tor-browser

commit 9af10c35781679ffa7a54488b14badd61f9fc7e2
parent 0c8136611b84cecbb6f470d14709788c4abbcb8f
Author: David Shin <dshin@mozilla.com>
Date:   Fri, 31 Oct 2025 23:52:22 +0000

Bug 1997418: Simplify `nsBlockFrame`'s abspos cb computation. r=layout-reviewers,emilio,TYLin

Most paths in the removed function returns the frame's padding
rect size. It doesn't seem that the single path that further
modifies the value is used.

This was added as Bug 282754, to account for scroll frames' behaviour
then.

Differential Revision: https://phabricator.services.mozilla.com/D270727

Diffstat:
M
layout/generic/nsBlockFrame.cpp
 | 
82
+++----------------------------------------------------------------------------

1 file changed, 3 insertions(+), 79 deletions(-)
diff --git a/layout/generic/nsBlockFrame.cpp b/layout/generic/nsBlockFrame.cpp
@@ -1110,81 +1110,6 @@ static bool AvailableSpaceShrunk(WritingMode aWM,
          aNewAvailableSpace.IEnd(aWM) < aOldAvailableSpace.IEnd(aWM);
 }
 
-static LogicalSize CalculateContainingBlockSizeForAbsolutes(
-    WritingMode aWM, const ReflowInput& aReflowInput,
-    const LogicalSize& aFrameSize) {
-  // The issue here is that for a 'height' of 'auto' the reflow input
-  // code won't know how to calculate the containing block height
-  // because it's calculated bottom up. So we use our own computed
-  // size as the dimensions.
-  nsIFrame* frame = aReflowInput.mFrame;
-
-  LogicalSize cbSize(aFrameSize);
-  // Containing block is relative to the padding edge
-  const LogicalMargin border = aReflowInput.ComputedLogicalBorder(aWM);
-  cbSize.ISize(aWM) -= border.IStartEnd(aWM);
-  cbSize.BSize(aWM) -= border.BStartEnd(aWM);
-
-  if (frame->GetParent()->GetContent() != frame->GetContent() ||
-      frame->GetParent()->IsCanvasFrame()) {
-    return cbSize;
-  }
-
-  // We are a wrapped frame for the content (and the wrapper is not the
-  // canvas frame, whose size is not meaningful here).
-  // Use the container's dimensions, if they have been precomputed.
-  // XXX This is a hack! We really should be waiting until the outermost
-  // frame is fully reflowed and using the resulting dimensions, even
-  // if they're intrinsic.
-  // In fact we should be attaching absolute children to the outermost
-  // frame and not always sticking them in block frames.
-
-  // First, find the reflow input for the outermost frame for this content.
-  const ReflowInput* lastRI = &aReflowInput;
-  DebugOnly<const ReflowInput*> lastButOneRI = &aReflowInput;
-  while (lastRI->mParentReflowInput &&
-         lastRI->mParentReflowInput->mFrame->GetContent() ==
-             frame->GetContent()) {
-    lastButOneRI = lastRI;
-    lastRI = lastRI->mParentReflowInput;
-  }
-
-  if (lastRI == &aReflowInput) {
-    return cbSize;
-  }
-
-  // For scroll containers, we can just use cbSize (which is the padding-box
-  // size of the scrolled-content frame).
-  if (lastRI->mFrame->IsScrollContainerOrSubclass()) {
-    // Assert that we're not missing any frames between the abspos containing
-    // block and the scroll container.
-    // the parent.
-    MOZ_ASSERT(lastButOneRI == &aReflowInput);
-    return cbSize;
-  }
-
-  // Same for fieldsets, where the inner anonymous frame has the correct padding
-  // area with the legend taken into account.
-  if (lastRI->mFrame->IsFieldSetFrame()) {
-    return cbSize;
-  }
-
-  // We found a reflow input for the outermost wrapping frame, so use
-  // its computed metrics if available, converted to our writing mode
-  const LogicalSize lastRISize = lastRI->ComputedSize(aWM);
-  const LogicalMargin lastRIPadding = lastRI->ComputedLogicalPadding(aWM);
-  if (lastRISize.ISize(aWM) != NS_UNCONSTRAINEDSIZE) {
-    cbSize.ISize(aWM) =
-        std::max(0, lastRISize.ISize(aWM) + lastRIPadding.IStartEnd(aWM));
-  }
-  if (lastRISize.BSize(aWM) != NS_UNCONSTRAINEDSIZE) {
-    cbSize.BSize(aWM) =
-        std::max(0, lastRISize.BSize(aWM) + lastRIPadding.BStartEnd(aWM));
-  }
-
-  return cbSize;
-}
-
 /**
  * Returns aFrame if it is an in-flow, non-BFC block frame, and null otherwise.
  *
@@ -1776,10 +1701,6 @@ void nsBlockFrame::Reflow(nsPresContext* aPresContext, ReflowOutput& aMetrics,
         }
       }
     } else {
-      LogicalSize containingBlockSize =
-          CalculateContainingBlockSizeForAbsolutes(parentWM, aReflowInput,
-                                                   aMetrics.Size(parentWM));
-
       // Mark frames that depend on changes we just made to this frame as dirty:
       // Now we can assume that the padding edge hasn't moved.
       // We need to reflow the absolutes if one of them depends on
@@ -1799,6 +1720,9 @@ void nsBlockFrame::Reflow(nsPresContext* aPresContext, ReflowOutput& aMetrics,
           !(isRoot && NS_UNCONSTRAINEDSIZE == aReflowInput.ComputedHeight()) &&
           aMetrics.Height() != oldSize.height;
 
+      const LogicalSize containingBlockSize =
+          aMetrics.Size(parentWM) -
+          aReflowInput.ComputedLogicalBorder(parentWM).Size(parentWM);
       nsRect containingBlock(nsPoint(0, 0),
                              containingBlockSize.GetPhysicalSize(parentWM));
       AbsPosReflowFlags flags{AbsPosReflowFlag::AllowFragmentation};