1 files changed, 108 insertions, 0 deletions
diff --git a/dom/grid/GridTracks.cpp b/dom/grid/GridTracks.cpp
new file mode 100644
index 0000000000..f3f4b98961
--- /dev/null
+++ b/dom/grid/GridTracks.cpp
@@ -0,0 +1,108 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "GridTracks.h"
+
+#include "GridDimension.h"
+#include "GridTrack.h"
+#include "mozilla/dom/GridBinding.h"
+#include "nsGridContainerFrame.h"
+
+namespace mozilla::dom {
+
+NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE(GridTracks, mParent, mTracks)
+NS_IMPL_CYCLE_COLLECTING_ADDREF(GridTracks)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(GridTracks)
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(GridTracks)
+  NS_WRAPPERCACHE_INTERFACE_MAP_ENTRY
+  NS_INTERFACE_MAP_ENTRY(nsISupports)
+NS_INTERFACE_MAP_END
+
+GridTracks::GridTracks(GridDimension* aParent) : mParent(aParent) {
+  MOZ_ASSERT(aParent, "Should never be instantiated with a null GridDimension");
+}
+
+GridTracks::~GridTracks() = default;
+
+JSObject* GridTracks::WrapObject(JSContext* aCx,
+                                 JS::Handle<JSObject*> aGivenProto) {
+  return GridTracks_Binding::Wrap(aCx, this, aGivenProto);
+}
+
+uint32_t GridTracks::Length() const { return mTracks.Length(); }
+
+GridTrack* GridTracks::Item(uint32_t aIndex) {
+  return mTracks.SafeElementAt(aIndex);
+}
+
+GridTrack* GridTracks::IndexedGetter(uint32_t aIndex, bool& aFound) {
+  aFound = aIndex < mTracks.Length();
+  if (!aFound) {
+    return nullptr;
+  }
+  return mTracks[aIndex];
+}
+
+void GridTracks::SetTrackInfo(const ComputedGridTrackInfo* aTrackInfo) {
+  // rebuild the tracks based on aTrackInfo
+  mTracks.Clear();
+
+  if (!aTrackInfo) {
+    return;
+  }
+
+  nscoord lastTrackEdge = 0;
+  uint32_t repeatIndex = 0;
+  auto AppendRemovedAutoFits = [this, &aTrackInfo, &lastTrackEdge,
+                                &repeatIndex]() {
+    uint32_t numRepeatTracks = aTrackInfo->mRemovedRepeatTracks.Length();
+    // Add in removed auto-fit tracks
+    while (repeatIndex < numRepeatTracks &&
+           aTrackInfo->mRemovedRepeatTracks[repeatIndex]) {
+      RefPtr<GridTrack> track = new GridTrack(this);
+      mTracks.AppendElement(track);
+      track->SetTrackValues(
+          nsPresContext::AppUnitsToDoubleCSSPixels(lastTrackEdge),
+          nsPresContext::AppUnitsToDoubleCSSPixels(0),
+          GridDeclaration::Explicit, GridTrackState::Removed);
+      repeatIndex++;
+    }
+    repeatIndex++;
+  };
+
+  for (size_t i = aTrackInfo->mStartFragmentTrack;
+       i < aTrackInfo->mEndFragmentTrack; i++) {
+    if (i >= aTrackInfo->mRepeatFirstTrack) {
+      // Append removed auto-fit tracks, if appropriate. The
+      // AppendRemovedAutoFits function exits early once it has been called
+      // aTrackInfo->mRemovedRepeatTracks.Length() times -- a check we don't
+      // replicate here or at subsequent calling sites.
+      AppendRemovedAutoFits();
+    }
+
+    RefPtr<GridTrack> track = new GridTrack(this);
+    mTracks.AppendElement(track);
+    track->SetTrackValues(
+        nsPresContext::AppUnitsToDoubleCSSPixels(aTrackInfo->mPositions[i]),
+        nsPresContext::AppUnitsToDoubleCSSPixels(aTrackInfo->mSizes[i]),
+        (
+            // Implicit if index is before the first explicit track, or after
+            // the last explicit track.
+            (i < aTrackInfo->mNumLeadingImplicitTracks) ||
+                    (i >= aTrackInfo->mNumLeadingImplicitTracks +
+                              aTrackInfo->mNumExplicitTracks)
+                ? GridDeclaration::Implicit
+                : GridDeclaration::Explicit),
+        GridTrackState(aTrackInfo->mStates[i]));
+
+    lastTrackEdge = aTrackInfo->mPositions[i] + aTrackInfo->mSizes[i];
+  }
+
+  // Append any trailing removed auto-fit tracks.
+  AppendRemovedAutoFits();
+}
+
+}  // namespace mozilla::dom