Add a presentational-hints option

weasyprint/__init__.py

@@ -110,7 +110,8 @@ class HTML(object):
     def _get_metadata(self):
         return get_html_metadata(self.root_element)
 
-    def render(self, stylesheets=None, enable_hinting=False):
+    def render(self, stylesheets=None, enable_hinting=False,
+               presentational_hints=False):
         """Lay out and paginate the document, but do not (yet) export it
         to PDF or another format.
 
@@ -129,10 +130,14 @@ class HTML(object):
             Whether text, borders and background should be *hinted* to fall
             at device pixel boundaries. Should be enabled for pixel-based
             output (like PNG) but not vector based output (like PDF).
+        :type presentational_hints: bool
+        :param presentational_hints: Whether HTML presentational hints are
+            followed.
         :returns: A :class:`~document.Document` object.
 
         """
-        return Document._render(self, stylesheets, enable_hinting)
+        return Document._render(
+            self, stylesheets, enable_hinting, presentational_hints)
 
     def write_pdf(self, target=None, stylesheets=None, zoom=1,
                   attachments=None):

weasyprint/__main__.py

@@ -66,6 +66,10 @@ def main(argv=None, stdout=None, stdin=None):
         Adds an attachment to the document which is included in the PDF output.
         This option can be added multiple times to attach more files.
 
+    .. option:: -p, --presentational-hints
+
+        Follow HTML presentational hints.
+
     .. option:: --version
 
         Show the version number. Other options and arguments are ignored.
@@ -100,6 +104,8 @@ def main(argv=None, stdout=None, stdin=None):
     parser.add_argument('-a', '--attachment', action='append',
                         help='URL or filename of a file '
                              'to attach to the PDF document')
+    parser.add_argument('-p', '--presentational-hints', action='store_true',
+                        help='Follow HTML presentational hints.')
     parser.add_argument(
         'input', help='URL or filename of the HTML input, or - for stdin')
     parser.add_argument(
@@ -152,7 +158,8 @@ def main(argv=None, stdout=None, stdin=None):
             parser.error('--attachment only applies for the PDF format.')
 
     html = HTML(source, base_url=args.base_url, encoding=args.encoding,
-                media_type=args.media_type)
+                media_type=args.media_type,
+                presentational_hints=args.presentational_hints)
     getattr(html, 'write_' + format_)(output, **kwargs)
 
 

weasyprint/css/__init__.py

@@ -798,9 +798,9 @@ def preprocess_stylesheet(device_media_type, base_url, rules, url_fetcher):
                     yield margin_rule, selector_list, declarations
 
 
-def get_all_computed_styles(html, user_stylesheets=None):
-    """Compute all the computed styles of all elements
-    in the given ``html`` document.
+def get_all_computed_styles(html, user_stylesheets=None,
+                            presentational_hints=False):
+    """Compute all the computed styles of all elements in ``html`` document.
 
     Do everything from finding author stylesheets to parsing and applying them.
 
@@ -848,14 +848,15 @@ def get_all_computed_styles(html, user_stylesheets=None):
                                 cascaded_styles, name, values, weight,
                                 element, pseudo_type)
 
-    specificity = (0, 0, 0, 0)
-    for element, declarations, base_url in find_presentational_hints(
-            element_tree):
-        for name, values, importance in preprocess_declarations(
-                base_url, declarations):
-            precedence = declaration_precedence('author', importance)
-            weight = (precedence, specificity)
-            add_declaration(cascaded_styles, name, values, weight, element)
+    if presentational_hints:
+        specificity = (0, 0, 0, 0)
+        for element, declarations, base_url in find_presentational_hints(
+                element_tree):
+            for name, values, importance in preprocess_declarations(
+                    base_url, declarations):
+                precedence = declaration_precedence('author', importance)
+                weight = (precedence, specificity)
+                add_declaration(cascaded_styles, name, values, weight, element)
 
     specificity = (1, 0, 0, 0)
     for element, declarations, base_url in find_style_attributes(element_tree):

weasyprint/document.py

@@ -313,11 +313,13 @@ class Document(object):
 
     """
     @classmethod
-    def _render(cls, html, stylesheets, enable_hinting):
-        style_for = get_all_computed_styles(html, user_stylesheets=[
-            css if hasattr(css, 'rules')
-            else CSS(guess=css, media_type=html.media_type)
-            for css in stylesheets or []])
+    def _render(cls, html, stylesheets, enable_hinting,
+                presentational_hints=False):
+        style_for = get_all_computed_styles(
+            html, presentational_hints=presentational_hints, user_stylesheets=[
+                css if hasattr(css, 'rules')
+                else CSS(guess=css, media_type=html.media_type)
+                for css in stylesheets or []])
         get_image_from_uri = functools.partial(
             images.get_image_from_uri, {}, html.url_fetcher)
         page_boxes = layout_document(