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Replicate NSAffineTransform logic for rotation to AffineTransform #11347

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Merged
merged 1 commit into from
Aug 4, 2017
Merged

Replicate NSAffineTransform logic for rotation to AffineTransform #11347

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19 changes: 13 additions & 6 deletions stdlib/public/SDK/Foundation/AffineTransform.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -166,12 +166,19 @@ public struct AffineTransform : ReferenceConvertible, Hashable, CustomStringConv
[ 0 0 1 ]
*/
public mutating func rotate(byRadians angle: CGFloat) {
let α = Double(angle)

let sine = CGFloat(sin(α))
let cosine = CGFloat(cos(α))

append(AffineTransform(m11: cosine, m12: sine, m21: -sine, m22: cosine, tX: 0, tY: 0))
let t2 = self
let t1 = AffineTransform(rotationByRadians: angle)

var t = AffineTransform.identity

t.m11 = t1.m11 * t2.m11 + t1.m12 * t2.m21
t.m12 = t1.m11 * t2.m12 + t1.m12 * t2.m22
t.m21 = t1.m21 * t2.m11 + t1.m22 * t2.m21
t.m22 = t1.m21 * t2.m12 + t1.m22 * t2.m22
t.tX = t1.tX * t2.m11 + t1.tY * t2.m21 + t2.tX
t.tY = t1.tX * t2.m12 + t1.tY * t2.m22 + t2.tY

self = t
}

/**
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11 changes: 11 additions & 0 deletions test/stdlib/TestAffineTransform.swift
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Expand Up @@ -372,6 +372,16 @@ class TestAffineTransform : TestAffineTransformSuper {
func test_unconditionallyBridgeFromObjectiveC() {
expectEqual(AffineTransform(), AffineTransform._unconditionallyBridgeFromObjectiveC(nil))
}

func test_rotation_compose() {
var t = AffineTransform.identity
t.translate(x: 1.0, y: 1.0)
t.rotate(byDegrees: 90)
t.translate(x: -1.0, y: -1.0)
let result = t.transform(NSPoint(x: 1.0, y: 2.0))
expectEqualWithAccuracy(0.0, Double(result.x), accuracy: accuracyThreshold)
expectEqualWithAccuracy(1.0, Double(result.y), accuracy: accuracyThreshold)
}
}

#if !FOUNDATION_XCTEST
Expand All @@ -395,6 +405,7 @@ AffineTransformTests.test("test_hashing_values") { TestAffineTransform().test_ha
AffineTransformTests.test("test_AnyHashableContainingAffineTransform") { TestAffineTransform().test_AnyHashableContainingAffineTransform() }
AffineTransformTests.test("test_AnyHashableCreatedFromNSAffineTransform") { TestAffineTransform().test_AnyHashableCreatedFromNSAffineTransform() }
AffineTransformTests.test("test_unconditionallyBridgeFromObjectiveC") { TestAffineTransform().test_unconditionallyBridgeFromObjectiveC() }
AffineTransformTests.test("test_rotation_compose") { TestAffineTransform().test_rotation_compose() }
runAllTests()
#endif

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