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218 lines
9.0 KiB
218 lines
9.0 KiB
import sys
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import os
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import re
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import itertools
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import tempfile
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import locale
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from collections import namedtuple
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from pdfminer.pdfinterp import PDFResourceManager , PDFPageInterpreter
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from pdfminer.converter import PDFPageAggregator
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from pdfminer.layout import LAParams , LTTextBoxHorizontal
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from pdfminer.pdfpage import PDFPage
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import ghostscript
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from PIL import Image , ImageChops
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from asl_cards.db import AslCard , AslCardImage
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# ---------------------------------------------------------------------
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class PdfParser:
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def __init__( self , progress=None , progress2=None ) :
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# initialize
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self.progress = progress # nb: for tracking file progress
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self.progress2 = progress2 # nb: for tracking page progress within a file
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self.cancelling = False
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def parse( self , target , max_pages=-1 , images=True ) :
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"""Extract the cards from a PDF file."""
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# locate the files we're going to parse
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if os.path.isfile( target ) :
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fnames = [ target ]
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else :
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fnames = [
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os.path.join( target , f )
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for f in os.listdir( target )
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if os.path.splitext( f )[1].lower() == ".pdf"
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]
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# parse each file
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cards = []
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for fname in fnames :
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if self.cancelling : raise RuntimeError("Cancelled.")
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cards.extend( self._do_parse_file( fname , max_pages , images ) )
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return cards
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def _do_parse_file( self , fname , max_pages , images ) :
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# extract the details of each card
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rmgr = PDFResourceManager()
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laparams = LAParams()
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dev = PDFPageAggregator( rmgr , laparams=laparams )
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interp = PDFPageInterpreter( rmgr , dev )
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cards = []
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with open(fname,"rb") as fp :
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self._progress( 0 , "Analyzing {}...".format( os.path.split(fname)[1] ) )
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pages = list( PDFPage.get_pages( fp ) )
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for page_no,page in enumerate(pages) :
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if self.cancelling : raise RuntimeError("Cancelled.")
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self._progress2( float(page_no) / len(pages) )
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page_cards = self._parse_page( cards , interp , page_no , page )
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cards.extend( page_cards )
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if max_pages > 0 and 1+page_no >= max_pages :
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break
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self._progress( 1.0 , "Done." )
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# extract the card images
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if images :
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card_images = self._extract_images( fname , max_pages )
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if len(cards) != len(card_images) :
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raise RuntimeError( "Found {} cards, {} card images.".format( len(cards) , len(card_images) ) )
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for i in range(0,len(cards)) :
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if self.cancelling : raise RuntimeError("Cancelled.")
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cards[i].card_image = AslCardImage( image_data=card_images[i] )
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return cards
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def _parse_page( self , cards , interp , page_no , page ) :
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"""Extract the cards from a PDF page."""
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cards = []
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interp.process_page( page )
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lt_page = interp.device.get_result()
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# locate the info box for each card (in the top-left corner)
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info_boxes = []
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for item in lt_page :
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if self.cancelling : raise RuntimeError("Cancelled.")
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if type(item) is not LTTextBoxHorizontal : continue
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item_text = item.get_text().strip()
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if item_text.startswith( ("Vehicle","Ordnance") ) :
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info_boxes.append( [item] )
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# get the details from each info box
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for item in lt_page :
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if self.cancelling : raise RuntimeError("Cancelled.")
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if type(item) is not LTTextBoxHorizontal : continue
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# check if the next item could be part of an info box - it must be within the left/right boundary
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# of the first item (within a certain tolerance), and below it (but not too far)
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eps = 50 # left/right tolerance
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for info_box in info_boxes :
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if item.x0 >= info_box[0].x0 - eps and item.x1 <= info_box[0].x1 + eps \
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and item.y1 < info_box[0].y1 and info_box[0].y0 - item.y1 < 50 :
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# yup - save it
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info_box.append( item )
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# generate an AslCard from each info box
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for info_box in info_boxes :
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card = self._make_asl_card( lt_page , info_box )
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cards.append( card )
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return cards
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def _make_asl_card( self , lt_page , items ) :
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# sort the items vertically
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items.sort( key=lambda i: i.y0 , reverse=True )
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# split out each line of item text
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item_texts = list( itertools.chain.from_iterable(
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i.get_text().strip().split("\n") for i in items
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) )
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# ignore short lines
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item_texts = [ s for s in item_texts if len(s) >= 5 ]
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# generate the AslCard
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page_pos = 0 if items[0].y0 > lt_page.height/2 else 1
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return AslCard(
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card_tag = _tidy( item_texts[0] ).replace( "# ", "#" ) ,
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nationality = _tidy( item_texts[1] ) ,
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name = _tidy( item_texts[2] ) ,
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page_id = lt_page.pageid ,
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page_pos = page_pos ,
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)
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def _extract_images( self , fname , max_pages ) :
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"""Extract card images from a file."""
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# extract each page from the PDF as an image
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fname_template = os.path.join( tempfile.gettempdir() , "asl_cards-%d.png" )
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resolution = 300 # pixels/inch
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args = [
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"_ignored_" , "-dQUIET" , "-dSAFER" , "-dNOPAUSE" ,
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"-sDEVICE=png16m" , "-r"+str(resolution) ,
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"-sOutputFile="+fname_template ,
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]
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if max_pages > 0 :
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args.append( "-dLastPage={}".format(max_pages) )
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args.extend( [ "-f" , fname ] )
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# FIXME! clean up left-over temp files before we start
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args = [ s.encode(locale.getpreferredencoding()) for s in args ]
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# FIXME! stop GhostScript from issuing warnings (stdout).
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self._progress( 0 , "Extracting images from {}...".format( os.path.split(fname)[1] ) )
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ghostscript.Ghostscript( *args )
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# figure out how many files were created (so we can show progress)
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npages = 0
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for i in range(0,99999) :
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fname = fname_template % (1+i)
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if not os.path.isfile( fname ) :
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break
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npages += 1
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# extract the cards from each page
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card_images = []
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for page_no in range(0,npages) :
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if self.cancelling : raise RuntimeError("Cancelled.")
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# open the next page image
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self._progress2( float(page_no) / npages )
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fname = fname_template % (1+page_no)
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img = Image.open( fname )
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img_width , img_height = img.size
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# extract the cards (by splitting the page in half)
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fname2 = list( os.path.split( fname ) )
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fname2[1] = os.path.splitext( fname2[1] )
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ypos = img_height * 48 / 100
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buf1 , size1 = self._crop_image(
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img , (0,0,img_width,ypos) ,
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os.path.join( fname2[0] , fname2[1][0]+"a"+fname2[1][1] )
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)
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buf2 , size2 = self._crop_image(
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img , (0,ypos+1,img_width,img_height) ,
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os.path.join( fname2[0] , fname2[1][0]+"b"+fname2[1][1] )
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)
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# check if this is the last page, and it has just 1 card on it
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if page_no == npages-1 and size1[1] < 1000 and size2[1] < 1000 :
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# yup - extract it
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buf , _ = self._crop_image(
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img , (0,0,img_width,img_height) ,
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os.path.join( fname2[0] , fname2[1][0]+"a"+fname2[1][1] )
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)
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card_images.append( buf )
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else :
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# nope - save the extracted cards
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card_images.append( buf1 )
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card_images.append( buf2 )
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# clean up
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os.unlink( fname )
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self._progress( 1.0 , "Done." )
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return card_images
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def _crop_image( self , img , bbox , fname ) :
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# crop the image
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rgn = img.crop( bbox )
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# trim the cropped region
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bgd_col = img.getpixel( (0,0) )
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bgd_img = Image.new( img.mode , img.size , bgd_col )
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diff = ImageChops.difference( rgn , bgd_img )
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diff = ImageChops.add(diff, diff, 2.0, -100)
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bbox = diff.getbbox()
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if bbox :
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rgn = rgn.crop( bbox )
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# save the cropped image
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rgn.save( fname )
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with open( fname , "rb" ) as fp :
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buf = fp.read()
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os.unlink( fname )
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return buf , rgn.size
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def _progress( self , pval , msg ) :
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"""Call the progress callback."""
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if self.progress :
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self.progress( pval , msg )
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def _progress2( self , pval ) :
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"""Call the progress callback."""
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if self.progress2 :
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self.progress2( pval )
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# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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_tidy_regex = re.compile( r"[,.()+-]" )
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def _tidy( val ) : return _tidy_regex.sub(" ",val).strip()
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