from reportlab.pdfgen import canvas
from reportlab.lib.pagesizes import A4
from reportlab.lib.units import mm


width, height = (181.7 * mm, 256.8 * mm)
numv = int((width - ((17 + 4) * mm)) / (5 * mm))
numh = int((height / 2.0 - (5 + 5) * mm) / (5 * mm))
voff = 17 * mm
hoff = (height / 2 - numh * 5 * mm) / 2.0
c = canvas.Canvas("b6.pdf", pagesize=(width, height))

# Draw grid
c.setLineWidth(0.15)
c.setStrokeColorRGB(0.5, 0.5, 1)
for xi in xrange(numv + 1):
    c.line(xi * mm * 5 + voff, hoff,
           xi * mm * 5 + voff, hoff + numh * mm * 5)
    c.line(xi * mm * 5 + voff, height - hoff,
           xi * mm * 5 + voff, height - (hoff + numh * mm * 5))

for yi in xrange(numh + 1):
    c.line(voff, hoff + yi * mm * 5,
           voff + numv * mm * 5, hoff + yi * mm * 5)
    c.line(voff, height - (hoff + yi * mm * 5),
           voff + numv * mm * 5, height - (hoff + yi * mm * 5))

# Draw horizontal center
c.setDash(1)
c.setStrokeColorRGB(0.5, 0.5, 1)
c.circle(5 * mm, height / 4, 0.5, fill=1)
c.circle(5 * mm, height / 4 * 3, 0.5, fill=1)

# Draw splitter line
c.setDash([3, 3])
c.setStrokeColorRGB(0.4, 0.4, 0.4)
c.line(0, height / 2, width, height / 2)

c.save()