From 1aa157b196b85d81e2e2115815c073fe8c0730c4 Mon Sep 17 00:00:00 2001
From: Nick Gerleman <ngerlem@meta.com>
Date: Tue, 15 Nov 2022 19:51:48 -0800
Subject: [PATCH] Incorporate gap space into main axis overflow flag (#1173)

Summary:
X-link: https://github.com/facebook/yoga/pull/1173

In https://github.com/facebook/react-native/issues/35351 we see incorrect child item height when the flex-wrap is enabled, the cross-axis is to be stretched, and main-axis overflow is caused by gap.

In YGDistributeFreeSpaceSecondPass, if we do not have overflow (determined by flexBasisOverflows), we have stretch cross-alignment, and we reason that nothing can add to main axis dimensions, we know we're a single line and want to take full cross dimensions. and can set YGMeasureModeExactly which uses parent dimensions. Guessing an optimization?

If we do have overflow, then we set YGMeasureModeAtMost to find minimum possible cross-axis dimensions instead.

`flexBasisOverflows` incorporates both computed flex basis, and margin, so it is more generally a flag for whether we will wrap. So we should incorporate gap spacing into it. E.g. it is also used for whether we should the match main axis parent dimension of the overall container. This change does just that, and renames the flag to `mainAxisOverflows`.

We will want to cherry-pick the fix for this into RN 0.71 since we have not yet introduced the community to the incorrect behavior, and we expect a lot of usage of flex-gap.

Changelog:
[General][Fixed] - Fix incorrect height when gap causes main axis to overflow and cross-axis is stretched

Reviewed By: yungsters

Differential Revision: D41311424

fbshipit-source-id: bd0c3b5aac478a56878703b6da84fc3993cc14da
---
 ReactCommon/yoga/yoga/Yoga.cpp | 29 +++++++++++++++++++----------
 1 file changed, 19 insertions(+), 10 deletions(-)

diff --git a/ReactCommon/yoga/yoga/Yoga.cpp b/ReactCommon/yoga/yoga/Yoga.cpp
index a5c70b478df000..88c77ab8501406 100644
--- a/ReactCommon/yoga/yoga/Yoga.cpp
+++ b/ReactCommon/yoga/yoga/Yoga.cpp
@@ -2079,7 +2079,7 @@ static float YGDistributeFreeSpaceSecondPass(
     const float availableInnerCrossDim,
     const float availableInnerWidth,
     const float availableInnerHeight,
-    const bool flexBasisOverflows,
+    const bool mainAxisOverflows,
     const YGMeasureMode measureModeCrossDim,
     const bool performLayout,
     const YGConfigRef config,
@@ -2175,7 +2175,7 @@ static float YGDistributeFreeSpaceSecondPass(
         !YGNodeIsStyleDimDefined(
             currentRelativeChild, crossAxis, availableInnerCrossDim) &&
         measureModeCrossDim == YGMeasureModeExactly &&
-        !(isNodeFlexWrap && flexBasisOverflows) &&
+        !(isNodeFlexWrap && mainAxisOverflows) &&
         YGNodeAlignItem(node, currentRelativeChild) == YGAlignStretch &&
         currentRelativeChild->marginLeadingValue(crossAxis).unit !=
             YGUnitAuto &&
@@ -2383,7 +2383,7 @@ static void YGResolveFlexibleLength(
     const float availableInnerCrossDim,
     const float availableInnerWidth,
     const float availableInnerHeight,
-    const bool flexBasisOverflows,
+    const bool mainAxisOverflows,
     const YGMeasureMode measureModeCrossDim,
     const bool performLayout,
     const YGConfigRef config,
@@ -2411,7 +2411,7 @@ static void YGResolveFlexibleLength(
       availableInnerCrossDim,
       availableInnerWidth,
       availableInnerHeight,
-      flexBasisOverflows,
+      mainAxisOverflows,
       measureModeCrossDim,
       performLayout,
       config,
@@ -2884,7 +2884,9 @@ static void YGNodelayoutImpl(
 
   // STEP 3: DETERMINE FLEX BASIS FOR EACH ITEM
 
-  float totalOuterFlexBasis = YGNodeComputeFlexBasisForChildren(
+  // Computed basis + margins + gap
+  float totalMainDim = 0;
+  totalMainDim += YGNodeComputeFlexBasisForChildren(
       node,
       availableInnerWidth,
       availableInnerHeight,
@@ -2899,10 +2901,17 @@ static void YGNodelayoutImpl(
       depth,
       generationCount);
 
-  const bool flexBasisOverflows = measureModeMainDim == YGMeasureModeUndefined
-      ? false
-      : totalOuterFlexBasis > availableInnerMainDim;
-  if (isNodeFlexWrap && flexBasisOverflows &&
+  if (childCount > 1) {
+    totalMainDim +=
+        node->getGapForAxis(mainAxis, availableInnerCrossDim).unwrap() *
+        (childCount - 1);
+  }
+
+  const bool mainAxisOverflows =
+      (measureModeMainDim != YGMeasureModeUndefined) &&
+      totalMainDim > availableInnerMainDim;
+
+  if (isNodeFlexWrap && mainAxisOverflows &&
       measureModeMainDim == YGMeasureModeAtMost) {
     measureModeMainDim = YGMeasureModeExactly;
   }
@@ -3025,7 +3034,7 @@ static void YGNodelayoutImpl(
           availableInnerCrossDim,
           availableInnerWidth,
           availableInnerHeight,
-          flexBasisOverflows,
+          mainAxisOverflows,
           measureModeCrossDim,
           performLayout,
           config,