string :
	0x56 0xc9 0xbd 0xfe 
	Widget Text length: 13
	Widget Text: MÉvÉÉ VɽþVɺ
	0x4d 0xc9 0x76 0xc9 0xc9 0x20 0x56 0xc9 0xbd 0xfe 0x56 0xc9 0xba 
	Widget Text Pos: 10
	KLUDGE: Del Status: 1
	KLUDGE: After Delete: Widget Text length: 10
	KLUDGE: After Delete: Widget Text: MÉvÉÉ Vɽþ
	0x4d 0xc9 0x76 0xc9 0xc9 0x20 0x56 0xc9 0xbd 0xfe

so on, and so forth ...

Could it be, that even though I am trapping the KEY_PRESS events, they
make their way to the GtkWidget?

If so, how to disable this? Or a better method to get input into teh
GtkTextWidget?

Thanks a lot and soryy for the outrageously long mail.

Warm regards,

Sachin

Hubbard's Law:
        Don't take life too seriously; you won't get out of it alive.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                 Sachin Garg, Member Technical Staff 
      Centre for Development of Advanced Computing,BANGALORE,INDIA  
            Phone: +91-80-5584271/143/982 Fax: +91-80-5584893
               http://sangam.cjb.net <sachin@cdacb.ernet.in>