Issue #1230 - Part 1: Fix Back-computing percentages for intrinsic sizing in Layout CSS-Grid

List of relevant patches applied:

1398537 part 2 - [css-multicol] Implement percentages for 'column-gap' (Gecko part).

1434478 part 1 - [css-grid] Stop back-computing percentage grid gaps when the percentage basis is indefinite. Treat them as zero sized instead.

1434478 part 2 - Stop back-computing percentage padding/margin when the percentage basis is indefinite. Treat them as zero sized instead.

1434478 part 3 - Remove IntrinsicISizeOffsetData::hPctPadding/hPctMargin members since they are now unused.

1434478 part 4 - Factor out constants like NS_UNCONSTRAINEDSIZE so they can be used in headers without needing nsIFrame.h (idempotent patch).

1434478 part 5 - Create nsLayoutUtils::ResolveToLength for resolving CSS <length-percentage> (idempotent patch).

1434478 part 6 - Propagate a percentage basis to nsIFrame::IntrinsicISizeOffsets for resolving padding/margin.

This is needed only for CSS Grid since in other cases we're only using IntrinsicISizeOffsets in the inline-axis and the percentage basis is always indefinite for *intrinsic sizing*. When calculating the intrinsic size of grid items in the grid container's block axis however, we do have a definite size for the grid area in the inline-axis and it should be used per: https://drafts.csswg.org/css-grid/#algo-overview "2. Next, the track sizing algorithm resolves the sizes of the grid rows, using the grid column sizes calculated in the previous step." (Percentage padding/margin for grid items is always resolved against the grid area's inline-size nowadays.)

1 files changed, 8 insertions, 11 deletions

diff --git a/layout/generic/nsColumnSetFrame.cpp b/layout/generic/nsColumnSetFrame.cpp
index ad36ba1a8..6ea15d4d2 100644
--- a/layout/generic/nsColumnSetFrame.cpp
+++ b/layout/generic/nsColumnSetFrame.cpp
@@ -183,18 +183,15 @@ nsColumnSetFrame::GetAvailableContentBSize(const ReflowInput& aReflowInput)
 
 static nscoord
 GetColumnGap(nsColumnSetFrame*    aFrame,
-             const nsStyleColumn* aColStyle)
+             const nsStyleColumn* aColStyle,
+             nscoord              aPercentageBasis)
 {
-  if (eStyleUnit_Normal == aColStyle->mColumnGap.GetUnit())
+  const auto& columnGap = aColStyle->mColumnGap;
+  if (columnGap.GetUnit() == eStyleUnit_Normal) {
     return aFrame->StyleFont()->mFont.size;
-  if (eStyleUnit_Coord == aColStyle->mColumnGap.GetUnit()) {
-    nscoord colGap = aColStyle->mColumnGap.GetCoordValue();
-    NS_ASSERTION(colGap >= 0, "negative column gap");
-    return colGap;
   }
 
-  NS_NOTREACHED("Unknown gap type");
-  return 0;
+  return nsLayoutUtils::ResolveGapToLength(columnGap, aPercentageBasis);
 }
 
 nsColumnSetFrame::ReflowConfig
@@ -227,7 +224,7 @@ nsColumnSetFrame::ChooseColumnStrategy(const ReflowInput& aReflowInput,
     colBSize = std::min(colBSize, aReflowInput.ComputedMaxBSize());
   }
 
-  nscoord colGap = GetColumnGap(this, colStyle);
+  nscoord colGap = GetColumnGap(this, colStyle, aReflowInput.ComputedISize());
   int32_t numColumns = colStyle->mColumnCount;
 
   // If column-fill is set to 'balance', then we want to balance the columns.
@@ -403,7 +400,7 @@ nsColumnSetFrame::GetMinISize(nsRenderingContext *aRenderingContext)
     // include n-1 column gaps.
     colISize = iSize;
     iSize *= colStyle->mColumnCount;
-    nscoord colGap = GetColumnGap(this, colStyle);
+    nscoord colGap = GetColumnGap(this, colStyle, NS_UNCONSTRAINEDSIZE);
     iSize += colGap * (colStyle->mColumnCount - 1);
     // The multiplication above can make 'width' negative (integer overflow),
     // so use std::max to protect against that.
@@ -424,7 +421,7 @@ nsColumnSetFrame::GetPrefISize(nsRenderingContext *aRenderingContext)
   nscoord result = 0;
   DISPLAY_PREF_WIDTH(this, result);
   const nsStyleColumn* colStyle = StyleColumn();
-  nscoord colGap = GetColumnGap(this, colStyle);
+  nscoord colGap = GetColumnGap(this, colStyle, NS_UNCONSTRAINEDSIZE);
 
   nscoord colISize;
   if (colStyle->mColumnWidth.GetUnit() == eStyleUnit_Coord) {