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tikzpicture: faça uma parada \foreach \draw [yshift=\n*\u] na coordenada 1

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tikzpicture: faça uma parada \foreach \draw [yshift=\n*\u] na coordenada 1

Considere a seção inferior deste MWE, ou seja, tudo abaixo ( % Image Ruler y):

\documentclass{article}

\usepackage{mwe} % Dummy images
\usepackage[skins]{tcolorbox}
\tcbuselibrary{raster}

\usepackage{tikz}
\usepackage{tikzpagenodes} % current page text area.center
\usetikzlibrary{calc} 
\pgfkeys{/tikz/savevalue/.code 2 args={\global\edef#1{#2}}}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\def\ShowHelps{0} %    1 'yes'        0   'no'

\newcommand{\UOneCoordinateX}{0.2}
\newcommand{\UOneCoordinateY}{0.09}
\newcommand{\UTwoCoordinateX}{0.2}
\newcommand{\UTwoCoordinateY}{0.284}

\newcommand{\GridSize}{0.05}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\begin{document}

\begin{tikzpicture}[
remember picture, overlay, % page center 1/3
shift={(current page.center)}, % page center 2/3
font=\sffamily,
Help/.style={font=\Huge, red}
]
\node[anchor=center, %south west,
inner sep=0 pt] (myimage) at (0,0) {

\begin{tcbitemize}[size=tight, halign=center, colback=gray, raster equal skip=0pt, raster left skip=0mm, raster right skip=0mm, raster width=1\textwidth, boxrule = 0pt, frame hidden]
\tcbitem \includegraphics[width=\textwidth]{example-image.jpg}
\tcbitem \includegraphics[width=\textwidth]{example-image.jpg}
\end{tcbitemize}  
};
\begin{scope}[x={($2*(myimage.east)$)},y={($2*(myimage.north)$)},
shift={(myimage.south west)} % page center 3/3
]

% Restrict the draw area
\clip (-0.1,-0.1) rectangle (1.1,1.1);

%%%%%ShowHelps
\path[] (\UOneCoordinateX,\UOneCoordinateY) coordinate(U1) -- (\UTwoCoordinateX,\UTwoCoordinateY) coordinate(U2);
\ifnum\ShowHelps=1 \draw[Help] (U1) circle(2pt) node[label=left:U1]{} -- (U2) circle(2pt) node[label=left:U2]{};\fi % show unitlength line

\path let \p1=($(U2)-(U1)$) in 
\pgfextra{  \pgfmathsetlengthmacro{\unitlength}{veclen(\x1,\y1)}   }
[savevalue={\u}{\unitlength}];
\ifnum\ShowHelps=1 \node[Help] at (0.725,0.25) {unitlength U1U2 = \u}; \fi%<--- show unitlength
\ifnum\ShowHelps=1 \draw[blue, transform canvas={xshift=2mm}] (U1) -- +(0,\u);\fi  % Test

% Image Ruler y
\draw[very thick] (0,0) coordinate(B) -- (0, 1);
\foreach \n in {0,1,...,10}{%%
\draw[very thick] ([yshift=\n*\u]B) -- +(-3mm,0) node[left]{
\ifnum\n=0 \else \ifnum\n=1 \n\,cm \else \n \fi\fi}; 
}%%
\foreach \n in {0.1,0.2,...,10}{%% 
\draw[] ([yshift=\n*\u]B) -- +(-1.5mm,0);
}%%

\end{scope}
\end{tikzpicture}

\end{document}

Nomeadamente:

\draw[very thick] (0,0) coordinate(B) -- (0, 1);
\foreach \n in {0,1,...,10}{%%
\draw[very thick] ([yshift=\n*\u]B) -- +(-3mm,0) node[left]{
\ifnum\n=0 \else \ifnum\n=1 \n\,cm \else \n \fi\fi}; 
}%%
\foreach \n in {0.1,0.2,...,10}{%% 
\draw[] ([yshift=\n*\u]B) -- +(-1.5mm,0);
}%%

O 1in \draw[very thick] (0,0) coordinate(B) -- (0, 1);garante que a linha vertical grossa da régua pare na coordenada 1. Isso é ótimo!

Porém, como fazer também com que as linhas pequenas parem em 1, sem alterar o recorte ( \clip (-0.1,-0.1) rectangle (1.1,1.1);)?

Isso poderia ser feito mudando o 10in \foreach \n in {0.1,0.2,...,10}{%%para 5, mas não é isso que pretendo, pois não sei antecipadamente de quantos números vou precisar. Tudo o que sei é que vou querer parar na coordenada y 1, da mesma forma que a linha vertical grossa para em 1using \draw[very thick] (0,0) coordinate(B) -- (0, 1);.

Aqui está uma captura de tela:

insira a descrição da imagem aqui

Então, resumindo:

Preciso de um método para conseguir extrair a coordenada atual de y... Não sei quantas vezes terei que incrementar em loop os centímetros e os milímetros, só sei que deve parar em 1

Responder1

Método usandodecoration insira a descrição da imagem aqui

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{decorations}
\usepackage{mwe}

\newcount\tick
\newcount\majortick
\newif\ifmajortick

\pgfdeclaredecoration{ruler}{initial}{
  \state{initial}[
    width=0mm, next state=ruler,
    persistent precomputation={
      \tick=10
      \majortick=0
    }
  ]{
  }
  \state{ruler}[width=1mm,
    persistent precomputation={
      \ifnum \tick=10\relax
        \majorticktrue
        \tick=0
      \else
        \majortickfalse
      \fi
      \advance\tick by 1
    },
    persistent postcomputation={
      \ifnum \tick=10\relax
        \advance\majortick by 1
      \fi
    }
  ]{
    \ifmajortick
      \pgfscope
      \pgftransformrotate{-90}
      \pgftransformshift{\pgfpoint{-4mm}{0pt}}
      \pgfnode{rectangle}{east}{\the\majortick}{}{\pgfusepath{}}
      \endpgfscope
    \fi
    \pgfpathmoveto{\pgfpointorigin}
    \ifmajortick
      \pgfsetlinewidth{1pt}
      \pgfpathlineto{\pgfpoint{0pt}{3mm}}
    \else
      \pgfsetlinewidth{0.4pt}
      \pgfpathlineto{\pgfpoint{0pt}{1mm}}
    \fi
    \pgfusepath{stroke}
  }
  \state{final}{}
}

\begin{document}
\begin{tikzpicture}
\node[inner sep=0pt] (a) {\includegraphics[width=.5\textwidth]{example-image}};
\draw[postaction=decorate, decoration=ruler] (a.south west) -- (a.north west);
\end{tikzpicture}
\end{document}

Responder2

Eu não acho que você realmente precisará \clip (-0.1,-0.1) rectangle (1.1,1.1);devido ao trabalho com o tcolorbox.

Mas como resposta à pergunta "Como cortar o eixo y":
Você precisa saber quantos pontos "1", a altura da imagem, tem. E isso é medido exatamente da mesma maneira que o "comprimento unitário" foi medido no código:

\path[draw=none] (0,0) coordinate(LL) -- (0,1) coordinate(UL);
\path let \p1=($(UL)-(LL)$) in 
\pgfextra{  \pgfmathsetlengthmacro{\ImageHeight}{veclen(\x1,\y1)}   }
[savevalue={\h}{\ImageHeight}];

\foreach \n in {0.1,0.2,...,10}{%%
\pgfmathsetmacro\Yshift{\n*\u}
\pgfmathsetmacro\YshiftTest{\n*\u < \h ?  1 : 0}
\ifnum\YshiftTest=1 \draw[] ([yshift=\Yshift]B) -- +(-1.5mm,0); \else\fi
}%%
\ifnum\ShowHelps=1
\draw[red] (LL) circle(2pt) node[below]{LL};
\draw[red] (UL) circle(2pt) node[above]{UL};
\node[right=3mm, Help] at (UL) {Image Height h=\h};    \fi

insira a descrição da imagem aqui

\documentclass{article}

\usepackage{mwe} % Dummy images
\usepackage[skins]{tcolorbox}
\tcbuselibrary{raster}

\usepackage{tikz}
\usepackage{tikzpagenodes} % current page text area.center
\usetikzlibrary{calc} 
\pgfkeys{/tikz/savevalue/.code 2 args={\global\edef#1{#2}}}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\def\ShowHelps{1} %    1 'yes'        0   'no'

\newcommand{\UOneCoordinateX}{0.2}
\newcommand{\UOneCoordinateY}{0.09}
\newcommand{\UTwoCoordinateX}{0.2}
\newcommand{\UTwoCoordinateY}{0.284}

\newcommand{\GridSize}{0.05}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\begin{document}

\begin{tikzpicture}[
remember picture, overlay, % page center 1/3
shift={(current page.center)}, % page center 2/3
font=\sffamily,
Help/.style={font=\large, text=red, fill=yellow}
]
\node[anchor=center, %south west,
inner sep=0 pt] (myimage) at (0,0) {

\begin{tcbitemize}[size=tight, halign=center, colback=gray, raster equal skip=0pt, raster left skip=0mm, raster right skip=0mm, raster width=1\textwidth, boxrule = 0pt, frame hidden]
\tcbitem \includegraphics[width=\textwidth]{example-image.jpg}
\tcbitem \includegraphics[width=\textwidth]{example-image.jpg}
\end{tcbitemize}  
};
\begin{scope}[x={($2*(myimage.east)$)},y={($2*(myimage.north)$)},
shift={(myimage.south west)} % page center 3/3
]

% Restrict the draw area
\clip (-0.1,-0.1) rectangle (1.1,1.1);
\ifnum\ShowHelps=1 \draw[red] (-0.1,-0.1) rectangle (1.1,1.1);\fi

%%%%%ShowHelps
\path[] (\UOneCoordinateX,\UOneCoordinateY) coordinate(U1) -- (\UTwoCoordinateX,\UTwoCoordinateY) coordinate(U2);
\ifnum\ShowHelps=1 \draw[red] (U1) circle(2pt) node[label=left:U1]{} -- (U2) circle(2pt) node[label=left:U2]{};\fi % show unitlength line

\path let \p1=($(U2)-(U1)$) in 
\pgfextra{  \pgfmathsetlengthmacro{\unitlength}{veclen(\x1,\y1)}   }
[savevalue={\u}{\unitlength}];
\ifnum\ShowHelps=1 \node[Help] at (0.3,0.5) {unitlength U1U2 = \u}; \fi%<--- show unitlength
\ifnum\ShowHelps=1 \draw[blue, transform canvas={xshift=2mm}] (U1) -- +(0,\u);\fi  % Test



% Image Ruler y
\draw[very thick] (0,0) coordinate(B) -- (0, 1);
\foreach \n in {0,1,...,10}{%%
\draw[very thick] ([yshift=\n*\u]B) -- +(-3mm,0) node[left]{
\ifnum\n=0 \else \ifnum\n=1 \n\,cm \else \n \fi\fi}; 
}%%

\path[draw=none] (0,0) coordinate(LL) -- (0,1) coordinate(UL);
\path let \p1=($(UL)-(LL)$) in 
\pgfextra{  \pgfmathsetlengthmacro{\ImageHeight}{veclen(\x1,\y1)}   }
[savevalue={\h}{\ImageHeight}];

\foreach \n in {0.1,0.2,...,10}{%%
\pgfmathsetmacro\Yshift{\n*\u}
\pgfmathsetmacro\YshiftTest{\n*\u < \h ?  1 : 0}
\ifnum\YshiftTest=1 \draw[] ([yshift=\Yshift]B) -- +(-1.5mm,0); \else\fi
}%%
\ifnum\ShowHelps=1
\draw[red] (LL) circle(2pt) node[below]{LL};
\draw[red] (UL) circle(2pt) node[above]{UL};
\node[right=3mm, Help] at (UL) {Image Height h=\h};    \fi 
\end{scope}
\end{tikzpicture}

\end{document}

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