Start work on CSS rule transformer

src/calibre/ebooks/css_transform_rules.py

@@ -0,0 +1,16 @@
+#!/usr/bin/env python2
+# vim:fileencoding=utf-8
+# License: GPLv3 Copyright: 2016, Kovid Goyal <kovid at kovidgoyal.net>
+
+from __future__ import (unicode_literals, division, absolute_import,
+                        print_function)
+
+import regex
+
+REGEX_FLAGS = regex.VERSION1 | regex.UNICODE
+
+def compile_pat(pat):
+    return regex.compile(pat, flags=REGEX_FLAGS)
+
+def parse_length(raw):
+    raise NotImplementedError('TODO: implement this')

src/calibre/gui2/css_transform_rules.py

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+#!/usr/bin/env python2
+# vim:fileencoding=utf-8
+# License: GPLv3 Copyright: 2016, Kovid Goyal <kovid at kovidgoyal.net>
+
+from __future__ import (unicode_literals, division, absolute_import,
+                        print_function)
+from collections import OrderedDict
+
+from PyQt5.Qt import (
+    QWidget, QVBoxLayout, QHBoxLayout, QLabel, QComboBox, QLineEdit, QListWidgetItem
+)
+
+from calibre.ebooks.css_transform_rules import compile_pat, parse_length
+from calibre.gui2 import error_dialog, elided_text
+from calibre.gui2.tag_mapper import RuleEditDialog as RuleEditDialogBase, Rules as RulesBase
+
+class RuleEdit(QWidget):  # {{{
+
+    ACTION_MAP = OrderedDict((
+        ('remove', _('Remove the property')),
+        ('append', _('Add extra properties')),
+        ('change', _('Change the value to')),
+        ('*', _('Multiply the value by')),
+        ('/', _('Divide the value by')),
+        ('+', _('Add to the value')),
+        ('-', _('Subtract from the value')),
+    ))
+
+    MATCH_TYPE_MAP = OrderedDict((
+        ('==', _('is')),
+        ('<', _('is less than')),
+        ('>', _('is greater than')),
+        ('<=', _('is less than or equal to')),
+        ('>=', _('is greater than or equal to')),
+        ('matches', _('matches pattern')),
+        ('not_matches', _('does not match pattern'))
+    ))
+
+    def __init__(self, parent=None):
+        QWidget.__init__(self, parent)
+        self.l = l = QVBoxLayout(self)
+        self.h = h = QHBoxLayout()
+
+        self.la = la = QLabel(self.MSG)
+        la.setWordWrap(True)
+        l.addWidget(la)
+        l.addLayout(h)
+        english_sentence = '{preamble} {property} {match_type} {query}'
+        sentence = _('{preamble} {property} {match_type} {query}')
+        if set(sentence.split()) != set(english_sentence.split()):
+            sentence = english_sentence
+        parts = sentence.split()
+        for clause in parts:
+            if clause == '{preamble}':
+                self.preamble = w = QLabel(_('If the &property:'))
+            elif clause == '{property}':
+                self.property = w = QLineEdit(self)
+                w.setToolTip(_('The name of a CSS property, for example: font-size\n'))
+            elif clause == '{match_type}':
+                self.match_type = w = QComboBox(self)
+                for action, text in self.MATCH_TYPE_MAP.iteritems():
+                    w.addItem(text, action)
+            elif clause == '{query}':
+                self.query = w = QLineEdit(self)
+            h.addWidget(w)
+            if clause is not parts[-1]:
+                h.addWidget(QLabel('\xa0'))
+
+        self.h2 = h = QHBoxLayout()
+        l.addLayout(h)
+        english_sentence = '{action} {action_data}'
+        sentence = _('{action} {action_data}')
+        if set(sentence.split()) != set(english_sentence.split()):
+            sentence = english_sentence
+        parts = sentence.split()
+        for clause in parts:
+            if clause == '{action}':
+                self.action = w = QComboBox(self)
+                for action, text in self.ACTION_MAP.iteritems():
+                    w.addItem(text, action)
+            elif clause == '{action_data}':
+                self.action_data = w = QLineEdit(self)
+            h.addWidget(w)
+            if clause is not parts[-1]:
+                h.addWidget(QLabel('\xa0'))
+
+        self.update_state()
+
+    def sizeHint(self):
+        a = QWidget.sizeHint(self)
+        a.setHeight(a.height() + 75)
+        a.setWidth(a.width() + 100)
+        return a
+
+    def update_state(self):
+        r = self.rule
+        self.action_data.setVisible(r['action'] != 'remove')
+        tt = _('The CSS property value')
+        mt = r['match_type']
+        if 'matches' in mt:
+            tt = _('A regular expression')
+        elif mt in '< > <= >='.split():
+            tt = _('Either a CSS length, such as 10pt or a unit less number. If a unitless'
+                   ' number is used it will compared with the CSS value using whatever unit'
+                   ' the value has.')
+        self.query.setToolTip(tt)
+        tt = ''
+        ac = r['action']
+        if ac == 'append':
+            tt = _('CSS properties for to add to the rule that contains the matching style. You'
+                   ' can specify more than one property, separated by semi-colons, for example:'
+                   ' color:red; font-weight: bold')
+        elif ac in '+=*/':
+            tt = _('A number')
+        self.action_data.setToolTip(tt)
+
+    @property
+    def rule(self):
+        return {
+            'property':self.property.text().strip(),
+            'match_type': self.match_type.currentData(),
+            'query': self.query.text().strip(),
+            'action': self.action.currentData(),
+            'action_data': self.action_data.text().strip(),
+        }
+
+    @rule.setter
+    def rule(self, rule):
+        def sc(name):
+            c = getattr(self, name)
+            idx = c.findData(unicode(rule.get(name, '')))
+            if idx < 0:
+                idx = 0
+            c.setCurrentIndex(idx)
+        sc('action'), sc('match_type')
+        self.query.setText(unicode(rule.get('query', '')).strip())
+        self.action_data.setText(unicode(rule.get('action_data', '')).strip())
+
+    def validate(self):
+        rule = self.rule
+        if not rule['query']:
+            error_dialog(self, _('Query required'), _(
+                'You must specify a value for the CSS property to match'), show=True)
+            return False
+        mt = rule['match_type']
+        if 'matches' in mt:
+            try:
+                compile_pat(rule['query'])
+            except Exception:
+                error_dialog(self, _('Query invalid'), _(
+                    '%s is not a valid regular expression') % rule['query'], show=True)
+                return False
+        elif mt in '< > <= >='.split():
+            try:
+                parse_length(rule['query'])
+            except Exception:
+                error_dialog(self, _('Query invalid'), _(
+                    '%s is not a valid length or number') % rule['query'], show=True)
+                return False
+        ac, ad = rule['action'], rule['action_data']
+        if not ad and ac != 'remove':
+            msg = _('You must specify a number')
+            if ac == 'append':
+                msg = _('You must specify at least one CSS property to add')
+            elif ac == 'change':
+                msg = _('You must specify a value to change the property to')
+            error_dialog(self, _('No data'), msg, show=True)
+            return False
+        if ac in '+-*/':
+            try:
+                float(ad)
+            except Exception:
+                error_dialog(self, _('Invalid number'), _('%s is not a number') % ad, show=True)
+                return False
+        return True
+# }}}
+
+class RuleEditDialog(RuleEditDialogBase):  # {{{
+
+    PREFS_NAME = 'edit-css-transform-rule'
+    DIALOG_TITLE = _('Edit rule')
+    RuleEditClass = RuleEdit
+# }}}
+
+class RuleItem(QListWidgetItem):  # {{{
+
+    @staticmethod
+    def text_from_rule(rule, parent):
+        query = elided_text(rule['query'], font=parent.font(), width=200, pos='right')
+        text = _(
+            'If the property <i>{property}</i> <b>{match_type}</b> <b>{query}</b><br>{action}').format(
+                property=rule['property'], action=RuleEdit.ACTION_MAP[rule['action']],
+                match_type=RuleEdit.MATCH_TYPE_MAP[rule['match_type']], query=query)
+        if rule['action_data']:
+            ad = elided_text(rule['action_data'], font=parent.font(), width=200, pos='right')
+            text += ' <code>%s</code>' % ad
+        return text
+# }}}
+
+class Rules(RulesBase):
+
+    RuleItemClass = RuleItem
+    RuleEditDialogClass = RuleEditDialog
+
+    MSG = _('You can specify rules to transform styles here. Click the "Add Rule" button'
+            ' below to get started.')