TikZ 图形相对于标题似乎没有居中

Question

我是 Ti 新手钾Z 和我在居中 Ti 时遇到了问题钾Z 图片相对于其标题（以及页边距）的大小。通过激活图片的background rectangle，似乎在图片的顶部和右侧都添加了额外的空白（矩形居中，但图片不在）。

其他 Ti 没有出现同样的问题钾同一文档中的 Z 张图片。

以下是代码：

\documentclass[11pt]{article}

\usepackage{showframe} % Activate to show the page margins

\usepackage{tikz}
\usetikzlibrary{intersections, backgrounds, shapes, arrows, shadows}

\begin{document}

\begin{figure*}[!ht]
  \centering
% \includegraphics[width=0.30\textwidth]{Figure03.png}
  \begin{tikzpicture}
  [show background rectangle]
    % Fading settings
    \tikzfading[name         = fade out
               , inner color = transparent!100
               , outer color = transparent!10 ]
    % Axes
    \draw [->, >=stealth] (0,0) -- (-0.6,-0.6) node[anchor=north west]{$X$};
    \draw [->, >=stealth] (0,0) -- (1.2,0)     node[anchor=north]{$Y$};
    \draw [->, >=stealth] (0,0) -- (0,1.2)     node[anchor=east]{$Z$};
    % Ellipse filling
    \fill [ color        = cyan
          , opacity      = 0.25
          , path fading  = fade out
          , fading angle = -30
          , rotate       = -30]
          (0,0) ellipse (1.5cm and 3.0cm);
    % Ellipse
    \draw [ name path  = ellipse 1
          , rotate     = -30]
          (0,0) ellipse (1.5cm and 3.0cm);
    % Oblique axis
    \draw [ name path = oblique axis
          , dashed]
          (-2.5,-1.3)  node[anchor=south east]{$a$} -- (2.5,1.3);
    % Intersection
    \path [name intersections={of=ellipse 1 and oblique axis}] ;
    \fill [color=red] (intersection-1) circle (0.6mm)
          node[anchor=north west]{$A$};
    \draw [thick, ->, >=stealth] (0,0) -- (intersection-1);
    % Origin
    \fill (0,0) circle (0.6mm);
    \draw (0,0) node[anchor=north west]{$O$};
  \end{tikzpicture}
  \caption{Ellipsoid of inertia.}\label{figure:fig03}
\end{figure*}

\end{document}

Answer 1

出现错误是因为 ，\tikzfading而与 无关background rectangle。我想您可能在一个简单的 中遇到同样的问题\fbox。您可以在以下 MWE 中看到这一点：

% arara: pdflatex

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{backgrounds,shadows}

\begin{document}    
\begin{tikzpicture}[show background rectangle]
    \fill (0,0) circle (5mm);
\end{tikzpicture}   
\begin{tikzpicture}[show background rectangle]
    \tikzfading[name=test]
    \fill (0,0) circle (5mm);
\end{tikzpicture}
\end{document}

或者甚至更好（表明这backgrounds不是罪魁祸首），例如：

% arara: lualatex

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{shadows}
\usepackage{lua-visual-debug}

\begin{document}    
\begin{tikzpicture}
    \fill (0,0) circle (5mm);
\end{tikzpicture}   
\begin{tikzpicture}
    \tikzfading[name=test]
    \fill (0,0) circle (5mm);
\end{tikzpicture}
\end{document}

一个简单的解决方法是将 放入\tikzfading前言中或放在图片前面。我不知道这个库的手册，但我猜这是推荐的使用方式。

% arara: pdflatex

\documentclass[11pt]{article}
\usepackage{showframe}
\usepackage{tikz}
\usetikzlibrary{%
    ,intersections
    ,backgrounds
    ,shadows
    }
\tikzset{>=stealth}

\begin{document}    
\begin{figure}[!ht]
    \centering
    % Fading settings
    \tikzfading[%
        ,name = fade out
        ,inner color = transparent!100
        ,outer color = transparent!10
        ]
    \begin{tikzpicture}[show background rectangle]
        % Axes
        \draw [->] (0,0) -- (-0.6,-0.6) node[anchor=north west]{$X$};
        \draw [->] (0,0) -- (1.2,0)     node[anchor=north]{$Y$};
        \draw [->] (0,0) -- (0,1.2)     node[anchor=east]{$Z$};
         % Ellipse
        \filldraw [% 
            ,draw         = black
            ,fill         = cyan
            ,fill opacity = 0.25
            ,path fading  = fade out
            ,fading angle = -30
            ,name path    = ellipse 1
            ,rotate       = -30
            ]
        (0,0) ellipse (1.5cm and 3.0cm);
        % Oblique axis
        \draw [name path = oblique axis,dashed](-2.5,-1.3)  node[anchor=south east]{$a$} -- (2.5,1.3);
        % Intersection
        \path [name intersections={of=ellipse 1 and oblique axis}];
        \fill [color=red] (intersection-1) circle (0.6mm) node[anchor=north west]{$A$};
        \draw [thick, ->, >=stealth] (0,0) -- (intersection-1);
        % Origin
        \fill (0,0) circle (0.6mm) node[anchor=north west]{$O$};
    \end{tikzpicture}
    \caption{Ellipsoid of inertia.}\label{figure:fig03}
\end{figure}
\end{document}