Cfrgtkky

I am trying to draw over a figure using tikz, using a method for adding scalebars from this answer. The figures that are drawn over this way have extra padding around them (i.e. between the subfigures) that I can't get rid of. Compare the top row of the image below with the bottom row.

I can kind of workaround it by adding an hskip and manually finding the right number for a give figure (see commented out portion of MWE)

  documentclass[12pt,a4paper]{article}

  usepackage{graphicx}

  usepackage{subcaption}

  usepackage{tikz}



  % Add a scalebar to an image

  newcommand{scalebar}[5][white]{%

   noindentbegin{tikzpicture}

    draw (0,0) node[anchor=south west,inner sep=0] (image) { #2 };

    begin{scope}[x={(image.south east)},y={(image.north west)}]

     fill [fill=black, fill opacity=0.5] (0.02,0.1cm) rectangle (#4/#3+0.12,1cm);

     fill [#1] (0.05,0.2cm) rectangle (#4/#3+0.05,0.4cm);

     draw [#1] (0.00,0.4cm) node[anchor=south west, font=footnotesize] {{#4}{#5} };

    end{scope}

   end{tikzpicture} %hskip -1pt % This is my only workaround

  }



  begin{document}



  begin{figure}[h]

      centering

      begin{subfigure}{textwidth}

          caption{}

          includegraphics[width=.3textwidth]{example-image-golden}

          includegraphics[width=.3textwidth]{example-image-golden}

          includegraphics[width=.3textwidth]{example-image-golden}

      end{subfigure}

      begin{subfigure}{textwidth}

          caption{}

          scalebar{includegraphics[width=.3textwidth]{example-image-golden}}{6}{1}{mm}

          scalebar{includegraphics[width=.3textwidth]{example-image-golden}}{6}{1}{mm}

          includegraphics[width=.3textwidth]{example-image-golden}

      end{subfigure}

  end{figure}



  end{document}

Ok, I figured this a little after posting. I guess making the MWE simplified it enough I figured out what was wrong.

My defined command had an invisible space in it - that was all that was showing up, I think. See the two spots where I inserted a % at the end of the line:

% Inserts a scale bar into an image

% Optional argument 1: the colour of the bar and text

% Argument 2: an includegraphics command

% Argument 3: the real world width of the image

% Argument 4: the length of the scale bar

% Argument 5: the units in which the scale bar is measured

newcommand{scalebar}[5][white]{%

 begin{tikzpicture}

  draw (0,0) node[anchor=south west,inner sep=0] (image) { #2 };

  begin{scope}[x={(image.south east)},y={(image.north west)}]

   fill [#1] (0.05,0.2cm) rectangle (#4/#3+0.05,0.4cm);

   draw [#1] (0.05,0.4cm) node[anchor=south west] { SI{#4}{#5} };

  end{scope}

 end{tikzpicture}%

}