From 62f47190fb2c13d47b13efacfc237f30ab312b51 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Lukas=20W=C3=B6hrl?= <lukas@woehrl.net>
Date: Fri, 3 Mar 2017 10:47:42 -0800
Subject: [PATCH] Added bool config to YGConfig to configure using web defaults

Summary:
Added bool config to YGConfig to configure using web defaults. See #445.
Closes https://github.com/facebook/yoga/pull/449

Reviewed By: astreet

Differential Revision: D4642272

Pulled By: emilsjolander

fbshipit-source-id: 4f35bd17b7f764f42295052a4a8b4ae46c192d7e
---
 tests/YGDefaultValuesTest.cpp | 13 +++++++++++++
 yoga/Yoga.c                   | 27 ++++++++++++++++++++++-----
 yoga/Yoga.h                   |  6 ++++++
 3 files changed, 41 insertions(+), 5 deletions(-)

diff --git a/tests/YGDefaultValuesTest.cpp b/tests/YGDefaultValuesTest.cpp
index a1d33eee..7e6b341f 100644
--- a/tests/YGDefaultValuesTest.cpp
+++ b/tests/YGDefaultValuesTest.cpp
@@ -90,3 +90,16 @@ TEST(YogaTest, assert_default_values) {
 
   YGNodeFreeRecursive(root);
 }
+
+TEST(YogaTest, assert_webdefault_values) {
+  YGConfig * config = YGConfigNew();
+  YGConfigSetUseWebDefaults(config, true);
+  const YGNodeRef root = YGNodeNewWithConfig(config);
+
+  ASSERT_EQ(YGFlexDirectionRow, YGNodeStyleGetFlexDirection(root));
+  ASSERT_EQ(YGAlignStretch, YGNodeStyleGetAlignContent(root));
+  ASSERT_FLOAT_EQ(1.0f, YGNodeStyleGetFlexShrink(root));
+
+  YGNodeFreeRecursive(root);
+  YGConfigFree(config);
+}
diff --git a/yoga/Yoga.c b/yoga/Yoga.c
index d4743518..7338319e 100644
--- a/yoga/Yoga.c
+++ b/yoga/Yoga.c
@@ -94,7 +94,10 @@ typedef struct YGStyle {
   float aspectRatio;
 } YGStyle;
 
-typedef struct YGConfig { bool experimentalFeatures[YGExperimentalFeatureCount + 1]; } YGConfig;
+typedef struct YGConfig {
+  bool experimentalFeatures[YGExperimentalFeatureCount + 1];
+  bool useWebDefaults;
+} YGConfig;
 
 typedef struct YGNode {
   YGStyle style;
@@ -144,6 +147,7 @@ typedef struct YGNode {
 
 static const float kDefaultFlexGrow = 0.0f;
 static const float kDefaultFlexShrink = 0.0f;
+static const float kWebDefaultFlexShrink = 1.0f;
 
 static YGNode gYGNodeDefaults = {
     .parent = NULL,
@@ -201,6 +205,7 @@ static YGConfig gYGConfigDefaults = {
                 [YGExperimentalFeatureMinFlexFix] = false,
                 [YGExperimentalFeatureWebFlexBasis] = false,
         },
+    .useWebDefaults = false,
 };
 
 static void YGNodeMarkDirtyInternal(const YGNodeRef node);
@@ -309,6 +314,10 @@ WIN_EXPORT YGNodeRef YGNodeNewWithConfig(const YGConfigRef config) {
   gNodeInstanceCount++;
 
   memcpy(node, &gYGNodeDefaults, sizeof(YGNode));
+  if (config->useWebDefaults) {
+    node->style.flexDirection = YGFlexDirectionRow;
+    node->style.alignContent = YGAlignStretch;
+  }
   node->config = config;
   return node;
 }
@@ -463,17 +472,17 @@ float YGNodeStyleGetFlexGrow(const YGNodeRef node) {
 }
 
 float YGNodeStyleGetFlexShrink(const YGNodeRef node) {
-  return YGFloatIsUndefined(node->style.flexShrink) ? kDefaultFlexShrink : node->style.flexShrink;
+  return YGFloatIsUndefined(node->style.flexShrink) ? (node->config->useWebDefaults ? kWebDefaultFlexShrink : kDefaultFlexShrink) : node->style.flexShrink;
 }
 
 static inline float YGNodeResolveFlexShrink(const YGNodeRef node) {
   if (!YGFloatIsUndefined(node->style.flexShrink)) {
     return node->style.flexShrink;
   }
-  if (!YGFloatIsUndefined(node->style.flex) && node->style.flex < 0.0f) {
+  if (!node->config->useWebDefaults && !YGFloatIsUndefined(node->style.flex) && node->style.flex < 0.0f) {
     return -node->style.flex;
   }
-  return kDefaultFlexShrink;
+  return node->config->useWebDefaults ? kWebDefaultFlexShrink : kDefaultFlexShrink;
 }
 
 static inline const YGValue *YGNodeResolveFlexBasisPtr(const YGNodeRef node) {
@@ -481,7 +490,7 @@ static inline const YGValue *YGNodeResolveFlexBasisPtr(const YGNodeRef node) {
     return &node->style.flexBasis;
   }
   if (!YGFloatIsUndefined(node->style.flex) && node->style.flex > 0.0f) {
-    return &YGValueZero;
+    return node->config->useWebDefaults ? &YGValueAuto : &YGValueZero;
   }
   return &YGValueAuto;
 }
@@ -3440,6 +3449,14 @@ inline bool YGConfigIsExperimentalFeatureEnabled(const YGConfigRef config,
   return config->experimentalFeatures[feature];
 }
 
+void YGConfigSetUseWebDefaults(const YGConfigRef config, const bool enabled) {
+  config->useWebDefaults = enabled;
+}
+
+bool YGConfigGetUseWebDefaults(const YGConfigRef config) {
+  return config->useWebDefaults;
+}
+
 void YGSetMemoryFuncs(YGMalloc ygmalloc, YGCalloc yccalloc, YGRealloc ygrealloc, YGFree ygfree) {
   YG_ASSERT(gNodeInstanceCount == 0, "Cannot set memory functions: all node must be freed first");
   YG_ASSERT((ygmalloc == NULL && yccalloc == NULL && ygrealloc == NULL && ygfree == NULL) ||
diff --git a/yoga/Yoga.h b/yoga/Yoga.h
index cbcf92ee..3b3b84a9 100644
--- a/yoga/Yoga.h
+++ b/yoga/Yoga.h
@@ -235,6 +235,12 @@ WIN_EXPORT void YGConfigSetExperimentalFeatureEnabled(const YGConfigRef config,
 WIN_EXPORT bool YGConfigIsExperimentalFeatureEnabled(const YGConfigRef config,
                                                      const YGExperimentalFeature feature);
 
+// Using the web defaults is the prefered configuration for new projects. 
+// Usage of non web defaults should be considered as legacy.
+WIN_EXPORT void YGConfigSetUseWebDefaults(const YGConfigRef config, const bool enabled);
+
+WIN_EXPORT bool YGConfigGetUseWebDefaults(const YGConfigRef config);
+
 WIN_EXPORT void
 YGSetMemoryFuncs(YGMalloc ygmalloc, YGCalloc yccalloc, YGRealloc ygrealloc, YGFree ygfree);