Fix AffineTransform initializer

Author: parkera

apinotes/Foundation.apinotes

@@ -1255,8 +1255,6 @@ Tags:
 - Name: NSURLHandleStatus
   SwiftName: NSURLHandle.Status
 Typedefs:
-- Name: NSAffineTransformStruct
-  SwiftName: AffineTransform
 - Name: NSComparator
   SwiftName: Comparator
 - Name: NSDecimal

stdlib/public/SDK/Foundation/AffineTransform.swift

@@ -16,19 +16,48 @@
 
 private let ε: CGFloat = 2.22045e-16
 
-extension AffineTransform : ReferenceConvertible, Hashable, CustomStringConvertible {
+public struct AffineTransform : ReferenceConvertible, Hashable, CustomStringConvertible {
+    public var m11, m12, m21, m22, tX, tY: CGFloat
+    
     public typealias ReferenceType = NSAffineTransform
-
-    private init(reference: NSAffineTransform) {
-        self = reference.transformStruct
+    
+    /**
+     Creates an affine transformation.
+    */
+    public init(m11: CGFloat, m12: CGFloat, m21: CGFloat, m22: CGFloat, tX: CGFloat, tY: CGFloat) {
+        self.m11 = m11
+        self.m12 = m12
+        self.m21 = m21
+        self.m22 = m22
+        self.tX = tX
+        self.tY = tY
+    }
+    
+    fileprivate init(reference: NSAffineTransform) {
+        m11 = reference.transformStruct.m11
+        m12 = reference.transformStruct.m12
+        m21 = reference.transformStruct.m21
+        m22 = reference.transformStruct.m22
+        tX = reference.transformStruct.tX
+        tY = reference.transformStruct.tY
     }
 
-    private var reference : NSAffineTransform {
+    fileprivate var reference : NSAffineTransform {
         let ref = NSAffineTransform()
-        ref.transformStruct = self
+        ref.transformStruct = NSAffineTransformStruct(m11: m11, m12: m12, m21: m21, m22: m22, tX: tX, tY: tY)
         return ref
     }
 
+    /**
+     Creates an affine transformation matrix with identity values.
+     - seealso: identity
+    */
+    public init() {
+        self.init(m11: CGFloat(1.0), m12: CGFloat(0.0),
+                  m21: CGFloat(0.0), m22: CGFloat(1.0),
+                  tX: CGFloat(0.0), tY: CGFloat(0.0))
+    }
+    
     /**
      Creates an affine transformation matrix from translation values.
      The matrix takes the following form:
@@ -270,9 +299,7 @@ extension AffineTransform : _ObjectiveCBridgeable {
 
     @_semantics("convertToObjectiveC")
     public func _bridgeToObjectiveC() -> NSAffineTransform {
-        let t = NSAffineTransform()
-        t.transformStruct = self
-        return t
+        return self.reference
     }
 
     public static func _forceBridgeFromObjectiveC(_ x: NSAffineTransform, result: inout AffineTransform?) {
@@ -282,7 +309,7 @@ extension AffineTransform : _ObjectiveCBridgeable {
     }
 
     public static func _conditionallyBridgeFromObjectiveC(_ x: NSAffineTransform, result: inout AffineTransform?) -> Bool {
-        result = x.transformStruct
+        result = AffineTransform(reference: x)
         return true // Can't fail
     }
 

test/1_stdlib/TestAffineTransform.swift

@@ -61,7 +61,10 @@ class TestAffineTransform : TestAffineTransformSuper {
     }
 
     func test_BasicConstruction() {
+        let defaultAffineTransform = AffineTransform()
         let identityTransform = AffineTransform.identity
+
+        expectEqual(defaultAffineTransform, identityTransform)
 
         // The diagonal entries (1,1) and (2,2) of the identity matrix are ones. The other entries are zeros.
         // TODO: These should use DBL_MAX but it's not available as part of Glibc on Linux
@@ -324,8 +327,7 @@ class TestAffineTransform : TestAffineTransformSuper {
             AffineTransform(m11: 0.498, m12: -0.284, m21: -0.742, m22: 0.3248, tX: 12, tY: 44)
         ]
         for val in values {
-            let ref = NSAffineTransform()
-            ref.transformStruct = val
+            let ref = val as NSAffineTransform
             expectEqual(ref.hashValue, val.hashValue)
         }
     }