[Tex/LaTex] How to frame a figure in Lyx

Question

I use Lyx 2.1.
I want to frame the figures. I inserted a simple box and I put the figure inside it.

But, I encountered these errors :

Answer 1

Three different ways, for three different scenarios.

1. Frame tightly enclosing image

Step by step:

1. Add a Figure float, with Insert --> Float --> Figure, or the button on the toolbar.

2. Add a framebox with Insert --> Box --> Simple frame inside the Figure float.

3. Right click the box and choose Settings.

4. Set the Inner box to None, and remove the checkmark from the Width box:

   

5. Insert the image inside this box, with Insert --> Graphics or the button on the toolbar.

2. Just image inside frame, frame width of the text

If the caption should not be inside the frame, go to Document --> Settings --> LaTeX preamble, and add the following:

\usepackage{float}
\floatstyle{boxed} 
\restylefloat{figure}

This will make all your figures (added with Insert --> Float --> Figure, or the corresponding button on the toolbar) framed.

If you want the caption a little further away from the frame in this case, replace the three code lines above with

\usepackage{float}
\renewcommand\fs@boxed{\def\@fs@cfont{\bfseries}\let\@fs@capt\floatc@plain
  \def\@fs@pre{\setbox\@currbox\vbox{\hbadness10000
    \moveleft3.4pt\vbox{\advance\hsize by6.8pt
      \hrule \hbox to\hsize{\vrule\kern3pt
        \vbox{\kern3pt\box\@currbox\kern3pt}\kern3pt\vrule}\hrule}}}%
  \def\@fs@mid{\vspace{\abovecaptionskip}}%
  \def\@fs@post{}\let\@fs@iftopcapt\iffalse}

\floatstyle{boxed} 
\restylefloat{figure}

3. Both caption and image inside frame

You can use Peter Grill's answer to Rounded corner colored box around figure. For a simple black frame, and add this code to the LaTeX preamble:

\usepackage{float}
\usepackage[framemethod=tikz]{mdframed}

\mdfdefinestyle{myFigureBoxStyle}{tikzsetting={draw=black, line width=1pt}}%

 \newcommand\fs@myRoundBox{\def\@fs@cfont{\bfseries}\let\@fs@capt\floatc@plain
  \def\@fs@pre{\begin{mdframed}[style=myFigureBoxStyle]}%
  \def\@fs@mid{\vspace{\abovecaptionskip}}%
  \def\@fs@post{\end{mdframed}}\let\@fs@iftopcapt\iffalse}

\floatstyle{myRoundBox} 
\restylefloat{figure}

This will make figures, including the caption, framed.