Repeat footers in paginated context

third_party/WebKit/Source/core/layout/LayoutTableSection.cpp

Index: third_party/WebKit/Source/core/layout/LayoutTableSection.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutTableSection.cpp b/third_party/WebKit/Source/core/layout/LayoutTableSection.cpp
index 8a1142cdb14577b5d0c8887879d86d4df13473a1..ecf682782ea5ad236c40b2ca10c939905013a229 100644
--- a/third_party/WebKit/Source/core/layout/LayoutTableSection.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutTableSection.cpp
@@ -94,7 +94,8 @@ LayoutTableSection::LayoutTableSection(Element* element)
       force_full_paint_(false),
       has_multiple_cell_levels_(false),
       has_spanning_cells_(false),
-      is_repeating_header_group_(false) {
+      is_repeating_header_group_(false),
+      is_repeating_footer_group_(false) {
   // init LayoutObject attributes
   SetInline(false);  // our object is not Inline
 }
@@ -1215,15 +1216,24 @@ void LayoutTableSection::LayoutRows() {
 int LayoutTableSection::PaginationStrutForRow(LayoutTableRow* row,
                                               LayoutUnit logical_offset) const {
   DCHECK(row);
-  if (row->GetPaginationBreakability() == kAllowAnyBreaks)
+  const LayoutTableSection* footer = Table()->Footer();
+  bool make_room_for_repeating_footer =
+      footer && footer->IsRepeatingFooterGroup() && row->RowIndex();
+  if (!make_room_for_repeating_footer &&
+      row->GetPaginationBreakability() == kAllowAnyBreaks)
     return 0;
   if (!IsPageLogicalHeightKnown())
     return 0;
   LayoutUnit page_logical_height = PageLogicalHeightForOffset(logical_offset);
   // If the row is too tall for the page don't insert a strut.
   LayoutUnit row_logical_height = row->LogicalHeight();
-  if (row_logical_height > page_logical_height)
+  if (row_logical_height > page_logical_height) {

[mstensho (USE GERRIT), 2017/06/16 08:43:06]

No need for the curls.

[rhogan, 2017/06/20 18:46:05]

OK.

     return 0;
+  }
+
+  LayoutState* layout_state = View()->GetLayoutState();

[mstensho (USE GERRIT), 2017/06/16 08:43:06]

Please move it inside the "if (make_room_for_repeating_footer)" block. Might as
well do View()->GetLayoutState()->HeightOffsetForTableFooters() directly there,
unless the code formatter is going to turn that into soup.

[rhogan, 2017/06/20 18:46:05]

Sure.

+  if (make_room_for_repeating_footer)
+    row_logical_height += layout_state->HeightOffsetForTableFooters();
 
   LayoutUnit remaining_logical_height = PageRemainingLogicalHeightForOffset(
       logical_offset, LayoutBlock::kAssociateWithLatterPage);
@@ -1945,15 +1955,14 @@ void LayoutTableSection::AdjustRowForPagination(LayoutTableRow& row_object,
   row_object.SetLogicalHeight(LayoutUnit(LogicalHeightForRow(row_object)));
 }
 
-bool LayoutTableSection::HeaderGroupShouldRepeat() const {
-  if (Table()->Header() != this)
-    return false;
-
+bool LayoutTableSection::GroupShouldRepeat() const {
   if (GetPaginationBreakability() == kAllowAnyBreaks)

[mstensho (USE GERRIT), 2017/06/16 08:43:06]

I wonder if you should add a DCHECK at the beginning of this method, to document
that we only expect headers and footers here.

[rhogan, 2017/06/20 18:46:06]

Done.

     return false;
+
   // TODO(rhogan): Sections can be self-painting.
   if (HasSelfPaintingLayer())
     return false;
+
   // If we don't know the page height yet, just assume we fit.
   if (!IsPageLogicalHeightKnown())
     return true;
@@ -1970,23 +1979,39 @@ bool LayoutTableSection::HeaderGroupShouldRepeat() const {
   return true;
 }
 
+bool LayoutTableSection::HeaderGroupShouldRepeat() const {
+  if (Table()->Header() != this)
+    return false;
+  return GroupShouldRepeat();
+}
+
+bool LayoutTableSection::FooterGroupShouldRepeat() const {
+  if (Table()->Footer() != this)
+    return false;
+  return GroupShouldRepeat();
+}
+
 bool LayoutTableSection::MapToVisualRectInAncestorSpaceInternal(
     const LayoutBoxModelObject* ancestor,
     TransformState& transform_state,
     VisualRectFlags flags) const {
   if (ancestor == this)
     return true;
-  // Repeating table headers are painted once per fragmentation page/column.
+  // Repeating table headers and footers are painted once per fragmentation

[mstensho (USE GERRIT), 2017/06/16 08:43:06]

Instead of "fragmentation page/column", I suggest "fragmentainer" or
"page/column".

[rhogan, 2017/06/20 18:46:05]

Indeed.

+  // page/column. So we need to use the rect for the entire table because
+  // the repeating headers/footers will appear throughout it.
   // This does not go through the regular fragmentation machinery, so we need
   // special code to expand the invalidation rect to contain all positions of
   // the header in all columns.
   // Note that this is in flow thread coordinates, not visual coordinates. The
   // enclosing LayoutFlowThread will convert to visual coordinates.
-  if (IsRepeatingHeaderGroup()) {
+  if (IsRepeatingHeaderGroup() || IsRepeatingFooterGroup()) {
     transform_state.Flatten();
     FloatRect rect = transform_state.LastPlanarQuad().BoundingBox();
     rect.SetHeight(Table()->LogicalHeight());
     transform_state.SetQuad(FloatQuad(rect));
+    return Table()->MapToVisualRectInAncestorSpaceInternal(
+        ancestor, transform_state, flags);

[rhogan, 2017/06/20 18:46:06]

This is the place which used to trigger the DCHECK I removed above. Pretty sure
it's safe to remove now.

[mstensho (USE GERRIT), 2017/06/20 21:39:05]

I see no DCHECK removed.

   }
   return LayoutTableBoxComponent::MapToVisualRectInAncestorSpaceInternal(
       ancestor, transform_state, flags);