Btukfyl

I am writing a function to generate a legend in beamer based on:

• the position on the page


• the max and min value


• the colormap to use

Here is an example:

documentclass[table]{beamer}



usepackage{tikz,pgfplots}

usetikzlibrary{calc}

usetikzlibrary{backgrounds}



% Colormaps

pgfplotsset{

    colormap={Legend1}{

        rgb255=(255, 113,   0),

        rgb255=(255, 227,   0),

        rgb255=(170, 255,   0),

        rgb255=( 57, 255,   0),

        rgb255=( 40, 255, 185),

        rgb255=(  0, 199, 221),

        rgb255=( 21, 121, 255),

    }

}



% Len of above/below triangle

deflen{0.75cm}



% Horizontal Legend

newcommand{LegendH}[4]{

    begin{tikzpicture}[remember picture,overlay]

        % Min/Max/Colormap

        pgfmathsetmacro{Min}{#2}

        pgfmathsetmacro{Max}{#3}

        defcolormap{#4}



        % Tick distance

        pgfmathsetmacro{XTickDistance}{

            (Min - Max) / pgfplotscolormapsizeof{colormap}

        }



        % Above/Below

        ifnumpdfstrcmp{colormap}{Legend1}=0

            definecolor{Lcolor}{RGB}{192, 192, 192}

            definecolor{Rcolor}{RGB}{255,   0,   0}

            defprecision{2}

        fi



        % Axis

        begin{axis}[

        hide axis, scale only axis, height=0pt, width=0pt, % hide axis

        colormap name = colormap,

        colorbar sampled,

        colorbar horizontal,

        point meta min=Min,

        point meta max=Max,

        colorbar style = {

            name = cb,

            at={(#1)}, anchor=center,

            samples = pgfplotscolormapsizeof{colormap} + 1,

            height = 0.5cm,

            width = 10cm,

            xtick style = {draw=none},

            xticklabel style = {

                text width = 2.5em,

                align = center,

                /pgf/number format/.cd,

                fixed,

                fixed zerofill,

                precision = precision,

                /tikz/.cd

            },

            xtick distance=XTickDistance,

        }

        ]

        addplot [draw=none] coordinates {(0,0)};

        end{axis}



        % Above/Below  triangle

        foreach i/j in {south east/a, north east/b, north west/c, south west/d}

        {coordinate (j) at (current colorbar axis.i);}

        filldraw[fill=Lcolor] (a) -- ($(a)!0.5!(b)+(len,0)$) -- (b);

        filldraw[fill=Rcolor] (c) -- ($(c)!0.5!(d)+(-len,0)$)-- (d);



        % Background

        scoped[on background layer]

        fill [white] ([shift={(-0.25cm,-0.5cm)}]cb.outer south west) rectangle ([shift={(+0.0cm,+0.5cm)}]cb.outer north east);

    end{tikzpicture}

}   



begin{document}

    begin{frame}{Legend}

        LegendH{$(current page.center)+(0cm, -2cm)$}{1.0}{2.0}{Legend1}

        LegendH{$(current page.center)+(0cm, +0cm)$}{1.0}{3.0}{Legend1}

    end{frame}

end{document}

This is what I get:

As you can see the lower legend (between 1 and 2) is right.

The upper one is wrong: should start on 1 and end on 3, the ticks should be 1.00, 1.29, 1.57, 1.86, 2.14, 2.43, 2.71, 3.00.

I don't understand why there is this odd behavior.

Thanks