MetaFun - Pragma ADE

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pickup pencircle scaled .5cm ;
filldraw unitsquare xscaled 8cm yscaled 1cm withcolor .625white ;
path bb ; bboxmargin := 0pt ; bb := bbox currentpicture ;
draw bb withpen pencircle scaled 1pt withcolor .625red ;
draw origin withpen pencircle scaled 5pt withcolor .625yellow ;
The resulting graphic has the bounding box of the fill. Note how the path, because it is stroked with
a .5cm pen, extends beyond the border of the previous bounding box. The way this image shows
up depends on the viewer (settings) you use to render the graphic. For example, in GHOSTVIEW, if
you disable clipping to the bounding box, only the positive quadrant of the graphic is shown. 4
From the previous examples, you can conclude that the following alternative results in a proper
bounding box:
pickup pencircle scaled .5cm ;
path p ; p := unitsquare xscaled 8cm yscaled 1cm ;
fill p withcolor .625white ;
draw p withcolor .625white ;
path bb ; bboxmargin := 0pt ; bb := bbox currentpicture ;
draw bb withpen pencircle scaled 1pt withcolor .625red ;
draw origin withpen pencircle scaled 5pt withcolor .625yellow ;
The CONTEXT distribution comes with a set of METAPOST modules, one of which contains the
drawfill macro, which provides the outer bounding box. 5 Next we demonstrate its use in another,
more complicated example.
picture finalpicture ; finalpicture := nullpicture ;
numeric n ; n := 0 ; bboxmargin := 0pt ;
pickup pencircle scaled .5cm ;
def shape =
unitsquare scaled 2cm withcolor .625white ;
draw bbox currentpicture
withpen pencircle scaled .5mm withcolor .625red ;
addto finalpicture also currentpicture shifted(n*3cm,0) ;
currentpicture := nullpicture ; n := n+1 ;
enddef ;
Old versions of METAPOST calculated the boundingbox differently for a filldraw: through the middle of the penpath.
Starting from version 1.0 METAPOST calculates the boundingbox differently and the distinction between drawfill and
filldraw is gone. We keep them around both for compatibility.
A few more details Bounding boxes