动态图片大小

Question 1

可以使用tikzpagenodes和\pgfextracty来确定页面上的剩余空间。请注意，图中增加了\intextsep上方的间隙（下方的间隙被页面底部吸收）。

\documentclass{article}
\usepackage{graphicx}
\usepackage{lipsum}
\usepackage{float}
\usepackage{duckuments}
\usepackage{showframe}

\usepackage{tikzpagenodes}
\newlength{\checkspaceleft}% reserve global name

\newcommand{\checkspace}{\ifvmode\else\par\fi
  \noindent\tikz[remember picture,overlay]{%
    \pgfextracty{\checkspaceleft}{\pgfpointdiff%
      {\pgfpointanchor{current page text area}{south}}%
      {\pgfpointorigin}}%
    \global\checkspaceleft=\checkspaceleft}%
  \hrule height0pt}% not on same line

\newcommand{\myfigure}[2]{% #1 = image, #2 = caption
  \checkspace
  \begin{figure}[H]
    \sbox0{\begin{minipage}[b]{\textwidth}
      #2
      \end{minipage}}% measure caption
    \dimen0=\dimexpr \checkspaceleft-\ht0-\dp0-\intextsep\relax
    \sbox1{#1}% measure image
    \centering
    \ifdim \dimen0<\ht1\relax
      \resizebox{!}{\dimen0}{\usebox1}
    \else
      \usebox1
    \fi
    \usebox0
  \end{figure}}

\begin{document}
    \lipsum[1-4]

    \myfigure{\includegraphics{example-image-duck}}%
      {\caption{This is a duck}}

    \lipsum[4-7]
\end{document}

Answer

可以使用tikzpagenodes和\pgfextracty来确定页面上的剩余空间。请注意，图中增加了\intextsep上方的间隙（下方的间隙被页面底部吸收）。

\documentclass{article}
\usepackage{graphicx}
\usepackage{lipsum}
\usepackage{float}
\usepackage{duckuments}
\usepackage{showframe}

\usepackage{tikzpagenodes}
\newlength{\checkspaceleft}% reserve global name

\newcommand{\checkspace}{\ifvmode\else\par\fi
  \noindent\tikz[remember picture,overlay]{%
    \pgfextracty{\checkspaceleft}{\pgfpointdiff%
      {\pgfpointanchor{current page text area}{south}}%
      {\pgfpointorigin}}%
    \global\checkspaceleft=\checkspaceleft}%
  \hrule height0pt}% not on same line

\newcommand{\myfigure}[2]{% #1 = image, #2 = caption
  \checkspace
  \begin{figure}[H]
    \sbox0{\begin{minipage}[b]{\textwidth}
      #2
      \end{minipage}}% measure caption
    \dimen0=\dimexpr \checkspaceleft-\ht0-\dp0-\intextsep\relax
    \sbox1{#1}% measure image
    \centering
    \ifdim \dimen0<\ht1\relax
      \resizebox{!}{\dimen0}{\usebox1}
    \else
      \usebox1
    \fi
    \usebox0
  \end{figure}}

\begin{document}
    \lipsum[1-4]

    \myfigure{\includegraphics{example-image-duck}}%
      {\caption{This is a duck}}

    \lipsum[4-7]
\end{document}

Question 2

好吧，我继续自己构建一些东西。我决定创建一个包，所以当您想要复制和粘贴我的代码时，您必须dynimage.sty在工作目录中创建一个文件并将以下代码粘贴到其中：

\NeedsTeXFormat{LaTeX2e}

\ProvidesPackage{dynimage}[2018/09/14 Package for dynamic images that will fit on current page]

%%%%%%%%%%%%%%%%%%%%%%%%%%%%% REQUIREMENTS %%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\RequirePackage{pgfkeys}
\RequirePackage{etoolbox}
\RequirePackage{xstring}
\RequirePackage{graphicx}
\RequirePackage{pgf}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%% INTERNAL VARS %%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\newtoggle{@dynimageDebug}
\def\@dyinmageMinScaleFactor{0.75}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%% KEY SETUP %%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\pgfkeys{%
    /dynimage/.cd,%
    min scale factor/.estore in = {\@dyinmageMinScaleFactor},%
    min scale factor/.value required,%
    reckless/.style = {/dynimage/min scale factor=0.1},%
    reckless/.value forbidden,%
}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%% CONFIGURATION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\DeclareOption{debug}{\toggletrue{@dynimageDebug}}

\DeclareOption*{%
    \pgfkeys{%
        /dynimage/.cd,%
        \CurrentOption,%
    }%
}

\ProcessOptions\relax


%%%%%%%%%%%%%%%%%%%%%%%%%%%%% IMPLEMENTATION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\DeclareRobustCommand{\dynImage}[2][]{%
    \iftoggle{@dynimageDebug}{%
        \PackageInfo{dynimage}{Minimum scale factor set to \@dyinmageMinScaleFactor}
    }{}%
    %
    % Get the height of the image if it was placed without any further processing
    \newlength{\@nativeImageHeight}%
    \settoheight{\@nativeImageHeight}{\hbox{\includegraphics[#1]{#2}}}%
    %
    % Get the remaining page height
    \newlength{\@remainingPageHeight}%
    \@remainingPageHeight=\dimexpr\textheight-\pagetotal\relax%
    %
    % Calculate the scaling-factor that needs to be used in order to keep the image on the current page
    \pgfmathparse{(floor(\@remainingPageHeight))/ceil(max(\@nativeImageHeight,0.1))}%
    \edef\@scaleFactor{\pgfmathresult}
    %
    % Log all gathered sizes until this point if in debug mode
    \iftoggle{@dynimageDebug}{\PackageInfo{dynimage}{The scale for “#2” is \the\@remainingPageHeight /\the\@nativeImageHeight =\@scaleFactor}}{}
    %
    % don't enlarge images (no up-scaling)
    \ifdimgreater{\@scaleFactor pt}{1pt}{\gdef\@scaleFactor{1}}{}%
    %
    % don't scale down more than allowed
    \ifdimgreater{\@scaleFactor pt}{\@dyinmageMinScaleFactor pt}{}{\gdef\@scaleFactor{1}\gdef\@tooMuchScaling{}}%
    %
    % scale if the scale isn't equal to 1
    \ifdimequal{\@scaleFactor pt}{1pt}{%
        % Output appropriate info/warning
        \ifdef{\@tooMuchScaling}{%
            \PackageWarning{dynimage}{The image "#2" would require too much down-scaling and is therefore placed on the next side}%
        }{%
            \PackageInfo{dynimage}{The image "#2" fits on the page without height-adjustments}%
        }%
        %
        % insert image as is
        \includegraphics[#1]{#2}%
    }{%
        % scale down
        %
        % calculate the scaled image height
        \pgfmathparse{\@scaleFactor * \@nativeImageHeight}
        \let\@scaledImageHeight\pgfmathresult
        %
        % Add some difference between remaining height and scaled image height in order to
        % avoid rounding inaccuracies
        \pgfmathparse{(\@remainingPageHeight - \@scaledImageHeight) < 4}
        \ifnumequal{\pgfmathresult}{1}{\pgfmathparse{\@scaledImageHeight - 4} \edef\@scaledImageHeight{\pgfmathresult}}{}
        %
        % Set up macro for all non-height specifications
        \def\@graphicOptions{}\relax%
        %
        % Set up dummy-keys for processing the \includegraphics-options
        \pgfkeys{%
            /dynimage/dummy/.cd,%
            height/.code = {\gdef\specifiesHeight{}},%
            /dynimage/dummy/.unknown/.code = {%
                % get unchanhed key-path
                \edef\keypath{\pgfkeyscurrentpath}%
                \IfBeginWith{\keypath}{/dynimage/dummy}{%
                    % trim away the local dummy path in order to get unchanged key-path
                    \StrBehind{\keypath}{/dynimage/dummy}[\keypath]
                    \xdef\keypath{\keypath}
                }{}%
                %
                % Add the respective key to \@graphicOptions but don't introduce equals where there shouldn't be any
                \edef\@val{##1}
                \ifdefequal{\@val}{\pgfkeysnovalue{}}{%
                    \xdef\@graphicOptions{\@graphicOptions,\keypath\pgfkeyscurrentname}
                }{%
                    \xdef\@graphicOptions{\@graphicOptions,\keypath\pgfkeyscurrentname=##1}%
                }%
            },%
        }%
        %
        % process the keys originally intended for the \includegraphics[]{imagefile} in order
        % to check for a possible height-definition. All other keys are stored in \@graphicOptions
        \pgfkeys{/dynimage/dummy/.cd, #1}%      
        %
        % Check if an explicit height for the image is given
        \ifdef{\specifiesHeight}{%
            % Create warning that the use of height prvented scaling
            \PackageWarning{dynimage}{Inserting image "#2" with specified height instead of adjusted height}%
            %
            % insert image as is
            \includegraphics[#1]{#2}
        }{%
            % log the scaled size of the image if in debug mode
            \iftoggle{@dynimageDebug}{%
                \PackageInfo{dynimage}{Inserting image "#2" with a height of \@scaledImageHeight pt}%
            }{}%
            %
            % add a height-specification to the keys for the image
            \xdef\@graphicOptions{height=\@scaledImageHeight pt,\@graphicOptions}
            %
            % Gobble away any leading and trailing commas as the keyvals-package used by
            % graphics can't deal with them
            \IfBeginWith{\@graphicOptions}{,}{%
                % removing leading comma
                \StrGobbleLeft{\@graphicOptions}{1}[\@graphicOptions]%
                \xdef\@graphicOptions{\@graphicOptions}%
            }{}%
            \IfEndWith{\@graphicOptions}{,}{%
                % remove trailing comma
                \StrGobbleRight{\@graphicOptions}{1}[\@graphicOptions]%
                \xdef\@graphicOptions{\@graphicOptions}%
            }{}%
            %
            % Fully expand options
            \edef\doPrintImage{\noexpand\includegraphics[\@graphicOptions]{#2}}%
            %
            % print out the scaled image
            \doPrintImage%
        }%
    }%
}

然后，您可以继续\usepackage{dynimage}在允许您使用\dynImage[<options>{<image>}宏的文档中使用。<option>是您想要传递给\includegraphics-command 的选项（注意：指定显式height将禁用任何缩放）并且<image>是应包含的图像文件的路径。

使用此宏代替\includegraphics将产生以下效果：
如果页面上有足够的空间，则将插入图像而不对其进行任何修改（如果直接使用则为\includegraphics）。但是，如果不是这种情况，则将计算一个缩放因子，图像必须使用该缩放因子进行缩放才能适合当前页面（就其高度而言）。如果缩放因子不低于最小缩放因子（可使用min scale factor包的 - 选项配置 - 默认值为0.75）并且如果选项中未指定任何明确说明height，则图像的高度将减小，以便它适合当前页面并填充它（可能除了几个点之外）。
如果您不介意图像缩小，可以将reckless- 选项传递给包，这将导致min scale factor设置为0.1。

从我的问题中取出（稍微修改过的）MWE，然后将其用作

\documentclass{article}
\usepackage{graphicx}
\usepackage{lipsum}
\usepackage{duckuments}
\usepackage{showframe}
\usepackage{dynimage}

\begin{document}
    \lipsum[1-4]

    Here comes the image:

    \dynImage{example-image-duck}
%    \includegraphics{example-image-duck}

    \lipsum[4-7]
\end{document}

笔记

如您所见，该软件包尚未处理浮点数（包含标题）或类似构造。我打算扩展此软件包的功能以解决这些问题，并可能在某个时候更新此答案。

我遇到过几种情况，图像的大小设置为小于计算出的剩余大小，但它仍然被放在下一页。我不确定为什么会这样。我认为这要么是由于舍入问题，要么是由于计算剩余页面大小的方式不准确（或两者兼而有之）。这就是为什么我确保缩放后的图像大小始终至少小于4pt计算出的剩余页面高度。这似乎运行得相当好，但并不理想。
我也会研究这个问题，但如果你知道如何解决这个问题，我将非常感激你的评论 ;)

Answer