\starttext

\startbuffer[MyText]
     \definedfont[name:texgyrepagellabold*default]foo f o o%
\stopbuffer

\startbuffer[MyText]
     \framed[align=normal,frame=off]{a sample text}%
\stopbuffer

\setbox\scratchbox\hbox\bgroup
     \startMPcode
          draw lmt_outline [
              kind = "outline",
              text = "\getbuffer[MyText]",
          ]
              withshademethod "linear"
              withshadedirection down
              withshadecolors (red, blue)
          ;
     \stopMPcode
\egroup

\startoverlay

{\scale[height=\htdp\scratchbox,width=\wd\scratchbox]{\effect[hidden]{\getbuffer[MyText]}}}
     {\box\scratchbox}
\stopoverlay

\stoptext