Added support for page background (#138)

- The variable `page-background` specifies the path to a background image for any page. The background image is scaled to cover the entire page.
- The variable `page-background-opacity` specifies the background image opacity and has a default value of `0.2`.

README.md

@@ -76,6 +76,14 @@ This template defines some new variables to control the appearance of the result
 
     the path to a background image for the title page. The background image is scaled to cover the entire page. In the examples folder under `titlepage-background` are a few example background images.
 
+  - `page-background`
+
+    the path to a background image for any page. The background image is scaled to cover the entire page. In the examples folder under `page-background` are a few example background images.
+
+  - `page-background-opacity` (defaults to `0.2`)
+
+    the background image opacity
+
   - `caption-justification` (defaults to `raggedright`)
 
     justification setting for captions (uses the `justification` parameter of the [caption](https://ctan.org/pkg/caption?lang=en) package)

eisvogel.tex

@@ -531,6 +531,10 @@ $endfor$
 \fi
 $endif$
 
+$if(page-background)$
+\usepackage[pages=all]{background}
+$endif$
+
 %
 % for the background color of the title page
 %
@@ -828,6 +832,17 @@ $else$
   \renewcommand{\footrulewidth}{0.4pt}
 }
 \pagestyle{eisvogel-header-footer}
+$if(page-background)$
+\backgroundsetup{
+scale=1,
+color=black,
+opacity=$if(page-background-opacity)$$page-background-opacity$$else$0.2$endif$,
+angle=0,
+contents={%
+  \includegraphics[width=\paperwidth,height=\paperheight]{$page-background$}
+  }%
+}
+$endif$
 $endif$
 $endif$