☰

如何修復 svg.path tikz 函式庫上的相對座標

tag-icon • tag-icon tikz-pgf svg
如何修復 svg.path tikz 函式庫上的相對座標

使用相關命令時似乎存在錯誤或錯誤。就我而言，我發現繪製平滑曲線會錯誤地繪製曲線的實例。

檢查以下情況（第一個是完全相對的，最後一個是完全絕對的），其中命令的相對使用繪製錯誤，而絕對命令按預期工作。

\documentclass{article}

\usepackage{tikz}
\usetikzlibrary{svg.path}

\begin{document}
  % Original
  \begin{tikzpicture}
    \draw svg "M 256 8 C 119 8 8 119 8 256 s 111 248 248 248 s 248 -111 248 -248 S 393 8 256 8 z";
  \end{tikzpicture}
  % Mix of relative
  \begin{tikzpicture}
  \draw svg "M 256 8 C 119 8 8 119 8 256 s 111 248 248 248 S 504 393 504 256 S 393 8 256 8 z";
  \end{tikzpicture}
  % Mix of relative
  \begin{tikzpicture}
  \draw svg "M 256 8 C 119 8 8 119 8 256 S 119 504 256 504 s 248 -111 248 -248 S 393 8 256 8 z";
  \end{tikzpicture}
  % Full absolute
  \begin{tikzpicture}
  \draw svg "M256 8 C 119 8 8 119 8 256 S 119 504 256 504 S 504 393 504 256 S 393 8 256 8 z";
  \end{tikzpicture}
\end{document}

答案1

s在運算符的定義中

\pgfparserdef{svgpath}{all}{the letter s}
{
  \pgf@lib@svg@finish@prev
  \pgf@lib@svg@read@nums{4}{\pgf@lib@svg@curveto@rel@smooth}
}

\def\pgf@lib@svg@curveto@rel@smooth{%
  \ifnum\pgf@lib@svg@count=0\relax% nothing read
  \else%
    % Draw curve
    % Compute first control point
    \ifx\pgf@lib@svg@bezier@last\pgfutil@empty%
      \def\pgf@lib@svg@first@cp{\pgfqpoint{\pgf@lib@svg@last@x}{\pgf@lib@svg@last@y}}
    \else
      \def\pgf@lib@svg@first@cp{
        \pgfpointadd
        {\pgfqpoint{\pgf@lib@svg@last@x}{\pgf@lib@svg@last@y}}
        {\pgfpointdiff
          {\pgf@lib@svg@bezier@last}
          {\pgfqpoint{\pgf@lib@svg@last@x}{\pgf@lib@svg@last@y}}
        }
      }
    \fi
    \pgfpathcurveto
    {\pgf@lib@svg@first@cp}
    {\pgfpointadd{\pgfqpoint{\pgf@lib@svg@last@x}{\pgf@lib@svg@last@y}}{\pgfqpoint{\pgf@lib@svg@get@num{0}pt}{\pgf@lib@svg@get@num{1}pt}}}%
    {\pgfpointadd{\pgfqpoint{\pgf@lib@svg@last@x}{\pgf@lib@svg@last@y}}{\pgfqpoint{\pgf@lib@svg@get@num{2}pt}{\pgf@lib@svg@get@num{3}pt}}}%
    % Clear quadratic last point and save new last control point:
    \let\pgf@lib@svg@quad@last=\pgfutil@empty%
    \pgf@process{\pgfpointadd{\pgfqpoint{\pgf@lib@svg@last@x}{\pgf@lib@svg@last@y}}{\pgfqpoint{\pgf@lib@svg@get@num{2}pt}{\pgf@lib@svg@get@num{3}pt}}}
    \edef\pgf@lib@svg@bezier@last{\noexpand\pgfqpoint{\the\pgf@x}{\the\pgf@y}}%
    % update
    \advance\pgf@lib@svg@last@x by\pgf@lib@svg@get@num{2}pt%
    \advance\pgf@lib@svg@last@y by\pgf@lib@svg@get@num{3}pt%
    % Go on
    \pgf@lib@svg@read@nums{4}{\pgf@lib@svg@curveto@rel@smooth}
  \fi
}

以下行（目前為第 386 行）pgflibrarysvg.path.code.tex

\pgf@process{\pgfpointadd{\pgfqpoint{\pgf@lib@svg@last@x}{\pgf@lib@svg@last@y}}{\pgfqpoint{\pgf@lib@svg@get@num{2}pt}{\pgf@lib@svg@get@num{3}pt}}}
\edef\pgf@lib@svg@bezier@last{\noexpand\pgfqpoint{\the\pgf@x}{\the\pgf@y}}%

是錯的。這是因為\pgf@lib@svg@get@num{2}和{3}是上一條曲線的端點。但標準說它應該記住上一條曲線的第二個控制點。如果您將數字更改為{0}，{1}它將按預期工作。

（我懷疑該行是從第 300 行複製的，而在C運算符中， {2}and{3}確實表示第二個控制點。）

這是 MWE

\documentclass{article}

\usepackage{tikz}
\usetikzlibrary{svg.path}
\makeatletter

\def\pgf@lib@svg@curveto@rel@smooth{%
  \ifnum\pgf@lib@svg@count=0\relax% nothing read
  \else%
    % Draw curve
    % Compute first control point
    \ifx\pgf@lib@svg@bezier@last\pgfutil@empty%
      \def\pgf@lib@svg@first@cp{\pgfqpoint{\pgf@lib@svg@last@x}{\pgf@lib@svg@last@y}}
    \else
      \def\pgf@lib@svg@first@cp{
        \pgfpointadd
        {\pgfqpoint{\pgf@lib@svg@last@x}{\pgf@lib@svg@last@y}}
        {\pgfpointdiff
          {\pgf@lib@svg@bezier@last}
          {\pgfqpoint{\pgf@lib@svg@last@x}{\pgf@lib@svg@last@y}}
        }
      }
    \fi
    \pgfpathcurveto
    {\pgf@lib@svg@first@cp}
    {\pgfpointadd{\pgfqpoint{\pgf@lib@svg@last@x}{\pgf@lib@svg@last@y}}{\pgfqpoint{\pgf@lib@svg@get@num{0}pt}{\pgf@lib@svg@get@num{1}pt}}}%
    {\pgfpointadd{\pgfqpoint{\pgf@lib@svg@last@x}{\pgf@lib@svg@last@y}}{\pgfqpoint{\pgf@lib@svg@get@num{2}pt}{\pgf@lib@svg@get@num{3}pt}}}%
    % Clear quadratic last point and save new last control point:
    \let\pgf@lib@svg@quad@last=\pgfutil@empty%
    \pgf@process{\pgfpointadd{\pgfqpoint{\pgf@lib@svg@last@x}{\pgf@lib@svg@last@y}}{\pgfqpoint{\pgf@lib@svg@get@num{0}pt}{\pgf@lib@svg@get@num{1}pt}}} %%%%%% fixing this line
    \edef\pgf@lib@svg@bezier@last{\noexpand\pgfqpoint{\the\pgf@x}{\the\pgf@y}}%
    % update
    \advance\pgf@lib@svg@last@x by\pgf@lib@svg@get@num{2}pt%
    \advance\pgf@lib@svg@last@y by\pgf@lib@svg@get@num{3}pt%
    % Go on
    \pgf@lib@svg@read@nums{4}{\pgf@lib@svg@curveto@rel@smooth}
  \fi
}


\begin{document}
  % Original
  \begin{tikzpicture}
    \draw svg "M 256 8 C 119 8 8 119 8 256 s 111 248 248 248 s 248 -111 248 -248 S 393 8 256 8 z";
  \end{tikzpicture}
  % Mix of relative
  \begin{tikzpicture}
  \draw svg "M 256 8 C 119 8 8 119 8 256 s 111 248 248 248 S 504 393 504 256 S 393 8 256 8 z";
  \end{tikzpicture}
  % Mix of relative
  \begin{tikzpicture}
  \draw svg "M 256 8 C 119 8 8 119 8 256 S 119 504 256 504 s 248 -111 248 -248 S 393 8 256 8 z";
  \end{tikzpicture}
  % Full absolute
  \begin{tikzpicture}
  \draw svg "M256 8 C 119 8 8 119 8 256 S 119 504 256 504 S 504 393 504 256 S 393 8 256 8 z";
  \end{tikzpicture}
\end{document}

相關內容