Merge pull request #2260 from Kozea/float-overflow

Avoid float collision with box establishing formatting context

weasyprint/formatting_structure/boxes.py

@@ -310,6 +310,17 @@ def is_monolithic(self):
             (self.style['overflow'] == 'hidden' and
              self.style['height'] != 'auto'))
 
+    def establishes_formatting_context(self):
+        """Return whether this box establishes a block formatting context."""
+        # See https://www.w3.org/TR/CSS2/visuren.html#block-formatting
+        return (
+            self.is_floated() or
+            self.is_absolutely_positioned() or
+            self.is_column or
+            (isinstance(self, BlockContainerBox) and not isinstance(self, BlockBox)) or
+            (isinstance(self, BlockBox) and self.style['overflow'] != 'visible') or
+            'flow-root' in self.style['display'])
+
     # Start and end page values for named pages
 
     def page_values(self):

weasyprint/layout/block.py

@@ -124,8 +124,11 @@ def block_box_layout(context, box, bottom_space, skip_stack,
     result = block_container_layout(
         context, box, bottom_space, skip_stack, page_is_empty,
         absolute_boxes, fixed_boxes, adjoining_margins, discard, max_lines)
-    new_box = result[0]
-    if new_box and new_box.is_table_wrapper:
+    # TODO: columns shouldn't be block boxes, this condition would then be
+    # useless when this is fixed.
+    if not (new_box := result[0]) or new_box.is_column:
+        return result
+    if new_box.is_table_wrapper or new_box.establishes_formatting_context():
         # Don't collide with floats
         # https://www.w3.org/TR/CSS21/visuren.html#floats
         position_x, position_y, _ = avoid_collisions(
@@ -630,7 +633,7 @@ def block_container_layout(context, box, bottom_space, skip_stack,
     # block_container_layout, there's probably a better solution.
     assert isinstance(box, (boxes.BlockContainerBox, boxes.FlexBox))
 
-    if establishes_formatting_context(box):
+    if box.establishes_formatting_context():
         context.create_block_formatting_context()
 
     is_start = skip_stack is None
@@ -652,7 +655,7 @@ def block_container_layout(context, box, bottom_space, skip_stack,
 
     collapsing_with_children = not (
         box.border_top_width or box.padding_top or box.is_flex_item or
-        box.is_grid_item or establishes_formatting_context(box) or
+        box.is_grid_item or box.establishes_formatting_context() or
         box.is_for_root_element)
     if collapsing_with_children:
         # Not counting margins in adjoining_margins, if any
@@ -800,7 +803,7 @@ def block_container_layout(context, box, bottom_space, skip_stack,
 
     if (box.border_bottom_width or
             box.padding_bottom or
-            establishes_formatting_context(box) or
+            box.establishes_formatting_context() or
             box.is_for_root_element or
             box.is_table_wrapper):
         position_y += collapse_margin(adjoining_margins)
@@ -837,7 +840,7 @@ def block_container_layout(context, box, bottom_space, skip_stack,
     for child in new_box.children:
         relative_positioning(child, (new_box.width, new_box.height))
 
-    if establishes_formatting_context(new_box):
+    if new_box.establishes_formatting_context():
         context.finish_block_formatting_context(new_box)
 
     if discard or not box_is_fragmented:
@@ -875,30 +878,6 @@ def collapse_margin(adjoining_margins):
     return max(positives) + min(negatives)
 
 
-def establishes_formatting_context(box):
-    """Return whether a box establishes a block formatting context.
-
-    See https://www.w3.org/TR/CSS2/visuren.html#block-formatting
-
-    """
-    return (
-        box.is_floated()
-    ) or (
-        box.is_absolutely_positioned()
-    ) or (
-        # TODO: columns shouldn't be block boxes, this condition would then be
-        # useless when this is fixed
-        box.is_column
-    ) or (
-        isinstance(box, boxes.BlockContainerBox) and
-        not isinstance(box, boxes.BlockBox)
-    ) or (
-        isinstance(box, boxes.BlockBox) and box.style['overflow'] != 'visible'
-    ) or (
-        'flow-root' in box.style['display']
-    )
-
-
 def block_level_page_break(sibling_before, sibling_after):
     """Get the correct page break value between siblings.
 

weasyprint/layout/float.py

@@ -195,12 +195,13 @@ def avoid_collisions(context, box, containing_block, outer=True):
     # - line boxes
     # - table wrappers
     # - block-level replaced box
-    # - element establishing new formatting contexts (not handled)
+    # - element establishing new formatting contexts
     assert (
         (box.style['float'] in ('right', 'left')) or
         isinstance(box, boxes.LineBox) or
         box.is_table_wrapper or
-        isinstance(box, boxes.BlockReplacedBox))
+        isinstance(box, boxes.BlockReplacedBox) or
+        box.establishes_formatting_context())
 
     # The x-position of the box depends on its type.
     position_x = max_left_bound