Bug 1498273 Part 3: Define and set ComputedFlexItemInfo::mClampState. r=dholbert

Depends on D9727

Differential Revision: https://phabricator.services.mozilla.com/D9728

--HG--
extra : moz-landing-system : lando

dom/flex/FlexItemValues.cpp

@@ -61,7 +61,7 @@ FlexItemValues::FlexItemValues(FlexLineValues* aParent,
     aItem->mCrossMinSize);
   mCrossMaxSize = ToPossiblyUnconstrainedPixels(aItem->mCrossMaxSize);
 
-  mClampState = FlexItemClampState::Unclamped;
+  mClampState = aItem->mClampState;
 }
 
 JSObject*

layout/generic/nsFlexContainerFrame.cpp

@@ -1457,6 +1457,11 @@ nsFlexContainerFrame::GenerateFlexItemForChild(
   // valid size, so we freeze to keep ourselves from flexing.
   if (isFixedSizeWidget || (flexGrow == 0.0f && flexShrink == 0.0f)) {
     item->Freeze();
+    if (flexBaseSize < mainMinSize) {
+      item->SetWasMinClamped();
+    } else if (flexBaseSize > mainMaxSize) {
+      item->SetWasMaxClamped();
+    }
   }
 
   // Resolve "flex-basis:auto" and/or "min-[width|height]:auto" (which might
@@ -2608,6 +2613,11 @@ FlexLine::FreezeItemsEarly(bool aIsUsingFlexGrow,
       if (shouldFreeze) {
         // Freeze item! (at its hypothetical main size)
         item->Freeze();
+        if (item->GetFlexBaseSize() < item->GetMainSize()) {
+          item->SetWasMinClamped();
+        } else if (item->GetFlexBaseSize() > item->GetMainSize()) {
+          item->SetWasMaxClamped();
+        }
         mNumFrozenItems++;
       }
     }
@@ -2647,9 +2657,11 @@ FlexLine::FreezeOrRestoreEachFlexibleSize(const nscoord aTotalViolation,
       MOZ_ASSERT(!item->HadMinViolation() || !item->HadMaxViolation(),
                  "Can have either min or max violation, but not both");
 
+      bool hadMinViolation = item->HadMinViolation();
+      bool hadMaxViolation = item->HadMaxViolation();
       if (eFreezeEverything == freezeType ||
-          (eFreezeMinViolations == freezeType && item->HadMinViolation()) ||
-          (eFreezeMaxViolations == freezeType && item->HadMaxViolation())) {
+          (eFreezeMinViolations == freezeType && hadMinViolation) ||
+          (eFreezeMaxViolations == freezeType && hadMaxViolation)) {
 
         MOZ_ASSERT(item->GetMainSize() >= item->GetMainMinSize(),
                    "Freezing item at a size below its minimum");
@@ -2657,6 +2669,11 @@ FlexLine::FreezeOrRestoreEachFlexibleSize(const nscoord aTotalViolation,
                    "Freezing item at a size above its maximum");
 
         item->Freeze();
+        if (hadMinViolation) {
+          item->SetWasMinClamped();
+        } else if (hadMaxViolation) {
+          item->SetWasMaxClamped();
+        }
         mNumFrozenItems++;
       } else if (MOZ_UNLIKELY(aIsFinalIteration)) {
         // XXXdholbert If & when bug 765861 is fixed, we should upgrade this
@@ -4867,6 +4884,28 @@ nsFlexContainerFrame::DoFlexLayout(nsPresContext*           aPresContext,
     line->ResolveFlexibleLengths(aContentBoxMainSize, lineInfo);
   }
 
+  // If needed, capture the final clamp state from all the items.
+  if (containerInfo) {
+    uint32_t lineIndex = 0;
+    for (const FlexLine* line = lines.getFirst(); line;
+         line = line->getNext(), ++lineIndex) {
+      ComputedFlexLineInfo* lineInfo = &containerInfo->mLines[lineIndex];
+
+      uint32_t itemIndex = 0;
+      for (const FlexItem* item = line->GetFirstItem(); item;
+           item = item->getNext(), ++itemIndex) {
+        ComputedFlexItemInfo* itemInfo = &lineInfo->mItems[itemIndex];
+
+        itemInfo->mClampState =
+          item->WasMinClamped() ?
+          mozilla::dom::FlexItemClampState::Clamped_to_min :
+          (item->WasMaxClamped() ?
+           mozilla::dom::FlexItemClampState::Clamped_to_max :
+           mozilla::dom::FlexItemClampState::Unclamped);
+      }
+    }
+  }
+
   // Cross Size Determination - Flexbox spec section 9.4
   // ===================================================
   // Calculate the hypothetical cross size of each item:

layout/generic/nsFlexContainerFrame.h

@@ -54,6 +54,7 @@ struct ComputedFlexItemInfo
   nscoord mMainMaxSize;
   nscoord mCrossMinSize;
   nscoord mCrossMaxSize;
+  mozilla::dom::FlexItemClampState mClampState;
 };
 
 struct ComputedFlexLineInfo