Demonstration of issues with height of fonts gotten from PIL.

image_height_issue.py

from __future__ import absolute_import, division, print_function, unicode_literals

"""
I'm trying to create fonts with a specific pixel height and then render them
into a box.

Unfortunately, the actual height of the font that's created is always somewhat
larger than the requested height.  How do I create a font that has exactly the
right height?

"""


import sys

from PIL import Image, ImageDraw, ImageFont

TEXT = '||| ABCDEFGHIJKLMNOPQRSTUVWYZabcdefghijklmnopqrstuvwyz |||'

try:
  FONT_FILE = sys.argv[1]
except:
  FONT_FILE = 'DejaVuSansMono-Bold.ttf'

try:
  HEIGHT = int(sys.argv[2])
except:
  HEIGHT = 12

font = ImageFont.truetype(FONT_FILE, HEIGHT)
width, height = font.getsize(TEXT)
offset = font.getoffset(TEXT)
image = Image.new('RGBA', (width, height))
draw = ImageDraw.Draw(image)
draw.text((-offset[0], -offset[1]), text=TEXT, font=font)

image.show()
print('width=%d, height=%d, SLOP=%d' % (width, height, height - HEIGHT))