sms_latex.tex

% https://tex.stackexchange.com/questions/632271/chat-like-text-bock-in-tikz-environment

\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage{mathpazo}
\usepackage{tikz}
\usepackage{xcolor}
\usepackage{xparse}
\usepackage{calc}
\usepackage{varwidth}

\usetikzlibrary{positioning,calc}

\ExplSyntaxOn

\def\ChatBlockWidth{8cm}
\def\UserMinWidth{2cm}
\def\UserMaxWidth{6cm}
\def\NumberOfBubbles{8}
\def\SmallestBubbleDiameter{2pt}
\def\ChatInterval{0.3cm}
\def\BubbleScaleCoef{1.3}
\def\BubbleHeight{2cm}
\def\BubbleHShift{1.5cm}

\definecolor{user-1-color}{HTML}{CCF4C6}
\definecolor{user-2-color}{HTML}{FDE9A9}
\definecolor{user-frame-color}{HTML}{5D89B0}
\definecolor{face-eye-color-1}{HTML}{A3C39E}
\definecolor{face-eye-color-2}{HTML}{CABA87}

\newcommand{\ExtractCoordinate}[1]{\path (#1); \pgfgetlastxy{\XCoord}{\YCoord};}%


\tikzset{
  chatnode/.style={
    draw=user-frame-color,
    rounded~corners=4pt,
    inner~sep=6pt,
  }
}

\tikzset{
  pics/smiley-face/.style~n~args={3}{
    code={
      \begin{scope}[scale=#1]
        \draw[draw=user-frame-color, fill=#2] (0,0) circle (1cm);
        \draw[draw=user-frame-color, fill=#3] (-0.32,0.2) ellipse (0.08cm~and~0.15cm);
        \draw[draw=user-frame-color, fill=#3] (0.32,0.2) ellipse (0.08cm~and~0.15cm);
        \draw[draw=user-frame-color] (-0.6, -0.3) to[out=-60, in=-120] (0.6, -0.3);
      \end{scope}
    }
  }
}

    
% template for bubbles
\cs_set:Npn \__chat_node_template:nnnnn #1#2#3#4#5 {
  \exp_not:n {
    node[
      pos=#1,
      fill=#3,
      draw=user-frame-color,
      circle,
      inner~sep=0pt,
      outer~sep=0pt,
      minimum~width=#2,
      xshift={#4},
      yshift={#5}
    ]
    {}
  }
}

\cs_generate_variant:Nn \__chat_node_template:nnnnn {eennn}

\cs_set:Npn \__chat_pic_template:nnnnnn #1#2#3#4#5#6 {
  \exp_not:n {
    pic[
      pos=#1,
      xshift={#5},
      yshift={#6}
    ]
    {smiley-face={#2}{#3}{#4}}
  }
}

\fp_new:N \l_chat_tmpa_fp
\fp_new:N \l_chat_tmpb_fp
\fp_new:N \l_chat_tmpc_fp
\fp_new:N \l_chat_tmpa_tl

% pos1, pos2, color, in, out, last scale, last x offset , last y offset, eye color
\newcommand{\ChatBubble}[9]{
  \fp_set:Nn \l_chat_tmpa_fp {\dim_to_fp:n {\SmallestBubbleDiameter}}
  \fp_set:Nn \l_chat_tmpb_fp {1/(\NumberOfBubbles-1)}
  \tl_clear:N \l_chat_tmpa_tl
  \tl_set:Nn \l_chat_tmpa_tl {\path (#1) to[in=#4,out=#5]}
  \int_step_inline:nn {\NumberOfBubbles - 1} {
    \tl_put_right:Nx \l_chat_tmpa_tl {
      \__chat_node_template:eennn {\fp_eval:n {(##1 - 1) * \l_chat_tmpb_fp}}
                                  {\fp_use:N \l_chat_tmpa_fp~pt}
                                  {#3} {0pt} {0pt}
    }
    \fp_set:Nn \l_chat_tmpa_fp {\BubbleScaleCoef * \l_chat_tmpa_fp}
  }
  % the last bubble
  \fp_set:Nn \l_chat_tmpa_fp {#6 * \l_chat_tmpa_fp}
  % compute the relative scale for the face
  \fp_set:Nn \l_chat_tmpc_fp {\l_chat_tmpa_fp~pt/(2cm)}
  \tl_put_right:Nx \l_chat_tmpa_tl {
    \__chat_pic_template:nnnnnn {1.0} {\fp_use:N \l_chat_tmpc_fp} {#3} {#9}
                                {#7} {#8}
  }
  \tl_put_right:Nn \l_chat_tmpa_tl {(#2);}
  \tl_use:N \l_chat_tmpa_tl
}

\int_new:N \l_chat_box_index_int
\tl_new:N \l_chat_user_a_last_node_tl
\tl_new:N \l_chat_user_b_last_node_tl
\dim_new:N \l_chat_tmpa_dim
\dim_new:N \l_chat_tmpb_dim
\dim_new:N \l_chat_tmpc_dim
\dim_new:N \l_chat_tmpd_dim
\dim_new:N \l_chat_tmpe_dim
\dim_new:N \l_chat_last_vert_dim
\dim_new:N \l_chat_width_dim
\box_new:N \l_chat_tmpa_box

\newcommand{\GetLastVertPos}{
  \tl_if_empty:NTF \l_chat_user_a_last_node_tl {
    \dim_set:Nn \l_chat_tmpa_dim {-\ChatInterval}
  } {
    \ExtractCoordinate{\l_chat_user_a_last_node_tl.south}
    %\GetSouthY{\l_chat_user_a_last_node_tl}
    \dim_set:Nn \l_chat_tmpa_dim {\YCoord}
    \iow_term:x {y~coord~is~\YCoord}
  }
  \tl_if_empty:NTF \l_chat_user_b_last_node_tl {
    \dim_set:Nn \l_chat_tmpb_dim {-\ChatInterval}
  } {
    \ExtractCoordinate{\l_chat_user_b_last_node_tl.south}
    \dim_set:Nn \l_chat_tmpb_dim {\YCoord}
  }
  \dim_compare:nNnTF \l_chat_tmpa_dim < \l_chat_tmpb_dim {
    \dim_set_eq:NN \l_chat_last_vert_dim \l_chat_tmpa_dim
  } {
    \dim_set_eq:NN \l_chat_last_vert_dim \l_chat_tmpb_dim
  }
}

\newcommand{\CalcChatWidth}[1]{
  \hbox_set:Nn \l_chat_tmpa_box {\pgfinterruptpicture #1 \endpgfinterruptpicture}
  \dim_compare:nNnTF {\box_wd:N \l_chat_tmpa_box} < {\UserMinWidth} {
    \dim_set:Nn \l_chat_width_dim {\UserMinWidth}
  } {
    \dim_compare:nNnTF {\box_wd:N \l_chat_tmpa_box} < {\UserMaxWidth} {
      \dim_set:Nn \l_chat_width_dim {
          \dim_min:nn {\box_wd:N \l_chat_tmpa_box + 0.2cm} {\UserMaxWidth}
        }
    } {
      \dim_set:Nn \l_chat_width_dim {\UserMaxWidth}
    }
  }
}

\NewDocumentEnvironment{ChatBox}{}{
  \tl_clear:N \l_chat_user_a_last_node_tl
  \tl_clear:N \l_chat_user_b_last_node_tl
  \int_set:Nn \l_chat_box_index_int {1}
  \newcommand{\UserA}[1]{
    \GetLastVertPos
    \CalcChatWidth{##1}
    \node[chatnode, fill=user-1-color, anchor=north~west, text~width=\l_chat_width_dim]
      (chat-\int_use:N \l_chat_box_index_int) 
      at ($(0pt, \dim_use:N \l_chat_last_vert_dim)-(0pt, \ChatInterval)$)
      {##1};
    \tl_set:Nx \l_chat_user_a_last_node_tl {chat-\int_use:N \l_chat_box_index_int}
    \int_incr:N \l_chat_box_index_int
  }
  \newcommand{\UserB}[1]{
    \GetLastVertPos
    \CalcChatWidth{##1}
    \node[chatnode, fill=user-2-color, anchor=north~east, text~width=\l_chat_width_dim] 
      (chat-\int_use:N \l_chat_box_index_int) 
      at ($(\ChatBlockWidth, \dim_use:N \l_chat_last_vert_dim)-(0, \ChatInterval)$)
      {##1};
    \tl_set:Nx \l_chat_user_b_last_node_tl {chat-\int_use:N \l_chat_box_index_int}
    \int_incr:N \l_chat_box_index_int
  }
  \begin{tikzpicture}
}{
  \ChatBubble{\l_chat_user_a_last_node_tl.south~west}
             {$(\l_chat_user_a_last_node_tl.south~west)+(\BubbleHShift,-\BubbleHeight)$}
             {user-1-color}{120}{-120}{2.0}{0.5cm}{0em}{face-eye-color-1}
  
  \ChatBubble{\l_chat_user_b_last_node_tl.south~east}
               {$(\l_chat_user_b_last_node_tl.south~east)+(-\BubbleHShift,-\BubbleHeight)$}
               {user-2-color}{30}{-30}{2.0}{-0.5cm}{0em}{face-eye-color-2}
  \end{tikzpicture}
}

\ExplSyntaxOff

\begin{document}

\begin{ChatBox}
\UserA{Hello, it's me!}
\UserA{I was wondering if after all these years you'd like to meet.}
\UserB{\emph{Hi...but who are you?}}
\UserA{S'up}
\UserA{dude?}
\UserB{\emph{Well nothing man...}}
\UserB{\emph{Who is it?}}
\UserA{Well, of course as usual brother.}
\end{ChatBox}


%
%This is the environment
%\begin{tikzpicture}
%\node[chatnode] {hello};
%%\ChatBubble{0,0}{1,-3}{user-1-color}{120}{-120}{2.0}{3em}{0em}
%\end{tikzpicture}

\end{document}