廣場錨點，而這樣做的手勢

Question

我有這是爲了響應捏圖像，旋轉和平移手勢的視圖。我想要捏和圖像的旋轉將相對於放置在屏幕的中間定位點來完成，正是因爲它使用Xcode的iPhone模擬器按選項鍵完成。我怎樣才能把在屏幕中間的錨點如果圖像的中心可能被縮放和平移，以不同的位置？

這裏是我的縮放和旋轉手勢功能：

@IBAction func pinchGesture(_ gestureRecognizer: UIPinchGestureRecognizer) { 
    // Move the achor point of the view's layer to the touch point 
    // so that scaling the view and the layer becames simpler. 
    self.adjustAnchorPoint(gestureRecognizer: gestureRecognizer) 


    // Scale the view by the current scale factor. 
    if(gestureRecognizer.state == .began) { 
     // Reset the last scale, necessary if there are multiple objects with different scales 
     lastScale = gestureRecognizer.scale 
    } 

    if (gestureRecognizer.state == .began || gestureRecognizer.state == .changed) { 
     let currentScale = gestureRecognizer.view!.layer.value(forKeyPath:"transform.scale")! as! CGFloat 
     // Constants to adjust the max/min values of zoom 
     let kMaxScale:CGFloat = 15.0 
     let kMinScale:CGFloat = 1.0 
     var newScale = 1 - (lastScale - gestureRecognizer.scale) 
     newScale = min(newScale, kMaxScale/currentScale) 
     newScale = max(newScale, kMinScale/currentScale) 
     let transform = (gestureRecognizer.view?.transform)!.scaledBy(x: newScale, y: newScale); 
     gestureRecognizer.view?.transform = transform 
     lastScale = gestureRecognizer.scale // Store the previous scale factor for the next pinch gesture call 
     scale = currentScale // Save current scale for later use 
    } 
} 

@IBAction func rotationGesture(_ gestureRecognizer: UIRotationGestureRecognizer) { 
    // Move the achor point of the view's layer to the center of the 
    // user's two fingers. This creates a more natural looking rotation. 
    self.adjustAnchorPoint(gestureRecognizer: gestureRecognizer) 

    // Apply the rotation to the view's transform. 
    if gestureRecognizer.state == .began || gestureRecognizer.state == .changed { 
     gestureRecognizer.view?.transform = (gestureRecognizer.view?.transform.rotated(by: gestureRecognizer.rotation))! 
     // Set the rotation to 0 to avoid compouding the 
     // rotation in the view's transform. 
     angle += gestureRecognizer.rotation // Save rotation angle for later use 
     gestureRecognizer.rotation = 0.0 
    } 
} 

func adjustAnchorPoint(gestureRecognizer : UIGestureRecognizer) { 
    if gestureRecognizer.state == .began { 
     let view = gestureRecognizer.view 
     let locationInView = gestureRecognizer.location(in: view) 
     let locationInSuperview = gestureRecognizer.location(in: view?.superview) 

     // Move the anchor point to the the touch point and change the position of the view 
     view?.layer.anchorPoint = CGPoint(x: (locationInView.x/(view?.bounds.size.width)!), y: (locationInView.y/(view?.bounds.size.height)!)) 
     view?.center = locationInSuperview 
    } 
} 

編輯

我看到人們並不急於進入這個。分享一下我在過去幾天所取得的進展，讓我來幫助。

首先，我寫了一個函數centerAnchorPoint其圖像的錨點正確地放置到屏幕的中心，無論是定位點以前在哪裏。然而，圖像不能縮放或旋轉才能起作用。

func setAnchorPoint(_ anchorPoint: CGPoint, forView view: UIView) { 
    var newPoint = CGPoint(x: view.bounds.size.width * anchorPoint.x, y: view.bounds.size.height * anchorPoint.y) 
    var oldPoint = CGPoint(x: view.bounds.size.width * view.layer.anchorPoint.x, y: view.bounds.size.height * view.layer.anchorPoint.y) 

    newPoint = newPoint.applying(view.transform) 
    oldPoint = oldPoint.applying(view.transform) 

    var position = view.layer.position 
    position.x -= oldPoint.x 
    position.x += newPoint.x 

    position.y -= oldPoint.y 
    position.y += newPoint.y 

    view.layer.position = position 
    view.layer.anchorPoint = anchorPoint 
} 

func centerAnchorPoint(gestureRecognizer : UIGestureRecognizer) { 
    if gestureRecognizer.state == .ended { 

     view?.layer.anchorPoint = CGPoint(x: (photo.bounds.midX/(view?.bounds.size.width)!), y: (photo.bounds.midY/(view?.bounds.size.height)!)) 
    } 
} 

func centerAnchorPoint() { 

    // Position of the current anchor point 
    let currentPosition = photo.layer.anchorPoint 

    self.setAnchorPoint(CGPoint(x: 0.5, y: 0.5), forView: photo) 
    // Center of the image 
    let imageCenter = CGPoint(x: photo.center.x, y: photo.center.y) 
    self.setAnchorPoint(currentPosition, forView: photo) 

    // Center of the screen 
    let screenCenter = CGPoint(x: UIScreen.main.bounds.midX, y: UIScreen.main.bounds.midY) 

    // Distance between the centers 
    let distanceX = screenCenter.x - imageCenter.x 
    let distanceY = screenCenter.y - imageCenter.y 

    // Find new anchor point 
    let newAnchorPoint = CGPoint(x: (imageCenter.x+2*distanceX)/(UIScreen.main.bounds.size.width), y: (imageCenter.y+2*distanceY)/(UIScreen.main.bounds.size.height)) 

    //photo.layer.anchorPoint = newAnchorPoint 
    self.setAnchorPoint(newAnchorPoint, forView: photo) 

    let dotPath = UIBezierPath(ovalIn: CGRect(x: photo.layer.position.x-2.5, y: photo.layer.position.y-2.5, width: 5, height: 5)) 
    layer.path = dotPath.cgPath 
} 

功能setAchorPoint在這裏用來錨點設置到一個新的位置不移動的圖像。

然後，我通過它的結束將這個更新的功能panGesture：

if gestureRecognizer.state == .ended { 
     self.centerAnchorPoint() 
    } 

EDIT 2

好了，我會盡量簡單地解釋一下上面的代碼。

什麼我做的是：

1. 尋找照片的中心和屏幕
2. 的中心之間的距離套用這個公式找到定位點的新位置：

newAnchorPointX =（imageCenter.x-distanceX）/ screenWidth + distanceX/screenWidth

然後對y位置做同樣的操作。

設置此點作爲新的錨點，而無需使用setAnchorPoint功能

正如我所說的這個工作很大如果圖像不進行縮放移動的照片。如果是，那麼錨點不會停留在中心。

奇怪的是distanceX或distanceY並不完全依賴於刻度值，所以這樣的事情不是做得比較工作：

newAnchorPointX =（imageCenter.x-distanceX）/屏幕寬度+ distanceX /（scaleValue *屏幕寬度）

EDIT 3

我想出縮放。看來，正確的比例因子是：

scaleFactor = photo.frame.size.width/photo.layer.bounds.size.width 

我用這個來代替scaleValue，它出色地工作。

所以完成平移和縮放。剩下的唯一東西就是旋轉，但它似乎是最難的。

我想的第一件事是到旋轉矩陣適用於X增量和Y方向上，類似這樣的：

let incrementX = (distanceX)/(screenWidth) 
    let incrementY = (distanceY)/(screenHeight) 

    // Applying rotation matrix 
    let incX = incrementX*cos(angle)+incrementY*sin(angle) 
    let incY = -incrementX*sin(angle)+incrementY*cos(angle) 

    // Find new anchor point 
    let newAnchorPoint = CGPoint(x: 0.5+incX, y: 0.5+incY) 

然而，這是行不通的。

Answer 1

由於問題主要是在編輯中回答，所以我不想重複太多。

廣義我從張貼在原來問題的代碼更改：

1. 刪除調用在捏和旋轉手勢功能adjustAnchorPoint功能。

2. 放置這塊在平移手勢功能碼，以使得錨定點將平移後的照片更新其位置：

   如果gestureRecognizer.state == .ended { self.centerAnchorPoint（） }

3. 已更新centerAnchorPoint函數爲旋轉工作。

一個完全工作centerAnchorPoint功能（旋轉包括）：

func centerAnchorPoint() { 
     // Scale factor 
     photo.transform = photo.transform.rotated(by: -angle) 
     let curScale = photo.frame.size.width/photo.layer.bounds.size.width 
     photo.transform = photo.transform.rotated(by: angle) 

     // Position of the current anchor point 
     let currentPosition = photo.layer.anchorPoint 

     self.setAnchorPoint(CGPoint(x: 0.5, y: 0.5), forView: photo) 
     // Center of the image 
     let imageCenter = CGPoint(x: photo.center.x, y: photo.center.y) 
     self.setAnchorPoint(currentPosition, forView: photo) 

     // Center of the screen 
     let screenCenter = CGPoint(x: UIScreen.main.bounds.midX, y: UIScreen.main.bounds.midY) 

     // Distance between the centers 
     let distanceX = screenCenter.x - imageCenter.x 
     let distanceY = screenCenter.y - imageCenter.y 

     // Apply rotational matrix to the distances 
     let distX = distanceX*cos(angle)+distanceY*sin(angle) 
     let distY = -distanceX*sin(angle)+distanceY*cos(angle) 

     let incrementX = (distX)/(curScale*UIScreen.main.bounds.size.width) 
     let incrementY = (distY)/(curScale*UIScreen.main.bounds.size.height) 

     // Find new anchor point 
     let newAnchorPoint = CGPoint(x: 0.5+incrementX, y: 0.5+incrementY) 

     self.setAnchorPoint(newAnchorPoint, forView: photo) 
} 

這裏要注意的關鍵事情是，旋轉矩陣已被應用到distanceX和distanceY。比例係數也更新爲在整個輪換期間保持不變。