Size flexibility modes for RCTRootView

Reviewed By: javache

Differential Revision: D2526355

fb-gh-sync-id: 095a43bc01f883fdfdad3a086a35682c20c05597

React/Base/RCTRootView.h

@@ -11,6 +11,20 @@
 
 #import "RCTBridge.h"
 
+/**
+ * This enum is used to define size flexibility type of the root view.
+ * If a dimension is flexible, the view will recalculate that dimension
+ * so the content fits. Recalculations are performed when the root's frame,
+ * size flexibility mode or content size changes. After a recalculation,
+ * TODO:<DelegateName> will be called with the new size passed as an argument.
+ */
+typedef NS_ENUM(NSInteger, RCTRootViewSizeFlexibility) {
+  RCTRootViewSizeFlexibilityNone = 0,
+  RCTRootViewSizeFlexibilityWidth,
+  RCTRootViewSizeFlexibilityHeight,
+  RCTRootViewSizeFlexibilityWidthAndHeight,
+};
+
 /**
  * This notification is sent when the first subviews are added to the root view
  * after the application has loaded. This is used to hide the `loadingView`, and
@@ -71,6 +85,11 @@ extern NSString *const RCTContentDidAppearNotification;
  */
 @property (nonatomic, strong) Class executorClass;
 
+/**
+ * The size flexibility mode of the root view.
+ */
+@property (nonatomic, assign) RCTRootViewSizeFlexibility sizeFlexibility;
+
 /**
  * The backing view controller of the root view.
  */

React/Base/RCTRootView.m

@@ -72,6 +72,7 @@ NSString *const RCTContentDidAppearNotification = @"RCTContentDidAppearNotificat
     _initialProperties = [initialProperties copy];
     _loadingViewFadeDelay = 0.25;
     _loadingViewFadeDuration = 0.25;
+    _sizeFlexibility = RCTRootViewSizeFlexibilityNone;
 
     [[NSNotificationCenter defaultCenter] addObserver:self
                                              selector:@selector(javaScriptDidLoad:)
@@ -189,6 +190,12 @@ RCT_NOT_IMPLEMENTED(- (instancetype)initWithCoder:(NSCoder *)aDecoder)
                    args:@[moduleName, appParameters]];
 }
 
+- (void)setSizeFlexibility:(RCTRootViewSizeFlexibility)sizeFlexibility
+{
+  _sizeFlexibility = sizeFlexibility;
+  [self setNeedsLayout];
+}
+
 - (void)layoutSubviews
 {
   [super layoutSubviews];