Repeat footers in paginated context

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

Index: third_party/WebKit/Source/core/layout/LayoutBlockFlow.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutBlockFlow.cpp b/third_party/WebKit/Source/core/layout/LayoutBlockFlow.cpp
index 494e8708ce9a3bf916d99d34d9a85062af8ee3ab..4688374ba5f7e2acb97b218fbe4f6b42fb753fdb 100644
--- a/third_party/WebKit/Source/core/layout/LayoutBlockFlow.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutBlockFlow.cpp
@@ -1139,7 +1139,11 @@ void LayoutBlockFlow::AdjustLinePositionForPagination(RootInlineBox& line_box,
   LayoutUnit remaining_logical_height = PageRemainingLogicalHeightForOffset(
       logical_offset, kAssociateWithLatterPage);
   int line_index = LineCount(&line_box);
-  if (remaining_logical_height < line_height ||
+  // We need to detect if we overlap a repeating footer and if so take the
+  // full remaining logical height as our strut to the next page.
+  LayoutUnit remaining_logical_height_including_footer =
+      remaining_logical_height - layout_state->HeightOffsetForTableFooters();
+  if (remaining_logical_height_including_footer < line_height ||
       (ShouldBreakAtLineToAvoidWidow() &&
        LineBreakToAvoidWidow() == line_index)) {
     LayoutUnit pagination_strut = CalculatePaginationStrutToFitContent(
@@ -1246,7 +1250,10 @@ LayoutUnit LayoutBlockFlow::AdjustForUnsplittableChild(
     return logical_offset;
   LayoutUnit remaining_logical_height = PageRemainingLogicalHeightForOffset(
       logical_offset, kAssociateWithLatterPage);
-  if (remaining_logical_height >= child_logical_height)
+  LayoutUnit remaining_logical_height_including_footer =
+      remaining_logical_height -
+      View()->GetLayoutState()->HeightOffsetForTableFooters();
+  if (remaining_logical_height_including_footer >= child_logical_height)

[mstensho (USE GERRIT), 2017/07/17 10:38:08]

Why can't PageRemainingLogicalHeightForOffset() do this job? Look at all the
call sites for PageRemainingLogicalHeightForOffset(). And we only care about
footers at two of these sites?

[rhogan, 2017/07/24 18:56:06]

Because, as well as deciding whether the line or block fits on the page,
PageRemainingLogicalHeightForOffset() is used to figure out the strut we need to
apply to reach the top of the next page. When we have a footer it can be used
for the latter but not the former - we need to adjust its value by the height of
the footer in order to that.

[mstensho (USE GERRIT), 2017/07/25 08:59:32]

Ah, true.

PageRemainingLogicalHeightForOffset() should definitely take footers into
account. Otherwise it's not really answering how much space we have left.

Maybe CalculatePaginationStrutToFitContent() should always be used to calculate
the strut. Then it probably shouldn't take this |strut_to_next_page| parameter
anymore, since it's going to be impossible for the caller to calculate it.

How about this: https://chromium-review.googlesource.com/c/583619/

Then, afterwards, you can fix PageRemainingLogicalHeightForOffset() and
CalculatePaginationStrutToFitContent() to deal correctly with footers?

     return logical_offset;  // It fits fine where it is. No need to break.
   LayoutUnit pagination_strut = CalculatePaginationStrutToFitContent(
       logical_offset, remaining_logical_height, child_logical_height);