/*

 Copyright (C) 2016 Apple Inc. All Rights Reserved.

 See LICENSE.txt for this sample’s licensing information

 Abstract:

 The CanvasClipView subclasses NSClipView to demonstrate how to center the contents inside the clip view.

 */

import Cocoa

class CanvasClipView: NSClipView {

    override func constrainBoundsRect(_ proposedBounds: NSRect) -> NSRect {

        // Be polite and ask the superclass's opinion first.

        var constrainedBounds = super.constrainBoundsRect(proposedBounds)

        if let document = documentView {

            let documentFrame = document.frame

            // If either document dimension is too small, then offset the clip bounds to  

            if proposedBounds.width > documentFrame.width {

                constrainedBounds.origin.x = -(proposedBounds.width - documentFrame.width) / 2.0

                constrainedBounds.origin.x -= (contentInsets.left - contentInsets.right) / 2.0

            }

            if proposedBounds.height > documentFrame.height {

                constrainedBounds.origin.y = -(proposedBounds.height - documentFrame.height) / 2.0

                constrainedBounds.origin.y -= (contentInsets.top - contentInsets.bottom) / (isFlipped ? 2.0 : -2.0)

            }

        }

        return constrainedBounds

    }

}