[Tex/LaTex] Gradient to transparent (horizontal) for beamer frametitle

beamergradienttikz-pgf

I would like my frametitle bg to fade horizontally to a background image.

I have attempted to modify the solution for vertical gradients found here: Beamer theme with fading (=gradient to transparent) to background image by replacing "fade bottom" with "fade right", etc. However I cannot get the frametitle to appear within the horizontally faded area (or to overlay any other text in this area)—the solution given here creates a faded overlay beneath the frame title (whereas I want the faded overlay to be behind the title). Essentialy, what I want is a fade-to-transparent version of what is found here: How can I have a horizontally shaded frametitle in beamer?

I am using the Madrid theme.

I would much appreciate any help you can offer.

Thanks!

Edit: (apologetically inelegant) code follows:

\documentclass[aspectratio=169]{beamer}
\usetheme{Madrid}

%For the semi-transparent text boxes
\usepackage[framemethod=tikz]{mdframed}
\newmdenv[tikzsetting={draw=black,fill=tan,fill opacity=0.92, line width=0pt},
backgroundcolor=none,leftmargin=10,rightmargin=10,innertopmargin=4pt]
{titleBox}

\usepackage{ragged2e}
\usepackage{etoolbox,color,amsfonts}
\justifying
\title{My title}
\author[me]{Me}
\institute{My institute}
\date{Date}

%For the semi-transparent footline
\setbeamertemplate{footline}
{
\leavevmode%
\hbox{%
\pgfsetfillopacity{.65}\begin{beamercolorbox}[wd=.333333\paperwidth,ht=2.25ex,dp=1ex,center]{author in head/foot}%
\usebeamerfont{author in head/foot}\pgfsetfillopacity{1}\insertshortauthor~~(\insertshortinstitute)
\end{beamercolorbox}%
\pgfsetfillopacity{.75}\begin{beamercolorbox}[wd=.333333\paperwidth,ht=2.25ex,dp=1ex,center]{title in head/foot}%
\usebeamerfont{title in head/foot}\pgfsetfillopacity{1}\insertshorttitle
\end{beamercolorbox}%
\pgfsetfillopacity{.65}\begin{beamercolorbox}[wd=.333333\paperwidth,ht=2.25ex,dp=1ex,right]{date in head/foot}%
\usebeamerfont{date in head/foot}\pgfsetfillopacity{1}\insertshortdate{}\hspace*{2em}
\insertframenumber{} / \inserttotalframenumber\hspace*{2ex}
\end{beamercolorbox}}%
\vskip0pt%
}

%Various color/structure definitions (some of the custom colors are used elsewhere)
\definecolor{tan}{RGB}{244,229,192}
\definecolor{mypurple}{RGB}{88,68,70}
\definecolor{mytan}{RGB}{255,199,0}
\definecolor{wyte}{RGB}{210,210,210}
\setbeamercolor*{palette primary}{use=structure,fg=tan,bg=mypurple}
\setbeamercolor*{palette secondary}{use=structure,fg=mypurple,bg=tan}
\setbeamercolor*{palette tertiary}{use=structure,fg=tan,bg=mypurple}
\setbeamercolor{item projected}{fg=white,bg=mypurple}
\setbeamertemplate{enumerate items}[default]
\setbeamertemplate{navigation symbols}{}
\setbeamercolor{block title}{fg=mypurple}
\setbeamercolor{local structure}{fg=mypurple}
\setbeamertemplate{itemize item}[triangle]
\setbeamercolor{block title}{fg=white,bg=mypurple}
\setbeamercolor{block body}{fg=black,bg=wyte}
\setbeamercolor{title}{fg=black, bg=mytan}
\setbeamertemplate{title page}[default][colsep=-4bp,rounded=true]
\setbeamercolor*{frametitle}{fg=tan}

\usepackage{graphicx}

%For background image
\usebackgroundtemplate%
{%
\includegraphics[width=\paperwidth,height=\paperheight]{intro.jpg}%
}

\begin{document}

\begin{frame
\begin{titleBox}
\begin{center}
My Title
\end{center}
\end{titleBox}
\end{frame}

\begin{frame}{Introduction}%The title bg here is what I want to fade; but not the fg
\begin{titleBox}
Goal of the talk...
\end{titleBox}

\end{frame}
\end{document}

Best Answer

Here is a solution. It's rather inelegant as it involves vertical re-positioning of separate boxes---one for the fade, and a separate for the frametitle. The right hand side of the fade is somewhat sharper than I'd like, but here goes the relevant code addition:

\usepackage{tikz}
\usetikzlibrary{fadings}%To set up the fade parameters
\begin{tikzfadingfrompicture}[name=fade right]
\shade[left color=transparent!15,
right color=transparent!100] (0,0) rectangle (2,2);
\end{tikzfadingfrompicture}

\setbeamertemplate{headline}
{
\hbox{%For the fade box---this has to come first otherwise the title won't appear ``on top'' of the faded box                                                                                                                                                                                                            
\tikz\fill[scale=1.5,path fading= fade right, mypurple] (0,0) rectangle (.45\paperwidth,0.5);
        }%

\vspace{-3.5em} 

\hbox{%For the frame title
\pgfsetfillopacity{0}\begin{beamercolorbox}[wd=\paperwidth,ht=5.5ex,dp=3ex,left]{frame title}%
\usebeamerfont{frame title}\pgfsetfillopacity{1}\hspace{1em}{\large\insertframetitle}
\end{beamercolorbox}}%
}
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