MetaFun - Pragma ADE

4.2 Overlay variables
[offset=3pt,frameoffset=6pt,backgroundoffset=9pt,
background=screen,backgroundscreen=.85]
{Welcome in the hall of frame!}}
Welcome in the hall of frame!
Figure 4.2 The three offsets.
The communication between TEX and embedded METAPOST graphics takes place by means of some
macros.
overlay status macro meaning
\overlaywidth the width of the graphic, as calculated from the actual width and background
offset
\overlayheight the height of the graphic, as calculated from the actual height, depth and
background offset
\overlaydepth the depth of the graphic, if available
\overlaycolor the background color, if given
\overlaylinecolor the color of the frame
\overlaylinewidth the width of the frame
The dimensions of the overlay are determined by dimensions of the background, which normally
is the natural size of a \framed. When a background offset is specified, it is added to
overlayheight and overlaywidth.
Colors can be converted by \MPcolor and in addition to the macros mentioned, you can use all
macros that expand into a dimension or dimen register prefixed by the TEX primitive \the (this
and other primitives are explained in “The TEXbook”, by Donald Knuth).
4.3 Stacking overlays
A background can be a gray scale (screen), a color (color), a previously defined overlay identifier,
or any combination of these. The next assignments are therefore legal:
\framed[background=color,backgroundcolor=red]{...}
\framed[background=screen,backgroundscreen=.8]{...}
\framed[background=circle]{...}
\framed[background={color,cow},backgroundcolor=red]{...}
\framed[background={color,cow,grid},backgroundcolor=red]{...}
In the last three cases of course you have to define circle, cow and grid as overlay. These items
are packed in a comma separated list, which is to be surrounded by {}.
Overlay variables Enhancing the layout
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