From d9e5b313bb63a1ec0d402a96539c6df29bc72c42 Mon Sep 17 00:00:00 2001
From: Valentin Shergin <shergin@fb.com>
Date: Sun, 7 Jan 2018 18:21:39 -0800
Subject: [PATCH] Helpers for proper conversion float values between CG and YG
 representations

Summary:
Yoga and CoreGraphics have different opinions about how "infinity" value
should be represented.
Yoga uses `NAN` which requires additional effort to compare all those values,
whereas GoreGraphics uses `GFLOAT_MAX` which can be easyly compared with
standard `==` operator.

Messing with this can cause super weired bugs like 100% CPU load for couple of seconds somewhere in CoreGraphics.

Reviewed By: mmmulani

Differential Revision: D6665633

fbshipit-source-id: b6236c6fa50d1f8fb0c9576203922f7b24b7301e
---
 React/Views/RCTShadowView+Layout.h |  7 +++++
 React/Views/RCTShadowView+Layout.m | 42 ++++++++++++++++++++++++------
 2 files changed, 41 insertions(+), 8 deletions(-)

diff --git a/React/Views/RCTShadowView+Layout.h b/React/Views/RCTShadowView+Layout.h
index 917b5f4a5..fe40dca40 100644
--- a/React/Views/RCTShadowView+Layout.h
+++ b/React/Views/RCTShadowView+Layout.h
@@ -11,6 +11,13 @@
 
 #import <React/RCTShadowView.h>
 
+/**
+ * Converts float values between Yoga and CoreGraphics representations,
+ * especially in terms of edge cases.
+ */
+RCT_EXTERN float RCTYogaFloatFromCoreGraphicsFloat(CGFloat value);
+RCT_EXTERN CGFloat RCTCoreGraphicsFloatFromYogaFloat(float value);
+
 @interface RCTShadowView (Layout)
 
 #pragma mark - Computed Layout-Inferred Metrics
diff --git a/React/Views/RCTShadowView+Layout.m b/React/Views/RCTShadowView+Layout.m
index b5e11e8d6..614a53889 100644
--- a/React/Views/RCTShadowView+Layout.m
+++ b/React/Views/RCTShadowView+Layout.m
@@ -11,6 +11,32 @@
 
 #import <yoga/Yoga.h>
 
+/**
+ * Yoga and CoreGraphics have different opinions about how "infinity" value
+ * should be represented.
+ * Yoga uses `NAN` which requires additional effort to compare all those values,
+ * whereas GoreGraphics uses `GFLOAT_MAX` which can be easyly compared with
+ * standard `==` operator.
+ */
+
+float RCTYogaFloatFromCoreGraphicsFloat(CGFloat value)
+{
+  if (value == CGFLOAT_MAX || isnan(value) || isinf(value)) {
+    return YGUndefined;
+  }
+
+  return value;
+}
+
+CGFloat RCTCoreGraphicsFloatFromYogaFloat(float value)
+{
+  if (value == YGUndefined || isnan(value) || isinf(value)) {
+    return CGFLOAT_MAX;
+  }
+
+  return value;
+}
+
 @implementation RCTShadowView (Layout)
 
 #pragma mark - Computed Layout-Inferred Metrics
@@ -19,10 +45,10 @@
 {
   YGNodeRef yogaNode = self.yogaNode;
   return (UIEdgeInsets){
-    YGNodeLayoutGetPadding(yogaNode, YGEdgeTop),
-    YGNodeLayoutGetPadding(yogaNode, YGEdgeLeft),
-    YGNodeLayoutGetPadding(yogaNode, YGEdgeBottom),
-    YGNodeLayoutGetPadding(yogaNode, YGEdgeRight)
+    RCTCoreGraphicsFloatFromYogaFloat(YGNodeLayoutGetPadding(yogaNode, YGEdgeTop)),
+    RCTCoreGraphicsFloatFromYogaFloat(YGNodeLayoutGetPadding(yogaNode, YGEdgeLeft)),
+    RCTCoreGraphicsFloatFromYogaFloat(YGNodeLayoutGetPadding(yogaNode, YGEdgeBottom)),
+    RCTCoreGraphicsFloatFromYogaFloat(YGNodeLayoutGetPadding(yogaNode, YGEdgeRight))
   };
 }
 
@@ -30,10 +56,10 @@
 {
   YGNodeRef yogaNode = self.yogaNode;
   return (UIEdgeInsets){
-    YGNodeLayoutGetBorder(yogaNode, YGEdgeTop),
-    YGNodeLayoutGetBorder(yogaNode, YGEdgeLeft),
-    YGNodeLayoutGetBorder(yogaNode, YGEdgeBottom),
-    YGNodeLayoutGetBorder(yogaNode, YGEdgeRight)
+    RCTCoreGraphicsFloatFromYogaFloat(YGNodeLayoutGetBorder(yogaNode, YGEdgeTop)),
+    RCTCoreGraphicsFloatFromYogaFloat(YGNodeLayoutGetBorder(yogaNode, YGEdgeLeft)),
+    RCTCoreGraphicsFloatFromYogaFloat(YGNodeLayoutGetBorder(yogaNode, YGEdgeBottom)),
+    RCTCoreGraphicsFloatFromYogaFloat(YGNodeLayoutGetBorder(yogaNode, YGEdgeRight))
   };
 }