Rename uikit/CSSLayout to CSSLayoutKit.

Summary:
When trying to integrate this into an Xcode project that already included CSSLayout.[c|h], we were getting a linker error.

Upon digging in, I found out that Xcode was becoming confused because the imports of the uikit library and the c library are both `#import <CSSLayout/CSSLayout.h>`. So, it needed a new name.

Reviewed By: emilsjolander

Differential Revision: D4162621

fbshipit-source-id: b5f7624eb29f1b9eaebbed5104ec9ea8a12ad2e5

CSSLayoutKit/BUCK

@@ -0,0 +1,41 @@
+# Copyright (c) 2014-present, Facebook, Inc.
+# All rights reserved.
+#
+# This source code is licensed under the BSD-style license found in the
+# LICENSE file in the root directory of this source tree. An additional grant
+# of patent rights can be found in the PATENTS file in the same directory.
+
+include_defs('//CSSLAYOUT_DEFS')
+
+UIKIT_CSSLAYOUT_COMPILER_FLAGS = ['-fobjc-arc']
+
+apple_library(
+  name = 'CSSLayoutKit',
+  compiler_flags = UIKIT_CSSLAYOUT_COMPILER_FLAGS,
+  tests = [':CSSLayoutKitTests'],
+  srcs = glob(['*.m']),
+  exported_headers = glob(['*.h']),
+  frameworks = [
+    '$SDKROOT/System/Library/Frameworks/Foundation.framework',
+    '$SDKROOT/System/Library/Frameworks/UIKit.framework',
+  ],
+  deps = [
+    csslayout_dep(':CSSLayout'),
+  ],
+  visibility = ['PUBLIC'],
+)
+
+apple_test(
+  name = 'CSSLayoutKitTests',
+  compiler_flags = UIKIT_CSSLAYOUT_COMPILER_FLAGS,
+  info_plist = 'Tests/Info.plist',
+  srcs = glob(['Tests/**/*.m']),
+  frameworks = [
+    '$SDKROOT/System/Library/Frameworks/CoreGraphics.framework',
+    '$PLATFORM_DIR/Developer/Library/Frameworks/XCTest.framework',
+  ],
+  deps = [
+    ':CSSLayoutKit',
+  ],
+  visibility = ['PUBLIC'],
+)

CSSLayoutKit/Tests/CSSLayoutTests.m

@@ -0,0 +1,110 @@
+/**
+ * Copyright (c) 2014-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#import <XCTest/XCTest.h>
+
+#import "UIView+CSSLayout.h"
+
+@interface CSSLayoutTests : XCTestCase
+@end
+
+@implementation CSSLayoutTests
+
+- (void)testNodesAreDeallocedWithSingleView
+{
+  XCTAssertEqual(0, CSSNodeGetInstanceCount());
+
+  UIView *view = [[UIView alloc] initWithFrame:CGRectZero];
+  [view css_setFlexBasis:1];
+  XCTAssertEqual(1, CSSNodeGetInstanceCount());
+  view = nil;
+
+  XCTAssertEqual(0, CSSNodeGetInstanceCount());
+}
+
+- (void)testNodesAreDeallocedCascade
+{
+  XCTAssertEqual(0, CSSNodeGetInstanceCount());
+
+  UIView *view = [[UIView alloc] initWithFrame:CGRectZero];
+  [view css_setFlexBasis:1];
+
+  for (int i=0; i<10; i++) {
+    UIView *subview = [[UIView alloc] initWithFrame:CGRectZero];
+    [subview css_setFlexBasis:1];
+    [view addSubview:subview];
+  }
+  XCTAssertEqual(11, CSSNodeGetInstanceCount());
+  view = nil;
+
+  XCTAssertEqual(0, CSSNodeGetInstanceCount());
+}
+
+- (void)testUsesFlexbox
+{
+  UIView *view = [[UIView alloc] initWithFrame:CGRectZero];
+  XCTAssertFalse([view css_usesFlexbox]);
+
+  [view css_setUsesFlexbox:YES];
+  XCTAssertTrue([view css_usesFlexbox]);
+
+  [view css_setUsesFlexbox:NO];
+  XCTAssertFalse([view css_usesFlexbox]);
+}
+
+- (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]);
+  });
+}
+
+- (void)testSizeThatFitsSmoke
+{
+  UIView *view = [[UIView alloc] initWithFrame:CGRectZero];
+  [view css_setUsesFlexbox:YES];
+
+  const CGSize constrainedSize = CGSizeMake(50, 50);
+  const CGSize actualSize = [view css_sizeThatFits:constrainedSize];
+  XCTAssertTrue(CGSizeEqualToSize(constrainedSize, actualSize), @"Actual Size: %@", NSStringFromCGSize(actualSize));
+}
+
+- (void)testFrameAndOriginPlacement
+{
+  const CGSize containerSize = CGSizeMake(320, 50);
+
+  UIView *container = [[UIView alloc] initWithFrame:CGRectMake(0, 0, containerSize.width, containerSize.height)];
+  [container css_setUsesFlexbox:YES];
+  [container css_setFlexDirection:CSSFlexDirectionRow];
+
+  for (int i = 0; i < 3; i++) {
+    UIView *subview = [[UIView alloc] initWithFrame:CGRectZero];
+    [subview css_setUsesFlexbox:YES];
+    [subview css_setFlexGrow:1];
+
+    [container addSubview:subview];
+  }
+  [container css_applyLayout];
+
+  XCTAssertFalse(CGRectIntersectsRect([container.subviews objectAtIndex:0].frame, [container.subviews objectAtIndex:1].frame));
+  XCTAssertFalse(CGRectIntersectsRect([container.subviews objectAtIndex:1].frame, [container.subviews objectAtIndex:2].frame));
+  XCTAssertFalse(CGRectIntersectsRect([container.subviews objectAtIndex:0].frame, [container.subviews objectAtIndex:2].frame));
+
+  CGFloat totalWidth = 0;
+  for (UIView *view in container.subviews) {
+    totalWidth += view.bounds.size.width;
+  }
+
+  XCTAssertEqual(containerSize.width, totalWidth, @"The container's width is %.6f, the subviews take up %.6f", containerSize.width, totalWidth);
+}
+
+@end

CSSLayoutKit/Tests/Info.plist

@@ -0,0 +1,22 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>CFBundleDevelopmentRegion</key>
+	<string>en</string>
+	<key>CFBundleExecutable</key>
+	<string>${EXECUTABLE_NAME}</string>
+	<key>CFBundleIdentifier</key>
+	<string>com.facebook.${PRODUCT_NAME:rfc1034identifier}</string>
+	<key>CFBundleInfoDictionaryVersion</key>
+	<string>6.0</string>
+	<key>CFBundlePackageType</key>
+	<string>BNDL</string>
+	<key>CFBundleShortVersionString</key>
+	<string>1.0</string>
+	<key>CFBundleSignature</key>
+	<string>????</string>
+	<key>CFBundleVersion</key>
+	<string>1</string>
+</dict>
+</plist>

CSSLayoutKit/UIView+CSSLayout.h

@@ -0,0 +1,51 @@
+/**
+ * Copyright (c) 2014-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#import <UIKit/UIKit.h>
+#import <CSSLayout/CSSLayout.h>
+
+@interface UIView (CSSLayout)
+
+- (void)css_setUsesFlexbox:(BOOL)enabled;
+- (BOOL)css_usesFlexbox;
+
+- (void)css_setDirection:(CSSDirection)direction;
+- (void)css_setFlexDirection:(CSSFlexDirection)flexDirection;
+- (void)css_setJustifyContent:(CSSJustify)justifyContent;
+- (void)css_setAlignContent:(CSSAlign)alignContent;
+- (void)css_setAlignItems:(CSSAlign)alignItems;
+- (void)css_setAlignSelf:(CSSAlign)alignSelf;
+- (void)css_setPositionType:(CSSPositionType)positionType;
+- (void)css_setFlexWrap:(CSSWrapType)flexWrap;
+
+- (void)css_setFlexGrow:(CGFloat)flexGrow;
+- (void)css_setFlexShrink:(CGFloat)flexShrink;
+- (void)css_setFlexBasis:(CGFloat)flexBasis;
+
+- (void)css_setPosition:(CGFloat)position forEdge:(CSSEdge)edge;
+- (void)css_setMargin:(CGFloat)margin forEdge:(CSSEdge)edge;
+- (void)css_setPadding:(CGFloat)padding forEdge:(CSSEdge)edge;
+
+- (void)css_setWidth:(CGFloat)width;
+- (void)css_setHeight:(CGFloat)height;
+- (void)css_setMinWidth:(CGFloat)minWidth;
+- (void)css_setMinHeight:(CGFloat)minHeight;
+- (void)css_setMaxWidth:(CGFloat)maxWidth;
+- (void)css_setMaxHeight:(CGFloat)maxHeight;
+
+// Get the resolved direction of this node. This won't be CSSDirectionInherit
+- (CSSDirection)css_resolvedDirection;
+
+//! @abstract Perform a layout calculation and update the frames of the views in the hierarchy with th results
+- (void)css_applyLayout;
+
+//! @abstract Compute the size of a layout with a constrained size.
+- (CGSize)css_sizeThatFits:(CGSize)constrainedSize;
+
+@end

CSSLayoutKit/UIView+CSSLayout.m

@@ -0,0 +1,311 @@
+/**
+ * Copyright (c) 2014-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#import "UIView+CSSLayout.h"
+
+#import <objc/runtime.h>
+
+@interface CSSNodeBridge : NSObject
+@property (nonatomic, assign, readonly) CSSNodeRef cnode;
+@end
+
+@implementation CSSNodeBridge
+- (instancetype)init
+{
+  if ([super init]) {
+    _cnode = CSSNodeNew();
+  }
+
+  return self;
+}
+
+- (void)dealloc
+{
+  CSSNodeFree(_cnode);
+}
+@end
+
+@implementation UIView (CSSLayout)
+
+- (CSSNodeRef)cssNode
+{
+  CSSNodeBridge *node = objc_getAssociatedObject(self, @selector(cssNode));
+  if (!node) {
+    node = [CSSNodeBridge new];
+    CSSNodeSetContext(node.cnode, (__bridge void *) self);
+    objc_setAssociatedObject(self, @selector(cssNode), node, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
+  }
+
+  return node.cnode;
+}
+
+- (void)css_setUsesFlexbox:(BOOL)enabled
+{
+  objc_setAssociatedObject(
+    self,
+    @selector(css_usesFlexbox),
+    @(enabled),
+    OBJC_ASSOCIATION_RETAIN_NONATOMIC);
+}
+
+- (BOOL)css_usesFlexbox
+{
+  NSNumber *usesFlexbox = objc_getAssociatedObject(self, @selector(css_usesFlexbox));
+  return [usesFlexbox boolValue];
+}
+
+- (void)css_setDirection:(CSSDirection)direction
+{
+  CSSNodeStyleSetDirection([self cssNode], direction);
+}
+
+- (void)css_setFlexDirection:(CSSFlexDirection)flexDirection
+{
+  CSSNodeStyleSetFlexDirection([self cssNode], flexDirection);
+}
+
+- (void)css_setJustifyContent:(CSSJustify)justifyContent
+{
+  CSSNodeStyleSetJustifyContent([self cssNode], justifyContent);
+}
+
+- (void)css_setAlignContent:(CSSAlign)alignContent
+{
+  CSSNodeStyleSetAlignContent([self cssNode], alignContent);
+}
+
+- (void)css_setAlignItems:(CSSAlign)alignItems
+{
+  CSSNodeStyleSetAlignItems([self cssNode], alignItems);
+}
+
+- (void)css_setAlignSelf:(CSSAlign)alignSelf
+{
+  CSSNodeStyleSetAlignSelf([self cssNode], alignSelf);
+}
+
+- (void)css_setPositionType:(CSSPositionType)positionType
+{
+  CSSNodeStyleSetPositionType([self cssNode], positionType);
+}
+
+- (void)css_setFlexWrap:(CSSWrapType)flexWrap
+{
+  CSSNodeStyleSetFlexWrap([self cssNode], flexWrap);
+}
+
+- (void)css_setFlexGrow:(CGFloat)flexGrow
+{
+  CSSNodeStyleSetFlexGrow([self cssNode], flexGrow);
+}
+
+- (void)css_setFlexShrink:(CGFloat)flexShrink
+{
+  CSSNodeStyleSetFlexShrink([self cssNode], flexShrink);
+}
+
+- (void)css_setFlexBasis:(CGFloat)flexBasis
+{
+  CSSNodeStyleSetFlexBasis([self cssNode], flexBasis);
+}
+
+- (void)css_setPosition:(CGFloat)position forEdge:(CSSEdge)edge
+{
+  CSSNodeStyleSetPosition([self cssNode], edge, position);
+}
+
+- (void)css_setMargin:(CGFloat)margin forEdge:(CSSEdge)edge
+{
+  CSSNodeStyleSetMargin([self cssNode], edge, margin);
+}
+
+- (void)css_setPadding:(CGFloat)padding forEdge:(CSSEdge)edge
+{
+  CSSNodeStyleSetPadding([self cssNode], edge, padding);
+}
+
+- (void)css_setWidth:(CGFloat)width
+{
+  CSSNodeStyleSetWidth([self cssNode], width);
+}
+
+- (void)css_setHeight:(CGFloat)height
+{
+  CSSNodeStyleSetHeight([self cssNode], height);
+}
+
+- (void)css_setMinWidth:(CGFloat)minWidth
+{
+  CSSNodeStyleSetMinWidth([self cssNode], minWidth);
+}
+
+- (void)css_setMinHeight:(CGFloat)minHeight
+{
+  CSSNodeStyleSetMinHeight([self cssNode], minHeight);
+}
+
+- (void)css_setMaxWidth:(CGFloat)maxWidth
+{
+  CSSNodeStyleSetMaxWidth([self cssNode], maxWidth);
+}
+
+- (void)css_setMaxHeight:(CGFloat)maxHeight
+{
+  CSSNodeStyleSetMaxHeight([self cssNode], maxHeight);
+}
+
+- (CSSDirection)css_resolvedDirection
+{
+  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.");
+
+  _attachNodesRecursive(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];
+  _updateFrameRecursive(self);
+}
+
+#pragma mark - Private
+
+static CSSSize _measure(
+  CSSNodeRef node,
+  float width,
+  CSSMeasureMode widthMode,
+  float height,
+  CSSMeasureMode heightMode)
+{
+  const CGFloat constrainedWidth = (widthMode == CSSMeasureModeUndefined) ? CGFLOAT_MAX : width;
+  const CGFloat constrainedHeight = (heightMode == CSSMeasureModeUndefined) ? CGFLOAT_MAX: height;
+
+  UIView *view = (__bridge UIView*) CSSNodeGetContext(node);
+  const CGSize sizeThatFits = [view sizeThatFits:(CGSize) {
+    .width = constrainedWidth,
+    .height = constrainedHeight,
+  }];
+
+  return (CSSSize) {
+    .width = _sanitizeMeasurement(constrainedWidth, sizeThatFits.width, widthMode),
+    .height = _sanitizeMeasurement(constrainedHeight, sizeThatFits.height, heightMode),
+  };
+}
+
+static CGFloat _sanitizeMeasurement(
+  CGFloat constrainedSize,
+  CGFloat measuredSize,
+  CSSMeasureMode measureMode)
+{
+  CGFloat result;
+  if (measureMode == CSSMeasureModeExactly) {
+    result = constrainedSize;
+  } else if (measureMode == CSSMeasureModeAtMost) {
+    result = MIN(constrainedSize, measuredSize);
+  } else {
+    result = measuredSize;
+  }
+
+  return result;
+}
+
+static void _attachNodesRecursive(UIView *view) {
+  CSSNodeRef node = [view cssNode];
+  const BOOL usesFlexbox = [view css_usesFlexbox];
+  const BOOL isLeaf = !usesFlexbox || view.subviews.count == 0;
+
+  // Only leaf nodes should have a measure function
+  if (isLeaf) {
+    CSSNodeSetMeasureFunc(node, _measure);
+
+    // Clear any children
+    while (CSSNodeChildCount(node) > 0) {
+      CSSNodeRemoveChild(node, CSSNodeGetChild(node, 0));
+    }
+  } else {
+    CSSNodeSetMeasureFunc(node, NULL);
+
+    // Add any children which were added since the last call to css_applyLayout
+    for (NSUInteger i = 0; i < view.subviews.count; i++) {
+      CSSNodeRef childNode = [view.subviews[i] cssNode];
+      if (CSSNodeChildCount(node) < i + 1 || CSSNodeGetChild(node, i) != childNode) {
+        CSSNodeInsertChild(node, childNode, i);
+      }
+      _attachNodesRecursive(view.subviews[i]);
+    }
+
+    // Remove any children which were removed since the last call to css_applyLayout
+    while (view.subviews.count < CSSNodeChildCount(node)) {
+      CSSNodeRemoveChild(node, CSSNodeGetChild(node, CSSNodeChildCount(node) - 1));
+    }
+  }
+}
+
+static CGFloat _roundPixelValue(CGFloat value)
+{
+  static CGFloat scale;
+  static dispatch_once_t onceToken;
+  dispatch_once(&onceToken, ^(){
+    scale = [UIScreen mainScreen].scale;
+  });
+
+  return round(value * scale) / scale;
+}
+
+static void _updateFrameRecursive(UIView *view) {
+  NSCAssert([NSThread isMainThread], @"Framesetting should only be done on the main thread.");
+  CSSNodeRef node = [view cssNode];
+
+  const CGPoint topLeft = {
+    CSSNodeLayoutGetLeft(node),
+    CSSNodeLayoutGetTop(node),
+  };
+
+  const CGPoint bottomRight = {
+    topLeft.x + CSSNodeLayoutGetWidth(node),
+    topLeft.y + CSSNodeLayoutGetHeight(node),
+  };
+
+  view.frame = (CGRect) {
+    .origin = {
+      .x = _roundPixelValue(topLeft.x),
+      .y = _roundPixelValue(topLeft.y),
+    },
+    .size = {
+      .width = _roundPixelValue(bottomRight.x) - _roundPixelValue(topLeft.x),
+      .height = _roundPixelValue(bottomRight.y) - _roundPixelValue(topLeft.y),
+    },
+  };
+
+  const BOOL isLeaf = ![view css_usesFlexbox] || view.subviews.count == 0;
+  if (!isLeaf) {
+    for (NSUInteger i = 0; i < view.subviews.count; i++) {
+      _updateFrameRecursive(view.subviews[i]);
+    }
+  }
+}
+
+@end