SVGImageView Pinch Gesture changing frame issue.

[ajaydexati]

class SimpleDetailViewController: UIViewController {

    var svgImageView : SVGImageView!
    
    init(svgURL: URL) {
        super.init(nibName: nil, bundle: nil)

        view.backgroundColor = .white

        svgImageView = SVGImageView.init(contentsOf: svgURL)
        svgImageView.contentMode = .scaleAspectFit

        view.addSubview(svgImageView)
        svgImageView.translatesAutoresizingMaskIntoConstraints = false
        NSLayoutConstraint.activate([
            svgImageView.leftAnchor.constraint(equalTo: view.leftAnchor, constant: 12),
            svgImageView.rightAnchor.constraint(equalTo: view.rightAnchor, constant: -12),
            svgImageView.topAnchor.constraint(equalTo: topLayoutGuide.bottomAnchor, constant: 12),
            svgImageView.bottomAnchor.constraint(equalTo: bottomLayoutGuide.topAnchor, constant: -12),
            ])
        let pinchGesture = UIPinchGestureRecognizer.init(target: self, action: #selector(pinchTranslate(_:)))
        svgImageView.addGestureRecognizer(pinchGesture);
    }
    override func viewDidLoad() {
        super.viewDidLoad()
        
        
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    static var pinchTranslateBoundsBeforeScaling = CGRect.zero
    static var pinchTranslateTransformBeforeScaling: CGAffineTransform?
    
    @objc func pinchTranslate(_ recognizer: UIPinchGestureRecognizer?) {
        
        if recognizer?.state == .began {
            SimpleDetailViewController.pinchTranslateBoundsBeforeScaling = recognizer?.view?.bounds ?? CGRect.zero
            SimpleDetailViewController.pinchTranslateTransformBeforeScaling = recognizer?.view?.transform
        }
        
        let center = recognizer?.view?.center
        let scale: CGAffineTransform = CGAffineTransform.identity.scaledBy(x: recognizer!.scale, y: recognizer!.scale)
        var frame = SimpleDetailViewController.pinchTranslateBoundsBeforeScaling.applying(scale)
        
        frame.origin = CGPoint(x: (center?.x ?? 0.0) - frame.size.width / 2, y: (center?.y ?? 0.0) - frame.size.height / 2)
        
        recognizer?.view?.transform = .identity
        recognizer?.view?.frame = frame
        if let pinchTranslateTransformBeforeScaling = SimpleDetailViewController.pinchTranslateTransformBeforeScaling {
            recognizer?.view?.transform = pinchTranslateTransformBeforeScaling
        }
    }
}

Applying pinch gesture to zoom SVGImageView Frame result in delay and unwanted animation.

[arielelkin]

Hi @ajaydexati
I can see that you do the zoom using a CGAffineTransform, but I need more information about how SimpleDetailViewController is setup in order to assess the issue.

Instead of using CGAffineTransforms, I can recommend that you implement zooming by placing the imageview within a scrollview, returning it as the scrollview delegate's viewForZoomingInScrollView, and letting the scrollview do the zooming. If that doesn't work, feel free to reopen this issue with more details.