Add suggested ‘view size’ powers to -[RCTShadowView setFrame:]

Summary:The UICollectionView example is actually my use-case, which is discussed in a
bit more detail [here](https://github.com/alloy/ReactNativeExperiments/issues/2).

----

This is useful when wrapping native iOS components that determine their
own suggested size and which would be too hard/unnecessary to replicate
in the shadow view. For instance a `UICollectionView` that after layout
will update its `contentSize`, which could be used to suggest a size to
the shadow view.

The reason for adding it to -[RCTShadowView setFrame:] is mainly so it
can be used via the existing -[RCTUIManager setFrame:forView:] API and
because it might not be a feature you want to expose too prominently.

An origin of `{ NAN, NAN }` is used as a sentinel to indicate that the
frame should be used as a size suggestion. The size portion of the rect
may contain a `NAN` to skip that dimension or a suggested value for the
dimension which will be used if no explicit styling has been assigned.

Examples:

* Without any expl
Closes https://github.com/facebook/react-native/pull/6114

Differential Revision: D2994796

Pulled By: nicklockwood

fb-gh-sync-id: 6dd3dd86a352ca7d31a0da38bc38a2859ed0a410
shipit-source-id: 6dd3dd86a352ca7d31a0da38bc38a2859ed0a410

Examples/UIExplorer/UIExplorerUnitTests/RCTShadowViewTests.m

@@ -17,11 +17,23 @@
 #import "RCTShadowView.h"
 
 @interface RCTShadowViewTests : XCTestCase
-
+@property (nonatomic, strong) RCTShadowView *parentView;
 @end
 
 @implementation RCTShadowViewTests
 
+- (void)setUp
+{
+  [super setUp];
+  
+  self.parentView = [self _shadowViewWithStyle:^(css_style_t *style) {
+    style->flex_direction = CSS_FLEX_DIRECTION_COLUMN;
+    style->dimensions[0] = 440;
+    style->dimensions[1] = 440;
+  }];
+  self.parentView.reactTag = @1; // must be valid rootView tag
+}
+
 // Just a basic sanity test to ensure css-layout is applied correctly in the context of our shadow view hierarchy.
 //
 // ====================================
@@ -69,33 +81,87 @@
     style->flex = 1;
   }];
 
-  RCTShadowView *parentView = [self _shadowViewWithStyle:^(css_style_t *style) {
-    style->flex_direction = CSS_FLEX_DIRECTION_COLUMN;
-    style->padding[0] = 10;
-    style->padding[1] = 10;
-    style->padding[2] = 10;
-    style->padding[3] = 10;
-    style->dimensions[0] = 440;
-    style->dimensions[1] = 440;
-  }];
+  self.parentView.cssNode->style.padding[0] = 10;
+  self.parentView.cssNode->style.padding[1] = 10;
+  self.parentView.cssNode->style.padding[2] = 10;
+  self.parentView.cssNode->style.padding[3] = 10;
 
-  [parentView insertReactSubview:headerView atIndex:0];
-  [parentView insertReactSubview:mainView atIndex:1];
-  [parentView insertReactSubview:footerView atIndex:2];
+  [self.parentView insertReactSubview:headerView atIndex:0];
+  [self.parentView insertReactSubview:mainView atIndex:1];
+  [self.parentView insertReactSubview:footerView atIndex:2];
 
-  parentView.reactTag = @1; // must be valid rootView tag
-  [parentView collectRootUpdatedFrames];
+  [self.parentView collectRootUpdatedFrames];
 
-  XCTAssertTrue(CGRectEqualToRect([parentView measureLayoutRelativeToAncestor:parentView], CGRectMake(0, 0, 440, 440)));
-  XCTAssertTrue(UIEdgeInsetsEqualToEdgeInsets([parentView paddingAsInsets], UIEdgeInsetsMake(10, 10, 10, 10)));
+  XCTAssertTrue(CGRectEqualToRect([self.parentView measureLayoutRelativeToAncestor:self.parentView], CGRectMake(0, 0, 440, 440)));
+  XCTAssertTrue(UIEdgeInsetsEqualToEdgeInsets([self.parentView paddingAsInsets], UIEdgeInsetsMake(10, 10, 10, 10)));
 
-  XCTAssertTrue(CGRectEqualToRect([headerView measureLayoutRelativeToAncestor:parentView], CGRectMake(10, 10, 420, 100)));
-  XCTAssertTrue(CGRectEqualToRect([mainView measureLayoutRelativeToAncestor:parentView], CGRectMake(10, 120, 420, 200)));
-  XCTAssertTrue(CGRectEqualToRect([footerView measureLayoutRelativeToAncestor:parentView], CGRectMake(10, 330, 420, 100)));
+  XCTAssertTrue(CGRectEqualToRect([headerView measureLayoutRelativeToAncestor:self.parentView], CGRectMake(10, 10, 420, 100)));
+  XCTAssertTrue(CGRectEqualToRect([mainView measureLayoutRelativeToAncestor:self.parentView], CGRectMake(10, 120, 420, 200)));
+  XCTAssertTrue(CGRectEqualToRect([footerView measureLayoutRelativeToAncestor:self.parentView], CGRectMake(10, 330, 420, 100)));
 
-  XCTAssertTrue(CGRectEqualToRect([leftView measureLayoutRelativeToAncestor:parentView], CGRectMake(10, 120, 100, 200)));
-  XCTAssertTrue(CGRectEqualToRect([centerView measureLayoutRelativeToAncestor:parentView], CGRectMake(120, 120, 200, 200)));
-  XCTAssertTrue(CGRectEqualToRect([rightView measureLayoutRelativeToAncestor:parentView], CGRectMake(330, 120, 100, 200)));
+  XCTAssertTrue(CGRectEqualToRect([leftView measureLayoutRelativeToAncestor:self.parentView], CGRectMake(10, 120, 100, 200)));
+  XCTAssertTrue(CGRectEqualToRect([centerView measureLayoutRelativeToAncestor:self.parentView], CGRectMake(120, 120, 200, 200)));
+  XCTAssertTrue(CGRectEqualToRect([rightView measureLayoutRelativeToAncestor:self.parentView], CGRectMake(330, 120, 100, 200)));
+}
+
+- (void)testAssignsSuggestedWidthDimension
+{
+  [self _withShadowViewWithStyle:^(css_style_t *style) {
+                                   style->position[CSS_LEFT] = 0;
+                                   style->position[CSS_TOP] = 0;
+                                   style->dimensions[CSS_HEIGHT] = 10;
+                                 }
+            assertRelativeLayout:CGRectMake(0, 0, 3, 10)
+        withIntrinsicContentSize:CGSizeMake(3, UIViewNoIntrinsicMetric)];
+}
+
+- (void)testAssignsSuggestedHeightDimension
+{
+  [self _withShadowViewWithStyle:^(css_style_t *style) {
+                                   style->position[CSS_LEFT] = 0;
+                                   style->position[CSS_TOP] = 0;
+                                   style->dimensions[CSS_WIDTH] = 10;
+                                 }
+            assertRelativeLayout:CGRectMake(0, 0, 10, 4)
+        withIntrinsicContentSize:CGSizeMake(UIViewNoIntrinsicMetric, 4)];
+}
+
+- (void)testDoesNotOverrideDimensionStyleWithSuggestedDimensions
+{
+  [self _withShadowViewWithStyle:^(css_style_t *style) {
+                                   style->position[CSS_LEFT] = 0;
+                                   style->position[CSS_TOP] = 0;
+                                   style->dimensions[CSS_WIDTH] = 10;
+                                   style->dimensions[CSS_HEIGHT] = 10;
+                                 }
+          assertRelativeLayout:CGRectMake(0, 0, 10, 10)
+      withIntrinsicContentSize:CGSizeMake(3, 4)];
+}
+
+- (void)testDoesNotAssignSuggestedDimensionsWhenStyledWithFlexAttribute
+{
+  float parentWidth = self.parentView.cssNode->style.dimensions[CSS_WIDTH];
+  float parentHeight = self.parentView.cssNode->style.dimensions[CSS_HEIGHT];
+  [self _withShadowViewWithStyle:^(css_style_t *style) {
+                                   style->flex = 1;
+                                 }
+            assertRelativeLayout:CGRectMake(0, 0, parentWidth, parentHeight)
+        withIntrinsicContentSize:CGSizeMake(3, 4)];
+}
+
+- (void)_withShadowViewWithStyle:(void(^)(css_style_t *style))styleBlock
+            assertRelativeLayout:(CGRect)expectedRect
+        withIntrinsicContentSize:(CGSize)contentSize
+{
+  RCTShadowView *view = [self _shadowViewWithStyle:styleBlock];
+  [self.parentView insertReactSubview:view atIndex:0];
+  view.intrinsicContentSize = contentSize;
+  [self.parentView collectRootUpdatedFrames];
+  CGRect actualRect = [view measureLayoutRelativeToAncestor:self.parentView];
+  XCTAssertTrue(CGRectEqualToRect(expectedRect, actualRect),
+                @"Expected layout to be %@, got %@",
+                NSStringFromCGRect(expectedRect),
+                NSStringFromCGRect(actualRect));
 }
 
 - (RCTShadowView *)_shadowViewWithStyle:(void(^)(css_style_t *style))styleBlock

React/Modules/RCTUIManager.h

@@ -60,6 +60,12 @@ RCT_EXTERN NSString *const RCTUIManagerRootViewKey;
  */
 - (void)setFrame:(CGRect)frame forView:(UIView *)view;
 
+/**
+ * Set the natural size of a view, which is used when no explicit size is set.
+ * Use UIViewNoIntrinsicMetric to ignore a dimension.
+ */
+- (void)setIntrinsicContentSize:(CGSize)size forView:(UIView *)view;
+
 /**
  * Update the background color of a root view. This is usually triggered by
  * manually setting the background color of the root view with native code.

React/Modules/RCTUIManager.m

@@ -399,6 +399,21 @@ extern NSString *RCTBridgeModuleNameForClass(Class cls);
   });
 }
 
+- (void)setIntrinsicContentSize:(CGSize)size forView:(UIView *)view
+{
+  RCTAssertMainThread();
+
+  NSNumber *reactTag = view.reactTag;
+  dispatch_async(_shadowQueue, ^{
+    RCTShadowView *shadowView = _shadowViewRegistry[reactTag];
+    RCTAssert(shadowView != nil, @"Could not locate root view with tag #%@", reactTag);
+
+    shadowView.intrinsicContentSize = size;
+
+    [self batchDidComplete];
+  });
+}
+
 - (void)setBackgroundColor:(UIColor *)color forRootView:(UIView *)rootView
 {
   RCTAssertMainThread();

React/Views/RCTShadowView.h

@@ -68,6 +68,12 @@ typedef void (^RCTApplierBlock)(NSDictionary<NSNumber *, UIView *> *viewRegistry
 - (void)setTopLeft:(CGPoint)topLeft;
 - (void)setSize:(CGSize)size;
 
+/**
+ * Set the natural size of the view, which is used when no explicit size is set.
+ * Use UIViewNoIntrinsicMetric to ignore a dimension.
+ */
+- (void)setIntrinsicContentSize:(CGSize)size;
+
 /**
  * Size flexibility type used to find size constraints.
  * Default to RCTRootViewSizeFlexibilityNone

React/Views/RCTShadowView.m

@@ -535,6 +535,29 @@ RCT_POSITION_PROPERTY(Left, left, LEFT)
   [self dirtyLayout];
 }
 
+static inline BOOL
+RCTAssignSuggestedDimension(css_node_t *css_node, int dimension, CGFloat amount)
+{
+  if (amount != UIViewNoIntrinsicMetric
+      && isnan(css_node->style.dimensions[dimension])) {
+    css_node->style.dimensions[dimension] = amount;
+    return YES;
+  }
+  return NO;
+}
+
+- (void)setIntrinsicContentSize:(CGSize)size
+{
+  if (_cssNode->style.flex == 0) {
+    BOOL dirty = NO;
+    dirty |= RCTAssignSuggestedDimension(_cssNode, CSS_HEIGHT, size.height);
+    dirty |= RCTAssignSuggestedDimension(_cssNode, CSS_WIDTH, size.width);
+    if (dirty) {
+      [self dirtyLayout];
+    }
+  }
+}
+
 - (void)setTopLeft:(CGPoint)topLeft
 {
   _cssNode->style.position[CSS_LEFT] = topLeft.x;

runXcodeTests.sh

@@ -10,16 +10,9 @@ if [ -z "$1" ]
     exit 255
 fi
 
-xctool \
-  -project IntegrationTests/IntegrationTests.xcodeproj \
-  -scheme IntegrationTests \
-  -sdk iphonesimulator8.1 \
-  -destination "platform=iOS Simulator,OS=${1},name=iPhone 5" \
-  build test
-
 xctool \
   -project Examples/UIExplorer/UIExplorer.xcodeproj \
   -scheme UIExplorer \
-  -sdk iphonesimulator8.1 \
+  -sdk iphonesimulator${1} \
   -destination "platform=iOS Simulator,OS=${1},name=iPhone 5" \
   build test