/*

 Copyright (C) 2017 Apple Inc. All Rights Reserved.

 See LICENSE.txt for this sample’s licensing information

 Abstract:

 A NSView subclass showing how to draw and handle simple events.

 */

import Cocoa

class DotView: NSView {

    // We initialize the instance variables here in the same way they are

    // initialized in the storyboard. This is adequate, but a better solution is to make

    // sure the two places are initialized from the same place. Slightly more

    // sophisticated apps which load storyboards for each document or window would initialize

    // UI elements at the time they're loaded from values in the app.

    var color: NSColor = .red {

        // This property observer tells AppKit that the view needs to redraw after this property is changed

        didSet {

            self.needsDisplay = true

        }

    }

    var radius: CGFloat = 10 {

        // This property observer tells AppKit that the view needs to redraw after this property is changed

        didSet {

            self.needsDisplay = true

        }

    }

    var center = NSPoint(x: 50, y: 50) {

        // This property observer tells AppKit that the view needs to redraw after this property is changed

        didSet {

            self.needsDisplay = true

        }

    }

    // draw(_:) should be overridden in subclassers of NSView to do necessary

    // drawing in order to create the look of the view. It will be called

    // to draw the whole view or parts of it (pay attention the dirtyRect argument);

    // it will also be called during printing if your app is set up to print.

    // In DotView, we first clear the view to white, then draw the dot at its

    // current location and size.

    override func draw(_ dirtyRect: NSRect) {

        super.draw(dirtyRect)

        NSColor.white.set()

        self.bounds.fill()

        var dotRect = NSRect()

        dotRect.origin.x = center.x - radius

        dotRect.origin.y = center.y - radius

        let size = 2 * radius

        dotRect.size.width = size

        dotRect.size.height = size

        color.set()

        let path = NSBezierPath(ovalIn: dotRect)

        path.fill()

    }

    // Views which totally redraw their whole bounds without needing any of the

    // views behind it should override isOpaque to return true. This is a performance

    // optimization hint for the display subsystem. This applies to DotView, whose

    // draw(_:) fills the whole rect with a solid, opaque color.

    override var isOpaque: Bool {

        return true

    }

}