BREAKING: remove css_sizeThatFits:, replace with new API.

Summary: When I try to use this in practice, I have come to realize that css_sizeThatFits will 99% return to you the constrainedSize that you pass it, thus making it useless. Instead, we replace it with a new API that will tell you the optimal size of the resolved layout. From this we can choose to use that size, or scale it down.

Reviewed By: emilsjolander

Differential Revision: D4191873

fbshipit-source-id: d36a2850448d9d82f97e5ef4c7397778c2a14094

CSSLayoutKit/Tests/CSSLayoutKitTests.m

@@ -11,10 +11,10 @@
 
 #import "UIView+CSSLayout.h"
 
-@interface CSSLayoutTests : XCTestCase
+@interface CSSLayoutKitTests : XCTestCase
 @end
 
-@implementation CSSLayoutTests
+@implementation CSSLayoutKitTests
 
 #ifndef TRAVIS_CI
 
@@ -65,21 +65,35 @@
 - (void)testSizeThatFitsAsserts
 {
   UIView *view = [[UIView alloc] initWithFrame:CGRectZero];
-  XCTAssertThrows([view css_sizeThatFits:CGSizeZero]);
-
   dispatch_sync(dispatch_queue_create("com.facebook.CSSLayout.testing", DISPATCH_QUEUE_SERIAL), ^(void){
-    XCTAssertThrows([view css_sizeThatFits:CGSizeZero]);
+    XCTAssertThrows([view css_intrinsicSize]);
   });
 }
 
 - (void)testSizeThatFitsSmoke
 {
-  UIView *view = [[UIView alloc] initWithFrame:CGRectZero];
-  [view css_setUsesFlexbox:YES];
+  UIView *container = [[UIView alloc] initWithFrame:CGRectZero];
+  [container css_setUsesFlexbox:YES];
+  [container css_setFlexDirection:CSSFlexDirectionRow];
+  [container css_setAlignItems:CSSAlignFlexStart];
 
-  const CGSize constrainedSize = CGSizeMake(50, 50);
-  const CGSize actualSize = [view css_sizeThatFits:constrainedSize];
-  XCTAssertTrue(CGSizeEqualToSize(constrainedSize, actualSize), @"Actual Size: %@", NSStringFromCGSize(actualSize));
+  UILabel *longTextLabel = [[UILabel alloc] initWithFrame:CGRectZero];
+  longTextLabel.text = @"This is a very very very very very very very very long piece of text.";
+  longTextLabel.lineBreakMode = NSLineBreakByTruncatingTail;
+  longTextLabel.numberOfLines = 1;
+  [longTextLabel css_setUsesFlexbox:YES];
+  [longTextLabel css_setFlexShrink:1];
+  [container addSubview:longTextLabel];
+
+  UIView *textBadgeView = [[UIView alloc] initWithFrame:CGRectZero];
+  [textBadgeView css_setUsesFlexbox:YES];
+  [textBadgeView css_setMargin:3.0 forEdge:CSSEdgeLeft];
+  [textBadgeView css_setWidth:10];
+  [textBadgeView css_setHeight:10];
+  [container addSubview:textBadgeView];
+
+  const CGSize containerSize = [container css_intrinsicSize];
+  XCTAssertTrue(CGSizeEqualToSize(CGSizeMake(514,21), containerSize), @"Size is actually %@", NSStringFromCGSize(containerSize));
 }
 
 - (void)testFrameAndOriginPlacement

CSSLayoutKit/UIView+CSSLayout.h

@@ -52,8 +52,8 @@
 - (void)css_applyLayout;
 
 /**
- Compute the size of a layout with a constrained size.
+ Returns the size of the view if no constraints were given. This could equivalent to calling [self sizeThatFits:CGSizeMake(CGFLOAT_MAX, CGFLOAT_MAX)];
  */
-- (CGSize)css_sizeThatFits:(CGSize)constrainedSize;
+- (CGSize)css_intrinsicSize;
 
 @end

CSSLayoutKit/UIView+CSSLayout.m

@@ -157,32 +157,21 @@
   return CSSNodeLayoutGetDirection([self cssNode]);
 }
 
-- (CGSize)css_sizeThatFits:(CGSize)constrainedSize
-{
-  NSAssert([NSThread isMainThread], @"CSS Layout calculation must be done on main.");
-  NSAssert([self css_usesFlexbox], @"CSS Layout is not enabled for this view.");
-
-  CSSAttachNodesFromViewHierachy(self);
-
-  const CSSNodeRef node = [self cssNode];
-  CSSNodeCalculateLayout(
-    node,
-    constrainedSize.width,
-    constrainedSize.height,
-    CSSNodeStyleGetDirection(node));
-
-  return (CGSize) {
-    .width = CSSNodeLayoutGetWidth(node),
-    .height = CSSNodeLayoutGetHeight(node),
-  };
-}
-
 - (void)css_applyLayout
 {
-  [self css_sizeThatFits:self.bounds.size];
+  [self calculateLayoutWithSize:self.bounds.size];
   CSSApplyLayoutToViewHierarchy(self);
 }
 
+- (CGSize)css_intrinsicSize
+{
+  const CGSize constrainedSize = {
+      .width = CSSUndefined,
+      .height = CSSUndefined,
+  };
+  return [self calculateLayoutWithSize:constrainedSize];
+}
+
 #pragma mark - Private
 
 - (CSSNodeRef)cssNode
@@ -197,6 +186,26 @@
   return node.cnode;
 }
 
+- (CGSize)calculateLayoutWithSize:(CGSize)size
+{
+  NSAssert([NSThread isMainThread], @"CSS Layout calculation must be done on main.");
+  NSAssert([self css_usesFlexbox], @"CSS Layout is not enabled for this view.");
+
+  CSSAttachNodesFromViewHierachy(self);
+
+  const CSSNodeRef node = [self cssNode];
+  CSSNodeCalculateLayout(
+    node,
+    size.width,
+    size.height,
+    CSSNodeStyleGetDirection(node));
+
+  return (CGSize) {
+    .width = CSSNodeLayoutGetWidth(node),
+    .height = CSSNodeLayoutGetHeight(node),
+  };
+}
+
 static CSSSize CSSMeasureView(
   CSSNodeRef node,
   float width,