The Adobe Type 1 Font Format book (PDF: 445 KB) - Adobe Partners

mtx currentmatrix pop
mtx 0 get abs .00001 lt mtx 3 get abs .00001 lt or
{/flipXY -1 def }
{mtx 1 get abs .00001 lt mtx 2 get abs .00001 lt or
{/flipXY 1 def }
{/flipXY 0 def }
ifelse }
ifelse
/erosion 1 def
systemdict /internaldict known {
1183615869 systemdict /internaldict get exec dup
/erosion known
{/erosion get /erosion exch def}
{pop}
ifelse
} if
yflag
{flipXY 0 eq c3y2 c4y2 eq or
{false PickCoords }
{/shrink c3y2 c4y2 eq
{0}{c1y2 c4y2 sub c3y2 c4y2 sub div abs} ifelse def
/yshrink {c4y2 sub shrink mul c4y2 add} def
/c1y0 c3y0 yshrink def /c1y1 c3y1 yshrink def
/c2y0 c4y0 yshrink def /c2y1 c4y1 yshrink def
/c1x0 c3x0 def /c1x1 c3x1 def /c2x0 c4x0 def /c2x1 c4x1 def
/dY 0 c3y2 c1y2 sub round
dtransform flipXY 1 eq {exch} if pop abs def
dY dmin lt PickCoords
y2 c1y2 sub abs 0.001 gt {
c1x2 c1y2 transform flipXY 1 eq {exch} if
/cx exch def /cy exch def
/dY 0 y2 c1y2 sub round dtransform flipXY 1 eq {exch}
if pop def
dY round dup 0 ne
{/dY exdef }
{pop dY 0 lt {-1}{1} ifelse /dY exdef }
ifelse
/erode PaintType 2 ne erosion 0.5 ge and def
erode {/cy cy 0.5 sub def} if
/ey cy dY add def
/ey ey ceiling ey sub ey floor add def
erode {/ey ey 0.5 add def} if
ey cx flipXY 1 eq {exch} if itransform exch pop
y2 sub /eShift exch def
/y1 y1 eShift add def /y2 y2 eShift add def /y3 y3
eShift add def
} if
} ifelse
}
{flipXY 0 eq c3x2 c4x2 eq or
Appendix 3: OtherSubrs Programs 93