how to handle subfiles picture in latex

Question

Now I am using subfile to compile document independent, I want to insert a picture in the sub document like this:

\documentclass[../../../dolphin-book-2020.tex]{subfiles}
\begin{document}
\subsection{GitHub Slow}
balabalabala.......
\begin{figure}[htbp]
    \centering
    \includegraphics[scale=0.2]{githubspeedup}
    \caption{GitHub Speed Up}
    \label{fig:githubspeedup}
\end{figure}
\end{document}

when I compile using this command in macOS Catalina 10.15 :

 /Library/TeX/texbin/latexmk -pdfxe -pvc -xelatex -interaction=nonstopmode ./github-slow.tex

show this error:

(/usr/local/texlive/2020/texmf-dist/tex/latex/listings/lstlang1.sty)
(/usr/local/texlive/2020/texmf-dist/tex/latex/listings/lstlang1.sty)
Package fontspec Warning: Font "FandolFang-Regular" does not contain requested
(fontspec)                Script "CJK".
! LaTeX Error: File `githubspeedup' not found.
See the LaTeX manual or LaTeX Companion for explanation.
Type  H <return>  for immediate help.
 ...
l.31 ^^I\includegraphics[scale=0.2]{githubspeedup}
[1] (./github-slow.aux)
LaTeX Font Warning: Some font shapes were not available, defaults substituted.
LaTeX Warning: Label(s) may have changed. Rerun to get cross-references right.
)
(see the transcript file for additional information)
Output written on github-slow.xdv (1 page, 28900 bytes).
Transcript written on github-slow.log.
=== TeX engine is 'XeTeX'
Latexmk: Index file 'github-slow.idx' was written
Latexmk: Missing input file: 'githubspeedup' from line
  '! LaTeX Error: File `githubspeedup' not found.'
Latexmk: References changed.
Latexmk: Log file says output to 'github-slow.xdv'
Latexmk: Errors, so I did not complete making targets
Latexmk: Failure to make the files correctly
    ==> You will need to change a source file before I do another run <==
Collected error summary (may duplicate other messages):
  xelatex: Command for 'xelatex' gave return code 1
      Refer to 'github-slow.log' for details
=== Watching for updated files. Use ctrl/C to stop ...
^CLatexmk: User typed ctrl/C or ctrl/break.  I'll finish.
Collected error summary (may duplicate other messages):
  xelatex: Command for 'xelatex' gave return code 1
      Refer to 'github-slow.log' for details
Latexmk: Use the -f option to force complete processing,
 unless error was exceeding maximum runs, or warnings treated as errors.

what should I do to make it work? I have already added picture path in the main file dolphin-book-2020.tex like this(all the picture store in the folder and no picture store in sub folder):

\graphicspath{{./Pictures/}}

and this is the file structure:

I have tried define picture path in dolphin-book-2020.tex like this:

\graphicspath{{../../../Pictures/}{../../Pictures/}{../Pictures/}{./Pictures/}} 

this is the folder nested structure:

I also tried to write all possible path of picture:

\graphicspath{
    {Pictures/}
    {../../../Pictures/}
    {../../Pictures/}
    {image/}
    {/Users/dolphin/Documents/GitHub/dolphin-book-2020/Pictures}
}

still could not found file.

Answer 1

You need to add the search path to the image in the main document.

Assuming that:

(1) dolphin-book-2020.tex is in the directory BOOK

(2) The chapters are in BOOK/chapters

(3) The images are in BOOK/chapters/images and the sub-directory images contain githubspeedup.jpg

(4) The subsections are in BOOK/chapters/subsections and that sub-directory contains GitHubSlow.tex

you will get

compiling dolphin-book-2020.tex or GitHubSlow.tex

The searching path from the main file, and from the subfile, to the image was added as

\graphicspath{{./chapters/images/}}} % path to image githubspeedup.jpg

in the main file dolphin-book-2020.tex <<<<<<<<

Multiple searching paths might be added as

\graphicspath{{<path1>}{<path2>}{<path3>}}}

This is dolphin-book-2020.tex

 %% dolphin-book-2020.tex in its own directory BOOK
\documentclass[12pt,a4paper]{book}
\usepackage{graphicx}
\usepackage{subfiles}
\graphicspath{{./chapters/images/}} %  path from here to image githubspeedup.jpg   <<<<<<<<<<<<<<< added
\begin{document}
\subfile{./chapters/subsections/GitHubSlow}  % subsection file in  BOOK/chapters/subsections subdirectory
\end{document}

This is GitHubSlow.tex in the subsections sub-directory

% GitHubSlow.tex in BOOK/chapters/subsections
\documentclass[../../dolphin-book-2020.tex]{subfiles}
\begin{document}
\subsection{GitHub Slow}

balabalabala....... 

\begin{figure}[htbp]
    \centering
    \includegraphics[scale=0.2]{githubspeedup}
    \caption{GitHub Speed Up}
    \label{fig:githubspeedup}
\end{figure}    


\end{document}

Related: Unable to load picture or PDF file using subfiles and XeLaTeX

Answer 2

On the subfiles add picture path like this:

\documentclass[../../../dolphin-book-2020.tex]{subfiles}
\usepackage{graphics} % add package
\graphicspath{
    {../../../Pictures/}
} % add picture path
\begin{document}
\begin{figure}[htbp]
    \centering
    \includegraphics[scale=0.2]{codesign}
    \caption{fastlane}
    \label{fig:codesign}
\end{figure}
\end{document}