For TD User:

I use a method in Topdown Library (in tdCPrn3)

//~ determine text width of a particular string in a given font
method tdcPrn3:TextWidth(cText,nWidth)
local nLen,aPts,nTxtWd,cText2,i,nLen2

cText2 := left(cText, nWidth)
nLen := len(cText2)
whil .t.
i  := len(cText2)
aPts := GraQueryTextBox(::oPs,cText2)
** nTxtWd := int(((aPts[3,1] - aPts[1,1]) / ::nPPt) + 0.5)
nTxtWd := int(((aPts[3,1] - aPts[1,1]) / ::nPt) + 0.5)
if nTxtWd >= nWidth .or. i == 0 .or. len(cText2) >= len(cText)
  nLen := i
  exit
else
  cText2 += subs(cText, len(cText2)+1,1)
endif
enddo

return nLen

************************************************
//~ determine font point size to print a particular string in a given width
method tdcPrn3:TextPoint(cText,nWidth)
local aPts,nTxtWd,i,cNewFont
LOCAL cOldFont := tdStrnum(::oFont:nominalPointSize)+"."+::oFont:compoundName

cNewFont := cOldFont
whil .t.
::newFont(cNewFont)
aPts := GraQueryTextBox(::oPs,cText)
//nTxtWd := int(((aPts[3,1] - aPts[1,1]) / ::nPPt) + 0.5)
nTxtWd := int(((aPts[3,1] - aPts[1,1]) / ::nPt) + 0.5)
if nTxtWd <= nWidth .or. i == 6
  exit
else
  i   := ::oFont:nominalPointSize -1
  cNewFont := tdStrnum(i)+"."+::oFont:compoundName
endif
enddo
::newFont(cOldFont)

return cNewFont

Anand