How can I put four (or more) commands in one command, without repeating so much code using expl3?

Question

I'm trying to put together four commands that encapsulate tikzpicture environments and the use of tikzmark, in one, all have their own keys, but, they have a lot of code in common. The commands are as follows :

\tkm@ncbara[key=val]{mark-A}{mark-B}{text}
\tkm@ncbarb[key=val]{mark-A}{mark-B}{text}
\tkm@bracea[key=val]{mark-A}{mark-B}{text}
\tkm@braceb[key=val]{mark-A}{mark-B}{text}

and I created the tkmdraw command to work as follows:

\tkmdraw[ncbar-a, key val from ncbara]{mark-A}{mark-B}{text}
\tkmdraw[ncbar-b, key val from ncbarb]{mark-A}{mark-B}{text}
\tkmdraw[brace-a, key val from bracea]{mark-A}{mark-B}{text}
\tkmdraw[brace-a, key val from braceb]{mark-A}{mark-B}{text}

hypothetically I think adding more options to tkmdraw, but, I think I'm repeating a lot of code and for sure there is a correct way to do it, here's my question:

How can I put four (or more) commands in one command, without repeating so much code using expl3?

This is the FULL sample file (I can not reduce it):

% arara: pdflatex: {interaction: nonstopmode, draft: yes}
% arara: pdflatex: {interaction: nonstopmode}
% arara: clean: { extensions: [ aux, log, out ] }
\documentclass[10pt]{article}
\usepackage{amsmath,xparse,tikz}
\usetikzlibrary{tikzmark,arrows.meta,calc,decorations.pathreplacing}
\pagestyle{empty}

% Whidth for center node ... \TkM{name}{content}
\newlength{\MyL}
\newcommand*{\TkM}[2]{\settowidth{\MyL}{$\mathsurround0pt #2$}#2\hspace{-\MyL}\makebox[\MyL]{\pgfmark{#1}}}

\makeatletter
% active : for expl3 
\def\@colon{:}
% default style for ncbar
\tikzset{tkmdraw/ncbar-a/.style={ >={Straight Barb[length=1.5pt,round]},
                        font=\footnotesize,color=gray,text=red,above=-3.5pt,},}
\tikzset{tkmdraw/ncbar-b/.style={ >={Straight Barb[length=1.5pt,round]},
                        font=\footnotesize,color=gray,text=red,below=-2.5pt,},}
% default style for brace
\tikzset{tkmdraw/brace-a/.style={ font=\footnotesize,color=gray,text=red,},}
\tikzset{tkmdraw/brace-b/.style={ font=\footnotesize,color=gray,text=red,},}
\ExplSyntaxOn

\keys_define:nn { tkmdraw/ncbar-a }
 {
  ncbar-a  .bool_set:N        =  \l_tmpa_bool,
  tikz     .code:n            =  \tikzset{tkmdraw/ncbar-a/.append~style = {#1},},
  tikz     .initial:n         =  {},
  tikz     .value_required:n  =  true,
  text     .value_required:n  =  true,
  font     .value_required:n  =  true,
  color    .value_required:n  =  true,
  above    .value_required:n  =  true,
  arrow    .value_required:n  =  true,
  text     .meta:n            =  { tikz = { text = #1 }},
  font     .meta:n            =  { tikz = { font = #1 }},
  color    .meta:n            =  { tikz = { color = #1 }},
  above    .meta:n            =  { tikz = { above = #1 }},
  arrows   .meta:n            =  { tikz = { arrows = {#1} }},
  vsep-A   .dim_set:N         =  \l_ncbar_a_A_dim,
  vsep-A   .initial:n         =  1.85ex,
  vsep-B   .dim_set:N         =  \l_ncbar_a_B_dim,
  vsep-B   .initial:n         =  1.85ex,
  height   .dim_set:N         =  \l_ncbar_a_h_dim,
  height   .initial:n         =  0.5em,
  raise    .meta:n            =  { vsep-A = #1 , vsep-B = #1 }
 }

\NewDocumentCommand{\tkm@ncbara}{ O{} m  m +m}
  {
  \group_begin:
   \IfNoValueF {#1} { \keys_set:nn { tkmdraw/ncbar-a }{ #1 } }
    \begin{tikzpicture}[overlay,remember~ picture,tkmdraw/ncbar-a]
      \draw[<->]([yshift=\l_ncbar_a_A_dim]$(pic~ cs \@colon #2)$) -- ++(0,\l_ncbar_a_h_dim) -| 
        node[align=center,near~ start] {#4} 
       ([yshift=\l_ncbar_a_B_dim]$(pic~ cs \@colon #3)$);
    \end{tikzpicture}%
  \group_end:
  }

\keys_define:nn { tkmdraw/ncbar-b }
 {
  ncbar-b  .bool_set:N        =  \l_tmpa_bool,
  tikz     .code:n            =  \tikzset {tkmdraw/ncbar-b/.append~style = {#1},},
  tikz     .initial:n         =  {},
  tikz     .value_required:n  =  true,
  text     .value_required:n  =  true,
  font     .value_required:n  =  true,
  color    .value_required:n  =  true,
  above    .value_required:n  =  true,
  arrow    .value_required:n  =  true,
  text     .meta:n            =  { tikz = { text = #1 }},
  font     .meta:n            =  { tikz = { font = #1 }},
  color    .meta:n            =  { tikz = { color = #1 }},
  below    .meta:n            =  { tikz = { below = #1 }},
  arrows   .meta:n            =  { tikz = { arrows = {#1} }},
  vsep-A   .dim_set:N         =  \l_ncbar_b_A_dim,
  vsep-B   .dim_set:N         =  \l_ncbar_b_B_dim,
  height   .dim_set:N         =  \l_ncbar_b_h_dim,
  vsep-A   .initial:n         =  -0.5ex,
  vsep-B   .initial:n         =  -0.5ex,
  height   .initial:n         =  -0.5em,
  raise    .meta:n            =  { vsep-A = #1 , vsep-B = #1 }
 }

\NewDocumentCommand{\tkm@ncbarb}{ O{} m  m +m}
  {
  \group_begin:
   \IfNoValueF {#1} { \keys_set:nn { tkmdraw / ncbar-b }{ #1 } }
    \begin{tikzpicture}[overlay,remember~ picture,tkmdraw/ncbar-b]
      \draw[<->]([yshift=\l_ncbar_b_A_dim]$(pic~ cs \@colon #2)$) -- ++(0,\l_ncbar_b_h_dim) -| 
        node[align=center,near~ start] {#4} 
       ([yshift=\l_ncbar_b_B_dim]$(pic~ cs \@colon #3)$);
    \end{tikzpicture}%
  \group_end:
  }

\keys_define:nn { tkmdraw/brace-a }
 {
  brace-a    .bool_set:N        =  \l_tmpa_bool,
  tikz       .code:n            =  \tikzset{tkmdraw/brace-a/.append~style = {#1},},
  tikz       .initial:n         =  {},
  tikz       .value_required:n  =  true,
  text       .meta:n            =  { tikz = { text = #1 }},
  font       .meta:n            =  { tikz = { font = #1 }},
  color      .meta:n            =  { tikz = { color = #1 }},
  text       .value_required:n  =  true,
  font       .value_required:n  =  true,
  color      .value_required:n  =  true,
  above      .dim_set:N         =  \l_brace_above_dim,
  above      .initial:n         =  2.5pt,
  above      .value_required:n  =  true,
  amplitude  .dim_set:N         =  \l_brace_a_h_dim,
  amplitude  .initial:n         =  0.4em,
  amplitude  .value_required:n  =  true,
  vsep-A     .dim_set:N         =  \l_brace_a_A_dim,
  vsep-B     .dim_set:N         =  \l_brace_a_B_dim,
  vsep-A   .initial:n           =  1.85ex,
  vsep-B   .initial:n           =  1.85ex,
  raise    .meta:n              =  { vsep-A = #1 , vsep-B = #1 }
 }

\NewDocumentCommand{\tkm@bracea}{ O{} m  m +m}
  {
  \group_begin:
   \IfNoValueF {#1} { \keys_set:nn { tkmdraw / brace-a }{ #1 } }
    \begin{tikzpicture}[overlay,remember~ picture,tkmdraw/brace-a]
      \draw [decorate,decoration={brace, amplitude=\l_brace_a_h_dim}]
      ([yshift=\l_brace_a_A_dim]$(pic~ cs \@colon #2)$) -- ([yshift=\l_brace_a_B_dim]$(pic~ cs \@colon #3)$)
      node [align=center,midway,above = \l_brace_above_dim] {#4};
    \end{tikzpicture}
  \group_end:
  }

\keys_define:nn { tkmdraw/brace-b }
 {
  brace-b    .bool_set:N        =  \l_tmpa_bool,
  tikz       .code:n            =  \tikzset{tkmdraw/brace-b/.append~style = {#1},},
  tikz       .initial:n         =  {},
  tikz       .value_required:n  =  true,
  text       .meta:n            =  { tikz = { text = #1 }},
  font       .meta:n            =  { tikz = { font = #1 }},
  color      .meta:n            =  { tikz = { color = #1 }},
  text       .value_required:n  =  true,
  font       .value_required:n  =  true,
  color      .value_required:n  =  true,
  below      .dim_set:N         =  \l_brace_below_dim,
  below      .initial:n         =  2.5pt,
  below      .value_required:n  =  true,
  amplitude  .dim_set:N         =  \l_brace_b_h_dim,
  amplitude  .initial:n         =  0.4em,
  amplitude  .value_required:n  =  true,
  vsep-A     .dim_set:N         =  \l_brace_b_A_dim,
  vsep-B     .dim_set:N         =  \l_brace_b_B_dim,
  vsep-A     .initial:n         =  -1ex,
  vsep-B     .initial:n         =  -1ex,
  raise      .meta:n            =  { vsep-A = #1 , vsep-B = #1 }
 }

\NewDocumentCommand{\tkm@braceb}{ O{} m  m +m}
  {
  \group_begin:
   \IfNoValueF {#1} { \keys_set:nn { tkmdraw/brace-b }{ #1 } }
    \begin{tikzpicture}[overlay,remember~ picture,tkmdraw/brace-b]
      \draw [decorate,decoration={brace, mirror, amplitude=\l_brace_b_h_dim}]
      ([yshift=\l_brace_b_A_dim]$(pic~ cs \@colon #2)$) -- ([yshift=\l_brace_b_B_dim]$(pic~ cs \@colon #3)$)
      node [align=center,midway,below = \l_brace_below_dim] {#4};
    \end{tikzpicture}
  \group_end:
  }

\keys_define:nn { tkmdraw }
 {
  @ncbar-a  .bool_set:N  =  \l_ncbar_a_bool,
  @ncbar-b  .bool_set:N  =  \l_ncbar_b_bool,
  @brace-a  .bool_set:N  =  \l_brace_a_bool,
  @brace-b  .bool_set:N  =  \l_brace_b_bool,
  ncbar-a   .meta:n      =  { @ncbar-a = true, @ncbar-b = false, @brace-a = false, @brace-b = false },
  ncbar-b   .meta:n      =  { @ncbar-b = true, @ncbar-a = false, @brace-a = false, @brace-b = false },
  brace-a   .meta:n      =  { @brace-a = true, @ncbar-b = false, @ncbar-a = false, @brace-b = false },
  brace-b   .meta:n      =  { @brace-b = true, @ncbar-b = false, @ncbar-a = false, @brace-a = false },
 }

\NewDocumentCommand{\tkmdraw}{o m m +m}
 {
  \group_begin:
  \tkmdraw_test_options:n { #1 }
  \IfBooleanT{ \l_ncbar_a_bool } { \tkm@ncbara[#1]{#2}{#3}{#4} }
  \IfBooleanT{ \l_ncbar_b_bool } { \tkm@ncbarb[#1]{#2}{#3}{#4} }
  \IfBooleanT{ \l_brace_a_bool } { \tkm@bracea[#1]{#2}{#3}{#4} }
  \IfBooleanT{ \l_brace_b_bool } { \tkm@braceb[#1]{#2}{#3}{#4} }
  \group_end:
 }

\cs_new_protected:Npn \tkmdraw_test_options:n #1
 {
  \str_case:xnF { \clist_item:nn { #1 } { 1 } }
   {
   {ncbar-a} { \keys_set:nn { tkmdraw  } { ncbar-a } \keys_set:nn { tkmdraw/ncbar-a } {#1}}
   {ncbar-b} { \keys_set:nn { tkmdraw  } { ncbar-b } \keys_set:nn { tkmdraw/ncbar-b } {#1}}
   {brace-a} { \keys_set:nn { tkmdraw  } { brace-a } \keys_set:nn { tkmdraw/brace-a } {#1}}
   {brace-b} { \keys_set:nn { tkmdraw  } { brace-b } \keys_set:nn { tkmdraw/brace-b } {#1}}
   }
   {}
 }
\cs_generate_variant:Nn \str_case:nnF { x }
\ExplSyntaxOff
\makeatother

\begin{document}
Whit \verb+\tkm@ncbara+ and \verb+\tkm@ncbarb+ command  ... OK :)

\[ (\TkM{a1}{2}\TkM{a2}{p}q^{2})(\TkM{a3}{3}p\TkM{a4}{q})=6p^{2}q^{3} \]

\makeatletter
\tkm@ncbara[color=green,text=red,height= 0.3em]{a1}{a3}{ncbara}
\tkm@ncbarb[color=red,text=green,height= -0.3em]{a2}{a4}{ncbarb}
\makeatother

Whit \verb+\tkm@bracea+ and \verb+\tkm@braceb+ command  ... OK :)

\[ (\TkM{b1}{2}\TkM{b2}{p}q^{2})(\TkM{b3}{3}p\TkM{b4}{q})=6p^{2}q^{3} \]

\makeatletter
\tkm@bracea[color=green,text=red, amplitude= 0.3em]{b1}{b3}{bracea}
\tkm@braceb[color=red,text=green, amplitude= 0.3em]{b2}{b4}{braceb}
\makeatother

\par\vspace{0.65cm}

Whit \verb+\tkmdraw[key=val]{...}+ command  ... OK :)
\par\vspace{0.65cm}
% adapted from https://tex.stackexchange.com/a/76507/7832

\begin{align*}
(3{,}14 \times \TkM{c1}{10^{-2}}) + (1\TkM{c2}{{,}}2 \times  \TkM{c3}{10^{-4}}) 
             &= (3{,}14 \times \TkM{c4}{10^{-2}}) + (0\TkM{c5}{{,}}012 \times \TkM{c6}{10^{-2}})\\[3ex]
             &= (3{,}14+0{,}012) \times  10^{-2}\\
&= \TkM{c7}{3}{,}152 \times \TkM{c8}{10}^{-2} 
\end{align*}

\tkmdraw[ncbar-b,color=blue,text=red,raise=-3pt]{c1}{c3}{not equal}
\tkmdraw[ncbar-b,color=red,text=blue,raise=-3pt]{c4}{c6}{equal}
\tkmdraw[ncbar-a,color=red,text=blue]{c2}{c5}{The decimal is moved to the left \\ to increase the exponent}
\tkmdraw[brace-b,color=red,text=green, amplitude= 0.3em]{c7}{c8}{$0{,}30152$}
\end{document}

An image of the result that produces:

The idea behind is to "imitate" a bit, the old code that I had using pstricks, I'm trying to move my file to something more compatible with (pdf/lua)latex.

Best regards.

Answer 1

The code below really only rearranges the code in the OP with a few tweaks. The differences are:

• throughout -a and -b have been changed to -above and -below. It is debatable that this is more readable but the main motivation for doing this is so that I can write #1=<length> in the brace commands, where #1 is either "above" or "below"
• I have put the decoration code for the braces into the tkmdraw/brace-a* style settings so that the brace commands do not need to set this
• I have moved the tkdraw/brace-* and tkmdraw/ncbar-* style settings out of the tikzpicture environment and into the \draw[...] command because this is where I think it belongs -- and this also works better with the last change
• I have defined commands \DefineBarKeys and \DefineBraceKeys to set up the bar and brace keys, so that these code blocks do not need to be typed twice
• I have defined \tkm@ncbar and \tkm@brace commands that do the bulk of the work for bars and braces. Even though these two commands are similar I do not see an easy way to combine these two commands given the differences between bars and braces.

These changes save about 30 lines of code but, more importantly, reduce code duplication. The output is, I think, unchanged:

Here is the modified code:

\documentclass[10pt]{article}
\usepackage{amsmath,xparse,tikz}
\usetikzlibrary{tikzmark,arrows.meta,calc,decorations.pathreplacing}
\pagestyle{empty}

% Width for center node ... \TkM{name}{content}
\newlength{\MyL}
\newcommand*{\TkM}[2]{\settowidth{\MyL}{$\mathsurround0pt #2$}#2\hspace{-\MyL}\makebox[\MyL]{\pgfmark{#1}}}

\makeatletter

% default style for ncbar
\tikzset{
  tkmdraw/ncbar-above/.style={
    >={Straight Barb[length=1.5pt,round]},
   font=\footnotesize,color=gray,text=red,above=-3.5pt,
  },
  tkmdraw/ncbar-below/.style={
    >={Straight Barb[length=1.5pt,round]},
    font=\footnotesize,color=gray,text=red,below=-2.5pt,
  }
}

% default style for brace - amplitude set by \tkm@brace
\tikzset{
  tkmdraw/brace-above/.style={
     font=\footnotesize,color=gray, text=red,
     decorate, decoration={brace, amplitude=#1}
  },
  tkmdraw/brace-below/.style={
     font=\footnotesize,color=gray,text=red,
     decorate, decoration={brace, mirror, amplitude=#1}
  },
}

% active : for expl3
\def\@colon{:}

\ExplSyntaxOn
\cs_new_protected:Npn \__define_bar_keys:nnn #1#2#3 { % #1=above/below, #2=sep, #3=height
  \keys_define:nn { tkmdraw/ncbar-#1 }
   {
    ncbar-#1 .bool_set:N        =  \l_tmpa_bool,
    tikz     .code:n            =  \tikzset {tkmdraw/ncbar-#1/.append~style = {##1},},
    tikz     .initial:n         =  {},
    tikz     .value_required:n  =  true,
    text     .value_required:n  =  true,
    font     .value_required:n  =  true,
    color    .value_required:n  =  true,
    #1       .value_required:n  =  true,
    arrow    .value_required:n  =  true,
    text     .meta:n            =  { tikz = { text = ##1 }},
    font     .meta:n            =  { tikz = { font = ##1 }},
    color    .meta:n            =  { tikz = { color = ##1 }},
    #1       .meta:n            =  { tikz = { #1 = ##1 }},
    arrows   .meta:n            =  { tikz = { arrows = {##1} }},
    vsep-A   .dim_set:c         =  {l_ncbar_#1_A_dim},
    vsep-B   .dim_set:c         =  {l_ncbar_#1_B_dim},
    height   .dim_set:c         =  {l_ncbar_#1_h_dim},
    vsep-A   .initial:n         =  #2,
    vsep-B   .initial:n         =  #2,
    height   .initial:n         =  #3,
    raise    .meta:n            =  { vsep-A = ##1 , vsep-B = ##1 }
   }
}

\__define_bar_keys:nnn{above}{1.85ex}{0.5em}
\__define_bar_keys:nnn{below}{-0.5ex}{-0.5em}

\NewDocumentCommand{\tkm@ncbar}{ m m m  m +m}
  {
  \group_begin:
    \IfNoValueF {#2} { \keys_set:nn { tkmdraw/ncbar-#1 }{ #2 } }
    \begin{tikzpicture}[overlay, remember~picture]
      \draw[tkmdraw/ncbar-#1, <->]
        ([yshift=\use:c{l_ncbar_#1_A_dim}]$(pic~cs \@colon #3)$) -- ++(0,\use:c{l_ncbar_#1_h_dim}) -|
        node[align=center,near~ start] {#5} ([yshift=\use:c{l_ncbar_#1_B_dim}]$(pic~cs \@colon #4)$);
    \end{tikzpicture}%
  \group_end:
  }

\NewDocumentCommand{\tkm@ncbara}{ O{} m m +m}
  {
  \tkm@ncbar{above}{#1}{#2}{#3}{#4}
  }

\NewDocumentCommand{\tkm@ncbarb}{ O{} m m +m}
  {
  \tkm@ncbar{below}{#1}{#2}{#3}{#4}
  }

\cs_new_protected:Npn \__define_brace_keys:nn #1#2 { % #1=above/below, #2=sep, #3=height
  \keys_define:nn { tkmdraw/brace-#1 }
   {
    brace-#1 .bool_set:N        =  \l_tmpa_bool,
    tikz        .code:n            =  \tikzset{tkmdraw/brace-#1/.append~style = {##1},},
    tikz        .initial:n         =  {},
    tikz        .value_required:n  =  true,
    text        .meta:n            =  { tikz = { text = ##1 }},
    font        .meta:n            =  { tikz = { font = ##1 }},
    color       .meta:n            =  { tikz = { color = ##1 }},
    text        .value_required:n  =  true,
    font        .value_required:n  =  true,
    color       .value_required:n  =  true,
    #1          .dim_set:c         =  {l_brace_#1_dim},
    #1          .initial:n         =  2.5pt,
    #1          .value_required:n  =  true,
    amplitude   .dim_set:c         =  {l_brace_#1_h_dim},
    amplitude   .initial:n         =  0.4em,
    amplitude   .value_required:n  =  true,
    vsep-A      .dim_set:c         =  {l_brace_#1_A_dim},
    vsep-B      .dim_set:c         =  {l_brace_#1_B_dim},
    vsep-A      .initial:n         =  #2,
    vsep-B      .initial:n         =  #2,
    raise       .meta:n            =  { vsep-A = ##1 , vsep-B = ##1 }
   }
}
\__define_brace_keys:nn{above}{1.85ex}
\__define_brace_keys:nn{below}{-1.00ex}

\NewDocumentCommand{\tkm@brace}{m m m m +m}
  {
  \group_begin:
    \IfNoValueF{#2} { \keys_set:nn{tkmdraw/brace-#1}{#2} }
    \begin{tikzpicture}[overlay, remember~picture]
      \draw[tkmdraw/brace-#1=\use:c{l_brace_#1_h_dim}]
        ([yshift=\use:c{l_brace_#1_A_dim}]$(pic~cs \@colon #3)$)--([yshift=\use:c{l_brace_#1_B_dim}]$(pic~cs \@colon #4)$)
        node [align=center, midway, #1=\use:c{l_brace_#1_dim}] {#5};
    \end{tikzpicture}
  \group_end:
  }

\NewDocumentCommand{\tkm@bracea}{ O{} m m +m}
  {
  \tkm@brace{above}{#1}{#2}{#3}{#4}
  }

\NewDocumentCommand{\tkm@braceb}{ O{} m m +m}
  {
  \tkm@brace{below}{#1}{#2}{#3}{#4}
  }

\keys_define:nn { tkmdraw }
 {
  @ncbar-above  .bool_set:N  =  \l_ncbar_a_bool,
  @ncbar-below  .bool_set:N  =  \l_ncbar_b_bool,
  @brace-above  .bool_set:N  =  \l_brace_a_bool,
  @brace-below  .bool_set:N  =  \l_brace_b_bool,
  ncbar-above   .meta:n      =  { @ncbar-above = true, @ncbar-below = false, @brace-above = false, @brace-below = false },
  ncbar-below   .meta:n      =  { @ncbar-below = true, @ncbar-above = false, @brace-above = false, @brace-below = false },
  brace-above   .meta:n      =  { @brace-above = true, @ncbar-below = false, @ncbar-above = false, @brace-below = false },
  brace-below   .meta:n      =  { @brace-below = true, @ncbar-below = false, @ncbar-above = false, @brace-above = false },
 }

\NewDocumentCommand{\tkmdraw}{o m m +m}
 {
  \group_begin:
  \tkmdraw_test_options:n { #1 }
  \IfBooleanT{ \l_ncbar_a_bool } { \tkm@ncbara[#1]{#2}{#3}{#4} }
  \IfBooleanT{ \l_ncbar_b_bool } { \tkm@ncbarb[#1]{#2}{#3}{#4} }
  \IfBooleanT{ \l_brace_a_bool } { \tkm@bracea[#1]{#2}{#3}{#4} }
  \IfBooleanT{ \l_brace_b_bool } { \tkm@braceb[#1]{#2}{#3}{#4} }
  \group_end:
 }

\cs_new_protected:Npn \tkmdraw_test_options:n #1
 {
  \str_case:xnF { \clist_item:nn { #1 } { 1 } }
   {
   {ncbar-above} { \keys_set:nn { tkmdraw  } { ncbar-above } \keys_set:nn { tkmdraw/ncbar-above } {#1}}
   {ncbar-below} { \keys_set:nn { tkmdraw  } { ncbar-below } \keys_set:nn { tkmdraw/ncbar-below } {#1}}
   {brace-above} { \keys_set:nn { tkmdraw  } { brace-above } \keys_set:nn { tkmdraw/brace-above } {#1}}
   {brace-below} { \keys_set:nn { tkmdraw  } { brace-below } \keys_set:nn { tkmdraw/brace-below } {#1}}
   }
   {}
 }
\cs_generate_variant:Nn \str_case:nnF { x }
\ExplSyntaxOff
\makeatother

\begin{document}
With \verb+\tkm@ncbara+ and \verb+\tkm@ncbarb+ command  ... OK :)

\[ (\TkM{a1}{2}\TkM{a2}{p}q^{2})(\TkM{a3}{3}p\TkM{a4}{q})=6p^{2}q^{3} \]

\makeatletter
\tkm@ncbara[color=green,text=red,height= 0.3em]{a1}{a3}{ncbara}
\tkm@ncbarb[color=red,text=green,height= -0.3em]{a2}{a4}{ncbarb}
\makeatother

With \verb+\tkm@bracea+ and \verb+\tkm@braceb+ command  ... OK :)

\[ (\TkM{b1}{2}\TkM{b2}{p}q^{2})(\TkM{b3}{3}p\TkM{b4}{q})=6p^{2}q^{3} \]

\makeatletter
\tkm@bracea[color=green,text=red, amplitude= 0.3em]{b1}{b3}{bracea}
\tkm@braceb[color=red,text=green, amplitude= 0.3em]{b2}{b4}{braceb}
\makeatother

\par\vspace{0.65cm}

With \verb+\tkmdraw[key=val]{...}+ command  ... OK :)
\par\vspace{0.65cm}
% adapted from https://tex.stackexchange.com/a/76507/7832

\begin{align*}
(3{,}14 \times \TkM{c1}{10^{-2}}) + (1\TkM{c2}{{,}}2 \times  \TkM{c3}{10^{-4}})
             &= (3{,}14 \times \TkM{c4}{10^{-2}}) + (0\TkM{c5}{{,}}012 \times \TkM{c6}{10^{-2}})\\[3ex]
             &= (3{,}14+0{,}012) \times  10^{-2}\\
&= \TkM{c7}{3}{,}152 \times \TkM{c8}{10}^{-2}
\end{align*}

\tkmdraw[ncbar-below,color=blue,text=red,raise=-3pt]{c1}{c3}{not equal}
\tkmdraw[ncbar-below,color=red,text=blue,raise=-3pt]{c4}{c6}{equal}
\tkmdraw[ncbar-above,color=red,text=blue]{c2}{c5}{The decimal is moved to the left \\ to increase the exponent}
\tkmdraw[brace-below,color=red,text=green, amplitude= 0.3em]{c7}{c8}{$0{,}30152$}
\end{document}