Mdthbs

I'm trying to draw the following diagram:

What I could do so far:

The code:

documentclass[tikz,border=20pt]{standalone}



usetikzlibrary{shapes,arrows}

usetikzlibrary{decorations.pathreplacing}

usetikzlibrary{babel}

usetikzlibrary{calc,arrows.meta,patterns,backgrounds}

usetikzlibrary{shapes.multipart}



tikzstyle{block} = [draw, rectangle, rounded corners, minimum size=1cm, text centered]

tikzstyle{transform} = [draw, block, path picture={draw (path picture bounding box.south west)--(path picture bounding box.north east);}]

tikzstyle{state} = [draw, rectangle split,rectangle split parts=2,rounded corners, minimum size=1cm, text centered]



begin{document}



begin{tikzpicture}

    node at (0.0,0.0) [transform](inverter){$qd0$};

    node at (2.0,0.0) [state] {$qd0$ nodepart{two} $abc$};

end{tikzpicture}



end{document}

I need some help :)

The computations are basic,

and if you consider using a pic instead of a full-fledged the node shape, the implementation is straightforward, too. The free parameter is taken to be the height of the full shape. The width is then computed in such a way that the diagonal does not cut any of the nodes (where the "safety distance" is given by the inner sep).

documentclass{article}

usepackage{tikz}

tikzset{pics/dbox/.style 2 args={code={%

pgfmathsetmacro{w}{max((width("#1")+2*pgfkeysvalueof{/pgf/inner xsep})/(pgfkeysvalueof{/tikz/dbox/height}-2*pgfkeysvalueof{/pgf/inner xsep}-height("#1")),%

(width("#2")+2*pgfkeysvalueof{/pgf/inner xsep})/(pgfkeysvalueof{/tikz/dbox/height}-2*pgfkeysvalueof{/pgf/inner xsep}-height("#2")))*pgfkeysvalueof{/tikz/dbox/height}}

path[pic actions] (-w*1pt/2,-pgfkeysvalueof{/tikz/dbox/height}/2) 

 node[above right] {#2}

 rectangle

(w*1pt/2,pgfkeysvalueof{/tikz/dbox/height}/2)

 node[below left] {#1} (-w*1pt/2,pgfkeysvalueof{/tikz/dbox/height}/2)

 -- (w*1pt/2,-pgfkeysvalueof{/tikz/dbox/height}/2) ;

}},dbox/.cd,height/.initial=2cm}

begin{document}

begin{tikzpicture}

 path pic[draw]{dbox={abc}{xyzuv}} (3,0) pic[draw,blue]{dbox={abc}{xyz}}

 (6,0) pic[draw,red,thick]{dbox={abcdefgh}{xyz}};

end{tikzpicture}

end{document}

You can give this shape the usual anchors with a simple trick: just turn it into a node using fit. The names have then to be set using dbox/name=<name>.

documentclass{article}

usepackage{tikz}

usetikzlibrary{fit}

tikzset{pics/dbox/.style 2 args={code={%

pgfmathsetmacro{w}{max((width("#1")+2*pgfkeysvalueof{/pgf/inner xsep})/(pgfkeysvalueof{/tikz/dbox/height}-2*pgfkeysvalueof{/pgf/inner xsep}-height("#1")),%

(width("#2")+2*pgfkeysvalueof{/pgf/inner xsep})/(pgfkeysvalueof{/tikz/dbox/height}-2*pgfkeysvalueof{/pgf/inner xsep}-height("#2")))*pgfkeysvalueof{/tikz/dbox/height}}

path (-w*1pt/2,-pgfkeysvalueof{/tikz/dbox/height}/2) 

 node[above right] (bl) {#2}

 rectangle

(w*1pt/2,pgfkeysvalueof{/tikz/dbox/height}/2)

 node[below left] (tr) {#1};

 node[pic actions,inner sep=0pt,fit=(bl)(tr),path picture={path[pic actions]

 (path picture bounding box.north west)

 -- (path picture bounding box.south east);}] 

 (pgfkeysvalueof{/tikz/dbox/name}){};

}},dbox/.cd,height/.initial=2cm,name/.initial=}

begin{document}

begin{tikzpicture}

 path pic[draw]  {dbox={abc}{xyzuv}} (3,0) 

 pic[draw,blue,dbox/name=A] {dbox={abc}{xyz}}

 (6,0) pic[draw,red,thick,rounded corners,dbox/name=B] {dbox={abcdefgh}{xyz}};

 draw[stealth-stealth] (A.north) to[out=80,in=100](B.100);

end{tikzpicture}

end{document}

Are you looking for a simple code like this? Think geometrically: just a (scaling) square with some text inside that can be manually adjusted.

documentclass[border=5mm]{standalone}

usepackage{tikz}

begin{document}

begin{tikzpicture}[xscale=.8,yscale=1.5]

draw[thick] (1,0)--(0,1) (0,0) rectangle (1,1);

path[magenta] 

(0,0)+(.3,.3)    node{$dq$}

(1,1)+(-.4,-.15) node{$abc$};

end{tikzpicture}



begin{tikzpicture}[xscale=2.5,yscale=1.5]

draw[thick] (1,0)--(0,1) (0,0) rectangle (1,1);

path[blue] 

(0,0)+(.2,.15)    node{$TikZ$}

(1,1)+(-.4,-.15)  node{$Asymptote$};

end{tikzpicture}



end{document}