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|
"""abc.py
Implements a 'music' directive that accepts musical passages written
in ABC notation. Requires that abcm2ps and Ghostscript be installed.
.. music::
% Sample file to test various features of abc2ps
X:1
T:Scale
M:C
K: clef=bass
"C,"C,"D,"D,
"""
import os, sys, tempfile, popen2
from docutils import nodes
from docutils.parsers.rst.directives import register_directive
music_counter = 1
def ABCDirective (name, arguments, options, content, lineno,
content_offset, block_text, state, state_machine):
abc_temp = tempfile.NamedTemporaryFile("wt")
abc_temp.write("\n".join(content))
abc_temp.flush()
fd, ps_temp = tempfile.mkstemp()
global music_counter
output_path = state.document.settings._destination or '.'
output_name = os.path.join(output_path, 'music-%i.png' % music_counter)
music_counter += 1
sts1 = sts2 = sts3 = 0
pipe = popen2.Popen3('abcm2ps -O/dev/stdout - < %s > %s'
% (abc_temp.name, ps_temp),
capturestderr=True
)
pipe.tochild.close()
pipe.fromchild.read()
errors = pipe.childerr.read()
errors = parse_errors(errors, lineno)
sts1 = pipe.wait()
if sts1 == 0:
sts2 = os.system('gs -q -sOutputFile=%s -sDEVICE=pngmono - <%s'
% (output_name, ps_temp))
if sts2 == 0:
sts3 = os.system('gs -q -sOutputFile=%s -sDEVICE=pngmono - <%s'
% (output_name, ps_temp))
try:
os.unlink(ps_temp)
except os.error:
pass
abc_temp.close()
if sts1 != 0 or sts2 != 0:
error = state_machine.reporter.error(
'Error processing music directive:\n\t' +
('\n\t'.join(errors)),
nodes.literal_block(block_text, block_text),
line=lineno)
return [error]
else:
# Crop excess whitespace from the image
crop_image(output_name)
# Return an image directive.
options['uri'] = os.path.basename(output_name)
return [nodes.image(output_name, **options)]
import re
error_pat = re.compile('(in line )(\d+)')
def parse_errors (errors, line_start):
lines = errors.split('\n')
lines = [ line for line in lines if line.startswith('Error')]
def f (m):
return m.group(1) + str(line_start+int(m.group(2)))
lines = [ error_pat.sub(f, line) for line in lines]
return lines
def crop_image (filename):
"""Reads the image specified by filename, crops excess space off it,
and writes it out to the same file."""
from PIL import Image
image = Image.open(filename)
for edge in 'NSWE':
image = _crop(image, edge)
image.save(filename)
def _crop (image, edge):
im_x, im_y = image.size
if edge == 'N':
start = (0,0)
scan_increment = (1,0)
line_increment = (0,1)
elif edge == 'S':
start = (0,im_y-1)
scan_increment = (1,0)
line_increment = (0,-1)
elif edge == 'E':
start = (im_x-1,0)
scan_increment = (0,1)
line_increment = (-1,0)
elif edge == 'W':
start = (0,0)
scan_increment = (0,1)
line_increment = (1,0)
# Look for blank lines
def is_white (color):
return color == 255
def is_blank (x,y):
x_inc, y_inc = scan_increment
while 0 <= x < im_x and 0 <= y < im_y:
point = image.getpixel((x,y))
if not is_white(point):
return False
x += x_inc
y += y_inc
return True
# Look for blank edges, jumping in increments of JUMP pixels.
JUMP = 5
x, y = start
x_inc, y_inc = line_increment
while is_blank(x,y):
x += x_inc * JUMP
y += y_inc * JUMP
# Found a non-blank line, so scan back
x -= x_inc
y -= y_inc
while not is_blank(x,y):
x -= x_inc
y -= y_inc
# OK; x,y are now on the first blank line, so crop it
if edge == 'N':
box = (0,y, im_x, im_y)
elif edge == 'S':
box = (0,0, im_x, y)
elif edge == 'E':
box = (0,0, x, im_y)
elif edge == 'W':
box = (x,0, im_x, im_y)
image = image.crop(box)
image.load()
return image
ABCDirective.content = True
def register():
register_directive('music', ABCDirective)
|
