Bug 1627125 Part 1 - Allow ReflowFlexItem to take available size as an input, and output reflow status. r=dholbert

Differential Revision: https://phabricator.services.mozilla.com/D69469

layout/generic/ReflowInput.h

@@ -758,8 +758,9 @@ struct ReflowInput : public SizeComputationInput {
    * @param aPresContext Must be equal to aFrame->PresContext().
    * @param aFrame The frame for whose reflow input is being constructed.
    * @param aRenderingContext The rendering context to be used for measurements.
-   * @param aAvailableSpace See comments for availableHeight and availableWidth
-   *        members.
+   * @param aAvailableSpace The available space to reflow aFrame (in aFrame's
+   *        writing-mode). See comments for mAvailableHeight and mAvailableWidth
+   *        members for more information.
    * @param aFlags A set of flags used for additional boolean parameters (see
    *        below).
    */
@@ -775,8 +776,9 @@ struct ReflowInput : public SizeComputationInput {
    * @param aParentReflowInput A reference to an ReflowInput object that
    *        is to be the parent of this object.
    * @param aFrame The frame for whose reflow input is being constructed.
-   * @param aAvailableSpace See comments for availableHeight and availableWidth
-   *        members.
+   * @param aAvailableSpace The available space to reflow aFrame (in aFrame's
+   *        writing-mode). See comments for mAvailableHeight and mAvailableWidth
+   *        members for more information.
    * @param aContainingBlockSize An optional size, in app units, specifying
    *        the containing block size to use instead of the default which is
    *        computed by ComputeContainingBlockRectangle().

layout/generic/nsFlexContainerFrame.cpp

@@ -4856,8 +4856,25 @@ void nsFlexContainerFrame::ReflowChildren(
       // to clear out a -webkit-line-clamp ellipsis, we can just reposition it
       // as-needed.
       if (item.NeedsFinalReflow()) {
+        // The available size must be in item's writing-mode.
+        const WritingMode itemWM = item.GetWritingMode();
+        LogicalSize availableSize = aReflowInput.ComputedSize(itemWM);
+
+        // XXX: Unconditionally give our children unconstrained block-size until
+        // we support flex item fragmentation.
+        availableSize.BSize(itemWM) = NS_UNCONSTRAINEDSIZE;
+
+        const nsReflowStatus childReflowStatus =
             ReflowFlexItem(aAxisTracker, aReflowInput, item, framePos,
-                       containerSize, aHasLineClampEllipsis);
+                           availableSize, containerSize, aHasLineClampEllipsis);
+
+        // XXXdholbert Once we do pagination / splitting, we'll need to actually
+        // handle incomplete childReflowStatuses. But for now, we give our kids
+        // unconstrained available height, which means they should always
+        // complete.
+        MOZ_ASSERT(childReflowStatus.IsComplete(),
+                   "We gave flex item unconstrained available height, so it "
+                   "should be complete");
       } else {
         MoveFlexItemToFinalPosition(aReflowInput, item, framePos,
                                     containerSize);
@@ -5026,16 +5043,14 @@ void nsFlexContainerFrame::MoveFlexItemToFinalPosition(
   PositionChildViews(aItem.Frame());
 }
 
-void nsFlexContainerFrame::ReflowFlexItem(
+nsReflowStatus nsFlexContainerFrame::ReflowFlexItem(
     const FlexboxAxisTracker& aAxisTracker, const ReflowInput& aReflowInput,
     const FlexItem& aItem, LogicalPoint& aFramePos,
-    const nsSize& aContainerSize, bool aHasLineClampEllipsis) {
+    const LogicalSize& aAvailableSize, const nsSize& aContainerSize,
+    bool aHasLineClampEllipsis) {
   WritingMode outerWM = aReflowInput.GetWritingMode();
-  WritingMode wm = aItem.Frame()->GetWritingMode();
-  LogicalSize availSize = aReflowInput.ComputedSize(wm);
-  availSize.BSize(wm) = NS_UNCONSTRAINEDSIZE;
   ReflowInput childReflowInput(PresContext(), aReflowInput, aItem.Frame(),
-                               availSize);
+                               aAvailableSize);
   childReflowInput.mFlags.mInsideLineClamp = GetLineClampValue() != 0;
   // This is the final reflow of this flex item; if we previously had a
   // -webkit-line-clamp, and we missed our chance to clear the ellipsis
@@ -5124,19 +5139,13 @@ void nsFlexContainerFrame::ReflowFlexItem(
 
   // XXXdholbert Perhaps we should call CheckForInterrupt here; see bug 1495532.
 
-  // XXXdholbert Once we do pagination / splitting, we'll need to actually
-  // handle incomplete childReflowStatuses. But for now, we give our kids
-  // unconstrained available height, which means they should always
-  // complete.
-  MOZ_ASSERT(childReflowStatus.IsComplete(),
-             "We gave flex item unconstrained available height, so it "
-             "should be complete");
-
   FinishReflowChild(aItem.Frame(), PresContext(), childReflowOutput,
                     &childReflowInput, outerWM, aFramePos, aContainerSize,
                     ReflowChildFlags::ApplyRelativePositioning);
 
   aItem.SetAscent(childReflowOutput.BlockStartAscent());
+
+  return childReflowStatus;
 }
 
 void nsFlexContainerFrame::ReflowPlaceholders(

layout/generic/nsFlexContainerFrame.h

@@ -502,13 +502,19 @@ class nsFlexContainerFrame final : public nsContainerFrame {
    * @param aItem           The flex item to be reflowed.
    * @param aFramePos       The position where the flex item's frame should
    *                        be placed. (pre-relative positioning)
+   * @param aAvailableSize  The available size to reflow the child frame (in the
+   *                        child frame's writing-mode).
    * @param aContainerSize  The flex container's size (required by some methods
    *                        that we call, to interpret aFramePos correctly).
+   * @return the child frame's reflow status.
    */
-  void ReflowFlexItem(const FlexboxAxisTracker& aAxisTracker,
-                      const ReflowInput& aReflowInput, const FlexItem& aItem,
+  nsReflowStatus ReflowFlexItem(const FlexboxAxisTracker& aAxisTracker,
+                                const ReflowInput& aReflowInput,
+                                const FlexItem& aItem,
                                 mozilla::LogicalPoint& aFramePos,
-                      const nsSize& aContainerSize, bool aHasLineClampEllipsis);
+                                const mozilla::LogicalSize& aAvailableSize,
+                                const nsSize& aContainerSize,
+                                bool aHasLineClampEllipsis);
 
   /**
    * Helper-function to perform a "dummy reflow" on all our nsPlaceholderFrame