Re: Inability to change color of individual substrings

[Daniel J S. <dan...@ie...>]

On 09/30/2016 12:24 AM, sfeam wrote:
> On Thursday, 29 September 2016 10:21:13 PM Daniel J Sebald wrote:
>> I've noticed that enhanced text mode cannot control the color of a
>> substring.  Just as a brainstorming exercise, has anyone thought of
>> adding such a thing in some way?  In principle it's pretty
>> straightforward: just change terminal color at various points when
>> processing the string.  But I've a feeling implementation may not be so
>> easy.  Approaches might be:
>>
>> 1) Add some color code extension to the enhanced text processing.  The
>> code word may not agree with some "standard" described in ps_guide.ps,
>> but I don't see why that should be a problem.  The problem is that all
>> terminal drivers would need to be modified to process that code word.
>>
>> 2) Create a tex-processing feature, which is similar to enhanced text
>> (and could use much of the same code), but it would allow using things
>> like "{\color[rgb]{.3 .7 .3}Hello} World".  Of course, this is no simple
>> task, but I'm just thinking long term wish if there is no better approach.
>>
>> 3) If there were some way of getting the position at which one
>> label/string ends, then one could concatenate strings.  I've a feeling
>> this isn't possible.  I mean, one has to effective do the plot to get
>> the string-end position, which would be clumsy.
>>
>> 4) However, #3 in theory could be implemented as "not lifting pen".
>> Does gnuplot core code have knowledge of this?  That is, can it do one
>> label, not lift the pen, then continue with another label?  If so, the
>> following concept might work:
>>
>> set label 1 "{/Times:Bold hello}" textcolor "red" at 1,2
>> set label 2 "world^3" textcolor "blue" after label 1
>>
>> Or, maybe just allow multiple substring specifications, but only a
>> single "at x,y":
>>
>> set label 1 "{/Times:Bold hello}" textcolor "red" "world^3" textcolor
>> "blue" at 1,2
>>
>> Would that work easily internally?  Or is there still a problem as far
>> as laying out string alignment?
>>
>> Dan
>
> Always been there:
>
> # enhanced text occupy-space-but-don't-print mode
> #
> set label 1 at 0,0 "I am a &{red} word in blue"
> set label 2 at 0,0 "&{I am a} red &{word in blue}"
> set label 1 tc "blue"
> set label 2 tc "red"
>
> 	Ethan

Aaaaah, creative.  The use of &{} is already present in 
enhanced_utf8.dem, but adding a bit of code for this idea to that demo 
might be helpful.  Attached is a diff to illustrate.

I think there may be a bug in Qt terminal with regard to the space 
between &{} and what follows it when there is a space-character 
immediately after.  I tried explicitly using a \040, but that too was 
dropped.  After applying the attached patch, try

set term x11 enhanced
load 'enhanced_utf8.dem'

and

set term qt enhanced
load 'enhanced_utf8.dem'

The only way I could get the proper spacing with the Qt terminal is by 
adding '|', e.g., "&{{/:Bold Bold} and|} {/:Italic Italic}"

Dan