From f96f9c5fd692000f561e87cba68642ef7daf43e7 Mon Sep 17 00:00:00 2001
From: Valentin Shergin <shergin@fb.com>
Date: Sun, 7 Jan 2018 18:21:41 -0800
Subject: [PATCH] Sideeffectless measuring of shadow views

Summary:
That's now possible thanks to new Yoga's clonning API.
That will speed up RCTSurface measuring (see the next diff in stack) and should illuminate a class of problems in CK interop layer.
We also will use it in the new text layout engine (in React Native).

Reviewed By: gkassabli

Differential Revision: D6665632

fbshipit-source-id: e94909f0af89e9c7fc5e46b95090ecb3c52546a2
---
 React/Views/RCTShadowView+Layout.h |  7 +++++++
 React/Views/RCTShadowView+Layout.m | 33 ++++++++++++++++++++++++++++++
 2 files changed, 40 insertions(+)

diff --git a/React/Views/RCTShadowView+Layout.h b/React/Views/RCTShadowView+Layout.h
index fe40dca40dcefd..c0711a63530782 100644
--- a/React/Views/RCTShadowView+Layout.h
+++ b/React/Views/RCTShadowView+Layout.h
@@ -27,6 +27,13 @@ RCT_EXTERN CGFloat RCTCoreGraphicsFloatFromYogaFloat(float value);
 @property (nonatomic, readonly) UIEdgeInsets compoundInsets;
 @property (nonatomic, readonly) CGSize availableSize;
 
+#pragma mark - Measuring
+
+/**
+ * Measures shadow view without side-effects.
+ */
+- (CGSize)sizeThatFitsMinimumSize:(CGSize)minimumSize maximumSize:(CGSize)maximumSize;
+
 #pragma mark - Dirty Propagation Control
 
 /**
diff --git a/React/Views/RCTShadowView+Layout.m b/React/Views/RCTShadowView+Layout.m
index 614a538892249a..e554e23e1b7c15 100644
--- a/React/Views/RCTShadowView+Layout.m
+++ b/React/Views/RCTShadowView+Layout.m
@@ -81,6 +81,39 @@ - (CGSize)availableSize
   return UIEdgeInsetsInsetRect((CGRect){CGPointZero, self.frame.size}, self.compoundInsets).size;
 }
 
+#pragma mark - Measuring
+
+- (CGSize)sizeThatFitsMinimumSize:(CGSize)minimumSize maximumSize:(CGSize)maximumSize
+{
+  YGNodeRef clonnedYogaNode = YGNodeClone(self.yogaNode);
+  YGNodeRef constraintYogaNode = YGNodeNewWithConfig([[self class] yogaConfig]);
+
+  YGNodeInsertChild(constraintYogaNode, clonnedYogaNode, 0);
+
+  YGNodeStyleSetMinWidth(constraintYogaNode, RCTYogaFloatFromCoreGraphicsFloat(minimumSize.width));
+  YGNodeStyleSetMinHeight(constraintYogaNode, RCTYogaFloatFromCoreGraphicsFloat(minimumSize.height));
+  YGNodeStyleSetMaxWidth(constraintYogaNode, RCTYogaFloatFromCoreGraphicsFloat(maximumSize.width));
+  YGNodeStyleSetMaxHeight(constraintYogaNode, RCTYogaFloatFromCoreGraphicsFloat(maximumSize.height));
+
+  YGNodeCalculateLayout(
+    constraintYogaNode,
+    YGUndefined,
+    YGUndefined,
+    self.layoutDirection
+  );
+
+  CGSize measuredSize = (CGSize){
+    RCTCoreGraphicsFloatFromYogaFloat(YGNodeLayoutGetWidth(constraintYogaNode)),
+    RCTCoreGraphicsFloatFromYogaFloat(YGNodeLayoutGetHeight(constraintYogaNode)),
+  };
+
+  YGNodeRemoveChild(constraintYogaNode, clonnedYogaNode);
+  YGNodeFree(constraintYogaNode);
+  YGNodeFree(clonnedYogaNode);
+
+  return measuredSize;
+}
+
 #pragma mark - Dirty Propagation Control
 
 - (void)dirtyLayout