scrollview.swift

class CenteredClipView: NSClipView {
    override func constrainBoundsRect(_ proposedBounds: NSRect) -> NSRect {
        var rect = super.constrainBoundsRect(proposedBounds)
        if let containerView = self.documentView {
            
            if (rect.size.width > containerView.frame.size.width) {
                rect.origin.x = (containerView.frame.width - rect.width) / 2
            }
            
            if(rect.size.height > containerView.frame.size.height) {
                rect.origin.y = -(containerView.frame.height - rect.height) / 2
            }
        }
        
        return rect
    }
}

class ImageWell: NSImageView {
    override var image: NSImage? {
        didSet {
            self.frame.size = image?.size ?? self.frame.size
        }
    }
}