Re: Inability to change color of individual substrings

[Ethan A M. <sf...@us...>]

On Friday, 30 September, 2016 17:00:34 pl...@pi... wrote:
> On 30/09/16 07:28, Daniel J Sebald wrote:
> > 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
> >
> >
> 
> I was not aware of this &{} syntax.  Looks very useful.
> 
> Where can I find the relevant documentation? What is this feature 
> called, for example, in help?

gnuplot> help enhanced text

 Many terminal types support an enhanced text mode in which additional
 formatting information is embedded in the text string.  For example, "x^2"
 will write x-squared as we are used to seeing it, with a superscript 2.
 This mode is selected by default when you set the terminal, but may be
 toggled afterward using "set termoption [no]enhanced", or by marking
 individual strings as in "set label 'x_2' noenhanced".

  Control      Examples        Explanation
   ^           a^x             superscript
   _           a_x             subscript
   @           @x or a@^b_{cd} phantom box (occupies no width)
   &           &{space}        inserts space of specified length
   ~           ~a{.8-}         overprints '-' on 'a', raised by .8
                               times the current fontsize
   {/Times abc}                print abc in font Times at current size
   {/Times*2 abc}              print abc in font Times at twice current size
   {/Times:Italic abc}         print abc in font Times with style italic
   {/Arial:Bold=20 abc}        print abc in boldface Arial font size 20 

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