[css-grid] Ignore collapsed tracks on content-distribution alignment

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

Index: third_party/WebKit/Source/core/layout/LayoutGrid.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutGrid.cpp b/third_party/WebKit/Source/core/layout/LayoutGrid.cpp
index 00436b95c574ea8221b85725c835a36ec99822cc..0747afe4cfe606eac2eed4819e1a9be794b98269 100644
--- a/third_party/WebKit/Source/core/layout/LayoutGrid.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutGrid.cpp
@@ -1405,20 +1405,22 @@ void LayoutGrid::PopulateGridPositionsForDirection(
   size_t number_of_tracks = tracks.size();
   size_t number_of_lines = number_of_tracks + 1;
   size_t last_line = number_of_lines - 1;
+  auto& grid = track_sizing_algorithm_.GetGrid();

[svillar, 2017/04/25 08:03:29]

Same comment, I know this was already here, but you don't need to ask the
algorithm for the grid. This method is only called from LayoutGridItems which is
called during layout so you can directly use the attribute grid_ here.

+  bool has_collapsed_tracks = grid.HasAutoRepeatEmptyTracks(direction);
+  size_t number_of_collapsed_tracks =
+      has_collapsed_tracks ? grid.AutoRepeatEmptyTracks(direction)->size() : 0;
   ContentAlignmentData offset = ComputeContentPositionAndDistributionOffset(
       direction, track_sizing_algorithm_.FreeSpace(direction).value(),
-      number_of_tracks);
+      number_of_tracks - number_of_collapsed_tracks);
   auto& positions = is_row_axis ? column_positions_ : row_positions_;
   positions.Resize(number_of_lines);
   auto border_and_padding =
       is_row_axis ? BorderAndPaddingLogicalLeft() : BorderAndPaddingBefore();
   positions[0] = border_and_padding + offset.position_offset;
-  const Grid& grid = track_sizing_algorithm_.GetGrid();
   if (number_of_lines > 1) {
     // If we have collapsed tracks we just ignore gaps here and add them later
     // as we might not compute the gap between two consecutive tracks without
     // examining the surrounding ones.
-    bool has_collapsed_tracks = grid.HasAutoRepeatEmptyTracks(direction);
     LayoutUnit gap = !has_collapsed_tracks ? GridGap(direction) : LayoutUnit();
     size_t next_to_last_line = number_of_lines - 2;
     for (size_t i = 0; i < next_to_last_line; ++i)
@@ -1432,12 +1434,13 @@ void LayoutGrid::PopulateGridPositionsForDirection(
     // they become 0.
     if (has_collapsed_tracks) {
       gap = GridGap(direction);
-      size_t remaining_empty_tracks =
-          grid.AutoRepeatEmptyTracks(direction)->size();
+      size_t remaining_empty_tracks = number_of_collapsed_tracks;
+      size_t last_empty_track = 0;
       LayoutUnit gap_accumulator;
       for (size_t i = 1; i < last_line; ++i) {
         if (grid.IsEmptyAutoRepeatTrack(direction, i - 1)) {
           --remaining_empty_tracks;
+          last_empty_track = i - 1;
         } else {
           // Add gap between consecutive non empty tracks. Add it also just once
           // for an arbitrary number of empty tracks between two non empty ones.
@@ -1447,7 +1450,8 @@ void LayoutGrid::PopulateGridPositionsForDirection(
               !grid.IsEmptyAutoRepeatTrack(direction, i))
             gap_accumulator += gap;
         }
-        positions[i] += gap_accumulator;
+        positions[i] +=
+            gap_accumulator - last_empty_track * offset.distribution_offset;

[svillar, 2017/04/25 08:03:29]

I think this is wrong. Instead of the last empty track you need a counter of the
empty tracks. For example a grid with 10 tracks and track 9 is empty, when
computing the track 10 you'd be substracting 9 * offset instead just 1 offset.

       }
       positions[last_line] += gap_accumulator;
     }