From 7457010aa75f555625b19f82c7734ca9a814d779 Mon Sep 17 00:00:00 2001
From: Mats Palmgren <mats@mozilla.com>
Date: Wed, 1 May 2019 23:53:47 +0200
Subject: [PATCH] Bug 1466358 part 11 - [css-grid-2] Update the frame's subgrid
 state when the style changes.  r=dholbert

Differential Revision: https://phabricator.services.mozilla.com/D29578

--HG--
extra : rebase_source : 49ffcf3927761705680522750306fabfaa126cb9
---
 layout/generic/nsGridContainerFrame.cpp | 67 +++++++++++++++++++------
 layout/generic/nsGridContainerFrame.h   | 14 ++++++
 2 files changed, 65 insertions(+), 16 deletions(-)

diff --git a/layout/generic/nsGridContainerFrame.cpp b/layout/generic/nsGridContainerFrame.cpp
index 32f57e435ca8..1ae54e55f14f 100644
--- a/layout/generic/nsGridContainerFrame.cpp
+++ b/layout/generic/nsGridContainerFrame.cpp
@@ -46,6 +46,9 @@ typedef nsTHashtable<nsPtrHashKey<nsIFrame>> FrameHashtable;
 typedef mozilla::CSSAlignUtils::AlignJustifyFlags AlignJustifyFlags;
 typedef nsLayoutUtils::IntrinsicISizeType IntrinsicISizeType;
 
+static const nsFrameState kIsSubgridBits = (NS_STATE_GRID_IS_COL_SUBGRID |
+                                            NS_STATE_GRID_IS_ROW_SUBGRID);
+
 // https://drafts.csswg.org/css-sizing/#constraints
 enum class SizingConstraint {
   MinContent,   // sizing under min-content constraint
@@ -6944,8 +6947,12 @@ void nsGridContainerFrame::Reflow(nsPresContext* aPresContext,
 
   const nsStylePosition* stylePos = aReflowInput.mStylePosition;
   auto prevInFlow = static_cast<nsGridContainerFrame*>(GetPrevInFlow());
-  if (!prevInFlow) {
+  if (MOZ_LIKELY(!prevInFlow)) {
     InitImplicitNamedAreas(stylePos);
+  } else {
+    MOZ_ASSERT((prevInFlow->GetStateBits() & kIsSubgridBits) ==
+                   (GetStateBits() & kIsSubgridBits),
+               "continuations should have same kIsSubgridBits");
   }
   GridReflowInput gridReflowInput(this, aReflowInput);
   if (gridReflowInput.mIter.ItemsAreAlreadyInOrder()) {
@@ -7366,35 +7373,63 @@ void nsGridContainerFrame::Reflow(nsPresContext* aPresContext,
   NS_FRAME_SET_TRUNCATION(aStatus, aReflowInput, aDesiredSize);
 }
 
+void nsGridContainerFrame::UpdateSubgridFrameState() {
+  nsFrameState oldBits = GetStateBits() & kIsSubgridBits;
+  nsFrameState newBits = ComputeSelfSubgridBits();
+  if (newBits != oldBits) {
+    RemoveStateBits(kIsSubgridBits);
+    if (!newBits) {
+      DeleteProperty(Subgrid::Prop());
+    } else {
+      AddStateBits(newBits);
+    }
+  }
+}
+
+nsFrameState nsGridContainerFrame::ComputeSelfSubgridBits() const {
+  // skip our scroll frame and such if we have it
+  auto* parent = GetParent();
+  while (parent && parent->GetContent() == GetContent()) {
+    parent = parent->GetParent();
+  }
+  nsFrameState bits = nsFrameState(0);
+  if (parent && parent->IsGridContainerFrame()) {
+    const auto* pos = StylePosition();
+    if (pos->GridTemplateColumns().mIsSubgrid) {
+      bits |= NS_STATE_GRID_IS_COL_SUBGRID;
+    }
+    if (pos->GridTemplateRows().mIsSubgrid) {
+      bits |= NS_STATE_GRID_IS_ROW_SUBGRID;
+    }
+  }
+  return bits;
+}
+
 void nsGridContainerFrame::Init(nsIContent* aContent, nsContainerFrame* aParent,
                                 nsIFrame* aPrevInFlow) {
   nsContainerFrame::Init(aContent, aParent, aPrevInFlow);
 
   nsFrameState bits = nsFrameState(0);
   if (MOZ_LIKELY(!aPrevInFlow)) {
-    // skip our scroll frame and such if we have it
-    auto* parent = aParent;
-    while (parent && parent->GetContent() == aContent) {
-      parent = parent->GetParent();
-    }
-    if (parent && parent->IsGridContainerFrame()) {
-      const auto* pos = StylePosition();
-      if (pos->GridTemplateColumns().mIsSubgrid) {
-        bits |= NS_STATE_GRID_IS_COL_SUBGRID;
-      }
-      if (pos->GridTemplateRows().mIsSubgrid) {
-        bits |= NS_STATE_GRID_IS_ROW_SUBGRID;
-      }
-    }
+    bits = ComputeSelfSubgridBits();
   } else {
     bits = aPrevInFlow->GetStateBits() &
-           (NS_STATE_GRID_IS_COL_SUBGRID | NS_STATE_GRID_IS_ROW_SUBGRID |
+           (kIsSubgridBits |
             NS_STATE_GRID_HAS_COL_SUBGRID_ITEM |
             NS_STATE_GRID_HAS_ROW_SUBGRID_ITEM);
   }
   AddStateBits(bits);
 }
 
+void nsGridContainerFrame::DidSetComputedStyle(ComputedStyle* aOldStyle) {
+  nsContainerFrame::DidSetComputedStyle(aOldStyle);
+
+  if (!aOldStyle) {
+    return; // Init() already initialized the bits.
+  }
+  UpdateSubgridFrameState();
+}
+
 nscoord nsGridContainerFrame::IntrinsicISize(gfxContext* aRenderingContext,
                                              IntrinsicISizeType aType) {
   // Calculate the sum of column sizes under intrinsic sizing.
diff --git a/layout/generic/nsGridContainerFrame.h b/layout/generic/nsGridContainerFrame.h
index 05965863c13e..bcb7b7d0fb78 100644
--- a/layout/generic/nsGridContainerFrame.h
+++ b/layout/generic/nsGridContainerFrame.h
@@ -105,6 +105,7 @@ class nsGridContainerFrame final : public nsContainerFrame {
               nsReflowStatus& aStatus) override;
   void Init(nsIContent* aContent, nsContainerFrame* aParent,
             nsIFrame* aPrevInFlow) override;
+  void DidSetComputedStyle(ComputedStyle* aOldStyle) override;
   nscoord GetMinISize(gfxContext* aRenderingContext) override;
   nscoord GetPrefISize(gfxContext* aRenderingContext) override;
   void MarkIntrinsicISizesDirty() override;
@@ -414,6 +415,19 @@ class nsGridContainerFrame final : public nsContainerFrame {
   void SanityCheckGridItemsBeforeReflow() const;
 #endif  // DEBUG
 
+  /**
+   * Update our NS_STATE_GRID_IS_COL/ROW_SUBGRID bits and related subgrid state
+   * on our entire continuation chain based on the current style.
+   * This is needed because grid-template-columns/rows style changes only
+   * trigger a reflow so we need to update this dynamically.
+   */
+  void UpdateSubgridFrameState();
+
+  /**
+   * Return the NS_STATE_GRID_IS_COL/ROW_SUBGRID bits we ought to have.
+   */
+  nsFrameState ComputeSelfSubgridBits() const;
+
  private:
   // Helpers for ReflowChildren
   struct Fragmentainer {