This is a follow up question to https://tex.stackexchange.com/a/307507/36296. The linked answer works perfectly fine, as long as each chapter title fit into a single line. For two line entries, the blue bar is too long (marked by the red circle).
Requirements (already fulfilled for single line chapters):
The blue line should reach until the baseline of the last line (the lower edge of non descending characters)
In case the image is larger than the entry (the cases without sections), the line should reach until the lower edge of the image.
\documentclass[a4paper]{book}
\usepackage{xcolor}
\usepackage{geometry}
\usepackage{framed}
\usepackage{etoc}\etocglobaldefs
\usepackage{mwe}
\usepackage[linktoc=all, colorlinks=true, linkcolor=black]{hyperref}
\colorlet{tocleftbarcolour}{blue}
\newlength{\tocmargin}
\setlength{\tocmargin}{1cm}
\newlength{\tocleftbarsep}
\setlength{\tocleftbarsep}{2pt}
\newlength{\tocleftbarwidth}
\setlength{\tocleftbarwidth}{2pt}
\newlength{\tocleftbardepth}
\setlength{\tocleftbardepth}{0pt}
\newenvironment{tocleftbar}
{\def\FrameCommand {%
\hspace{\dimexpr\tocmargin\relax}%
\textcolor{tocleftbarcolour}
{\vrule width \tocleftbarwidth depth \tocleftbardepth\relax}%
\hspace{\tocleftbarsep}%
\hspace{-\dimexpr\tocmargin\relax}%
}%
\MakeFramed {\leftskip\tocmargin\rightskip\tocmargin
\FrameRestore}%
}
{\endMakeFramed}
\newif\ifintocleftbar
\newbox\tempdecobox
\newcommand*{\EmergencyEndLeftBarEnv}{%
% previous chapter had no section
\LARGE
\vskip-\baselineskip
\vskip-\lineskip % assume height of images > baseline
\vskip-\parskip
\vskip-\tocleftbardepth % for fun
\noindent
\vphantom{\usebox{\tempdecobox}}%
% we close a group here hence \etocname, etc.. get lost
% immediately thereafter; this is preemptively counteracted
% by the \etocglobaldefs issued after loading etoc
\end{tocleftbar}%
}
\etocsetstyle{chapter}
{\nobreak\etocskipfirstprefix}% don't break immediately after Part
{\pagebreak[2]}% but allow break after section or subsection
{\ifintocleftbar\EmergencyEndLeftBarEnv\fi
\begin{tocleftbar}
\LARGE
\intocleftbartrue
\sbox\tempdecobox{\sectocdeco}%
\edef\heightoflastbox{\the\ht\tempdecobox}%
\noindent\makebox[0pt][r]
{\smash
{\raisebox{\dimexpr-\height+\ht\strutbox\relax}{\usebox{\tempdecobox}}}%
\hspace{\dimexpr2\tocleftbarsep+\tocleftbarwidth\relax}}%
\parbox[t]{\dimexpr\hsize-2\tocmargin\relax}
{\strut\etocname\strut
\hspace{0.5em}\dotfill\nobreak\hspace{0.5em}\strut\etocpage}%
\par
\normalsize
\leftskip\dimexpr\leftskip+\tocmargin\relax
}
{\ifintocleftbar\EmergencyEndLeftBarEnv\fi}
\etocsetstyle {section}
{\nopagebreak[3]\vspace{1pt}\etocskipfirstprefix}
{\vspace {1pt plus .2pt minus .2pt}}
{\noindent\llap{\makebox[\tocmargin][l]{\etocnumber}}%
\etocname
\nobreak\hspace{0.5em}{\itshape\etocpage}\par }
{\end{tocleftbar}}
\newcommand*{\setsectocdeco}[1]% need to make a global def here
% because the \end{tocleftbar} will close a group
{\addtocontents{toc}{\gdef\string\sectocdeco{\protect#1}}}
\begin{document}
\tableofcontents
\setsectocdeco{\includegraphics[height=1.5cm]{example-image-c}}
\chapter{This is the first chapter. No sections here.}
\chapter{Another chapter}
\section{foo}
bar
\section{foo}
bar
\section{foo}
bar
\section{foo}
bar
\chapter{And this one is the last chapter but with a very long title}
\end{document}
\setsectocdecoexpects two arguments and receives one. It gobbles chapter. Actually it was originally[1]in its definition. – user4686 Sep 22 '16 at 17:46[1]presumably became[2]it happened to me once here on tex.sx I don't recall the reason. – user4686 Sep 22 '16 at 17:47