Take care of floats when removing placeholders

Removing placeholders is something we have to do when we must discard a part of
the layout that has already been done. It currently removes absolutely
positioned placeholders and footnotes.

The same has to be done with split floats, that’s what this commit is about.

We have to change the structure of the broken_out_of_flow attribute, as we have
to get a reliable way to reach the saved data using from the real element in
the tree. The new structure is thus a dictionary whose keys are the boxes in
the tree (placeholder for absolutes, partial elements for floats) and whose
values are the original_box+parent+resume_at.

Fix #1669.

tests/draw/test_float.py

@@ -659,3 +659,84 @@ def test_float_split_10(assert_pixels):
         <div>bbbbb bbbbb</div>
         <div class="split">aa aa</div>
         <div>bbb bbb</div>''')
+
+
+@assert_no_logs
+def test_float_split_11(assert_pixels):
+    assert_pixels('''
+        BBBBBBBBBBBBBBBB
+        BBBBBBBBBBBBBBBB
+        BBBBBBBBBBBBBBBB
+        BBBBBBBBBBBBBBBB
+        BBBBBBBBBBBBBBBB
+        BBBBGG______BBBB
+        BBBBGG______BBBB
+        BBBB________BBBB
+        BBBB________BBBB
+        ________________
+    ''', '''
+        <style>
+            @font-face {src: url(weasyprint.otf); font-family: weasyprint}
+            @page {
+                size: 16px 5px;
+            }
+            body {
+                color: lime;
+                font-family: weasyprint;
+                font-size: 2px;
+                line-height: 1;
+            }
+            article {
+                background: blue;
+                height: 5px;
+            }
+            div {
+                background: red;
+                color: blue;
+            }
+        </style>
+        <article></article>
+        a
+        <div style="float: left"><p>aa<p>aa</div>
+        <div style="float: right"><p>bb<p>bb</div>''')
+
+
+@assert_no_logs
+def test_float_split_12(assert_pixels):
+    assert_pixels('''
+        BBBBBBBBBBBBBBBB
+        BBBBBBBBBBBBBBBB
+        BBBBBBBBBBBBBBBB
+        BBBBBBBBBBBBBBBB
+        BBBBBBBBBBBBBBBB
+        BBBBGG______BBBB
+        BBBBGG______BBBB
+        BBBB________BBBB
+        BBBB________BBBB
+        ________________
+    ''', '''
+        <style>
+            @font-face {src: url(weasyprint.otf); font-family: weasyprint}
+            @page {
+                size: 16px 5px;
+            }
+            body {
+                color: lime;
+                font-family: weasyprint;
+                font-size: 2px;
+                line-height: 1;
+            }
+            article {
+                background: blue;
+                height: 5px;
+            }
+            div {
+                background: red;
+                color: blue;
+            }
+        </style>
+        <article></article>
+        <section>
+          <div style="float: left"><p>aa<p>aa</div>
+          a
+          <div style="float: right"><p>bb<p>bb</div>''')

weasyprint/layout/__init__.py

@@ -233,7 +233,7 @@ def __init__(self, style_for, get_image_from_uri, font_config,
         self.running_elements = defaultdict(lambda: defaultdict(lambda: []))
         self.current_page = None
         self.forced_break = False
-        self.broken_out_of_flow = []
+        self.broken_out_of_flow = {}
         self.in_column = False
 
         # Cache

weasyprint/layout/absolute.py

@@ -229,7 +229,8 @@ def absolute_layout(context, placeholder, containing_block, fixed_boxes,
         context, box, containing_block, fixed_boxes, bottom_space, skip_stack)
     placeholder.set_laid_out_box(new_box)
     if resume_at:
-        context.broken_out_of_flow.append((box, containing_block, resume_at))
+        context.broken_out_of_flow[placeholder] = (
+            box, containing_block, resume_at)
 
 
 def absolute_box_layout(context, box, containing_block, fixed_boxes,

weasyprint/layout/block.py

@@ -230,7 +230,7 @@ def _out_of_flow_layout(context, box, index, child, new_children,
 
     child.position_y += collapse_margin(adjoining_margins)
     if child.is_absolutely_positioned():
-        placeholder = AbsolutePlaceholder(child)
+        new_child = placeholder = AbsolutePlaceholder(child)
         placeholder.index = index
         new_children.append(placeholder)
         if child.style['position'] == 'absolute':
@@ -262,7 +262,7 @@ def _out_of_flow_layout(context, box, index, child, new_children,
         page = context.current_page
         context.running_elements[running_name][page].append(child)
 
-    return stop, resume_at, out_of_flow_resume_at
+    return stop, resume_at, new_child, out_of_flow_resume_at
 
 
 def _break_line(context, box, line, new_children, lines_iterator,
@@ -629,7 +629,7 @@ def block_container_layout(context, box, bottom_space, skip_stack,
     new_children = []
     next_page = {'break': 'any', 'page': None}
     all_footnotes = []
-    broken_out_of_flow = []
+    broken_out_of_flow = {}
 
     last_in_flow_child = None
 
@@ -649,12 +649,14 @@ def block_container_layout(context, box, bottom_space, skip_stack,
 
         if not child.is_in_normal_flow():
             abort = False
-            stop, resume_at, out_of_flow_resume_at = _out_of_flow_layout(
-                context, box, index, child, new_children, page_is_empty,
-                absolute_boxes, fixed_boxes, adjoining_margins,
-                bottom_space)
+            stop, resume_at, new_child, out_of_flow_resume_at = (
+                _out_of_flow_layout(
+                    context, box, index, child, new_children, page_is_empty,
+                    absolute_boxes, fixed_boxes, adjoining_margins,
+                    bottom_space))
             if out_of_flow_resume_at:
-                broken_out_of_flow.append((child, box, out_of_flow_resume_at))
+                broken_out_of_flow[new_child] = (
+                    child, box, out_of_flow_resume_at)
 
         elif isinstance(child, boxes.LineBox):
             (abort, stop, resume_at, position_y,
@@ -696,6 +698,8 @@ def block_container_layout(context, box, bottom_space, skip_stack,
 
         if abort:
             page = child.page_values()[0]
+            remove_placeholders(
+                context, box.children[skip:], absolute_boxes, fixed_boxes)
             for footnote in new_footnotes:
                 context.unlayout_footnote(footnote)
             return (
@@ -720,7 +724,8 @@ def block_container_layout(context, box, bottom_space, skip_stack,
         return (
             None, None, {'break': 'any', 'page': None}, [], False, max_lines)
 
-    context.broken_out_of_flow.extend(broken_out_of_flow)
+    for key, value in broken_out_of_flow.items():
+        context.broken_out_of_flow[key] = value
 
     if collapsing_with_children:
         box.position_y += (
@@ -1005,6 +1010,8 @@ def remove_placeholders(context, box_list, absolute_boxes, fixed_boxes):
     For boxes that have been removed in find_earlier_page_break(), remove the
     matching placeholders in absolute_boxes and fixed_boxes.
 
+    Also takes care of removed footnotes and floats.
+
     """
     for box in box_list:
         if isinstance(box, boxes.ParentBox):
@@ -1017,6 +1024,8 @@ def remove_placeholders(context, box_list, absolute_boxes, fixed_boxes):
             fixed_boxes.remove(box)
         if box.footnote:
             context.unlayout_footnote(box.footnote)
+        if box in context.broken_out_of_flow:
+            context.broken_out_of_flow.pop(box)
 
 
 def avoid_page_break(page_break, context):

weasyprint/layout/inline.py

@@ -169,8 +169,8 @@ def get_next_linebox(context, linebox, position_y, bottom_space, skip_stack,
             fixed_boxes, bottom_space, skip_stack=None)
         float_children.append(new_waiting_float)
         if waiting_float_resume_at:
-            context.broken_out_of_flow.append(
-                (waiting_float, containing_block, waiting_float_resume_at))
+            context.broken_out_of_flow[new_waiting_float] = (
+                waiting_float, containing_block, waiting_float_resume_at)
     if float_children:
         line.children += tuple(float_children)
 
@@ -559,8 +559,8 @@ def _out_of_flow_layout(context, box, containing_block, index, child,
                 context, child, containing_block, absolute_boxes, fixed_boxes,
                 bottom_space, skip_stack=None)
             if float_resume_at:
-                context.broken_out_of_flow.append(
-                    (child, containing_block, float_resume_at))
+                context.broken_out_of_flow[child] = (
+                    child, containing_block, float_resume_at)
             waiting_children.append((index, new_child, child))
             child = new_child
 

weasyprint/layout/page.py

@@ -564,8 +564,9 @@ def make_page(context, root_box, page_type, resume_at, page_number,
     adjoining_margins = []
     positioned_boxes = []  # Mixed absolute and fixed
     out_of_flow_boxes = []
-    broken_out_of_flow = []
-    for box, containing_block, skip_stack in context.broken_out_of_flow:
+    broken_out_of_flow = {}
+    context_out_of_flow = context.broken_out_of_flow.values()
+    for box, containing_block, skip_stack in context_out_of_flow:
         box.position_y = 0
         if box.is_floated():
             out_of_flow_box, out_of_flow_resume_at = float_layout(
@@ -578,8 +579,8 @@ def make_page(context, root_box, page_type, resume_at, page_number,
                 skip_stack)
         out_of_flow_boxes.append(out_of_flow_box)
         if out_of_flow_resume_at:
-            broken_out_of_flow.append(
-                (box, containing_block, out_of_flow_resume_at))
+            broken_out_of_flow[out_of_flow_box] = (
+                box, containing_block, out_of_flow_resume_at)
     context.broken_out_of_flow = broken_out_of_flow
     root_box, resume_at, next_page, _, _, _ = block_level_layout(
         context, root_box, 0, resume_at, initial_containing_block,