想在一个 imageView 上限制平移手势的区域 swift 5

Question

我有一个 imageview，它有 2 个 gestureRecognizers 1)捏 2)潘

我可以捏合图像并使用比例缩放属性我无法实现的是，当我缩放该图像并拖动到所有 4 个边时，我可以拖动图像并且我能够看到 imageview 后面的背景视图想要限制 imageview 的拖动直到显示 zommed 图像

这是捏合和平移手势的代码

  @objc func pinchRecognized(pinch: UIPinchGestureRecognizer) {

            if let view = pinch.view {
                view.transform = view.transform.scaledBy(x: pinch.scale, y: pinch.scale)
                pinch.scale = 1
            }
        }
    
    @objc func PangestureMethod(gestureRecognizer: UIPanGestureRecognizer){
       guard gestureRecognizer.view != nil else {return}
       let piece = gestureRecognizer.view!
  
    
       let translation = gestureRecognizer.translation(in: piece.superview)
        
       if gestureRecognizer.state == .began {
          self.initialCenter = piece.center
       }
       if gestureRecognizer.state != .cancelled {
          let newCenter = CGPoint(x: initialCenter.x + translation.x, y: initialCenter.y + translation.y)
          piece.center = newCenter
       }
       else {
          piece.center = initialCenter
       }
    }

Answer 1

首先，重置平移手势的翻译（可能）更容易，因此我们计算相对移动：

if gestureRecognizer.state != .cancelled {
    
    // translation will be + or - a small number of points
    // do what's needed to move the view

    // reset recognizer
    gestureRecognizer.setTranslation(.zero, in: superV)

}

否则，假设您向右拖动（平移）300 磅，但视图只能移动 20 磅，然后它不会开始向左移动，直到您向左拖动 280 磅。

所以，当水平拖动时我们想在拖动视图位于其 superView 的左边缘或右边缘时停止...

计算 MAX centerX 位置
- 这将是拖动视图宽度的 1/2
计算 MIN centerX 位置
- 这将是 superView 的宽度减去拖动视图宽度的 1/2

例如，如果 superView 的宽度为 100，拖动视图的宽度为 200，则 MAX centerX 将为 100，MIN centerX 将为 Zero.

然后我们对 centerY 位置做同样的事情。

尝试将其用作您的平移手势处理程序：

@objc func PangestureMethod(gestureRecognizer: UIPanGestureRecognizer){
    
    // unwrap the view from the gesture
    // AND
    // unwrap that view's superView
    guard let piece = gestureRecognizer.view,
          let superV = piece.superview
    else {
        return
    }
    
    let translation = gestureRecognizer.translation(in: superV)
    
    if gestureRecognizer.state == .began {
        self.initialCenter = piece.center
    }
    if gestureRecognizer.state != .cancelled {

        // what the new centerX and centerY will be
        var newX: CGFloat = piece.center.x + translation.x
        var newY: CGFloat = piece.center.y + translation.y

        // MAX centerX is 1/2 the width of the piece's frame
        let mxX = piece.frame.width * 0.5
        
        // MIN centerX is Width of superView minus 1/2 the width of the piece's frame
        let mnX = superV.bounds.width - piece.frame.width * 0.5
        
        // make sure new centerX is neither greater than MAX nor less than MIN
        newX = max(min(newX, mxX), mnX)
        
        // MAX centerY is 1/2 the height of the piece's frame
        let mxY = piece.frame.height * 0.5
        
        // MIN centerY is Height of superView minus 1/2 the height of the piece's frame
        let mnY = superV.bounds.height - piece.frame.height * 0.5
        
        // make sure new centerY is neither greater than MAX nor less than MIN
        newY = max(min(newY, mxY), mnY)
        
        // set the new center
        piece.center = CGPoint(x: newX, y: newY)
        
        // reset recognizer
        gestureRecognizer.setTranslation(.zero, in: superV)

    }
    else {
        piece.center = initialCenter
    }
}

编辑

为了防止捏合手势将视图缩小到小于其 superView 框架，我们可以将手势的新缩放值应用到视图的 框架 [=] 的 CGRect 57=] 在将其应用到视图之前。

然后，如果生成的矩形不小于 superView 的框架，则仅将缩放应用于视图。

试一试：

@objc func pinchRecognized(pinch: UIPinchGestureRecognizer) { // unwrap the view from the gesture // AND // unwrap that view's superView guard let piece = pinch.view, let superV = piece.superview else { return } // this is a bit verbose for clarity // get the new scale let sc = pinch.scale // get current frame of "piece" view let currentPieceRect = piece.frame // apply scaling transform to the rect let futureRect = currentPieceRect.applying(CGAffineTransform(scaleX: sc, y: sc)) // if the resulting rect's width will be // greater-than-or-equal to superView's width if futureRect.width >= superV.bounds.width { // go ahead and scale the piece view piece.transform = piece.transform.scaledBy(x: sc, y: sc) } pinch.scale = 1 }

想在一个 imageView 上限制平移手势的区域 swift 5

Want to restrict area of pan gesture on one imageView swift 5

uigesturerecognizer

ios

swift