"""Class to create pdfs from images"""

def __init__(self, gs):

self.load_invisible_font()

self.gs = gs # Pointer to ghostscript object

pass

def mergeRotateAroundPointPage(self,page, page2, rotation, tx, ty):

# Code taken from here:

# http://stackoverflow.com/questions/6041244/how-to-merge-two-landscape-pdf-pages-using-pypdf/17392824#17392824

# Unclear why PyPDF2 builtin page rotation functions don't work

translation = [[1, 0, 0],

[0, 1, 0],

[-tx,-ty,1]]

rotation = math.radians(rotation)

rotating = [[math.cos(rotation), math.sin(rotation),0],

[-math.sin(rotation),math.cos(rotation), 0],

[0, 0, 1]]

rtranslation = [[1, 0, 0],

[0, 1, 0],

[tx,ty,1]]

ctm = utils.matrixMultiply(translation, rotating)

ctm = utils.matrixMultiply(ctm, rtranslation)

return page.mergeTransformedPage(page2, [ctm[0][0], ctm[0][1],

ctm[1][0], ctm[1][1],

ctm[2][0], ctm[2][1]])

def overlay_hocr_pages(self, dpi, hocr_filenames, orig_pdf_filename):

logging.debug("Going to overlay following files onto %s" % orig_pdf_filename)

# Sort the hocr_filenames into natural keys!

hocr_filenames.sort(key=lambda x: self.natural_keys(x[0] ))

logging.debug(hocr_filenames)

pdf_dir, pdf_basename = os.path.split(orig_pdf_filename)

basename = os.path.splitext(pdf_basename)[0]

pdf_filename = os.path.join(pdf_dir, "%s_ocr.pdf" % (basename))

text_pdf_filenames = []

for img_filename, hocr_filename in hocr_filenames:

text_pdf_filename = self.overlay_hocr_page(dpi, hocr_filename, img_filename)

logging.info("Created temp OCR'ed pdf containing only the text as %s" % (text_pdf_filename))

text_pdf_filenames.append(text_pdf_filename)

writer = PdfFileWriter()

orig = open(orig_pdf_filename, 'rb')

for orig_pg, text_pg_filename in zip(self.iter_pdf_page(orig), text_pdf_filenames):

text_file = open(text_pg_filename, 'rb')

text_pg = self.iter_pdf_page(text_file).next()

orig_rotation_angle = int(orig_pg.get('/Rotate', 0))

if orig_rotation_angle != 0:

logging.info("Original Rotation: %s" % orig_pg.get("/Rotate", 0))

self.mergeRotateAroundPointPage(orig_pg, text_pg, orig_rotation_angle, text_pg.mediaBox.getWidth()/2, text_pg.mediaBox.getWidth()/2)

# None of these commands worked for me:

#orig_pg.rotateCounterClockwise(orig_rotation_angle)

#orig_pg.mergeRotatedPage(text_pg,text_rotation_angle)

else:

orig_pg.mergePage(text_pg)

orig_pg.compressContentStreams()

writer.addPage(orig_pg)

with open(pdf_filename, 'wb') as f:

# Flush out this page merge so we can close the text_file

writer.write(f)

text_file.close()

orig.close()

for fn in text_pdf_filenames:

os.remove(fn)

logging.info("Created OCR'ed pdf as %s" % (pdf_filename))

return pdf_filename

def _get_img_dims(self, img_filename):

"""

:rval: (width, height, dpi)

"""

img = Image.open(img_filename)

w,h = img.size

dpi = img.info['dpi']

width = w*72.0/dpi[0]

height = h*72.0/dpi[1]

del img

return (width, height, dpi)

def overlay_hocr_page(self, dpi, hocr_filename, img_filename):

hocr_dir, hocr_basename = os.path.split(hocr_filename)

img_dir, img_basename = os.path.split(img_filename)

logging.debug("hocr_filename:%s, hocr_dir:%s, hocr_basename:%s" % (hocr_filename, hocr_dir, hocr_basename))

assert(img_dir == hocr_dir)

#basename = hocr_basename.split('.')[0]

basename = os.path.splitext(hocr_basename)[0]

pdf_filename = os.path.join("text_%s_ocr.pdf" % (basename))

# Switch to the hocr directory to make this easier

cwd = os.getcwd()

if hocr_dir != "":

os.chdir(hocr_dir)

with open(pdf_filename, "wb") as f:

logging.info("Overlaying hocr and creating text pdf %s" % pdf_filename)

pdf = Canvas(f, pageCompression=1)

pdf.setCreator('pypdfocr')

pdf.setTitle(os.path.basename(hocr_filename))

pdf.setPageCompression(1)

width, height, dpi_jpg = self._get_img_dims(img_basename)

pdf.setPageSize((width,height))

logging.info("Page width=%f, height=%f" % (width, height))

pg_num = 1

logging.info("Adding text to page %s" % pdf_filename)

self.add_text_layer(pdf,hocr_basename,pg_num,height,dpi)

pdf.showPage()

pdf.save()

os.chdir(cwd)

return os.path.join(hocr_dir, pdf_filename)

def iter_pdf_page(self, f):

reader = PdfFileReader(f)

for pgnum in range(reader.getNumPages()):

pg = reader.getPage(pgnum)

yield pg

def _atoi(self,text):

return int(text) if text.isdigit() else text

def natural_keys(self, text):

'''

alist.sort(key=natural_keys) sorts in human order

http://nedbatchelder.com/blog/200712/human_sorting.html

(See Toothy's implementation in the comments)

'''

return [ self._atoi(c) for c in re.split('(\d+)', text) ]

def add_text_layer(self,pdf, hocrfile, page_num,height, dpi):

"""Draw an invisible text layer for OCR data"""

p1 = re.compile('bbox((\s+\d+){4})')

p2 = re.compile('baseline((\s+[\d\.\-]+){2})')

hocr = ElementTree()

hocr.parse(hocrfile)

logging.debug(xml.etree.ElementTree.tostring(hocr.getroot()))

for c in hocr.getroot(): # Find the <body> tag

if c.tag != 'body':

continue

for page in c: # Each child in the body is a page tag

if (page.attrib['class'] != "ocr_page"):

assert ("Why is this hocr not paging properly??")

if page.attrib['id'] == 'page_%d' %(page_num):

break

for line in page.findall(".//{http://www.w3.org/1999/xhtml}span"):

#for line in page.findall(".//span"):

if line.attrib['class'] != 'ocr_line':

continue

linebox = p1.search(line.attrib['title']).group(1).split()

try:

baseline = p2.search(line.attrib['title']).group(1).split()

except AttributeError:

baseline = [ 0, 0 ]

linebox = [float(i) for i in linebox]

baseline = [float(i) for i in baseline]

for word in line:

if word.attrib['class'] != 'ocrx_word':

continue

word_text = []

for child in word.iter():

if child.text:

word_text.append(child.text)

word.text = ' '.join(word_text)

logging.debug(word.text)

#for child in word:

#if child.tag:

#word.text = child.text

if word.text is None:

continue

font_width = pdf.stringWidth(word.text.strip(), 'invisible', 8)

if font_width <= 0:

continue

box = p1.search(word.attrib['title']).group(1).split()

box = [float(i) for i in box]

b = self.polyval(baseline, (box[0] + box[2]) / 2 - linebox[0]) + linebox[3]

text = pdf.beginText()

text.setTextRenderMode(3) # double invisible

text.setFont('invisible', 8)

text.setTextOrigin(box[0] * 72 / dpi, height - b * 72 / dpi)

box_width = (box[2] - box[0]) * 72 / dpi

text.setHorizScale(100.0 * box_width / font_width)

text.textLine(word.text.strip())

#logging.debug( "Pg%s: %s" % (page_num,word.text.strip()))

pdf.drawText(text)

def polyval(self,poly, x):

return x * poly[0] + poly[1]

# Glyphless variation of vedaal's invisible font retrieved from

# http://www.angelfire.com/pr/pgpf/if.html, which says:

# 'Invisible font' is unrestricted freeware. Enjoy, Improve, Distribute freely

def load_invisible_font(self):

font = """

eJzdlk1sG0UUx/+zs3btNEmrUKpCPxikSqRS4jpfFURUagmkEQQoiRXgAl07Y3vL2mvt2ml8APXG

hQPiUEGEVDhWVHyIC1REPSAhBOWA+BCgSoULUqsKcWhVBKjhzfPU+VCi3Flrdn7vzZv33ryZ3TUE

gC6chsTx8fHck1ONd98D0jnS7jn26GPjyMIleZhk9fT0wcHFl1/9GRDPkTxTqHg1dMkzJH9CbbTk

xbWlJfKEdB+Np0pBswi+nH/Nvay92VtfJp4nvEztUJkUHXsdksUOkveXK/X5FNuLD838ICx4dv4N

I1e8+ZqbxwCNP2jyqXoV/fmhy+WW/2SqFsb1pX68SfEpZ/TCrI3aHzcP//jitodvYmvL+6Xcr5mV

vb1ScCzRnPRPfz+LsRSWNasuwRrZlh1sx0E8AriddyzEDfE6EkglFhJDJO5u9fJbFJ0etEMB78D5

4Djm/7kjT0wqhSNURyS+u/2MGJKRu+0ExNkrt1pJti9p2x6b3TBJgmUXuzgnDmI8UWMbkVxeinCw

Mo311/l/v3rF7+01D+OkZYE0PrbsYAu+sSyxU0jLLtIiYzmBrFiwnCT9FcsdOOK8ZHbFleSn0znP

nDCnxbnAnGT9JeYtrP+FOcV8nTlNnsoc3bBAD85adtCNRcsSffjBsoseca/lBE7Q09LiJOm/ttyB

0+IqcwfncJt5q4krO5k7jV7uY+5m7mPebuLKUea7iHvk48w72OYF5rvZT8C8k/WvMN/Dc19j3s02

bzPvZZv3me9j/ox5P9t/xdzPzPVJcc7yGnPL/1+GO1lPVTXM+VNWOTRRg0YRHgrUK5yj1kvaEA1E

xAWiCtl4qJL2ADKkG6Q3XxYjzEcR0E9hCj5KtBd1xCxp6jV5mKP7LJBr1nTRK2h1TvU2w0akCmGl

5lWbBzJqMJsdyaijQaCm/FK5HqspHetoTtMsn4LO0T2mlqcwmlTVOT/28wGhCVKiNANKLiJRlxqB

F603axQznIzRhDSq6EWZ4UUs+xud0VHsh1U1kMlmNwu9kTuFaRqpURU0VS3PVmZ0iE7gct0MG/8+

2fmUvKlfRLYmisd1w8pk1LSu1XUlryM1MNTH9epTftWv+16gIh1oL9abJZyjrfF5a4qccp3oFAcz

Wxxx4DpvlaKKxuytRDzeth5rW4W8qBFesvEX8RFRmLBHoB+TpCmRVCCb1gFCruzHqhhW6+qUF6tC

pL26nlWN2K+W1LhRjxlVGKmRTFYVo7CiJug09E+GJb+QocMCPMWBK1wvEOfRFF2U0klK8CppqqvG

pylRc2Zn+XDQWZIL8iO5KC9S+1RekOex1uOyZGR/w/Hf1lhzqVfFsxE39B/ws7Rm3N3nDrhPuMfc

w3R/aE28KsfY2J+RPNp+j+KaOoCey4h+Dd48b9O5G0v2K7j0AM6s+5WQ/E0wVoK+pA6/3bup7bJf

CMGjwvxTsr74/f/F95m3TH9x8o0/TU//N+7/D/ScVcA=

"""

ttf = cStringIO.StringIO(zlib.decompress(base64.decodestring(font)))