Font metrics. The only way to generate accurate images
in any format that contain text is to know the font metrics.
Specifically, we need to know the width of every character and the
maximum height (since we want all characters to fit within same line height).
I used ttf2tfm to dump the font metrics from Mac TrueType fonts and
then converted that to a Java class for use in a PostScript generator
for trees. Commands:
$ ttf2tfm /Library/Fonts/Arial\ Black.ttf > metrics
Then run metrics into python code after stripping header/footer:
#
# Process lines from ttf2tfm that look like this:
# Glyph Code Glyph Name Width llx lly urx ury
# ------------------------------------------------------------------------
# 3 00020 space 333 0, 0 -- 0, 0
#
lines = open("metrics").read().split('\n')
print "public class FontName {"
print " {"
maxh = 0;
for line in lines[4:]: # skip header 0..3
all = line.split(' ')
words = [x for x in all if len(x)>0]
ascii = int(words[1], 16)
height = int(words[8])
if height>maxh: maxh = height
if ascii>=128: break
print " widths[%d] = %s; // %s" % (ascii, words[3], words[2])
print " maxCharHeight = "+str(maxh)+";"
print " }"
print "}"
Units are 1000th of an 'em'.