[Tex/LaTex] ConTeXt: Expand background image to fill page

backgroundscontextgraphicstitles

Background

Looking to make a background image scale to fill an entire page.

Code

I tried changing the dimensions of the page to fill the entire area and then drop in an external image:

\setuplayout[
  backspace=0mm,
  leftmargin=0mm,
  rightmargin=0mm,
  topdistance=0mm,
  header=0mm,
  footer=0mm,
]

\starttext

\startfrontmatter

  % Title page (front cover).
  \startstandardmakeup
    % Front Cover Photo
    % Front Cover Photo citation (author, author url, license, license url)
    \externalfigure[cover.png][width=\paperwidth,height=\paperheight]
  \stopstandardmakeup

  % Copyright page.
  \startstandardmakeup
    % date
    % author

    Copyright
  \stopstandardmakeup

  % Table of Contents.
  \completecontent
\stopfrontmatter

\stoptext

Update

Other attempts that don't quite work.

Layer

Using a defined layer:

\definelayer[cover][
  x=0mm,
  y=0mm,
  width=\paperwidth,
  height=\paperheight,
]

\setlayer[cover][
  hoffset=0mm,
  voffset=0mm,
]{%
  \framed[
    frame=off
    width=\paperwidth,
    height=\paperheight,
  ]{%
    \externalfigure[cover.png][width=\paperwidth,height=\paperheight]
  }
}

\starttext

\startfrontmatter
  \setupbackgrounds[page][background=cover]
  \startstandardmakeup
  \stopstandardmakeup
  \setupbackground[page][background=]
\stopfrontmatter
\stoptext

This produces a white border along the left and bottom edges:

White Border

Problem

There is a small amount of whitespace that is not taken up by the image:

Extra Whitespace

The wiki shows how to fill a page using an MP graphic, but that seems to be overly complicated for just adding an image to the page:

http://wiki.contextgarden.net/Simple_Cover_Page

The question on filling the background graphic across two pages is similar, but has text on top of the image:

How to span the background graphic across verso and recto pages in ConTeXt?

Additional Information

External figures are set up as follows:

\setupexternalfigures[
  order={svg,pdf,png,jpg},
  location=global,
  width=\hsize,
]

Question

What is the proper way to scale an image, without respecting its aspect ratio, such that it fills the entire page?

Best Answer

Normally, you use \setupbackgrounds[page][background=...] to set a page background. So, one option is to use

\setupbackgrounds[page][background=...]
\startstandardmakeup
...
\stopstandardmakeup
\setupbackground[page][background=] %Reset

A more elegant option is to extend the makeup mechanism to accept the background key:

\unprotect
\appendtoks
  \setupbackgrounds[\v!page][\c!background=\makeupparameter\c!background]
\to \t_page_makeup_every_setup
\protect

Then you can use

\setupexternalfigures[location={local,default,global}]

\defineoverlay
  [backgroundimage]
  [{\externalfigure[cow.pdf][width=\overlaywidth, height=\overlayheight]}]


\starttext

\startstandardmakeup[background=backgroundimage]
  Whatever
\stopstandardmakeup

Next

\stoptext

If you just want to include an image, you can also use:

\startTEXpage
  \externalfigure[cow.pdf][width=\paperwidth, height=\paperheight]
\stopTEXpage

How it works

First I define a layer that contains the chapter images. Then I hook into the chapter command. The setup s:chapter is placed before every chapter. It ensures that the page is a left one. Next, the page headers and footers are suppressed.

Then follows some ugly code that ensures that the entire page is filled with the graphic and the borders are cut off. I would like to see a cleaner solution for this (Aditya and Phillipp, are you listening?).

Finally the images are included. You need to two create new entries for each chapter image. One for the aspect ratio calculation and one which is finally included. Don't forget to add the \or. When you include less images than chapters, the dummy graphic is used for the remaining chapters.

Things to improve

The code to include the images is needed in two places, it would be much cleaner and less error-prone to define them only once.

As I mentioned before, the code to compute the full page images is not very ConTeXtish and can surely be improved. It doesn't center the graphic like in your sketch. The images are always left top aligned and cut off at the right or bottom.

EDIT: Here is a second version from phg (see comments below) with a more ConTeXtish interface and the advantage that the graphics are defined only once. It uses Lua to compare the graphic dimensions, since it tends to be quite tricky in TeX. Warning: More low-level, but rather pretty code ahead.

% macros=mkvi

% pretty dummy graphics
\useMPlibrary
  [dum]

% fake text
\usemodule
  [visual]

\setuppagenumbering
  [alternative=doublesided]

\setupbackgrounds
  [page]
  [background=chapterimages]

\definelayer
  [chapterimages]

\setuphead
  [chapter]
  [before=\setups{s:chapter}]

\definemakeup
  [chapterimage]

% zero page borders for the makeup
\definelayout
  [chapterimage]
  [page]

\setupmakeup
  [chapterimage]
  [page=left]

\unprotect

\newcount\image_counter
\newdimen\image_ht
\newdimen\image_wd

\def\defineimagelist{\dodoubleempty\do_define_image_list}

\def\do_define_image_list[#structurename][#lst]{%
  \edef\current_structure{#structurename}%
  \scratchcounter\zerocount
  \ifsecondargument
    \processcommalist[#lst]\define_structure_image
  \fi%
}

\def\define_structure_image#img{%
  \advance\scratchcounter\plusone
  \expandafter\def
    \csname\current_structure _image_\the\scratchcounter\endcsname{%
    \externalfigure[#img]%
  }%
}

\unexpanded\def\pickimage{\dosingleempty\do_pick_image}

\def\do_pick_image[#structurename]{%
  \global\advance\image_counter\plusone
  \ifcsname#{structurename}_image_\the\image_counter\endcsname
    \expandafter\let\expandafter%
      \current_structure_image\csname#{structurename}_image_\the\image_counter\endcsname
  \else
    \let\current_structure_image\structure_image_dummy
  \fi%
  \setbox\scratchbox\vbox{\current_structure_image}%
  \image_ht\ht\scratchbox
  \image_wd\wd\scratchbox
  \ctxcommand{test_image_dimensions()}
    {\current_structure_image[width=\paperwidth]}
    {\current_structure_image[height=\paperheight]}%
}

\def\structure_image_dummy{\externalfigure[dummy]}%

%% Since \externalfigure[foo][factor=max] doesn't work anymore, we'll
%% have to bypass TEX's inadequate integer arithmetic through Lua.
\startluacode
  local td = tex.dimen
  commands.test_image_dimensions = function ()
    local pht, pwd = td.paperheight, td.paperwidth
    local iht, iwd = td.image_ht,    td.image_wd
    local result = iht / iwd > pht / pwd
    commands.doifelse(result)
  end
\stopluacode

\protect

\startsetups s:chapter
  \startmakeup [chapterimage]
    \pickimage [chapter]
  \stopmakeup
\stopsetups

And here again the sample document, which is the same as in the example above, except that it contains a user interface to set up the graphics used for the chapter pages.

\starttext

\defineimagelist
  [chapter]
  [cow, mill, dummy]

\startchapter [title=First Chapter]
  \startsection [title=Some section]
    \fakewords{500}{1000}
  \stopsection
\stopchapter

\startchapter [title=Second Chapter]
  \startsection [title=Some other section]
    \fakewords{500}{1000}
  \stopsection
\stopchapter

\startchapter [title=Third Chapter]
  \startsection [title=Some new section]
    \fakewords{500}{1000}
  \stopsection
\stopchapter

\stoptext

The result is the same as in the screen shots above. All credits for the code go to phg, all bugs are mine :)

Due to the mkvi syntax, the code should be self-explanatory. What it basically does, is creating a list of macros named after the section level (here “chapter”) and a number that increments with each image. These macros typeset the image with \externalfigure. The rest is similar to the first code.

[Tex/LaTex] How to get coordinates going from 0 to 1 in tikz image

Since the image is scaled so that it covers the entire page, then all that is required is the width and the height of the paper to set the shift and the scale transformations. This could be done using the shift, x and y keys but I have defined a custom page cs coordinate system so that it is possible to use coordinates like (1,1) in the usual way:

\documentclass[a4paper]{article}
\usepackage{tikz}
\begin{document}
\tikzset{page cs/.cd, x/.store in=\px, y/.store in=\py}
\tikzdeclarecoordinatesystem{page}{%
  \tikzset{page cs/.cd, #1}% 
  \pgfpointadd{\pgfpointanchor{current page}{south west}}%
    {\pgfpoint{\px*\paperwidth}{\py*\paperheight}}%
}
\thispagestyle{empty}
\begin{tikzpicture}[remember picture,overlay]
\node at (current page.center)
{\includegraphics[height=\paperheight]{example-image}};
\fill [white, opacity=0.5] (page cs:x=0,y=0) rectangle (page cs:x=1,y=1/3);
\foreach \x in {0,.125,...,1}
  \foreach \y in {0,.125,...,1}
    \fill (page cs:x=\x,y=\y) circle [radius=1/10] node[above] {\tt(\x,\y)};
\end{tikzpicture}
\end{document}

enter image description here

[Tex/LaTex] ConTeXt: Expand background image to fill page

Background

Code

Update

Layer

Problem

Related

Additional Information

Question

Best Answer

Related Question

Background

Code

Update

Layer

Problem

Related

Additional Information

Question

Best Answer

Related Solutions

[Tex/LaTex] How to add illustrations before chapter titles in ConTeXt

How it works

Things to improve

[Tex/LaTex] How to get coordinates going from 0 to 1 in tikz image

Related Question