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Regular polygon VS circle shapes in TikZ


Draw a node as a square with TikZHow to draw inside a TikZ node, using node style?Creating node shapesFilling angles with arcs in TikZIncrease the thickness of node border in TikZComputing the rectangle encompassing a node and a pointcustom hatching pattern : arbitrary direction of hatchingHow to draw inside a TikZ node using node style with arguments?Draw a transparency gradient arc over a rectangle with tikzAdjusting edge alignment and positioning of fitted nodePositioning of Node Labels













6















This question is a kind of continuation this answer. There, it remains unclear which is the origin of the white space around the node content, if a square shape is used, and I would like to understand this. Given the following MWE



documentclass[tikz, border=1mm]standalone
usetikzlibraryshapes.geometric

begindocument
 begintikzpicture[every node/.style=draw, inner sep=0]
 node[regular polygon,regular polygon sides=4] (a) XX;
 node[regular polygon,regular polygon sides=100, blue] (b) XX;
 node[circle] (c) XX;
 foreach a in north,south,east,west,north east,south east,north west,south west
 fill[red] (a.a) circle(0.5pt);
 fill[yellow] (b.a) circle(0.25pt);
 fill[orange] (c.a) circle(0.25pt);
 
 endtikzpicture
enddocument


I am a bit surprised that the black circle has a radius which is smaller than that of the inscribed circle in the polygon, since the pgf manual says




[...] the border of the polygon is always constructed using the
incircle, whose radius is calculated to tightly fit the node contents
(including any inner sep).




To show what I would have expected and what I would like to have I added a blue "fake circle" to the MWE as a regular polygon with 100 sides. Is there a way to draw such a blue circle using the circle shape, i.e. node[circle, ...]XX;? Playing by hand with inner sep is not an option for me.



As clarification/additional information, I am interested in having a node shape to be used in a wider context, i.e. not in relation with the square. And also receiving an explanation about why the 4-sides polygon leaves so much space despite the inner sep=0 would be highly appreciated.



UPDATE: From the comments, indeed, there is some room of interpretation in the question. In short, I would like to answer these questions.



  1. How is it possible to have a Circle shape (or Circle tikzstyle) that draws exactly the inscribed circle of the correspondent regular polygon around a given node content?

  2. Where does the discrepancy between black circle and square in my MWE come from?

  3. If easier (I can also use this other approach), how is it possible to have a Regular Polygon shape (or tikzstyle) that has as inscribed circle the correspondent circle around a given node content?

                 Figure MWE






tikz-pgf







share|improve this question
























  • You can see in the manual that for empty nodes the ratio is sqrt(2) (but I don't know why). In the manual a regular polygon with inner space equal to 0.3535cm (which is sqrt(2)/4) is tangent to circle with radius 1/2 cm.

    – Kpym
    Mar 21 at 12:50











  • I had noticed that strange inner sep in the example. But I had also noticed that it was about an empty node. If I have an arbitrary node content, I would then need to adjust that 0.3535cm magic number (and I should think about how). Are you suggesting something like that?

    – Axel Krypton
    Mar 21 at 13:07






  • 1





    This sqrt(2) factor does make sense if you assume the the content is approximately quadratic. And I do not understand the question. That is, I thought I did before I saw the answers. Could you perhaps indicate to which extent the answers address the question. I am really confused.

    – marmot
    Mar 21 at 14:19






  • 1





    @marmot As I understand the answer is "How to draw a circular shape that has the same inner circle as all other regular polygons".

    – Kpym
    Mar 21 at 14:32






  • 1





    @marmot I think that I have answered this par of the question : the the origin of the white space around the node content is that in the definition of the regular polygon shape the inner radius is calculated differently from the circle shape (and the ratio between both depends on the shape, i.e. the aspect ratio).

    – Kpym
    Mar 21 at 15:52















6















This question is a kind of continuation this answer. There, it remains unclear which is the origin of the white space around the node content, if a square shape is used, and I would like to understand this. Given the following MWE



documentclass[tikz, border=1mm]standalone
usetikzlibraryshapes.geometric

begindocument
 begintikzpicture[every node/.style=draw, inner sep=0]
 node[regular polygon,regular polygon sides=4] (a) XX;
 node[regular polygon,regular polygon sides=100, blue] (b) XX;
 node[circle] (c) XX;
 foreach a in north,south,east,west,north east,south east,north west,south west
 fill[red] (a.a) circle(0.5pt);
 fill[yellow] (b.a) circle(0.25pt);
 fill[orange] (c.a) circle(0.25pt);
 
 endtikzpicture
enddocument


I am a bit surprised that the black circle has a radius which is smaller than that of the inscribed circle in the polygon, since the pgf manual says




[...] the border of the polygon is always constructed using the
incircle, whose radius is calculated to tightly fit the node contents
(including any inner sep).




To show what I would have expected and what I would like to have I added a blue "fake circle" to the MWE as a regular polygon with 100 sides. Is there a way to draw such a blue circle using the circle shape, i.e. node[circle, ...]XX;? Playing by hand with inner sep is not an option for me.



As clarification/additional information, I am interested in having a node shape to be used in a wider context, i.e. not in relation with the square. And also receiving an explanation about why the 4-sides polygon leaves so much space despite the inner sep=0 would be highly appreciated.



UPDATE: From the comments, indeed, there is some room of interpretation in the question. In short, I would like to answer these questions.



  1. How is it possible to have a Circle shape (or Circle tikzstyle) that draws exactly the inscribed circle of the correspondent regular polygon around a given node content?

  2. Where does the discrepancy between black circle and square in my MWE come from?

  3. If easier (I can also use this other approach), how is it possible to have a Regular Polygon shape (or tikzstyle) that has as inscribed circle the correspondent circle around a given node content?

                 Figure MWE






tikz-pgf







share|improve this question
























  • You can see in the manual that for empty nodes the ratio is sqrt(2) (but I don't know why). In the manual a regular polygon with inner space equal to 0.3535cm (which is sqrt(2)/4) is tangent to circle with radius 1/2 cm.

    – Kpym
    Mar 21 at 12:50











  • I had noticed that strange inner sep in the example. But I had also noticed that it was about an empty node. If I have an arbitrary node content, I would then need to adjust that 0.3535cm magic number (and I should think about how). Are you suggesting something like that?

    – Axel Krypton
    Mar 21 at 13:07






  • 1





    This sqrt(2) factor does make sense if you assume the the content is approximately quadratic. And I do not understand the question. That is, I thought I did before I saw the answers. Could you perhaps indicate to which extent the answers address the question. I am really confused.

    – marmot
    Mar 21 at 14:19






  • 1





    @marmot As I understand the answer is "How to draw a circular shape that has the same inner circle as all other regular polygons".

    – Kpym
    Mar 21 at 14:32






  • 1





    @marmot I think that I have answered this par of the question : the the origin of the white space around the node content is that in the definition of the regular polygon shape the inner radius is calculated differently from the circle shape (and the ratio between both depends on the shape, i.e. the aspect ratio).

    – Kpym
    Mar 21 at 15:52













6












6








6








This question is a kind of continuation this answer. There, it remains unclear which is the origin of the white space around the node content, if a square shape is used, and I would like to understand this. Given the following MWE



documentclass[tikz, border=1mm]standalone
usetikzlibraryshapes.geometric

begindocument
 begintikzpicture[every node/.style=draw, inner sep=0]
 node[regular polygon,regular polygon sides=4] (a) XX;
 node[regular polygon,regular polygon sides=100, blue] (b) XX;
 node[circle] (c) XX;
 foreach a in north,south,east,west,north east,south east,north west,south west
 fill[red] (a.a) circle(0.5pt);
 fill[yellow] (b.a) circle(0.25pt);
 fill[orange] (c.a) circle(0.25pt);
 
 endtikzpicture
enddocument


I am a bit surprised that the black circle has a radius which is smaller than that of the inscribed circle in the polygon, since the pgf manual says




[...] the border of the polygon is always constructed using the
incircle, whose radius is calculated to tightly fit the node contents
(including any inner sep).




To show what I would have expected and what I would like to have I added a blue "fake circle" to the MWE as a regular polygon with 100 sides. Is there a way to draw such a blue circle using the circle shape, i.e. node[circle, ...]XX;? Playing by hand with inner sep is not an option for me.



As clarification/additional information, I am interested in having a node shape to be used in a wider context, i.e. not in relation with the square. And also receiving an explanation about why the 4-sides polygon leaves so much space despite the inner sep=0 would be highly appreciated.



UPDATE: From the comments, indeed, there is some room of interpretation in the question. In short, I would like to answer these questions.



  1. How is it possible to have a Circle shape (or Circle tikzstyle) that draws exactly the inscribed circle of the correspondent regular polygon around a given node content?

  2. Where does the discrepancy between black circle and square in my MWE come from?

  3. If easier (I can also use this other approach), how is it possible to have a Regular Polygon shape (or tikzstyle) that has as inscribed circle the correspondent circle around a given node content?

                 Figure MWE






tikz-pgf







share|improve this question
















This question is a kind of continuation this answer. There, it remains unclear which is the origin of the white space around the node content, if a square shape is used, and I would like to understand this. Given the following MWE



documentclass[tikz, border=1mm]standalone
usetikzlibraryshapes.geometric

begindocument
 begintikzpicture[every node/.style=draw, inner sep=0]
 node[regular polygon,regular polygon sides=4] (a) XX;
 node[regular polygon,regular polygon sides=100, blue] (b) XX;
 node[circle] (c) XX;
 foreach a in north,south,east,west,north east,south east,north west,south west
 fill[red] (a.a) circle(0.5pt);
 fill[yellow] (b.a) circle(0.25pt);
 fill[orange] (c.a) circle(0.25pt);
 
 endtikzpicture
enddocument


I am a bit surprised that the black circle has a radius which is smaller than that of the inscribed circle in the polygon, since the pgf manual says




[...] the border of the polygon is always constructed using the
incircle, whose radius is calculated to tightly fit the node contents
(including any inner sep).




To show what I would have expected and what I would like to have I added a blue "fake circle" to the MWE as a regular polygon with 100 sides. Is there a way to draw such a blue circle using the circle shape, i.e. node[circle, ...]XX;? Playing by hand with inner sep is not an option for me.



As clarification/additional information, I am interested in having a node shape to be used in a wider context, i.e. not in relation with the square. And also receiving an explanation about why the 4-sides polygon leaves so much space despite the inner sep=0 would be highly appreciated.



UPDATE: From the comments, indeed, there is some room of interpretation in the question. In short, I would like to answer these questions.



  1. How is it possible to have a Circle shape (or Circle tikzstyle) that draws exactly the inscribed circle of the correspondent regular polygon around a given node content?

  2. Where does the discrepancy between black circle and square in my MWE come from?

  3. If easier (I can also use this other approach), how is it possible to have a Regular Polygon shape (or tikzstyle) that has as inscribed circle the correspondent circle around a given node content?

                 Figure MWE






tikz-pgf




tikz-pgf






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited Mar 21 at 16:50







Axel Krypton

















asked Mar 21 at 11:17









Axel KryptonAxel Krypton

477211




477211












  • You can see in the manual that for empty nodes the ratio is sqrt(2) (but I don't know why). In the manual a regular polygon with inner space equal to 0.3535cm (which is sqrt(2)/4) is tangent to circle with radius 1/2 cm.

    – Kpym
    Mar 21 at 12:50











  • I had noticed that strange inner sep in the example. But I had also noticed that it was about an empty node. If I have an arbitrary node content, I would then need to adjust that 0.3535cm magic number (and I should think about how). Are you suggesting something like that?

    – Axel Krypton
    Mar 21 at 13:07






  • 1





    This sqrt(2) factor does make sense if you assume the the content is approximately quadratic. And I do not understand the question. That is, I thought I did before I saw the answers. Could you perhaps indicate to which extent the answers address the question. I am really confused.

    – marmot
    Mar 21 at 14:19






  • 1





    @marmot As I understand the answer is "How to draw a circular shape that has the same inner circle as all other regular polygons".

    – Kpym
    Mar 21 at 14:32






  • 1





    @marmot I think that I have answered this par of the question : the the origin of the white space around the node content is that in the definition of the regular polygon shape the inner radius is calculated differently from the circle shape (and the ratio between both depends on the shape, i.e. the aspect ratio).

    – Kpym
    Mar 21 at 15:52

















  • You can see in the manual that for empty nodes the ratio is sqrt(2) (but I don't know why). In the manual a regular polygon with inner space equal to 0.3535cm (which is sqrt(2)/4) is tangent to circle with radius 1/2 cm.

    – Kpym
    Mar 21 at 12:50











  • I had noticed that strange inner sep in the example. But I had also noticed that it was about an empty node. If I have an arbitrary node content, I would then need to adjust that 0.3535cm magic number (and I should think about how). Are you suggesting something like that?

    – Axel Krypton
    Mar 21 at 13:07






  • 1





    This sqrt(2) factor does make sense if you assume the the content is approximately quadratic. And I do not understand the question. That is, I thought I did before I saw the answers. Could you perhaps indicate to which extent the answers address the question. I am really confused.

    – marmot
    Mar 21 at 14:19






  • 1





    @marmot As I understand the answer is "How to draw a circular shape that has the same inner circle as all other regular polygons".

    – Kpym
    Mar 21 at 14:32






  • 1





    @marmot I think that I have answered this par of the question : the the origin of the white space around the node content is that in the definition of the regular polygon shape the inner radius is calculated differently from the circle shape (and the ratio between both depends on the shape, i.e. the aspect ratio).

    – Kpym
    Mar 21 at 15:52
















You can see in the manual that for empty nodes the ratio is sqrt(2) (but I don't know why). In the manual a regular polygon with inner space equal to 0.3535cm (which is sqrt(2)/4) is tangent to circle with radius 1/2 cm.

– Kpym
Mar 21 at 12:50





You can see in the manual that for empty nodes the ratio is sqrt(2) (but I don't know why). In the manual a regular polygon with inner space equal to 0.3535cm (which is sqrt(2)/4) is tangent to circle with radius 1/2 cm.

– Kpym
Mar 21 at 12:50













I had noticed that strange inner sep in the example. But I had also noticed that it was about an empty node. If I have an arbitrary node content, I would then need to adjust that 0.3535cm magic number (and I should think about how). Are you suggesting something like that?

– Axel Krypton
Mar 21 at 13:07





I had noticed that strange inner sep in the example. But I had also noticed that it was about an empty node. If I have an arbitrary node content, I would then need to adjust that 0.3535cm magic number (and I should think about how). Are you suggesting something like that?

– Axel Krypton
Mar 21 at 13:07




1




1





This sqrt(2) factor does make sense if you assume the the content is approximately quadratic. And I do not understand the question. That is, I thought I did before I saw the answers. Could you perhaps indicate to which extent the answers address the question. I am really confused.

– marmot
Mar 21 at 14:19





This sqrt(2) factor does make sense if you assume the the content is approximately quadratic. And I do not understand the question. That is, I thought I did before I saw the answers. Could you perhaps indicate to which extent the answers address the question. I am really confused.

– marmot
Mar 21 at 14:19




1




1





@marmot As I understand the answer is "How to draw a circular shape that has the same inner circle as all other regular polygons".

– Kpym
Mar 21 at 14:32





@marmot As I understand the answer is "How to draw a circular shape that has the same inner circle as all other regular polygons".

– Kpym
Mar 21 at 14:32




1




1





@marmot I think that I have answered this par of the question : the the origin of the white space around the node content is that in the definition of the regular polygon shape the inner radius is calculated differently from the circle shape (and the ratio between both depends on the shape, i.e. the aspect ratio).

– Kpym
Mar 21 at 15:52





@marmot I think that I have answered this par of the question : the the origin of the white space around the node content is that in the definition of the regular polygon shape the inner radius is calculated differently from the circle shape (and the ratio between both depends on the shape, i.e. the aspect ratio).

– Kpym
Mar 21 at 15:52










5 Answers
5






active

oldest

votes


















2














The "inner circle" in shapes.geometric has a radius that is half of the longest side of the content box plus the inner sep, and multiplied by 1.4142136, which is approximately sqrt(2). So to obtain a circle shape that has this behavior you can define a new shape, let's say Circle (with capital C) that is a slight modification of the existing ellipse shape. 



documentclass[tikz, border=7pt, convert=density=4200]standalone
usetikzlibraryshapes.geometric
makeatletter
pgfdeclareshapeCircle
%
% Draws a circle around the text
% (based on the original ellipse shape)
%
%
 savedanchorcenterpoint%
 pgf@x=.5wdpgfnodeparttextbox%
 pgf@y=.5htpgfnodeparttextbox%
 advancepgf@y by-.5dppgfnodeparttextbox%
 %
 savedanchorradius%
 %
 % Calculate ``height radius''
 %
 pgf@y=.5htpgfnodeparttextbox%
 advancepgf@y by.5dppgfnodeparttextbox%
 pgfmathsetlengthpgf@ybpgfkeysvalueof/pgf/inner ysep%
 advancepgf@y bypgf@yb%
 %
 % Calculate ``width radius''
 %
 pgf@x=.5wdpgfnodeparttextbox%
 pgfmathsetlengthpgf@xbpgfkeysvalueof/pgf/inner xsep%
 advancepgf@x bypgf@xb%
 %
 % Adjust
 %
 % ==============================
 % added to ellipse shape to become circle
 ifdimpgf@y>pgf@x%
 pgf@xpgf@y%
 else%
 pgf@ypgf@x%
 fi%
 % ==============================
 pgf@x=1.4142136pgf@x%
 pgf@y=1.4142136pgf@y%
 %
 % Adjust height, if necessary
 %
 pgfmathsetlengthpgf@ycpgfkeysvalueof/pgf/minimum height%
 ifdimpgf@y<.5pgf@yc%
 pgf@y=.5pgf@yc%
 fi%
 %
 % Adjust width, if necessary
 %
 pgfmathsetlengthpgf@xcpgfkeysvalueof/pgf/minimum width%
 ifdimpgf@x<.5pgf@xc%
 pgf@x=.5pgf@xc%
 fi%
 %
 % Add outer sep
 %
 pgfmathsetlengthpgf@xbpgfkeysvalueof/pgf/outer xsep%
 pgfmathsetlengthpgf@ybpgfkeysvalueof/pgf/outer ysep%
 advancepgf@x bypgf@xb%
 advancepgf@y bypgf@yb%
 %

 %
 % Anchors
 %
 anchorcentercenterpoint%
 anchormidcenterpointpgfmathsetlengthpgf@y.5ex%
 anchorbasecenterpointpgf@y=0pt%
 anchornorth
 
 pgf@processradius
 pgf@ya=pgf@y%
 pgf@processcenterpoint
 advancepgf@y bypgf@ya
 %
 anchorsouth
 
 pgf@processradius
 pgf@ya=pgf@y%
 pgf@processcenterpoint
 advancepgf@y by-pgf@ya
 %
 anchorwest
 
 pgf@processradius
 pgf@xa=pgf@x%
 pgf@processcenterpoint
 advancepgf@x by-pgf@xa
 %
 anchormid west
 %
 pgf@processradius
 pgf@xa=pgf@x%
 pgf@processcenterpoint
 advancepgf@x by-pgf@xa%
 pgfmathsetlengthpgf@y.5ex
 %
 anchorbase west
 %
 pgf@processradius
 pgf@xa=pgf@x%
 pgf@processcenterpoint
 advancepgf@x by-pgf@xa%
 pgf@y=0pt
 %
 anchornorth west
 
 pgf@processradius
 pgf@xa=pgf@x%
 pgf@ya=pgf@y%
 pgf@processcenterpoint
 advancepgf@x by-0.707107pgf@xa
 advancepgf@y by0.707107pgf@ya
 %
 anchorsouth west
 
 pgf@processradius
 pgf@xa=pgf@x%
 pgf@ya=pgf@y%
 pgf@processcenterpoint
 advancepgf@x by-0.707107pgf@xa
 advancepgf@y by-0.707107pgf@ya
 %
 anchoreast
 %
 pgf@processradius
 pgf@xa=pgf@x%
 pgf@processcenterpoint
 advancepgf@x bypgf@xa
 %
 anchormid east
 %
 pgf@processradius
 pgf@xa=pgf@x%
 pgf@processcenterpoint
 advancepgf@x bypgf@xa%
 pgfmathsetlengthpgf@y.5ex
 %
 anchorbase east
 %
 pgf@processradius
 pgf@xa=pgf@x%
 pgf@processcenterpoint
 advancepgf@x bypgf@xa%
 pgf@y=0pt
 %
 anchornorth east
 
 pgf@processradius
 pgf@xa=pgf@x%
 pgf@ya=pgf@y%
 pgf@processcenterpoint
 advancepgf@x by0.707107pgf@xa
 advancepgf@y by0.707107pgf@ya
 %
 anchorsouth east
 
 pgf@processradius
 pgf@xa=pgf@x%
 pgf@ya=pgf@y%
 pgf@processcenterpoint
 advancepgf@x by0.707107pgf@xa
 advancepgf@y by-0.707107pgf@ya
 %
 anchorborder
 edefpgf@marshal%
 noexpandpgfpointborderellipse
 noexpandpgfqpointthepgf@xthepgf@y
 noexpandradius%
 %
 pgf@marshal%
 pgf@xa=pgf@x%
 pgf@ya=pgf@y%
 centerpoint%
 advancepgf@x bypgf@xa%
 advancepgf@y bypgf@ya%
 %

 %
 % Background path
 %
 backgroundpath
 
 pgf@processradius%
 pgfutil@tempdima=pgf@x%
 pgfutil@tempdimb=pgf@y%
 pgfmathsetlengthpgf@xbpgfkeysvalueof/pgf/outer xsep%
 pgfmathsetlengthpgf@ybpgfkeysvalueof/pgf/outer ysep%
 advancepgfutil@tempdima by-pgf@xb%
 advancepgfutil@tempdimb by-pgf@yb%
 pgfpathellipsecenterpointpgfqpointpgfutil@tempdima0ptpgfqpoint0ptpgfutil@tempdimb%
 %
%
makeatother

begindocument
 begintikzpicture[nodes=draw, inner sep=0]
 node[regular polygon,regular polygon sides=4] (a) XX;
 node[Circle, blue] (b) XX;
 node[circle] (c) XX;
 foreach a in north,south,east,west,north east,south east,north west,south west
 fill[red] (a.a) circle(0.5pt);
 fill[yellow] (b.a) circle(0.25pt);
 fill[orange] (c.a) circle(0.25pt);
 
 endtikzpicture
enddocument


enter image description here



Addendum:



If you want to go the other way and create a circumscribed polygon around the standard circle node style, that do not use low level tricks, you can define circumscribed polygon that use append after command to add well sized regular polygon. This is not a robust code for meany reasons, it is just a proof of concept :



documentclass[tikz,border=7pt,convert=density=4200]standalone
usetikzlibrarycalc,shapes.geometric

% don't tell me to not use tikzstyle ;)
tikzstylecircumscribed polygon[draw]=[
 circle,draw=none,fill=none,shade=none,
 append after command=
 let p1=($(tikzlastnode.west)-(tikzlastnode.east)$),
 n1 = (veclen(p1)-pgflinewidth)/2.828427 % 2*sqrt(2) = 2.8284271247461903
 in
 (tikzlastnode.center) node[regular polygon, inner sep=n1, #1]
 
]
begindocument
 begintikzpicture[inner sep=1mm]
 foreach~in 3,...,7
 node[circumscribed polygon=draw=blue!~0!green,regular polygon sides=~] XX;
 node[circle,draw=red] XX;
 endtikzpicture
enddocument


enter image description here






share|improve this answer

























  • Very enlightening. I wonder if, then, rather than defining a completely new shape, it is not easier to find out a systematic way to give a proper, automatically determined inner separation to a normal circle. Analogously one could give an automatically determined negative inner sep to a regular polygon. I will think about it, but you helped already a lot!

    – Axel Krypton
    Mar 21 at 16:55











  • And I would also say that the pgf inherit...[from=ellipse] commands might be useful to shorten the code, but I have to still explore this world and I might be completely wrong.

    – Axel Krypton
    Mar 21 at 17:01












  • Thanks for the added information, very useful, indeed. I came up with a slightly different Circle and I shared this in a separate answer. :)

    – Axel Krypton
    Mar 22 at 9:02


















2














Using through library of Tikz.



documentclass[tikz, border=1mm]standalone
usetikzlibraryshapes.geometric,through

begindocument
 begintikzpicture[every node/.style=draw, inner sep=0]
 node[regular polygon,regular polygon sides=4] (a) XX;
 node (b) [draw,blue, circle through=(a.north)] at (a.center) XX;
 node[circle] (c) XX;
 foreach a in north,south,east,west,north east,south east,north west,south west
 fill[red] (a.a) circle(0.5pt);
 fill[yellow] (b.a) circle(0.25pt);
 fill[orange] (c.a) circle(0.25pt);
 

 endtikzpicture
enddocument


enter image description here






share|improve this answer























  • Although strictly speaking you proposed a valid way to draw the blue circle, I was more interested in a general way to draw that shape for a node, without having to rely to another node/point (see edit question). The only way I see I could use your idea is to always have two nodes, one invisible and one that would be the node I wish. However, this is not what I am looking for.

    – Axel Krypton
    Mar 21 at 12:25


















1














Just to share a different way to achieve what Kpym did in his very nice answer declaring a new shape, I thought one could have simply a Circle style which sets properly the minimum size of a circle shape (in this particular case it is always true that the content will never exceed the minimum size since we are trying to enlarge the circle). It should work for any node content, no matter if its width is larger than its height or vice-versa. A couple of remarks:



  • In this approach the node name and the node position must be declared before the options or inside them using the name and at keys, respectively.

  • A Circle inner sep has to be specified before the Circle style, but it might easily be improved, if needed otherwise.

Here the code:



documentclass[tikz, border=1mm]standalone
usetikzlibraryshapes.geometric

tikzset%
 Square/.style=regular polygon, regular polygon sides=4,
 Circle/.style=%
 circle,
 /utils/exec=%
 pgfmathsetmacropolygonIncircleDiameter
 sqrt(2)*max(width("#1")+2*pgfshapeinnerxsep, height("#1") + depth("#1") + 2 * pgfshapeinnerysep)
 
 ,
 minimum size=polygonIncircleDiameter,
 node contents=#1
 


begindocument
 begintikzpicture
 node[inner sep=0, Square, draw=cyan] at (0,0) xx;
 node[inner sep=0, Circle=xx, draw=blue];
 node[Square, draw=cyan] at (1,0) i;
 node[Circle=i, draw=blue, at=(1,0)];
 endtikzpicture
enddocument


                         
enter image description here






share|improve this answer

























  • Very nice ! Two remarks : it would be nice to not pass the node content as parameter to Circle but I think that this will be tricky, and probably polygonIncircleDiameter is better than to divide and then multiply by 2 the polygonIncircleRadius.

    – Kpym
    Mar 22 at 9:31











  • I implemented your suggestion, it definitely makes sense! :) About not passing the node content to the style, well, honestly I would not know how to then achieve the same result. Yes, it definitely looks tricky to me.

    – Axel Krypton
    Mar 22 at 9:41


















0














This wraps a polyogon around the circle.



documentclass[tikz,border=3.14mm]standalone
usetikzlibrarycalc

begindocument
 begintikzpicture[every node/.style=draw, inner sep=0,
 polygon with circle/.style args=#1 inscribed and #2 cornersinsert path=%
 let p1=($(#1.0)-(#1.center)$),n1=abs(x1)/cos(180/#2)
 in ($(#1.center)+(0:n1)$)
 foreach X in 1,...,numexpr#2-1 
 -- ($(#1.center)+(360*X/#2:n1)$) -- cycle]
 node[circle] (c) XX;
 draw[blue,polygon with circle=c inscribed and 12 corners] ;
 foreach a in north,south,east,west,north east,south east,north west,south west
 fill[orange] (c.a) circle(0.25pt);
 
 endtikzpicture
enddocument


enter image description here






share|improve this answer






























    0














    This solution uses calc library to compute regular polygon's inner radius. This way it's possible to compute circunscribed circle's minimum width. 



    documentclass[tikz, border=1mm]standalone
    usetikzlibraryshapes.geometric, calc

    begindocument
     begintikzpicture
     node[inner sep=0, regular polygon, regular polygon sides=4, draw=cyan] (a) xx;
     path let p1=($(a.center)-(a.side 1)$) in node[circle, inner sep=0, minimum width=2*veclen(x1,y1)-pgflinewidth, draw=blue] ;
     node[inner sep=0, draw=cyan, regular polygon, regular polygon sides=7] (b) at (1,0) i;
     path let p1=($(b.center)-(b.side 1)$) in node[circle, inner sep=0, minimum width=2*veclen(x1,y1)-pgflinewidth, draw=blue] at (b) ;
     endtikzpicture
    enddocument


    enter image description here






    share|improve this answer























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      2














      The "inner circle" in shapes.geometric has a radius that is half of the longest side of the content box plus the inner sep, and multiplied by 1.4142136, which is approximately sqrt(2). So to obtain a circle shape that has this behavior you can define a new shape, let's say Circle (with capital C) that is a slight modification of the existing ellipse shape. 



      documentclass[tikz, border=7pt, convert=density=4200]standalone
      usetikzlibraryshapes.geometric
      makeatletter
      pgfdeclareshapeCircle
      %
      % Draws a circle around the text
      % (based on the original ellipse shape)
      %
      %
       savedanchorcenterpoint%
       pgf@x=.5wdpgfnodeparttextbox%
       pgf@y=.5htpgfnodeparttextbox%
       advancepgf@y by-.5dppgfnodeparttextbox%
       %
       savedanchorradius%
       %
       % Calculate ``height radius''
       %
       pgf@y=.5htpgfnodeparttextbox%
       advancepgf@y by.5dppgfnodeparttextbox%
       pgfmathsetlengthpgf@ybpgfkeysvalueof/pgf/inner ysep%
       advancepgf@y bypgf@yb%
       %
       % Calculate ``width radius''
       %
       pgf@x=.5wdpgfnodeparttextbox%
       pgfmathsetlengthpgf@xbpgfkeysvalueof/pgf/inner xsep%
       advancepgf@x bypgf@xb%
       %
       % Adjust
       %
       % ==============================
       % added to ellipse shape to become circle
       ifdimpgf@y>pgf@x%
       pgf@xpgf@y%
       else%
       pgf@ypgf@x%
       fi%
       % ==============================
       pgf@x=1.4142136pgf@x%
       pgf@y=1.4142136pgf@y%
       %
       % Adjust height, if necessary
       %
       pgfmathsetlengthpgf@ycpgfkeysvalueof/pgf/minimum height%
       ifdimpgf@y<.5pgf@yc%
       pgf@y=.5pgf@yc%
       fi%
       %
       % Adjust width, if necessary
       %
       pgfmathsetlengthpgf@xcpgfkeysvalueof/pgf/minimum width%
       ifdimpgf@x<.5pgf@xc%
       pgf@x=.5pgf@xc%
       fi%
       %
       % Add outer sep
       %
       pgfmathsetlengthpgf@xbpgfkeysvalueof/pgf/outer xsep%
       pgfmathsetlengthpgf@ybpgfkeysvalueof/pgf/outer ysep%
       advancepgf@x bypgf@xb%
       advancepgf@y bypgf@yb%
       %

       %
       % Anchors
       %
       anchorcentercenterpoint%
       anchormidcenterpointpgfmathsetlengthpgf@y.5ex%
       anchorbasecenterpointpgf@y=0pt%
       anchornorth
       
       pgf@processradius
       pgf@ya=pgf@y%
       pgf@processcenterpoint
       advancepgf@y bypgf@ya
       %
       anchorsouth
       
       pgf@processradius
       pgf@ya=pgf@y%
       pgf@processcenterpoint
       advancepgf@y by-pgf@ya
       %
       anchorwest
       
       pgf@processradius
       pgf@xa=pgf@x%
       pgf@processcenterpoint
       advancepgf@x by-pgf@xa
       %
       anchormid west
       %
       pgf@processradius
       pgf@xa=pgf@x%
       pgf@processcenterpoint
       advancepgf@x by-pgf@xa%
       pgfmathsetlengthpgf@y.5ex
       %
       anchorbase west
       %
       pgf@processradius
       pgf@xa=pgf@x%
       pgf@processcenterpoint
       advancepgf@x by-pgf@xa%
       pgf@y=0pt
       %
       anchornorth west
       
       pgf@processradius
       pgf@xa=pgf@x%
       pgf@ya=pgf@y%
       pgf@processcenterpoint
       advancepgf@x by-0.707107pgf@xa
       advancepgf@y by0.707107pgf@ya
       %
       anchorsouth west
       
       pgf@processradius
       pgf@xa=pgf@x%
       pgf@ya=pgf@y%
       pgf@processcenterpoint
       advancepgf@x by-0.707107pgf@xa
       advancepgf@y by-0.707107pgf@ya
       %
       anchoreast
       %
       pgf@processradius
       pgf@xa=pgf@x%
       pgf@processcenterpoint
       advancepgf@x bypgf@xa
       %
       anchormid east
       %
       pgf@processradius
       pgf@xa=pgf@x%
       pgf@processcenterpoint
       advancepgf@x bypgf@xa%
       pgfmathsetlengthpgf@y.5ex
       %
       anchorbase east
       %
       pgf@processradius
       pgf@xa=pgf@x%
       pgf@processcenterpoint
       advancepgf@x bypgf@xa%
       pgf@y=0pt
       %
       anchornorth east
       
       pgf@processradius
       pgf@xa=pgf@x%
       pgf@ya=pgf@y%
       pgf@processcenterpoint
       advancepgf@x by0.707107pgf@xa
       advancepgf@y by0.707107pgf@ya
       %
       anchorsouth east
       
       pgf@processradius
       pgf@xa=pgf@x%
       pgf@ya=pgf@y%
       pgf@processcenterpoint
       advancepgf@x by0.707107pgf@xa
       advancepgf@y by-0.707107pgf@ya
       %
       anchorborder
       edefpgf@marshal%
       noexpandpgfpointborderellipse
       noexpandpgfqpointthepgf@xthepgf@y
       noexpandradius%
       %
       pgf@marshal%
       pgf@xa=pgf@x%
       pgf@ya=pgf@y%
       centerpoint%
       advancepgf@x bypgf@xa%
       advancepgf@y bypgf@ya%
       %

       %
       % Background path
       %
       backgroundpath
       
       pgf@processradius%
       pgfutil@tempdima=pgf@x%
       pgfutil@tempdimb=pgf@y%
       pgfmathsetlengthpgf@xbpgfkeysvalueof/pgf/outer xsep%
       pgfmathsetlengthpgf@ybpgfkeysvalueof/pgf/outer ysep%
       advancepgfutil@tempdima by-pgf@xb%
       advancepgfutil@tempdimb by-pgf@yb%
       pgfpathellipsecenterpointpgfqpointpgfutil@tempdima0ptpgfqpoint0ptpgfutil@tempdimb%
       %
      %
      makeatother

      begindocument
       begintikzpicture[nodes=draw, inner sep=0]
       node[regular polygon,regular polygon sides=4] (a) XX;
       node[Circle, blue] (b) XX;
       node[circle] (c) XX;
       foreach a in north,south,east,west,north east,south east,north west,south west
       fill[red] (a.a) circle(0.5pt);
       fill[yellow] (b.a) circle(0.25pt);
       fill[orange] (c.a) circle(0.25pt);
       
       endtikzpicture
      enddocument


      enter image description here



      Addendum:



      If you want to go the other way and create a circumscribed polygon around the standard circle node style, that do not use low level tricks, you can define circumscribed polygon that use append after command to add well sized regular polygon. This is not a robust code for meany reasons, it is just a proof of concept :



      documentclass[tikz,border=7pt,convert=density=4200]standalone
      usetikzlibrarycalc,shapes.geometric

      % don't tell me to not use tikzstyle ;)
      tikzstylecircumscribed polygon[draw]=[
       circle,draw=none,fill=none,shade=none,
       append after command=
       let p1=($(tikzlastnode.west)-(tikzlastnode.east)$),
       n1 = (veclen(p1)-pgflinewidth)/2.828427 % 2*sqrt(2) = 2.8284271247461903
       in
       (tikzlastnode.center) node[regular polygon, inner sep=n1, #1]
       
      ]
      begindocument
       begintikzpicture[inner sep=1mm]
       foreach~in 3,...,7
       node[circumscribed polygon=draw=blue!~0!green,regular polygon sides=~] XX;
       node[circle,draw=red] XX;
       endtikzpicture
      enddocument


      enter image description here






      share|improve this answer

























      • Very enlightening. I wonder if, then, rather than defining a completely new shape, it is not easier to find out a systematic way to give a proper, automatically determined inner separation to a normal circle. Analogously one could give an automatically determined negative inner sep to a regular polygon. I will think about it, but you helped already a lot!

        – Axel Krypton
        Mar 21 at 16:55











      • And I would also say that the pgf inherit...[from=ellipse] commands might be useful to shorten the code, but I have to still explore this world and I might be completely wrong.

        – Axel Krypton
        Mar 21 at 17:01












      • Thanks for the added information, very useful, indeed. I came up with a slightly different Circle and I shared this in a separate answer. :)

        – Axel Krypton
        Mar 22 at 9:02















      2














      The "inner circle" in shapes.geometric has a radius that is half of the longest side of the content box plus the inner sep, and multiplied by 1.4142136, which is approximately sqrt(2). So to obtain a circle shape that has this behavior you can define a new shape, let's say Circle (with capital C) that is a slight modification of the existing ellipse shape. 



      documentclass[tikz, border=7pt, convert=density=4200]standalone
      usetikzlibraryshapes.geometric
      makeatletter
      pgfdeclareshapeCircle
      %
      % Draws a circle around the text
      % (based on the original ellipse shape)
      %
      %
       savedanchorcenterpoint%
       pgf@x=.5wdpgfnodeparttextbox%
       pgf@y=.5htpgfnodeparttextbox%
       advancepgf@y by-.5dppgfnodeparttextbox%
       %
       savedanchorradius%
       %
       % Calculate ``height radius''
       %
       pgf@y=.5htpgfnodeparttextbox%
       advancepgf@y by.5dppgfnodeparttextbox%
       pgfmathsetlengthpgf@ybpgfkeysvalueof/pgf/inner ysep%
       advancepgf@y bypgf@yb%
       %
       % Calculate ``width radius''
       %
       pgf@x=.5wdpgfnodeparttextbox%
       pgfmathsetlengthpgf@xbpgfkeysvalueof/pgf/inner xsep%
       advancepgf@x bypgf@xb%
       %
       % Adjust
       %
       % ==============================
       % added to ellipse shape to become circle
       ifdimpgf@y>pgf@x%
       pgf@xpgf@y%
       else%
       pgf@ypgf@x%
       fi%
       % ==============================
       pgf@x=1.4142136pgf@x%
       pgf@y=1.4142136pgf@y%
       %
       % Adjust height, if necessary
       %
       pgfmathsetlengthpgf@ycpgfkeysvalueof/pgf/minimum height%
       ifdimpgf@y<.5pgf@yc%
       pgf@y=.5pgf@yc%
       fi%
       %
       % Adjust width, if necessary
       %
       pgfmathsetlengthpgf@xcpgfkeysvalueof/pgf/minimum width%
       ifdimpgf@x<.5pgf@xc%
       pgf@x=.5pgf@xc%
       fi%
       %
       % Add outer sep
       %
       pgfmathsetlengthpgf@xbpgfkeysvalueof/pgf/outer xsep%
       pgfmathsetlengthpgf@ybpgfkeysvalueof/pgf/outer ysep%
       advancepgf@x bypgf@xb%
       advancepgf@y bypgf@yb%
       %

       %
       % Anchors
       %
       anchorcentercenterpoint%
       anchormidcenterpointpgfmathsetlengthpgf@y.5ex%
       anchorbasecenterpointpgf@y=0pt%
       anchornorth
       
       pgf@processradius
       pgf@ya=pgf@y%
       pgf@processcenterpoint
       advancepgf@y bypgf@ya
       %
       anchorsouth
       
       pgf@processradius
       pgf@ya=pgf@y%
       pgf@processcenterpoint
       advancepgf@y by-pgf@ya
       %
       anchorwest
       
       pgf@processradius
       pgf@xa=pgf@x%
       pgf@processcenterpoint
       advancepgf@x by-pgf@xa
       %
       anchormid west
       %
       pgf@processradius
       pgf@xa=pgf@x%
       pgf@processcenterpoint
       advancepgf@x by-pgf@xa%
       pgfmathsetlengthpgf@y.5ex
       %
       anchorbase west
       %
       pgf@processradius
       pgf@xa=pgf@x%
       pgf@processcenterpoint
       advancepgf@x by-pgf@xa%
       pgf@y=0pt
       %
       anchornorth west
       
       pgf@processradius
       pgf@xa=pgf@x%
       pgf@ya=pgf@y%
       pgf@processcenterpoint
       advancepgf@x by-0.707107pgf@xa
       advancepgf@y by0.707107pgf@ya
       %
       anchorsouth west
       
       pgf@processradius
       pgf@xa=pgf@x%
       pgf@ya=pgf@y%
       pgf@processcenterpoint
       advancepgf@x by-0.707107pgf@xa
       advancepgf@y by-0.707107pgf@ya
       %
       anchoreast
       %
       pgf@processradius
       pgf@xa=pgf@x%
       pgf@processcenterpoint
       advancepgf@x bypgf@xa
       %
       anchormid east
       %
       pgf@processradius
       pgf@xa=pgf@x%
       pgf@processcenterpoint
       advancepgf@x bypgf@xa%
       pgfmathsetlengthpgf@y.5ex
       %
       anchorbase east
       %
       pgf@processradius
       pgf@xa=pgf@x%
       pgf@processcenterpoint
       advancepgf@x bypgf@xa%
       pgf@y=0pt
       %
       anchornorth east
       
       pgf@processradius
       pgf@xa=pgf@x%
       pgf@ya=pgf@y%
       pgf@processcenterpoint
       advancepgf@x by0.707107pgf@xa
       advancepgf@y by0.707107pgf@ya
       %
       anchorsouth east
       
       pgf@processradius
       pgf@xa=pgf@x%
       pgf@ya=pgf@y%
       pgf@processcenterpoint
       advancepgf@x by0.707107pgf@xa
       advancepgf@y by-0.707107pgf@ya
       %
       anchorborder
       edefpgf@marshal%
       noexpandpgfpointborderellipse
       noexpandpgfqpointthepgf@xthepgf@y
       noexpandradius%
       %
       pgf@marshal%
       pgf@xa=pgf@x%
       pgf@ya=pgf@y%
       centerpoint%
       advancepgf@x bypgf@xa%
       advancepgf@y bypgf@ya%
       %

       %
       % Background path
       %
       backgroundpath
       
       pgf@processradius%
       pgfutil@tempdima=pgf@x%
       pgfutil@tempdimb=pgf@y%
       pgfmathsetlengthpgf@xbpgfkeysvalueof/pgf/outer xsep%
       pgfmathsetlengthpgf@ybpgfkeysvalueof/pgf/outer ysep%
       advancepgfutil@tempdima by-pgf@xb%
       advancepgfutil@tempdimb by-pgf@yb%
       pgfpathellipsecenterpointpgfqpointpgfutil@tempdima0ptpgfqpoint0ptpgfutil@tempdimb%
       %
      %
      makeatother

      begindocument
       begintikzpicture[nodes=draw, inner sep=0]
       node[regular polygon,regular polygon sides=4] (a) XX;
       node[Circle, blue] (b) XX;
       node[circle] (c) XX;
       foreach a in north,south,east,west,north east,south east,north west,south west
       fill[red] (a.a) circle(0.5pt);
       fill[yellow] (b.a) circle(0.25pt);
       fill[orange] (c.a) circle(0.25pt);
       
       endtikzpicture
      enddocument


      enter image description here



      Addendum:



      If you want to go the other way and create a circumscribed polygon around the standard circle node style, that do not use low level tricks, you can define circumscribed polygon that use append after command to add well sized regular polygon. This is not a robust code for meany reasons, it is just a proof of concept :



      documentclass[tikz,border=7pt,convert=density=4200]standalone
      usetikzlibrarycalc,shapes.geometric

      % don't tell me to not use tikzstyle ;)
      tikzstylecircumscribed polygon[draw]=[
       circle,draw=none,fill=none,shade=none,
       append after command=
       let p1=($(tikzlastnode.west)-(tikzlastnode.east)$),
       n1 = (veclen(p1)-pgflinewidth)/2.828427 % 2*sqrt(2) = 2.8284271247461903
       in
       (tikzlastnode.center) node[regular polygon, inner sep=n1, #1]
       
      ]
      begindocument
       begintikzpicture[inner sep=1mm]
       foreach~in 3,...,7
       node[circumscribed polygon=draw=blue!~0!green,regular polygon sides=~] XX;
       node[circle,draw=red] XX;
       endtikzpicture
      enddocument


      enter image description here






      share|improve this answer

























      • Very enlightening. I wonder if, then, rather than defining a completely new shape, it is not easier to find out a systematic way to give a proper, automatically determined inner separation to a normal circle. Analogously one could give an automatically determined negative inner sep to a regular polygon. I will think about it, but you helped already a lot!

        – Axel Krypton
        Mar 21 at 16:55











      • And I would also say that the pgf inherit...[from=ellipse] commands might be useful to shorten the code, but I have to still explore this world and I might be completely wrong.

        – Axel Krypton
        Mar 21 at 17:01












      • Thanks for the added information, very useful, indeed. I came up with a slightly different Circle and I shared this in a separate answer. :)

        – Axel Krypton
        Mar 22 at 9:02













      2












      2








      2







      The "inner circle" in shapes.geometric has a radius that is half of the longest side of the content box plus the inner sep, and multiplied by 1.4142136, which is approximately sqrt(2). So to obtain a circle shape that has this behavior you can define a new shape, let's say Circle (with capital C) that is a slight modification of the existing ellipse shape. 



      documentclass[tikz, border=7pt, convert=density=4200]standalone
      usetikzlibraryshapes.geometric
      makeatletter
      pgfdeclareshapeCircle
      %
      % Draws a circle around the text
      % (based on the original ellipse shape)
      %
      %
       savedanchorcenterpoint%
       pgf@x=.5wdpgfnodeparttextbox%
       pgf@y=.5htpgfnodeparttextbox%
       advancepgf@y by-.5dppgfnodeparttextbox%
       %
       savedanchorradius%
       %
       % Calculate ``height radius''
       %
       pgf@y=.5htpgfnodeparttextbox%
       advancepgf@y by.5dppgfnodeparttextbox%
       pgfmathsetlengthpgf@ybpgfkeysvalueof/pgf/inner ysep%
       advancepgf@y bypgf@yb%
       %
       % Calculate ``width radius''
       %
       pgf@x=.5wdpgfnodeparttextbox%
       pgfmathsetlengthpgf@xbpgfkeysvalueof/pgf/inner xsep%
       advancepgf@x bypgf@xb%
       %
       % Adjust
       %
       % ==============================
       % added to ellipse shape to become circle
       ifdimpgf@y>pgf@x%
       pgf@xpgf@y%
       else%
       pgf@ypgf@x%
       fi%
       % ==============================
       pgf@x=1.4142136pgf@x%
       pgf@y=1.4142136pgf@y%
       %
       % Adjust height, if necessary
       %
       pgfmathsetlengthpgf@ycpgfkeysvalueof/pgf/minimum height%
       ifdimpgf@y<.5pgf@yc%
       pgf@y=.5pgf@yc%
       fi%
       %
       % Adjust width, if necessary
       %
       pgfmathsetlengthpgf@xcpgfkeysvalueof/pgf/minimum width%
       ifdimpgf@x<.5pgf@xc%
       pgf@x=.5pgf@xc%
       fi%
       %
       % Add outer sep
       %
       pgfmathsetlengthpgf@xbpgfkeysvalueof/pgf/outer xsep%
       pgfmathsetlengthpgf@ybpgfkeysvalueof/pgf/outer ysep%
       advancepgf@x bypgf@xb%
       advancepgf@y bypgf@yb%
       %

       %
       % Anchors
       %
       anchorcentercenterpoint%
       anchormidcenterpointpgfmathsetlengthpgf@y.5ex%
       anchorbasecenterpointpgf@y=0pt%
       anchornorth
       
       pgf@processradius
       pgf@ya=pgf@y%
       pgf@processcenterpoint
       advancepgf@y bypgf@ya
       %
       anchorsouth
       
       pgf@processradius
       pgf@ya=pgf@y%
       pgf@processcenterpoint
       advancepgf@y by-pgf@ya
       %
       anchorwest
       
       pgf@processradius
       pgf@xa=pgf@x%
       pgf@processcenterpoint
       advancepgf@x by-pgf@xa
       %
       anchormid west
       %
       pgf@processradius
       pgf@xa=pgf@x%
       pgf@processcenterpoint
       advancepgf@x by-pgf@xa%
       pgfmathsetlengthpgf@y.5ex
       %
       anchorbase west
       %
       pgf@processradius
       pgf@xa=pgf@x%
       pgf@processcenterpoint
       advancepgf@x by-pgf@xa%
       pgf@y=0pt
       %
       anchornorth west
       
       pgf@processradius
       pgf@xa=pgf@x%
       pgf@ya=pgf@y%
       pgf@processcenterpoint
       advancepgf@x by-0.707107pgf@xa
       advancepgf@y by0.707107pgf@ya
       %
       anchorsouth west
       
       pgf@processradius
       pgf@xa=pgf@x%
       pgf@ya=pgf@y%
       pgf@processcenterpoint
       advancepgf@x by-0.707107pgf@xa
       advancepgf@y by-0.707107pgf@ya
       %
       anchoreast
       %
       pgf@processradius
       pgf@xa=pgf@x%
       pgf@processcenterpoint
       advancepgf@x bypgf@xa
       %
       anchormid east
       %
       pgf@processradius
       pgf@xa=pgf@x%
       pgf@processcenterpoint
       advancepgf@x bypgf@xa%
       pgfmathsetlengthpgf@y.5ex
       %
       anchorbase east
       %
       pgf@processradius
       pgf@xa=pgf@x%
       pgf@processcenterpoint
       advancepgf@x bypgf@xa%
       pgf@y=0pt
       %
       anchornorth east
       
       pgf@processradius
       pgf@xa=pgf@x%
       pgf@ya=pgf@y%
       pgf@processcenterpoint
       advancepgf@x by0.707107pgf@xa
       advancepgf@y by0.707107pgf@ya
       %
       anchorsouth east
       
       pgf@processradius
       pgf@xa=pgf@x%
       pgf@ya=pgf@y%
       pgf@processcenterpoint
       advancepgf@x by0.707107pgf@xa
       advancepgf@y by-0.707107pgf@ya
       %
       anchorborder
       edefpgf@marshal%
       noexpandpgfpointborderellipse
       noexpandpgfqpointthepgf@xthepgf@y
       noexpandradius%
       %
       pgf@marshal%
       pgf@xa=pgf@x%
       pgf@ya=pgf@y%
       centerpoint%
       advancepgf@x bypgf@xa%
       advancepgf@y bypgf@ya%
       %

       %
       % Background path
       %
       backgroundpath
       
       pgf@processradius%
       pgfutil@tempdima=pgf@x%
       pgfutil@tempdimb=pgf@y%
       pgfmathsetlengthpgf@xbpgfkeysvalueof/pgf/outer xsep%
       pgfmathsetlengthpgf@ybpgfkeysvalueof/pgf/outer ysep%
       advancepgfutil@tempdima by-pgf@xb%
       advancepgfutil@tempdimb by-pgf@yb%
       pgfpathellipsecenterpointpgfqpointpgfutil@tempdima0ptpgfqpoint0ptpgfutil@tempdimb%
       %
      %
      makeatother

      begindocument
       begintikzpicture[nodes=draw, inner sep=0]
       node[regular polygon,regular polygon sides=4] (a) XX;
       node[Circle, blue] (b) XX;
       node[circle] (c) XX;
       foreach a in north,south,east,west,north east,south east,north west,south west
       fill[red] (a.a) circle(0.5pt);
       fill[yellow] (b.a) circle(0.25pt);
       fill[orange] (c.a) circle(0.25pt);
       
       endtikzpicture
      enddocument


      enter image description here



      Addendum:



      If you want to go the other way and create a circumscribed polygon around the standard circle node style, that do not use low level tricks, you can define circumscribed polygon that use append after command to add well sized regular polygon. This is not a robust code for meany reasons, it is just a proof of concept :



      documentclass[tikz,border=7pt,convert=density=4200]standalone
      usetikzlibrarycalc,shapes.geometric

      % don't tell me to not use tikzstyle ;)
      tikzstylecircumscribed polygon[draw]=[
       circle,draw=none,fill=none,shade=none,
       append after command=
       let p1=($(tikzlastnode.west)-(tikzlastnode.east)$),
       n1 = (veclen(p1)-pgflinewidth)/2.828427 % 2*sqrt(2) = 2.8284271247461903
       in
       (tikzlastnode.center) node[regular polygon, inner sep=n1, #1]
       
      ]
      begindocument
       begintikzpicture[inner sep=1mm]
       foreach~in 3,...,7
       node[circumscribed polygon=draw=blue!~0!green,regular polygon sides=~] XX;
       node[circle,draw=red] XX;
       endtikzpicture
      enddocument


      enter image description here






      share|improve this answer















      The "inner circle" in shapes.geometric has a radius that is half of the longest side of the content box plus the inner sep, and multiplied by 1.4142136, which is approximately sqrt(2). So to obtain a circle shape that has this behavior you can define a new shape, let's say Circle (with capital C) that is a slight modification of the existing ellipse shape. 



      documentclass[tikz, border=7pt, convert=density=4200]standalone
      usetikzlibraryshapes.geometric
      makeatletter
      pgfdeclareshapeCircle
      %
      % Draws a circle around the text
      % (based on the original ellipse shape)
      %
      %
       savedanchorcenterpoint%
       pgf@x=.5wdpgfnodeparttextbox%
       pgf@y=.5htpgfnodeparttextbox%
       advancepgf@y by-.5dppgfnodeparttextbox%
       %
       savedanchorradius%
       %
       % Calculate ``height radius''
       %
       pgf@y=.5htpgfnodeparttextbox%
       advancepgf@y by.5dppgfnodeparttextbox%
       pgfmathsetlengthpgf@ybpgfkeysvalueof/pgf/inner ysep%
       advancepgf@y bypgf@yb%
       %
       % Calculate ``width radius''
       %
       pgf@x=.5wdpgfnodeparttextbox%
       pgfmathsetlengthpgf@xbpgfkeysvalueof/pgf/inner xsep%
       advancepgf@x bypgf@xb%
       %
       % Adjust
       %
       % ==============================
       % added to ellipse shape to become circle
       ifdimpgf@y>pgf@x%
       pgf@xpgf@y%
       else%
       pgf@ypgf@x%
       fi%
       % ==============================
       pgf@x=1.4142136pgf@x%
       pgf@y=1.4142136pgf@y%
       %
       % Adjust height, if necessary
       %
       pgfmathsetlengthpgf@ycpgfkeysvalueof/pgf/minimum height%
       ifdimpgf@y<.5pgf@yc%
       pgf@y=.5pgf@yc%
       fi%
       %
       % Adjust width, if necessary
       %
       pgfmathsetlengthpgf@xcpgfkeysvalueof/pgf/minimum width%
       ifdimpgf@x<.5pgf@xc%
       pgf@x=.5pgf@xc%
       fi%
       %
       % Add outer sep
       %
       pgfmathsetlengthpgf@xbpgfkeysvalueof/pgf/outer xsep%
       pgfmathsetlengthpgf@ybpgfkeysvalueof/pgf/outer ysep%
       advancepgf@x bypgf@xb%
       advancepgf@y bypgf@yb%
       %

       %
       % Anchors
       %
       anchorcentercenterpoint%
       anchormidcenterpointpgfmathsetlengthpgf@y.5ex%
       anchorbasecenterpointpgf@y=0pt%
       anchornorth
       
       pgf@processradius
       pgf@ya=pgf@y%
       pgf@processcenterpoint
       advancepgf@y bypgf@ya
       %
       anchorsouth
       
       pgf@processradius
       pgf@ya=pgf@y%
       pgf@processcenterpoint
       advancepgf@y by-pgf@ya
       %
       anchorwest
       
       pgf@processradius
       pgf@xa=pgf@x%
       pgf@processcenterpoint
       advancepgf@x by-pgf@xa
       %
       anchormid west
       %
       pgf@processradius
       pgf@xa=pgf@x%
       pgf@processcenterpoint
       advancepgf@x by-pgf@xa%
       pgfmathsetlengthpgf@y.5ex
       %
       anchorbase west
       %
       pgf@processradius
       pgf@xa=pgf@x%
       pgf@processcenterpoint
       advancepgf@x by-pgf@xa%
       pgf@y=0pt
       %
       anchornorth west
       
       pgf@processradius
       pgf@xa=pgf@x%
       pgf@ya=pgf@y%
       pgf@processcenterpoint
       advancepgf@x by-0.707107pgf@xa
       advancepgf@y by0.707107pgf@ya
       %
       anchorsouth west
       
       pgf@processradius
       pgf@xa=pgf@x%
       pgf@ya=pgf@y%
       pgf@processcenterpoint
       advancepgf@x by-0.707107pgf@xa
       advancepgf@y by-0.707107pgf@ya
       %
       anchoreast
       %
       pgf@processradius
       pgf@xa=pgf@x%
       pgf@processcenterpoint
       advancepgf@x bypgf@xa
       %
       anchormid east
       %
       pgf@processradius
       pgf@xa=pgf@x%
       pgf@processcenterpoint
       advancepgf@x bypgf@xa%
       pgfmathsetlengthpgf@y.5ex
       %
       anchorbase east
       %
       pgf@processradius
       pgf@xa=pgf@x%
       pgf@processcenterpoint
       advancepgf@x bypgf@xa%
       pgf@y=0pt
       %
       anchornorth east
       
       pgf@processradius
       pgf@xa=pgf@x%
       pgf@ya=pgf@y%
       pgf@processcenterpoint
       advancepgf@x by0.707107pgf@xa
       advancepgf@y by0.707107pgf@ya
       %
       anchorsouth east
       
       pgf@processradius
       pgf@xa=pgf@x%
       pgf@ya=pgf@y%
       pgf@processcenterpoint
       advancepgf@x by0.707107pgf@xa
       advancepgf@y by-0.707107pgf@ya
       %
       anchorborder
       edefpgf@marshal%
       noexpandpgfpointborderellipse
       noexpandpgfqpointthepgf@xthepgf@y
       noexpandradius%
       %
       pgf@marshal%
       pgf@xa=pgf@x%
       pgf@ya=pgf@y%
       centerpoint%
       advancepgf@x bypgf@xa%
       advancepgf@y bypgf@ya%
       %

       %
       % Background path
       %
       backgroundpath
       
       pgf@processradius%
       pgfutil@tempdima=pgf@x%
       pgfutil@tempdimb=pgf@y%
       pgfmathsetlengthpgf@xbpgfkeysvalueof/pgf/outer xsep%
       pgfmathsetlengthpgf@ybpgfkeysvalueof/pgf/outer ysep%
       advancepgfutil@tempdima by-pgf@xb%
       advancepgfutil@tempdimb by-pgf@yb%
       pgfpathellipsecenterpointpgfqpointpgfutil@tempdima0ptpgfqpoint0ptpgfutil@tempdimb%
       %
      %
      makeatother

      begindocument
       begintikzpicture[nodes=draw, inner sep=0]
       node[regular polygon,regular polygon sides=4] (a) XX;
       node[Circle, blue] (b) XX;
       node[circle] (c) XX;
       foreach a in north,south,east,west,north east,south east,north west,south west
       fill[red] (a.a) circle(0.5pt);
       fill[yellow] (b.a) circle(0.25pt);
       fill[orange] (c.a) circle(0.25pt);
       
       endtikzpicture
      enddocument


      enter image description here



      Addendum:



      If you want to go the other way and create a circumscribed polygon around the standard circle node style, that do not use low level tricks, you can define circumscribed polygon that use append after command to add well sized regular polygon. This is not a robust code for meany reasons, it is just a proof of concept :



      documentclass[tikz,border=7pt,convert=density=4200]standalone
      usetikzlibrarycalc,shapes.geometric

      % don't tell me to not use tikzstyle ;)
      tikzstylecircumscribed polygon[draw]=[
       circle,draw=none,fill=none,shade=none,
       append after command=
       let p1=($(tikzlastnode.west)-(tikzlastnode.east)$),
       n1 = (veclen(p1)-pgflinewidth)/2.828427 % 2*sqrt(2) = 2.8284271247461903
       in
       (tikzlastnode.center) node[regular polygon, inner sep=n1, #1]
       
      ]
      begindocument
       begintikzpicture[inner sep=1mm]
       foreach~in 3,...,7
       node[circumscribed polygon=draw=blue!~0!green,regular polygon sides=~] XX;
       node[circle,draw=red] XX;
       endtikzpicture
      enddocument


      enter image description here







      share|improve this answer














      share|improve this answer



      share|improve this answer








      edited Mar 22 at 8:20

























      answered Mar 21 at 14:05









      KpymKpym

      17.7k24191




      17.7k24191












      • Very enlightening. I wonder if, then, rather than defining a completely new shape, it is not easier to find out a systematic way to give a proper, automatically determined inner separation to a normal circle. Analogously one could give an automatically determined negative inner sep to a regular polygon. I will think about it, but you helped already a lot!

        – Axel Krypton
        Mar 21 at 16:55











      • And I would also say that the pgf inherit...[from=ellipse] commands might be useful to shorten the code, but I have to still explore this world and I might be completely wrong.

        – Axel Krypton
        Mar 21 at 17:01












      • Thanks for the added information, very useful, indeed. I came up with a slightly different Circle and I shared this in a separate answer. :)

        – Axel Krypton
        Mar 22 at 9:02

















      • Very enlightening. I wonder if, then, rather than defining a completely new shape, it is not easier to find out a systematic way to give a proper, automatically determined inner separation to a normal circle. Analogously one could give an automatically determined negative inner sep to a regular polygon. I will think about it, but you helped already a lot!

        – Axel Krypton
        Mar 21 at 16:55











      • And I would also say that the pgf inherit...[from=ellipse] commands might be useful to shorten the code, but I have to still explore this world and I might be completely wrong.

        – Axel Krypton
        Mar 21 at 17:01












      • Thanks for the added information, very useful, indeed. I came up with a slightly different Circle and I shared this in a separate answer. :)

        – Axel Krypton
        Mar 22 at 9:02
















      Very enlightening. I wonder if, then, rather than defining a completely new shape, it is not easier to find out a systematic way to give a proper, automatically determined inner separation to a normal circle. Analogously one could give an automatically determined negative inner sep to a regular polygon. I will think about it, but you helped already a lot!

      – Axel Krypton
      Mar 21 at 16:55





      Very enlightening. I wonder if, then, rather than defining a completely new shape, it is not easier to find out a systematic way to give a proper, automatically determined inner separation to a normal circle. Analogously one could give an automatically determined negative inner sep to a regular polygon. I will think about it, but you helped already a lot!

      – Axel Krypton
      Mar 21 at 16:55













      And I would also say that the pgf inherit...[from=ellipse] commands might be useful to shorten the code, but I have to still explore this world and I might be completely wrong.

      – Axel Krypton
      Mar 21 at 17:01






      And I would also say that the pgf inherit...[from=ellipse] commands might be useful to shorten the code, but I have to still explore this world and I might be completely wrong.

      – Axel Krypton
      Mar 21 at 17:01














      Thanks for the added information, very useful, indeed. I came up with a slightly different Circle and I shared this in a separate answer. :)

      – Axel Krypton
      Mar 22 at 9:02





      Thanks for the added information, very useful, indeed. I came up with a slightly different Circle and I shared this in a separate answer. :)

      – Axel Krypton
      Mar 22 at 9:02











      2














      Using through library of Tikz.



      documentclass[tikz, border=1mm]standalone
      usetikzlibraryshapes.geometric,through

      begindocument
       begintikzpicture[every node/.style=draw, inner sep=0]
       node[regular polygon,regular polygon sides=4] (a) XX;
       node (b) [draw,blue, circle through=(a.north)] at (a.center) XX;
       node[circle] (c) XX;
       foreach a in north,south,east,west,north east,south east,north west,south west
       fill[red] (a.a) circle(0.5pt);
       fill[yellow] (b.a) circle(0.25pt);
       fill[orange] (c.a) circle(0.25pt);
       

       endtikzpicture
      enddocument


      enter image description here






      share|improve this answer























      • Although strictly speaking you proposed a valid way to draw the blue circle, I was more interested in a general way to draw that shape for a node, without having to rely to another node/point (see edit question). The only way I see I could use your idea is to always have two nodes, one invisible and one that would be the node I wish. However, this is not what I am looking for.

        – Axel Krypton
        Mar 21 at 12:25















      2














      Using through library of Tikz.



      documentclass[tikz, border=1mm]standalone
      usetikzlibraryshapes.geometric,through

      begindocument
       begintikzpicture[every node/.style=draw, inner sep=0]
       node[regular polygon,regular polygon sides=4] (a) XX;
       node (b) [draw,blue, circle through=(a.north)] at (a.center) XX;
       node[circle] (c) XX;
       foreach a in north,south,east,west,north east,south east,north west,south west
       fill[red] (a.a) circle(0.5pt);
       fill[yellow] (b.a) circle(0.25pt);
       fill[orange] (c.a) circle(0.25pt);
       

       endtikzpicture
      enddocument


      enter image description here






      share|improve this answer























      • Although strictly speaking you proposed a valid way to draw the blue circle, I was more interested in a general way to draw that shape for a node, without having to rely to another node/point (see edit question). The only way I see I could use your idea is to always have two nodes, one invisible and one that would be the node I wish. However, this is not what I am looking for.

        – Axel Krypton
        Mar 21 at 12:25













      2












      2








      2







      Using through library of Tikz.



      documentclass[tikz, border=1mm]standalone
      usetikzlibraryshapes.geometric,through

      begindocument
       begintikzpicture[every node/.style=draw, inner sep=0]
       node[regular polygon,regular polygon sides=4] (a) XX;
       node (b) [draw,blue, circle through=(a.north)] at (a.center) XX;
       node[circle] (c) XX;
       foreach a in north,south,east,west,north east,south east,north west,south west
       fill[red] (a.a) circle(0.5pt);
       fill[yellow] (b.a) circle(0.25pt);
       fill[orange] (c.a) circle(0.25pt);
       

       endtikzpicture
      enddocument


      enter image description here






      share|improve this answer













      Using through library of Tikz.



      documentclass[tikz, border=1mm]standalone
      usetikzlibraryshapes.geometric,through

      begindocument
       begintikzpicture[every node/.style=draw, inner sep=0]
       node[regular polygon,regular polygon sides=4] (a) XX;
       node (b) [draw,blue, circle through=(a.north)] at (a.center) XX;
       node[circle] (c) XX;
       foreach a in north,south,east,west,north east,south east,north west,south west
       fill[red] (a.a) circle(0.5pt);
       fill[yellow] (b.a) circle(0.25pt);
       fill[orange] (c.a) circle(0.25pt);
       

       endtikzpicture
      enddocument


      enter image description here







      share|improve this answer












      share|improve this answer



      share|improve this answer










      answered Mar 21 at 11:40









      ferahfezaferahfeza

      7,35911933




      7,35911933












      • Although strictly speaking you proposed a valid way to draw the blue circle, I was more interested in a general way to draw that shape for a node, without having to rely to another node/point (see edit question). The only way I see I could use your idea is to always have two nodes, one invisible and one that would be the node I wish. However, this is not what I am looking for.

        – Axel Krypton
        Mar 21 at 12:25

















      • Although strictly speaking you proposed a valid way to draw the blue circle, I was more interested in a general way to draw that shape for a node, without having to rely to another node/point (see edit question). The only way I see I could use your idea is to always have two nodes, one invisible and one that would be the node I wish. However, this is not what I am looking for.

        – Axel Krypton
        Mar 21 at 12:25
















      Although strictly speaking you proposed a valid way to draw the blue circle, I was more interested in a general way to draw that shape for a node, without having to rely to another node/point (see edit question). The only way I see I could use your idea is to always have two nodes, one invisible and one that would be the node I wish. However, this is not what I am looking for.

      – Axel Krypton
      Mar 21 at 12:25





      Although strictly speaking you proposed a valid way to draw the blue circle, I was more interested in a general way to draw that shape for a node, without having to rely to another node/point (see edit question). The only way I see I could use your idea is to always have two nodes, one invisible and one that would be the node I wish. However, this is not what I am looking for.

      – Axel Krypton
      Mar 21 at 12:25











      1














      Just to share a different way to achieve what Kpym did in his very nice answer declaring a new shape, I thought one could have simply a Circle style which sets properly the minimum size of a circle shape (in this particular case it is always true that the content will never exceed the minimum size since we are trying to enlarge the circle). It should work for any node content, no matter if its width is larger than its height or vice-versa. A couple of remarks:



      • In this approach the node name and the node position must be declared before the options or inside them using the name and at keys, respectively.

      • A Circle inner sep has to be specified before the Circle style, but it might easily be improved, if needed otherwise.

      Here the code:



      documentclass[tikz, border=1mm]standalone
      usetikzlibraryshapes.geometric

      tikzset%
       Square/.style=regular polygon, regular polygon sides=4,
       Circle/.style=%
       circle,
       /utils/exec=%
       pgfmathsetmacropolygonIncircleDiameter
       sqrt(2)*max(width("#1")+2*pgfshapeinnerxsep, height("#1") + depth("#1") + 2 * pgfshapeinnerysep)
       
       ,
       minimum size=polygonIncircleDiameter,
       node contents=#1
       


      begindocument
       begintikzpicture
       node[inner sep=0, Square, draw=cyan] at (0,0) xx;
       node[inner sep=0, Circle=xx, draw=blue];
       node[Square, draw=cyan] at (1,0) i;
       node[Circle=i, draw=blue, at=(1,0)];
       endtikzpicture
      enddocument


                               
      enter image description here






      share|improve this answer

























      • Very nice ! Two remarks : it would be nice to not pass the node content as parameter to Circle but I think that this will be tricky, and probably polygonIncircleDiameter is better than to divide and then multiply by 2 the polygonIncircleRadius.

        – Kpym
        Mar 22 at 9:31











      • I implemented your suggestion, it definitely makes sense! :) About not passing the node content to the style, well, honestly I would not know how to then achieve the same result. Yes, it definitely looks tricky to me.

        – Axel Krypton
        Mar 22 at 9:41















      1














      Just to share a different way to achieve what Kpym did in his very nice answer declaring a new shape, I thought one could have simply a Circle style which sets properly the minimum size of a circle shape (in this particular case it is always true that the content will never exceed the minimum size since we are trying to enlarge the circle). It should work for any node content, no matter if its width is larger than its height or vice-versa. A couple of remarks:



      • In this approach the node name and the node position must be declared before the options or inside them using the name and at keys, respectively.

      • A Circle inner sep has to be specified before the Circle style, but it might easily be improved, if needed otherwise.

      Here the code:



      documentclass[tikz, border=1mm]standalone
      usetikzlibraryshapes.geometric

      tikzset%
       Square/.style=regular polygon, regular polygon sides=4,
       Circle/.style=%
       circle,
       /utils/exec=%
       pgfmathsetmacropolygonIncircleDiameter
       sqrt(2)*max(width("#1")+2*pgfshapeinnerxsep, height("#1") + depth("#1") + 2 * pgfshapeinnerysep)
       
       ,
       minimum size=polygonIncircleDiameter,
       node contents=#1
       


      begindocument
       begintikzpicture
       node[inner sep=0, Square, draw=cyan] at (0,0) xx;
       node[inner sep=0, Circle=xx, draw=blue];
       node[Square, draw=cyan] at (1,0) i;
       node[Circle=i, draw=blue, at=(1,0)];
       endtikzpicture
      enddocument


                               
      enter image description here






      share|improve this answer

























      • Very nice ! Two remarks : it would be nice to not pass the node content as parameter to Circle but I think that this will be tricky, and probably polygonIncircleDiameter is better than to divide and then multiply by 2 the polygonIncircleRadius.

        – Kpym
        Mar 22 at 9:31











      • I implemented your suggestion, it definitely makes sense! :) About not passing the node content to the style, well, honestly I would not know how to then achieve the same result. Yes, it definitely looks tricky to me.

        – Axel Krypton
        Mar 22 at 9:41













      1












      1








      1







      Just to share a different way to achieve what Kpym did in his very nice answer declaring a new shape, I thought one could have simply a Circle style which sets properly the minimum size of a circle shape (in this particular case it is always true that the content will never exceed the minimum size since we are trying to enlarge the circle). It should work for any node content, no matter if its width is larger than its height or vice-versa. A couple of remarks:



      • In this approach the node name and the node position must be declared before the options or inside them using the name and at keys, respectively.

      • A Circle inner sep has to be specified before the Circle style, but it might easily be improved, if needed otherwise.

      Here the code:



      documentclass[tikz, border=1mm]standalone
      usetikzlibraryshapes.geometric

      tikzset%
       Square/.style=regular polygon, regular polygon sides=4,
       Circle/.style=%
       circle,
       /utils/exec=%
       pgfmathsetmacropolygonIncircleDiameter
       sqrt(2)*max(width("#1")+2*pgfshapeinnerxsep, height("#1") + depth("#1") + 2 * pgfshapeinnerysep)
       
       ,
       minimum size=polygonIncircleDiameter,
       node contents=#1
       


      begindocument
       begintikzpicture
       node[inner sep=0, Square, draw=cyan] at (0,0) xx;
       node[inner sep=0, Circle=xx, draw=blue];
       node[Square, draw=cyan] at (1,0) i;
       node[Circle=i, draw=blue, at=(1,0)];
       endtikzpicture
      enddocument


                               
      enter image description here






      share|improve this answer















      Just to share a different way to achieve what Kpym did in his very nice answer declaring a new shape, I thought one could have simply a Circle style which sets properly the minimum size of a circle shape (in this particular case it is always true that the content will never exceed the minimum size since we are trying to enlarge the circle). It should work for any node content, no matter if its width is larger than its height or vice-versa. A couple of remarks:



      • In this approach the node name and the node position must be declared before the options or inside them using the name and at keys, respectively.

      • A Circle inner sep has to be specified before the Circle style, but it might easily be improved, if needed otherwise.

      Here the code:



      documentclass[tikz, border=1mm]standalone
      usetikzlibraryshapes.geometric

      tikzset%
       Square/.style=regular polygon, regular polygon sides=4,
       Circle/.style=%
       circle,
       /utils/exec=%
       pgfmathsetmacropolygonIncircleDiameter
       sqrt(2)*max(width("#1")+2*pgfshapeinnerxsep, height("#1") + depth("#1") + 2 * pgfshapeinnerysep)
       
       ,
       minimum size=polygonIncircleDiameter,
       node contents=#1
       


      begindocument
       begintikzpicture
       node[inner sep=0, Square, draw=cyan] at (0,0) xx;
       node[inner sep=0, Circle=xx, draw=blue];
       node[Square, draw=cyan] at (1,0) i;
       node[Circle=i, draw=blue, at=(1,0)];
       endtikzpicture
      enddocument


                               
      enter image description here







      share|improve this answer














      share|improve this answer



      share|improve this answer








      edited Mar 22 at 9:39

























      answered Mar 22 at 9:01









      Axel KryptonAxel Krypton

      477211




      477211












      • Very nice ! Two remarks : it would be nice to not pass the node content as parameter to Circle but I think that this will be tricky, and probably polygonIncircleDiameter is better than to divide and then multiply by 2 the polygonIncircleRadius.

        – Kpym
        Mar 22 at 9:31











      • I implemented your suggestion, it definitely makes sense! :) About not passing the node content to the style, well, honestly I would not know how to then achieve the same result. Yes, it definitely looks tricky to me.

        – Axel Krypton
        Mar 22 at 9:41

















      • Very nice ! Two remarks : it would be nice to not pass the node content as parameter to Circle but I think that this will be tricky, and probably polygonIncircleDiameter is better than to divide and then multiply by 2 the polygonIncircleRadius.

        – Kpym
        Mar 22 at 9:31











      • I implemented your suggestion, it definitely makes sense! :) About not passing the node content to the style, well, honestly I would not know how to then achieve the same result. Yes, it definitely looks tricky to me.

        – Axel Krypton
        Mar 22 at 9:41
















      Very nice ! Two remarks : it would be nice to not pass the node content as parameter to Circle but I think that this will be tricky, and probably polygonIncircleDiameter is better than to divide and then multiply by 2 the polygonIncircleRadius.

      – Kpym
      Mar 22 at 9:31





      Very nice ! Two remarks : it would be nice to not pass the node content as parameter to Circle but I think that this will be tricky, and probably polygonIncircleDiameter is better than to divide and then multiply by 2 the polygonIncircleRadius.

      – Kpym
      Mar 22 at 9:31













      I implemented your suggestion, it definitely makes sense! :) About not passing the node content to the style, well, honestly I would not know how to then achieve the same result. Yes, it definitely looks tricky to me.

      – Axel Krypton
      Mar 22 at 9:41





      I implemented your suggestion, it definitely makes sense! :) About not passing the node content to the style, well, honestly I would not know how to then achieve the same result. Yes, it definitely looks tricky to me.

      – Axel Krypton
      Mar 22 at 9:41











      0














      This wraps a polyogon around the circle.



      documentclass[tikz,border=3.14mm]standalone
      usetikzlibrarycalc

      begindocument
       begintikzpicture[every node/.style=draw, inner sep=0,
       polygon with circle/.style args=#1 inscribed and #2 cornersinsert path=%
       let p1=($(#1.0)-(#1.center)$),n1=abs(x1)/cos(180/#2)
       in ($(#1.center)+(0:n1)$)
       foreach X in 1,...,numexpr#2-1 
       -- ($(#1.center)+(360*X/#2:n1)$) -- cycle]
       node[circle] (c) XX;
       draw[blue,polygon with circle=c inscribed and 12 corners] ;
       foreach a in north,south,east,west,north east,south east,north west,south west
       fill[orange] (c.a) circle(0.25pt);
       
       endtikzpicture
      enddocument


      enter image description here






      share|improve this answer



























        0














        This wraps a polyogon around the circle.



        documentclass[tikz,border=3.14mm]standalone
        usetikzlibrarycalc

        begindocument
         begintikzpicture[every node/.style=draw, inner sep=0,
         polygon with circle/.style args=#1 inscribed and #2 cornersinsert path=%
         let p1=($(#1.0)-(#1.center)$),n1=abs(x1)/cos(180/#2)
         in ($(#1.center)+(0:n1)$)
         foreach X in 1,...,numexpr#2-1 
         -- ($(#1.center)+(360*X/#2:n1)$) -- cycle]
         node[circle] (c) XX;
         draw[blue,polygon with circle=c inscribed and 12 corners] ;
         foreach a in north,south,east,west,north east,south east,north west,south west
         fill[orange] (c.a) circle(0.25pt);
         
         endtikzpicture
        enddocument


        enter image description here






        share|improve this answer

























          0












          0








          0







          This wraps a polyogon around the circle.



          documentclass[tikz,border=3.14mm]standalone
          usetikzlibrarycalc

          begindocument
           begintikzpicture[every node/.style=draw, inner sep=0,
           polygon with circle/.style args=#1 inscribed and #2 cornersinsert path=%
           let p1=($(#1.0)-(#1.center)$),n1=abs(x1)/cos(180/#2)
           in ($(#1.center)+(0:n1)$)
           foreach X in 1,...,numexpr#2-1 
           -- ($(#1.center)+(360*X/#2:n1)$) -- cycle]
           node[circle] (c) XX;
           draw[blue,polygon with circle=c inscribed and 12 corners] ;
           foreach a in north,south,east,west,north east,south east,north west,south west
           fill[orange] (c.a) circle(0.25pt);
           
           endtikzpicture
          enddocument


          enter image description here






          share|improve this answer













          This wraps a polyogon around the circle.



          documentclass[tikz,border=3.14mm]standalone
          usetikzlibrarycalc

          begindocument
           begintikzpicture[every node/.style=draw, inner sep=0,
           polygon with circle/.style args=#1 inscribed and #2 cornersinsert path=%
           let p1=($(#1.0)-(#1.center)$),n1=abs(x1)/cos(180/#2)
           in ($(#1.center)+(0:n1)$)
           foreach X in 1,...,numexpr#2-1 
           -- ($(#1.center)+(360*X/#2:n1)$) -- cycle]
           node[circle] (c) XX;
           draw[blue,polygon with circle=c inscribed and 12 corners] ;
           foreach a in north,south,east,west,north east,south east,north west,south west
           fill[orange] (c.a) circle(0.25pt);
           
           endtikzpicture
          enddocument


          enter image description here







          share|improve this answer












          share|improve this answer



          share|improve this answer










          answered Mar 22 at 7:05









          marmotmarmot

          114k5145276




          114k5145276





















              0














              This solution uses calc library to compute regular polygon's inner radius. This way it's possible to compute circunscribed circle's minimum width. 



              documentclass[tikz, border=1mm]standalone
              usetikzlibraryshapes.geometric, calc

              begindocument
               begintikzpicture
               node[inner sep=0, regular polygon, regular polygon sides=4, draw=cyan] (a) xx;
               path let p1=($(a.center)-(a.side 1)$) in node[circle, inner sep=0, minimum width=2*veclen(x1,y1)-pgflinewidth, draw=blue] ;
               node[inner sep=0, draw=cyan, regular polygon, regular polygon sides=7] (b) at (1,0) i;
               path let p1=($(b.center)-(b.side 1)$) in node[circle, inner sep=0, minimum width=2*veclen(x1,y1)-pgflinewidth, draw=blue] at (b) ;
               endtikzpicture
              enddocument


              enter image description here






              share|improve this answer



























                0














                This solution uses calc library to compute regular polygon's inner radius. This way it's possible to compute circunscribed circle's minimum width. 



                documentclass[tikz, border=1mm]standalone
                usetikzlibraryshapes.geometric, calc

                begindocument
                 begintikzpicture
                 node[inner sep=0, regular polygon, regular polygon sides=4, draw=cyan] (a) xx;
                 path let p1=($(a.center)-(a.side 1)$) in node[circle, inner sep=0, minimum width=2*veclen(x1,y1)-pgflinewidth, draw=blue] ;
                 node[inner sep=0, draw=cyan, regular polygon, regular polygon sides=7] (b) at (1,0) i;
                 path let p1=($(b.center)-(b.side 1)$) in node[circle, inner sep=0, minimum width=2*veclen(x1,y1)-pgflinewidth, draw=blue] at (b) ;
                 endtikzpicture
                enddocument


                enter image description here






                share|improve this answer

























                  0












                  0








                  0







                  This solution uses calc library to compute regular polygon's inner radius. This way it's possible to compute circunscribed circle's minimum width. 



                  documentclass[tikz, border=1mm]standalone
                  usetikzlibraryshapes.geometric, calc

                  begindocument
                   begintikzpicture
                   node[inner sep=0, regular polygon, regular polygon sides=4, draw=cyan] (a) xx;
                   path let p1=($(a.center)-(a.side 1)$) in node[circle, inner sep=0, minimum width=2*veclen(x1,y1)-pgflinewidth, draw=blue] ;
                   node[inner sep=0, draw=cyan, regular polygon, regular polygon sides=7] (b) at (1,0) i;
                   path let p1=($(b.center)-(b.side 1)$) in node[circle, inner sep=0, minimum width=2*veclen(x1,y1)-pgflinewidth, draw=blue] at (b) ;
                   endtikzpicture
                  enddocument


                  enter image description here






                  share|improve this answer













                  This solution uses calc library to compute regular polygon's inner radius. This way it's possible to compute circunscribed circle's minimum width. 



                  documentclass[tikz, border=1mm]standalone
                  usetikzlibraryshapes.geometric, calc

                  begindocument
                   begintikzpicture
                   node[inner sep=0, regular polygon, regular polygon sides=4, draw=cyan] (a) xx;
                   path let p1=($(a.center)-(a.side 1)$) in node[circle, inner sep=0, minimum width=2*veclen(x1,y1)-pgflinewidth, draw=blue] ;
                   node[inner sep=0, draw=cyan, regular polygon, regular polygon sides=7] (b) at (1,0) i;
                   path let p1=($(b.center)-(b.side 1)$) in node[circle, inner sep=0, minimum width=2*veclen(x1,y1)-pgflinewidth, draw=blue] at (b) ;
                   endtikzpicture
                  enddocument


                  enter image description here







                  share|improve this answer












                  share|improve this answer



                  share|improve this answer










                  answered Mar 22 at 12:12









                  IgnasiIgnasi

                  95.7k4175320




                  95.7k4175320



























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