savannah: make tabs and trailing spaces visible

[slavazanko]

Original: ​http://savannah.gnu.org/bugs/?13146

Submitted by:	Oswald Buddenhagen <ossi>	Submitted on:	Sat 21 May 2005 07:25:17 PM UTC
Category:	Editor	Severity:	3 - Normal
Status:	In Progress	Privacy:	Public
Assigned to:	None	Open/Closed:	Open
Release:	current (CVS or snapshot)	Operating System:	All

Discussion:

Sun 06 Jul 2008 04:12:04 PM UTC, comment #24:

I noticed I cannot just use the Unicode characters (like p->ch = 
0xB7), as that does not take into account terminals that are not in 
UTF-8. But the fix is simple enough (p->ch = SLsmg_Is_Unicode ? 0xB7 : ".").

BTW, I also implemented the MS Word-style "tabs", i.e. printing a 
right-arrow in the middle of a tab. I sort of prefer it over the 
"<---->" tabs. It is a patch that currently replaces the existing 
tab mechanism, but IMHO this should all be made configurable once 
the maintainers decide to wake up and give me some sort of ok...

(file #16007)
	Jan Engelhardt <hirogen2>
Sun 06 Jul 2008 01:24:09 PM UTC, comment #23:

Patch #4 -- cedit-symbol-prefs.diff

This patch changes the space fill character to some Unicode dot (·) 
[this one is also available on the text console], and makes the 
<------> tab filler into the Unicode ◀──────▶ too.

(file #16006)
	Jan Engelhardt <hirogen2>
Sun 06 Jul 2008 01:21:22 PM UTC, comment #22:

Patch #3 -- cedit-fix-whitespace.diff

We definitely need to set MOD_WHITESPACE or the space between tab 
stops is drawn with some random color.

(file #16005)
	Jan Engelhardt <hirogen2>
Sun 06 Jul 2008 01:19:54 PM UTC, comment #21:

Patch #2 -- cedit-eol-mark.diff

This patch implements comment #8's suggestion to use ¶ as an EOL 
marker. It can be toggled using the Options>Highlight options 
dialog, or, of course, by editing ~/.mc/config directly.

(file #16004)
	Jan Engelhardt <hirogen2>
Sun 06 Jul 2008 01:17:43 PM UTC, comment #20:

Ok since nobody replied here are some patches of my own.
They require that mc(edit) has COMPLETE support for UTF-8!, which 
is not the case in the mc source distribution. The openSUSE 
.src.rpm has the required utf8 bits. Will try to make them submit 
theirs.

Patch #1 -- cedit-configurable-highlight.diff

This is for comment #19; it allows to switch highlighting. Firstly, 
it adds a dialog (Options > Highlight options) where you can 
precisely select what to highlight

[ ] Global syntax highlighting

[ ] Tab highlighting (those <------> markers, which, btw, can get 
very ugly if you have lots of code)

[ ] Whitespace highlighting (dots at the end-of-line, and, if tab 
highlighting is disabled, anywhere on the line)

One can already toggle Syntax highlighting with Ctrl-S in mc 4.6.2, 
for the latter two, I added Ctrl-V as a hotkey which cycles through 
the possibilities. My personal preference is to have Tab highlight 
OFF and Whitespace highlight ON.

(file #16003)
	Jan Engelhardt <hirogen2>
Fri 29 Feb 2008 07:16:33 PM UTC, comment #19:

Oh, god... I just updated my Debian box, and I now run MC 
4.6.2-pre1 (as outputted by mcedit --version). It appears that this 
patch is included in this version of mcedit. I really dislike it. 
Besides suffering from the 'cursor disappearing' thingy, I just 
think its ugly. But that's my humble opinion :)
How can I disable it? The patches attached to this report don't 
seem to make a new configurable parameter available in the 
configuration dialogs.
	Jurrie Overgoor <leadpumper>
Tue 04 Sep 2007 05:29:40 AM UTC, comment #18:

Pavel, I applied your patch to vte-0.16.8. It works.
	Andrew Borodin <a_borodin>
Mon 03 Sep 2007 01:15:42 PM UTC, comment #17:

Ok. I tracked the "bug" to vte_terminal_determine_colors() in the 
vte package. To request brighter colors one forces the terminal 
into "bold mode". It seems that in this mode vte allows only the 
foreground color to be bright. In vte's terms a bright color is the 
same color as the normal one but with a special flag set. So what 
happens is that when the time comes for the cursor to blink vte 
switches the current forground color with the current background 
color and vice versa... As I said above
both colors are indentified in the same way but one has a special 
flag, however vte uses this flag to brighten the foreground color 
so at the end we end up as if nothing happened. It's hard to say 
whether this is the desired behaviour .. I'll attach a simple patch 
which changes vte to do what seems more logically correct... and 
I'll open a report in gnome's bugzilla.

(file #13873)
	Pavel Tsekov <ptsekov>
Project Administrator
Fri 31 Aug 2007 04:19:43 PM UTC, comment #16:

IMO, this must be a bug in gnome-terminal. It doesn't behave 
properly if one uses both the bright and normal colors as the 
background and foreground of the same cell. I changed the
the definition of "editwhitespace" to "brightred,red" and the 
cursor is not displayed in this case as well. I also changed the 
color for brightblue in my gnome-terminal profile to a different 
color but no matter the cursor wasnt displayed. I'll see if they 
have a bugreport in their bugzilla.
	Pavel Tsekov <ptsekov>
Project Administrator
Fri 31 Aug 2007 09:28:17 AM UTC, comment #15:

This may be a bug in gnome-terminal as well... I am also using 
gnome-terminal and no matter the color scheme the cursor is 
invisible. I'll investigate further...
	Pavel Tsekov <ptsekov>
Project Administrator
Fri 31 Aug 2007 06:07:28 AM UTC, comment #14:

Oswald, you are right. This effect is depending on terminal 
emulation program and color scheme.

In linux console, cursor is visible every time. The color of cursor 
is changed to light blue in tab and trailing space positions, but 
cursor is visible.

The same is in xterm under X. xterm doesn't have any non-default 
cursor settings.

In gnome-terminal and multi-gnome-terminal, which I use, cursor 
changes its color and becomes invisible. ("Green on black" color 
scheme and "Linux console" palette are used in both those programs.)

Is it possible to make the same cursor color in positions of 
visualized tab an training space as in positions of other symbols?
	Andrew Borodin <a_borodin>
Thu 30 Aug 2007 12:58:35 PM UTC, comment #13:

that's weird ... i see no such effect (little surprisingly). though 
with some terminals/color combinations it becomes light blue, too, 
and thus hardly visible, but i don't think we can do much about 
that.
	Oswald Buddenhagen <ossi>
Thu 30 Aug 2007 12:39:39 PM UTC, comment #12:

Yep. As I said - i'll be fixing the patch... I prefer to have it in 
CVS even if it has minor glitches. In the meantime if you find any 
other problems with it - please, feel free to report them.
	Pavel Tsekov <ptsekov>
Project Administrator
Thu 30 Aug 2007 12:29:20 PM UTC, comment #11:

Cursor in TAB and trailing space position is disappeared. This is 
very uncomfortable.
	Andrew Borodin <a_borodin>
Mon 27 Aug 2007 12:08:04 PM UTC, comment #10:

The patch is in CVS now. I've commited mcedit-visible-ws-v2.diff 
with no changes whatsoever ... I'll be making changes to it as 
discussed in this bugreport in the next few weeks.
	Pavel Tsekov <ptsekov>
Project Administrator
Thu 09 Aug 2007 08:53:35 PM UTC, comment #9:

i considered making all whitespace visible, but somehow found it 
pointless and even counterproductive for my use cases.
for linefeeds, i really see no use case ...
regarding the use of special characters, this is not doable without 
utter hackery. mc is restricted to the abstract char set provided 
by ncurses/slang, which unfortunately does not provide these chars.
	Oswald Buddenhagen <ossi>
Thu 09 Aug 2007 08:28:12 PM UTC, comment #8:

This mcedit-visible-ws-v2.diff works great with mc-4.6.1
What a pity it is not inside mc by default. The light blue color is 
great - it shows invisible characters but not disturbs 
reading/editing.

There is one little thing I would like to see:
make tabs, all spaces and carriage returns visible like in OpenOffice/M$ Word.

This means that:
-all spaces are visible as dots ···· (unicode 00B7) (not only 
trailing but all - this is comfortable when hunting for 
double/multi spaces between words).
-tabs are visible as arrows → (unicode 2192) (somethhing like -> mc 
uses semigraphics so can draw arrows too)
-carriage returns are visible as reversed P character ¶ (unicode 
00B6)
(I know this is poor description but just run OO Writer or Word to 
see how these formating characters are marked).

I really would like to see this patch in mc as default. It is very 
helpful and allows to keep .conf files clean.
	Zbigniew Luszpinski <mr_zbiggy>
Sun 05 Feb 2006 04:51:56 PM UTC, comment #7:

it just occurred to me, that i don't want two separate shortcuts 
for toggling these options. two separate persistent options in the 
config dialog are ok, but there should be only one "quick toggle" 
shortcut (ctrl-w) that disables both at once, and is not saved 
anywhere.
i suppose the envisioned ctrl-s shortcut for toggling syntax 
highlighting should be non-persistent as well.
	Oswald Buddenhagen <ossi>
Mon 30 Jan 2006 05:16:22 PM UTC, comment #6:

Single patch is OK.
	Pavel Tsekov <ptsekov>
Project Administrator
Mon 30 Jan 2006 04:33:20 PM UTC, comment #5:

ok, here's a patch which allows enabling visible trailing 
whitespace and visible tabs independently. i'm not eager to split 
it into two patches; they are too much related.
i just threw in the options as variables right above the relevant 
function - i'd prefer you wrapping this into proper configurability 
(options in the edit config dialog and keyboard accels) yourself, 
as i'd have to research how to do it first. :}
	Oswald Buddenhagen <ossi>
Mon 30 Jan 2006 04:19:36 PM UTC, comment #4:

ok, i changed my mind - i have a strong opinion now. :)
i think it's right that trailing tabs should not prevent preceeding 
spaces from being marked as trailing: if trailing whitespace 
removal is implemented, all these chars will be equally killed away.
	Oswald Buddenhagen <ossi>
Mon 30 Jan 2006 03:53:54 PM UTC, comment #3:

I did try it and have been playing with it for a while. This patch
adds (1) visible trailing spaces and (2) visible tabs. In fact I 
prefer to think of it as two separate patches. As you suggested on 
the list it should be enhanced so that the user can switch this 
functionality on and off via a fast key. I would add that the user 
should be allowed to enable (1) without enabling (2) and vice versa.
	Pavel Tsekov <ptsekov>
Project Administrator
Mon 30 Jan 2006 03:35:14 PM UTC, comment #2:

well, tabs should stay tabs. masking them away in this special case 
would just lead to surprises.
not sure about your example. it's true that it looks a bit weird. 
otoh, such whitespace is plainly broken, so it should look broken. 
:) also, if you change it, suddenly chars in the middle of a line 
will vanish/appear if you (append past/remove up to) the trailing 
tabs. it depends on whether one wants to get the static or the 
dynamic case nicer.
the patch is really simple, so give it a try. after all, i have no 
particular opinion on this matter - i need to highlight trailing 
whitespace only to annihilate any occurrences of it anyway. :-)=)
	Oswald Buddenhagen <ossi>
Mon 30 Jan 2006 03:09:00 PM UTC, comment #1:

How about considering the trailing tabs a trailing whitespace too 
and marking all the traling whitespace with just a dot ?

Now if a have a like like this:

int func()<space><space><space><space><tab><tab>

i get

int func() <><------><------>

This is pretty inconsistent and annoying (IMO).
	Pavel Tsekov <ptsekov>
Project Administrator
Sat 21 May 2005 07:25:17 PM UTC, original submission:

visible tabs help putting the tabs where you want them, 
particularly when trying to stay consistent with the style of text 
written by somebody else.
making trailing whitespace visible helps avoiding it in undesired 
places.

here is a patch that accomplishes this. it is missing an option to 
disable this feature, so i post this as a wish instead of as a 
patch.

i wanted the visibility to be as subtle as possible. therefore just 
changing the background color (see leading tabs in Makefile 
highlite) was no option. so i paint tabs as excerpts of <------> 
and spaces as dots. to make it really subtle, i paint it bright 
blue on dark blue (the regular background) - this is hardly 
visible, unless you are looking for it. i know of no way to make it 
equally subtle on monochrome displays,
so the feature is disabled alltogether there.
the whitespace becomes invisible when the text is selected, as 
there is no possibility to merge colors. it'd be nice to fix this 
generally.
the highlite color is not defined by syntax highlighting, but by an 
extra palette entry. i think this makes sense.
this feature overrides other colors that might be defined for 
whitespace, like the red background of tabs in Makefiles. the block 
in #if 0 would preserve the color of already highlighted 
whitespace, but it's a too broad criterion. i don't think ignoring 
this fact is a problem, as you can recognize the tabs anyway 
(obviously).
note, that you can't just copy such text from the terminal, as the 
pseudo-whitespace chars will show up in the copy. therefore a 
hotkey to switch it off quickly would be useful. otoh, a) the 
problem that this feature is disabled in selected blocks is an 
advantage in this context and b) by copying, you would be 
destroying the original whitespace anyway.