Initial import

ebook_converter/ebooks/oeb/transforms/page_margin.py

@@ -0,0 +1,189 @@
+#!/usr/bin/env python2
+# vim:fileencoding=UTF-8:ts=4:sw=4:sta:et:sts=4:ai
+from __future__ import absolute_import, division, print_function, unicode_literals
+
+__license__   = 'GPL v3'
+__copyright__ = '2011, Kovid Goyal <kovid@kovidgoyal.net>'
+__docformat__ = 'restructuredtext en'
+
+import numbers
+from collections import Counter
+
+from calibre.ebooks.oeb.base import barename, XPath
+from polyglot.builtins import iteritems
+
+
+class RemoveAdobeMargins(object):
+    '''
+    Remove margins specified in Adobe's page templates.
+    '''
+
+    def __call__(self, oeb, log, opts):
+        self.oeb, self.opts, self.log = oeb, opts, log
+
+        for item in self.oeb.manifest:
+            if item.media_type in {
+                'application/vnd.adobe-page-template+xml', 'application/vnd.adobe.page-template+xml',
+                'application/adobe-page-template+xml', 'application/adobe.page-template+xml',
+            } and hasattr(item.data, 'xpath'):
+                self.log('Removing page margins specified in the'
+                        ' Adobe page template')
+                for elem in item.data.xpath(
+                        '//*[@margin-bottom or @margin-top '
+                        'or @margin-left or @margin-right]'):
+                    for margin in ('left', 'right', 'top', 'bottom'):
+                        attr = 'margin-'+margin
+                        elem.attrib.pop(attr, None)
+
+
+class NegativeTextIndent(Exception):
+    pass
+
+
+class RemoveFakeMargins(object):
+
+    '''
+    Remove left and right margins from paragraph/divs if the same margin is specified
+    on almost all the elements at that level.
+
+    Must be called only after CSS flattening
+    '''
+
+    def __call__(self, oeb, log, opts):
+        if not opts.remove_fake_margins:
+            return
+        self.oeb, self.log, self.opts = oeb, log, opts
+        stylesheet = None
+        self.levels = {}
+        self.stats = {}
+        self.selector_map = {}
+
+        stylesheet = self.oeb.manifest.main_stylesheet
+        if stylesheet is None:
+            return
+
+        self.log('Removing fake margins...')
+
+        stylesheet = stylesheet.data
+
+        from css_parser.css import CSSRule
+        for rule in stylesheet.cssRules.rulesOfType(CSSRule.STYLE_RULE):
+            self.selector_map[rule.selectorList.selectorText] = rule.style
+
+        self.find_levels()
+
+        for level in self.levels:
+            try:
+                self.process_level(level)
+            except NegativeTextIndent:
+                self.log.debug('Negative text indent detected at level '
+                        ' %s, ignoring this level'%level)
+
+    def get_margins(self, elem):
+        cls = elem.get('class', None)
+        if cls:
+            style = self.selector_map.get('.'+cls, None)
+            if style:
+                try:
+                    ti = style['text-indent']
+                except:
+                    pass
+                else:
+                    if ((hasattr(ti, 'startswith') and ti.startswith('-')) or
+                            isinstance(ti, numbers.Number) and ti < 0):
+                        raise NegativeTextIndent()
+                return style.marginLeft, style.marginRight, style
+        return '', '', None
+
+    def process_level(self, level):
+        elems = self.levels[level]
+        self.stats[level+'_left'] = Counter()
+        self.stats[level+'_right'] = Counter()
+
+        for elem in elems:
+            lm, rm = self.get_margins(elem)[:2]
+            self.stats[level+'_left'][lm] += 1
+            self.stats[level+'_right'][rm] += 1
+
+        self.log.debug(level, ' left margin stats:', self.stats[level+'_left'])
+        self.log.debug(level, ' right margin stats:', self.stats[level+'_right'])
+
+        remove_left = self.analyze_stats(self.stats[level+'_left'])
+        remove_right = self.analyze_stats(self.stats[level+'_right'])
+
+        if remove_left:
+            mcl = self.stats[level+'_left'].most_common(1)[0][0]
+            self.log('Removing level %s left margin of:'%level, mcl)
+
+        if remove_right:
+            mcr = self.stats[level+'_right'].most_common(1)[0][0]
+            self.log('Removing level %s right margin of:'%level, mcr)
+
+        if remove_left or remove_right:
+            for elem in elems:
+                lm, rm, style = self.get_margins(elem)
+                if remove_left and lm == mcl:
+                    style.removeProperty('margin-left')
+                if remove_right and rm == mcr:
+                    style.removeProperty('margin-right')
+
+    def find_levels(self):
+
+        def level_of(elem, body):
+            ans = 1
+            while elem.getparent() is not body:
+                ans += 1
+                elem = elem.getparent()
+            return ans
+
+        paras = XPath('descendant::h:p|descendant::h:div')
+
+        for item in self.oeb.spine:
+            body = XPath('//h:body')(item.data)
+            if not body:
+                continue
+            body = body[0]
+
+            for p in paras(body):
+                level = level_of(p, body)
+                level = '%s_%d'%(barename(p.tag), level)
+                if level not in self.levels:
+                    self.levels[level] = []
+                self.levels[level].append(p)
+
+        remove = set()
+        for k, v in iteritems(self.levels):
+            num = len(v)
+            self.log.debug('Found %d items of level:'%num, k)
+            level = int(k.split('_')[-1])
+            tag = k.split('_')[0]
+            if tag == 'p' and num < 25:
+                remove.add(k)
+            if tag == 'div':
+                if level > 2 and num < 25:
+                    remove.add(k)
+                elif level < 3:
+                    # Check each level < 3 element and only keep those
+                    # that have many child paras
+                    for elem in list(v):
+                        children = len(paras(elem))
+                        if children < 5:
+                            v.remove(elem)
+
+        for k in remove:
+            self.levels.pop(k)
+            self.log.debug('Ignoring level', k)
+
+    def analyze_stats(self, stats):
+        if not stats:
+            return False
+        mc = stats.most_common(1)
+        if len(mc) > 1:
+            return False
+        mc = mc[0]
+        most_common, most_common_count = mc
+        if not most_common or most_common == '0':
+            return False
+        total = sum(stats.values())
+        # True if greater than 95% of elements have the same margin
+        return most_common_count/total > 0.95