Tcolorbox set background color (colback) to color gradient / gradient to transparent

gradienttcolorboxtransparent

I wish to create a tcolorbox with a background that fades from a solid color to white, or even transparent, to be able to use it everywhere.

I have tried using [enhanced jigsaw, frame style={left color=black, right color=white}], but that only changes the color of the frame around the tcolorbox, not of the background. And the only option to change the opacity of the background that I could find (opacityback) seems to change everything at once.

The following is my box so far. The gradient you see in the frame is nice, but not what I want. I'd like the background (entirely transparent here) to fade from black to white/transparent.

The code for this box is as follows:

\usepackage[skins]{tcolorbox}

\begin{document}
\begin{tcolorbox}[title=My tcolorbox, boxrule=2mm, enhanced jigsaw,  frame style={left color=black, right color=white}, opacityback=0]
(Text content of the box, irrelevant)
\end{tcolorbox}
\end{document}

Best Answer

You want interior style, not frame style:

\documentclass{report}

\usepackage[skins]{tcolorbox}

\begin{document}
\begin{tcolorbox}[title=My tcolorbox, boxrule=2mm, enhanced jigsaw,
  frame style={left color=black, right color=white}, %opacityback=0, removed
  interior style={left color=black, right color=white} % added
]
(Text content of the box, irrelevant)
\end{tcolorbox}
\end{document}

Related Solutions

[Tex/LaTex] Color gradient as background in margins

The solution below defines two alternative ways of drawing a coloured gradient in the margin background on a selection of pages:

Invoke the \conditionalmarginbg (which takes no argument) at the beginning of your document and then toggle the margin background on/off in your document by using the \startdrawmarginbg and \stopdrawmarginbg macros.
Invoke \marginbgpagelist at the beginning of your document; its only argument is a list of pages on which to draw a margin background. That list uses pgffor's \foreach syntax, so you can specify 10,...,20 to draw a margin back on pages 10 to 20.

In the example below, I used \conditionalmarginbg and, for visualisation, I emphasised (red, bold text) where \startdrawmarginbg and \stopdrawmarginbg are invoked.

Notes:

You'll need to run pdflatex no fewer than 3 times to get the correct output.
I presume you need(ed) this for a book, so I didn't bother making my solution compatible with the oneside class option. It works fine with twoside, though.

References:

Claudio Fiandrino's answer to How to set colored ruled margins for different pages?

enter image description here

\documentclass[twoside]{book}

\usepackage{lipsum}                         % for filler text
\usepackage[margin=3cm]{geometry}           % for setting the dimensions
\usepackage{tikzpagenodes}                      
\usepackage{background}
    \backgroundsetup%
    {%
        contents    = {},%
        opacity     = 1,%
        scale       = 1,
    }
\usepackage{etoolbox}                       % defines the \ifnumodd macro
\usepackage{xcolor}



% Let's define some colours for this colour gradient
\definecolor{outercolor}{gray}{.7}
\definecolor{innercolor}{gray}{1}

% a switch for toggling margin background on/off
\newif\ifdrawmarginbg\drawmarginbgfalse
\newcommand\startdrawmarginbg{\drawmarginbgtrue}
\newcommand\stopdrawmarginbg{\drawmarginbgfalse}

% redefinition of \emph, just to show where
% my \startdrawmarginbg and \stopdrawmarginbg are invoked in the example
\renewcommand\emph[1]{\textcolor{red}{\bfseries#1}}


% ----- Two possible strategies -----

% --- \conditionalmarginbg ---
% Invoke the following macro at the beginning of the document and then
% use \startdrawmarginbg and \stopdrawmarginbg to toggle the margin background
% gradient on/off in the document.
\newcommand\conditionalmarginbg%
{%
    \AddEverypageHook%
    {%
        \ifdrawmarginbg%
            \thispagemarginbg%
        \fi%
    }%
}

% --- \marginbgpagelist ---
% Invoke the following macro at the beginning of the document.
% It's only (mandatory) argument is a list (using pgffor's \foreach syntax)
% corresponding to the pages on which a margin background gradient
% should be drawn.
\newcommand\marginbgpagelist[1]%
{%
    \AddEverypageHook%
    {%
        \foreach \p in {#1}%
        {%
            \ifnum\value{page}=\p%
                \thispagemarginbg%
            \fi
        }%
    }%
}


% ----- Auxiliary macros ----- 

% Auxiliary macro for both \conditionalmarginbg and \marginbgpagelist
\newcommand\thispagemarginbg
{%
    \ifnumodd{\value{page}}
        {\marginbgevenorodd{1}}
        {\marginbgevenorodd{0}}
    \BgMaterial
}%

% Auxiliary macro for \thispagemarginbg
\newcommand\marginbgevenorodd[1]%
{%
    \ifnum#1=1%
        \def\shadeangle{90}
        \def\marginrectangle
        {%
            (current page marginpar area.south west |- current page.south)%
            rectangle%
            (current page.north east)
        }
    \else%
        \ifnum#1=0%

            \def\shadeangle{-90}
            \def\marginrectangle
            {%
                (current page marginpar area.south east |- current page.south)%
                rectangle%
                (current page.north west)
            }
        \else%
            \errmessage{Incompatible value supplied to \string\marginbgevenorodd}   
        \fi%
    \fi%
    \backgroundsetup
    {%
        angle=0,%
        contents=%
        {%
            \tikz[remember picture,overlay]
            \shade
            [%
                bottom color    = outercolor,%
                top color       = innercolor,%
                shading angle   = \shadeangle,%
            ] \marginrectangle;%
        }%                  
    }%
}

% Use either...
% \marginbgpagelist{2,3,...,4}
% or...
\conditionalmarginbg

\begin{document} 

\lipsum[1-10]

\emph{A margin background gradient is drawn from this page onwards.}
\startdrawmarginbg

\lipsum[21-40]

\emph{No margin background gradient is drawn from this page onwards.}
\stopdrawmarginbg

\lipsum[41-50]

\end{document}

[Tex/LaTex] Background color gradient for entire document

\documentclass[x11names]{report}
\usepackage{background}
\usepackage{blindtext}
\backgroundsetup{
scale=1,
angle=0,
opacity=1,
contents={\begin{tikzpicture}[remember picture,overlay]
 \path [left color = Gold2,middle color = Gold2!30, right color = white] (current page.south west)rectangle (current page.north east);   % Adjust the position of the logo.
\end{tikzpicture}}
}
\begin{document}
\blinddocument

\end{document}

enter image description here

I have chosen a conspicuous color. You may choose any color of your choice.

Best Answer

Related Solutions

[Tex/LaTex] Color gradient as background in margins

[Tex/LaTex] Background color gradient for entire document

Related Question