这个示例不使用手势识别器，而是直接计算变换矩阵。它还正确处理了一到两个手指的过渡。
class PincherView: UIView {
override var bounds :CGRect {
willSet(newBounds) {
oldBounds = self.bounds
} didSet {
self.imageLayer.position = ┼self.bounds
self._adjustScaleForBoundsChange()
}
}
var oldBounds :CGRect
var touch₁ :UITouch?
var touch₂ :UITouch?
var p₁ :CGPoint?
var p₂ :CGPoint?
var p₁ʹ :CGPoint?
var p₂ʹ :CGPoint?
var image :UIImage? {
didSet {self._reset()}
}
var imageLayer :CALayer
var imageTransform :CGAffineTransform {
didSet {
self.backTransform = self.imageTransform.inverted()
self.imageLayer.transform = CATransform3DMakeAffineTransform(self.imageTransform)
}
}
var backTransform :CGAffineTransform
var solutionMatrix :HXMatrix?
required init?(coder aDecoder: NSCoder) {
self.oldBounds = CGRect.zero
let layer = CALayer();
self.imageLayer = layer
self.imageTransform = CGAffineTransform.identity
self.backTransform = CGAffineTransform.identity
super.init(coder: aDecoder)
self.oldBounds = self.bounds
self.isMultipleTouchEnabled = true
self.layer.addSublayer(layer)
}
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
for touch in touches {
let pʹ = touch.location(in: self).applying(self._backNormalizeTransform())
let p = pʹ.applying(self.backTransform)
if self.touch₁ == nil {
self.touch₁ = touch
self.p₁ʹ = pʹ
self.p₁ = p
} else if self.touch₂ == nil {
self.touch₂ = touch
self.p₂ʹ = pʹ
self.p₂ = p
}
}
self.solutionMatrix = self._computeSolutionMatrix()
}
override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
for touch in touches {
let pʹ = touch.location(in: self).applying(self._backNormalizeTransform())
if self.touch₁ == touch {
self.p₁ʹ = pʹ
} else if self.touch₂ == touch {
self.p₂ʹ = pʹ
}
}
CATransaction.begin()
CATransaction.setValue(true, forKey:kCATransactionDisableActions)
if let q₁ʹ = self.p₁ʹ, let q₂ʹ = self.p₂ʹ {
self.imageTransform = self._computeTransform(q₁ʹ, q₂ʹ)
} else if let q₁ʹ = (self.p₁ʹ != nil ? self.p₁ʹ : self.p₂ʹ) {
self.imageTransform = self._computeTransform(q₁ʹ, CGPoint(x:q₁ʹ.x + 10, y:q₁ʹ.y + 10))
}
CATransaction.commit()
}
override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
for touch in touches {
if self.touch₁ == touch {
self.touch₁ = nil
self.p₁ = nil
self.p₁ʹ = nil
} else if self.touch₂ == touch {
self.touch₂ = nil
self.p₂ = nil
self.p₂ʹ = nil
}
}
self.solutionMatrix = self._computeSolutionMatrix()
}
private func _reset() {
guard
let image = self.image,
let cgimage = image.cgImage else {
return
}
let r = CGRect(x:0, y:0, width:cgimage.width, height:cgimage.height)
imageLayer.contents = cgimage;
imageLayer.bounds = r
imageLayer.position = ┼self.bounds
self.imageTransform = self._initialTransform()
}
private func _normalizeTransform() -> CGAffineTransform {
let center = ┼self.bounds
return CGAffineTransform(translationX: center.x, y: center.y)
}
private func _backNormalizeTransform() -> CGAffineTransform {
return self._normalizeTransform().inverted();
}
private func _initialTransform() -> CGAffineTransform {
guard let image = self.image, let cgimage = image.cgImage else {
return CGAffineTransform.identity;
}
let r = CGRect(x:0, y:0, width:cgimage.width, height:cgimage.height)
let s = r.scaleIn(rect: self.bounds)
return CGAffineTransform(scaleX: s, y: s)
}
private func _adjustScaleForBoundsChange() {
guard let image = self.image, let cgimage = image.cgImage else {
return
}
let r = CGRect(x:0, y:0, width:cgimage.width, height:cgimage.height)
let oldIdeal = r.scaleAndCenterIn(rect: self.oldBounds)
let newIdeal = r.scaleAndCenterIn(rect: self.bounds)
let s = newIdeal.height / oldIdeal.height
self.imageTransform = self.imageTransform.scaledBy(x: s, y: s)
}
private func _computeSolutionMatrix() -> HXMatrix? {
if let q₁ = self.p₁, let q₂ = self.p₂ {
return _computeSolutionMatrix(q₁, q₂)
} else if let q₁ = self.p₁, let q₁ʹ = self.p₁ʹ {
let q₂ = CGPoint(x: q₁ʹ.x + 10, y: q₁ʹ.y + 10).applying(self.backTransform)
return _computeSolutionMatrix(q₁, q₂)
} else if let q₂ = self.p₂, let q₂ʹ = self.p₂ʹ {
let q₁ = CGPoint(x: q₂ʹ.x + 10, y: q₂ʹ.y + 10).applying(self.backTransform)
return _computeSolutionMatrix(q₂, q₁)
}
return nil
}
private func _computeSolutionMatrix(_ q₁:CGPoint, _ q₂:CGPoint) -> HXMatrix {
let x₁ = Double(q₁.x)
let y₁ = Double(q₁.y)
let x₂ = Double(q₂.x)
let y₂ = Double(q₂.y)
let A = HXMatrix(rows: 4, columns: 4, values:[
x₁, -y₁, 1, 0,
y₁, x₁, 0, 1,
x₂, -y₂, 1, 0,
y₂, x₂, 0, 1
])
return A.inverse()
}
private func _computeTransform(_ q₁ʹ:CGPoint, _ q₂ʹ:CGPoint) -> CGAffineTransform {
guard let solutionMatrix = self.solutionMatrix else {
return CGAffineTransform.identity
}
let B = HXMatrix(rows: 4, columns: 1, values: [
Double(q₁ʹ.x),
Double(q₁ʹ.y),
Double(q₂ʹ.x),
Double(q₂ʹ.y)
])
let C = solutionMatrix ⋅ B
let U = CGFloat(C[0,0])
let V = CGFloat(C[1,0])
let tx = CGFloat(C[2,0])
let ty = CGFloat(C[3,0])
var t :CGAffineTransform = CGAffineTransform.identity
t.a = U; t.b = V
t.c = -V; t.d = U
t.tx = tx; t.ty = ty
return t
}
}
viewDidLoad中使用代码创建它们了。只需将识别器拖到视图上，然后使用从识别器到文件所有者的控制拖动将识别器的委托和操作输出连接起来。 - rob mayoff