Fix sizing of non strech items

Summary:
Fixes the sizing of items so that under most scenarios it calcultes its height by it's content for non exact measurings. This introduces a new useLegacyStretchBehaviour flag on the config to opt out of this change as it is breaking.

See facebook/yoga#505
Closes https://github.com/facebook/yoga/pull/506

Reviewed By: astreet

Differential Revision: D4954016

Pulled By: emilsjolander

fbshipit-source-id: d28bd5d174cd76951fb94df85e3b0cfab7f81ff7

yoga/YGEnums.c

@@ -91,8 +91,6 @@ const char *YGExperimentalFeatureToString(const YGExperimentalFeature value){
   switch(value){
     case YGExperimentalFeatureWebFlexBasis:
       return "web-flex-basis";
-    case YGExperimentalFeatureMinFlexFix:
-      return "min-flex-fix";
   }
   return "unknown";
 }

yoga/YGEnums.h

@@ -62,10 +62,9 @@ typedef YG_ENUM_BEGIN(YGEdge) {
 } YG_ENUM_END(YGEdge);
 WIN_EXPORT const char *YGEdgeToString(const YGEdge value);
 
-#define YGExperimentalFeatureCount 2
+#define YGExperimentalFeatureCount 1
 typedef YG_ENUM_BEGIN(YGExperimentalFeature) {
   YGExperimentalFeatureWebFlexBasis,
-  YGExperimentalFeatureMinFlexFix,
 } YG_ENUM_END(YGExperimentalFeature);
 WIN_EXPORT const char *YGExperimentalFeatureToString(const YGExperimentalFeature value);
 

yoga/Yoga.c

@@ -97,6 +97,7 @@ typedef struct YGStyle {
 typedef struct YGConfig {
   bool experimentalFeatures[YGExperimentalFeatureCount + 1];
   bool useWebDefaults;
+  bool useLegacyStretchBehaviour;
   float pointScaleFactor;
 } YGConfig;
 
@@ -202,7 +203,6 @@ static YGNode gYGNodeDefaults = {
 static YGConfig gYGConfigDefaults = {
     .experimentalFeatures =
         {
-                [YGExperimentalFeatureMinFlexFix] = false,
                 [YGExperimentalFeatureWebFlexBasis] = false,
         },
     .useWebDefaults = false,
@@ -2199,23 +2199,25 @@ static void YGNodelayoutImpl(const YGNodeRef node,
     // If the main dimension size isn't known, it is computed based on
     // the line length, so there's no more space left to distribute.
 
+    bool sizeBasedOnContent = false;
     // If we don't measure with exact main dimension we want to ensure we don't violate min and max
     if (measureModeMainDim != YGMeasureModeExactly) {
       if (!YGFloatIsUndefined(minInnerMainDim) && sizeConsumedOnCurrentLine < minInnerMainDim) {
         availableInnerMainDim = minInnerMainDim;
       } else if (!YGFloatIsUndefined(maxInnerMainDim) && sizeConsumedOnCurrentLine > maxInnerMainDim) {
         availableInnerMainDim = maxInnerMainDim;
-      } else if (YGConfigIsExperimentalFeatureEnabled(node->config, YGExperimentalFeatureMinFlexFix) &&
-                 (totalFlexGrowFactors == 0 || YGResolveFlexGrow(node) == 0)) {
-        // TODO: this needs to be moved out of experimental feature, as this is legitimate fix
-        // If we don't have any children to flex or we can't flex the node itself,
-        // space we've used is all space we need
-        availableInnerMainDim = sizeConsumedOnCurrentLine;
+      } else {
+        if (!node->config->useLegacyStretchBehaviour && (totalFlexGrowFactors == 0 || YGResolveFlexGrow(node) == 0)) {
+          // If we don't have any children to flex or we can't flex the node itself,
+          // space we've used is all space we need
+          availableInnerMainDim = sizeConsumedOnCurrentLine;
+        }
+        sizeBasedOnContent = true;
       }
     }
 
     float remainingFreeSpace = 0;
-    if (!YGFloatIsUndefined(availableInnerMainDim)) {
+    if ((!sizeBasedOnContent || node->config->useLegacyStretchBehaviour) && !YGFloatIsUndefined(availableInnerMainDim)) {
       remainingFreeSpace = availableInnerMainDim - sizeConsumedOnCurrentLine;
     } else if (sizeConsumedOnCurrentLine < 0) {
       // availableInnerMainDim is indefinite which means the node is being sized
@@ -3427,6 +3429,10 @@ void YGConfigSetUseWebDefaults(const YGConfigRef config, const bool enabled) {
   config->useWebDefaults = enabled;
 }
 
+void YGConfigSetUseLegacyStretchBehaviour(const YGConfigRef config, const bool useLegacyStretchBehaviour) {
+  config->useLegacyStretchBehaviour = useLegacyStretchBehaviour;
+}
+
 bool YGConfigGetUseWebDefaults(const YGConfigRef config) {
   return config->useWebDefaults;
 }

yoga/Yoga.h

@@ -225,6 +225,11 @@ WIN_EXPORT void YGLog(YGLogLevel level, const char *message, ...);
 // If you want to avoid rounding - set PointScaleFactor to 0
 WIN_EXPORT void YGConfigSetPointScaleFactor(const YGConfigRef config, const float pixelsInPoint);
 
+// Yoga previously had an error where containers would take the maximum space possible instead of the minimum
+// like they are supposed to. In practice this resulted in implicit behaviour similar to align-self: stretch;
+// Because this was such a long-standing bug we must allow legacy users to switch back to this behaviour.
+WIN_EXPORT void YGConfigSetUseLegacyStretchBehaviour(const YGConfigRef config, const bool useLegacyStretchBehaviour);
+
 // YGConfig
 WIN_EXPORT YGConfigRef YGConfigNew(void);
 WIN_EXPORT void YGConfigFree(const YGConfigRef config);