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Some progress on PDF multicol support
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Kovid Goyal
parent
92f66311c6
commit
8117551bae
@ -15,7 +15,7 @@ pdfreflow, pdfreflow_err = plugins['pdfreflow']
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class PDFInput(InputFormatPlugin):
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name = 'PDF Input'
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author = 'John Schember'
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author = 'Kovid Goyal and John Schember'
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description = 'Convert PDF files to HTML'
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file_types = set(['pdf'])
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@ -18,9 +18,30 @@ class Font(object):
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self.color = spec.get('color')
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self.family = spec.get('family')
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class Text(object):
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class Element(object):
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def __init__(self, text, font_map, opts, log):
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def __eq__(self, other):
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return self.id == other.id
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def __hash__(self):
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return hash(self.id)
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class Image(Element):
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def __init__(self, img, opts, log, idc):
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self.opts, self.log = opts, log
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self.id = idc.next()
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self.top, self.left, self.width, self.height, self.iwidth, self.iheight = \
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map(float, map(img.get, ('top', 'left', 'rwidth', 'rheight', 'iwidth',
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'iheight')))
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self.src = img.get('src')
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class Text(Element):
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def __init__(self, text, font_map, opts, log, idc):
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self.id = idc.next()
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self.opts, self.log = opts, log
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self.font_map = font_map
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self.top, self.left, self.width, self.height = map(float, map(text.get,
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@ -90,47 +111,6 @@ class Interval(object):
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return hash('(%f,%f)'%self.left, self.right)
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class HorizontalBox(object):
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def __init__(self, base_text):
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self.texts = [base_text]
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self.bottom = base_text.bottom
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self.number_of_columns = None
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self.column_map = {}
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def append(self, t):
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self.texts.append(t)
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def sort(self, left_margin, right_margin):
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self.texts.sort(cmp=lambda x,y: cmp(x.left, y.left))
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self.top, self.bottom = sys.maxint, 0
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for t in self.texts:
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self.top = min(self.top, t.top)
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self.bottom = max(self.bottom, t.bottom)
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self.left = self.texts[0].left
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self.right = self.texts[-1].right
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self.gaps = []
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for i, t in enumerate(self.texts[1:]):
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gap = Interval(self.texts[i].right, t.left)
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if gap.width > 3:
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self.gaps.append(gap)
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left = Interval(left_margin, self.texts[0].left)
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if left.width > 3:
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self.gaps.insert(0, left)
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right = Interval(self.texts[-1].right, right_margin)
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if right.width > 3:
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self.gaps.append(right)
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def has_intersection_with(self, gap):
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for g in self.gaps:
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if g.intersection(gap):
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return True
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return False
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def identify_columns(self, column_gaps):
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self.number_of_columns = len(column_gaps) + 1
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class Page(object):
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# Fraction of a character width that two strings have to be apart,
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@ -141,8 +121,10 @@ class Page(object):
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# for them to be considered to be part of the same text fragment
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LINE_FACTOR = 0.4
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YFUZZ = 1.5
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def __init__(self, page, font_map, opts, log):
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def __init__(self, page, font_map, opts, log, idc):
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self.opts, self.log = opts, log
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self.font_map = font_map
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self.number = int(page.get('number'))
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@ -154,7 +136,7 @@ class Page(object):
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self.left_margin, self.right_margin = self.width, 0
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for text in page.xpath('descendant::text'):
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self.texts.append(Text(text, self.font_map, self.opts, self.log))
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self.texts.append(Text(text, self.font_map, self.opts, self.log, idc))
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text = self.texts[-1]
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self.left_margin = min(text.left, self.left_margin)
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self.right_margin = max(text.right, self.right_margin)
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@ -162,16 +144,22 @@ class Page(object):
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self.textwidth = self.right_margin - self.left_margin
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self.font_size_stats = {}
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self.average_text_height = 0
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for t in self.texts:
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if t.font_size not in self.font_size_stats:
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self.font_size_stats[t.font_size] = 0
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self.font_size_stats[t.font_size] += len(t.text_as_string)
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self.average_text_height += t.height
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self.average_text_height /= len(self.texts)
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self.font_size_stats = FontSizeStats(self.font_size_stats)
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self.coalesce_fragments()
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#self.identify_columns()
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self.elements = list(self.texts)
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for img in page.xpath('descendant::img'):
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self.elements.append(Image(img, self.opts, self.log, idc))
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self.elements.sort(cmp=lambda x,y:cmp(x.top, y.top))
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def coalesce_fragments(self):
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@ -196,46 +184,19 @@ class Page(object):
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if match is not None:
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self.texts.remove(match)
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def sort_into_horizontal_boxes(self, document_font_size_stats):
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self.horizontal_boxes = []
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def find_closest_match(text):
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'Return horizontal box whose bottom is closest to text or None'
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min, ans = 3.1, None
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for hb in self.horizontal_boxes:
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diff = abs(text.bottom - hb.bottom)
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if diff < min:
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diff, ans = min, hb
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return ans
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for t in self.texts:
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hb = find_closest_match(t)
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if hb is None:
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self.horizontal_boxes.append(HorizontalBox(t))
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else:
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hb.append(t)
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for hb in self.horizontal_boxes:
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hb.sort(self.left_margin, self.right_margin)
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self.horizontal_boxes.sort(cmp=lambda x,y: cmp(x.bottom, y.bottom))
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def identify_columns(self):
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def neighborhood(i):
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if i == len(self.horizontal_boxes)-1:
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return self.horizontal_boxes[i-2:i]
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if i == len(self.horizontal_boxes)-2:
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return (self.horizontal_boxes[i-1], self.horizontal_boxes[i+1])
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return self.horizontal_boxes[i+1], self.horizontal_boxes[i+2]
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for i, hbox in enumerate(self.horizontal_boxes):
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n1, n2 = neighborhood(i)
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for gap in hbox.gaps:
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gap.is_column_gap = n1.has_intersection_with(gap) and \
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n2.has_intersection_with(gap)
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def first_pass(self):
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self.regions = []
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if not self.elements:
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return
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for i, x in enumerate(self.elements):
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x.idx = i
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self.current_region = None
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for x in self.elements:
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self.find_elements_in_row_of(x)
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def find_elements_in_row_of(self, x):
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interval = Interval(x.top - self.YFUZZ * self.average_text_height,
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x.top + self.YFUZZ*(1+self.average_text_height))
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class PDFDocument(object):
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@ -244,6 +205,7 @@ class PDFDocument(object):
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self.opts, self.log = opts, log
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parser = etree.XMLParser(recover=True)
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self.root = etree.fromstring(xml, parser=parser)
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idc = iter(xrange(sys.maxint))
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self.fonts = []
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self.font_map = {}
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@ -256,14 +218,15 @@ class PDFDocument(object):
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self.page_map = {}
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for page in self.root.xpath('//page'):
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page = Page(page, self.font_map, opts, log)
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page = Page(page, self.font_map, opts, log, idc)
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self.page_map[page.id] = page
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self.pages.append(page)
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self.collect_font_statistics()
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for page in self.pages:
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page.sort_into_horizontal_boxes(self.font_size_stats)
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page.document_font_stats = self.font_size_stats
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page.first_pass()
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def collect_font_statistics(self):
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self.font_size_stats = {}
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