I cannot find a solution for
- Shift the circle to an origin as (0,0). As you can see in picture two, the picture is "distorted" (the same for circular sectors!)?. The placement should be arbitrarily on a chosen paper size.
- Implement a definite paper size (want to choose A4 or A5) without margins. Perhaps via a standalone package? The current output in this respect is ok, but the paper dimensions are not. Note: the mention of paper width and height for the black background changes to a letter format (where does this come from?).
\documentclass[tikz,border=0mm]{standalone}
\usepackage{color}
\usetikzlibrary{math,}
\definecolor{clr1}{RGB}{0.00,0.00,0.00}
\definecolor{clr2}{RGB}{40,0.00,40}%
\definecolor{clr3}{RGB}{60,0,60}%
\definecolor{clr4}{RGB}{80,0,80}%
\definecolor{clr5}{RGB}{100,255,100}%
\definecolor{clr6}{RGB}{139,0,139}%
\tikzset{
%%
%%
shade radial/.code={%
\tikzset{%
color four radial/.cd,%
#1,
cfradial
}%end second(!) tikzset
},%end code shade radial!
%
color four radial/.cd,%causes default path to be set to key(color four radial)
shade radial color/.code n args={2}
{\colorlet{cfradialcolor#1}{#2}},
shade radial color={1}{black},
shade radial color={2}{black},
shade radial color={3}{white},
shade radial color={4}{white},
shade radial color={5}{purple},
shade radial color={6}{purple},
%
cfradial/.style={/tikz/path picture={
\xdef\radius{\radius}
\pgfmathsetmacro{\rone}{0.65*\radius}
\pgfmathsetmacro{\rtwo}{0.90*\radius}
\pgfmathsetmacro{\rthree}{0.98*\radius}
\pgfmathsetmacro{\rfour}{0.99*\radius}
\pgfdeclareradialshading[cfradialcolor1,cfradialcolor2,cfradialcolor3,cfradialcolor4,cfradialcolor5,cfradialcolor6]
{cfradial}%shading name s. 3.01a, p. 1083
{\centerpoint}%center point
{color(0pt)=(cfradialcolor1); %color specifications
color(\rone pt)=(cfradialcolor2);
color(\rtwo pt)=(cfradialcolor3);
color(\rthree pt)=(cfradialcolor4);
color(\rfour pt)=(cfradialcolor5);
color(\radius)=(cfradialcolor6) %
}
\typeout{\radius,\rone,\rtwo}
\pgfuseshading{cfradial}
}%end path picture
}%end style cfradial
%%
%%
}%%en
\begin{document}
\begin{tikzpicture}%
\newdimen\circleradius
\tikzmath{
\circleradius=14.0 cm;
}%end tikzmath
\coordinate (circleorig) at (-1cm,0cm);%%wrong if differs from (0,0)
\tikzset{
recstyle/.style={minimum height=\paperheight,minimum width=\paperwidth,rectangle,draw=blue!50,fill=black!100,thick}
}
\node at (circleorig) [recstyle]{background black};
\node [shape=circle, opacity=.5,
inner sep=0cm,
shade radial={
shade radial color={1}{clr1},
shade radial color={2}{clr2},
shade radial color={3}{clr3},
shade radial color={4}{clr4},
shade radial color={5}{clr5},
shade radial color={6}{clr6}
},%the one parameter of shade radial
minimum size = \circleradius,
font=\sffamily
]
(thecircle) at (circleorig) {do};
\end{tikzpicture}
\end{document}
I have tried bounding boxes and many more, but my faculties are too small to get the desired output.



